Merge pull request #1477 from ispyisail/perf/parallel-picture-decode

Speed up opening folios with photos: decode pictures in parallel

sources/SearchAndReplace/searchandreplaceworker.cpp

@@ -226,9 +226,12 @@ void SearchAndReplaceWorker::replaceConductor(QList<Conductor *> list)
 	project_->undoStack()->beginMacro(QObject::tr("Search / replace conductors properties."));
 	for (Conductor *c : list)
 	{
-		ConductorProperties cp = applyChange(c->properties(), m_conductor_properties);
+			//Captured before the pushes below: QPropertyUndoCommand applies
+			//on push, so reading it afterwards would give back @a cp.
+		const ConductorProperties old_properties = c->properties();
+		ConductorProperties cp = applyChange(old_properties, m_conductor_properties);
 
-		if (cp != c->properties())
+		if (cp != old_properties)
 		{
 			QSet <Conductor *> conductors_list = c->relatedPotentialConductors(true);
 			conductors_list << c;
@@ -239,6 +242,26 @@ void SearchAndReplaceWorker::replaceConductor(QList<Conductor *> list)
 				new_value.setValue(cp);
 				project_->undoStack()->push(new QPropertyUndoCommand(cc, "properties", old_value, new_value));
 			}
+
+				//The other side of a function separated terminal element
+				//only receives the voltage / protocol, and only when this
+				//replacement really changed it: the comparison is this
+				//replacement's own before / after (@a old_properties vs
+				//@a cp), never the far wire's own value, which would make
+				//every replacement overwrite it (@see
+				//Conductor::functionSeparatedConductors).
+			for (Conductor *cc : c->functionSeparatedConductors(true))
+			{
+				ConductorProperties separated_cp = cc->properties();
+				separated_cp.applyTensionProtocolChange(old_properties, cp);
+				if (separated_cp == cc->properties())
+					continue;
+
+				QVariant old_value, new_value;
+				old_value.setValue(cc->properties());
+				new_value.setValue(separated_cp);
+				project_->undoStack()->push(new QPropertyUndoCommand(cc, "properties", old_value, new_value));
+			}
 		}
 	}
 	project_->undoStack()->endMacro();
@@ -351,6 +374,25 @@ void SearchAndReplaceWorker::replaceAdvanced(
 					new_value.setValue(new_properties);
 					project_->undoStack()->push(new QPropertyUndoCommand(c, "properties", old_value, new_value));
 				}
+
+					//The other side of a function separated terminal element
+					//only receives the voltage / protocol, and only when
+					//this replacement really changed it: the comparison is
+					//this replacement's own before / after, never the far
+					//wire's own value (@see
+					//Conductor::functionSeparatedConductors).
+				for (Conductor *c : conductor->functionSeparatedConductors(true))
+				{
+					ConductorProperties separated_properties = c->properties();
+					separated_properties.applyTensionProtocolChange(old_properties, new_properties);
+					if (separated_properties == c->properties())
+						continue;
+
+					QVariant old_value, new_value;
+					old_value.setValue(c->properties());
+					new_value.setValue(separated_properties);
+					project_->undoStack()->push(new QPropertyUndoCommand(c, "properties", old_value, new_value));
+				}
 			}
 		}
 	}

sources/bordertitleblock.cpp

@@ -321,8 +321,8 @@ TitleBlockProperties BorderTitleBlock::localTitleBlock() const
 /**
 	@brief BorderTitleBlock::current
 	@return the properties of the titleblock: for a folio placed in a
-	project the project's store holds them (DB-ACCESSORS-PLAN.md stage
+	project the project's store holds them, for any other this object's
-	4.4), for any other this object's own copy.
+	own copy.
 */
 TitleBlockProperties BorderTitleBlock::current() const
 {

sources/bordertitleblock.h

@@ -110,8 +110,8 @@ class BorderTitleBlock : public QObject
 		QRectF insideBorderRect() const;
 	
 		// methods to get title block basic data. A folio placed in a
-		// project reads them from the project's store
+		// project reads them from the project's store, any other from its
-		// (DB-ACCESSORS-PLAN.md stage 4.4), any other from its own copy.
+		// own copy.
 		/// @return the value of the title block "Author" field
 		QString author() const { const TitleBlockProperties *s = stored(); return(s ? s->author : btb_author_); }
 		/// @return the value of the title block "Date" field

sources/cli_export.cpp

@@ -283,7 +283,8 @@ int exportPdf(QETProject &project, const QString &output,
 }
 
 int exportImages(QETProject &project, const QString &format,
-				 const QString &out_dir, bool showTerminals = false)
+				 const QString &out_dir, bool showTerminals = false,
+				 bool svgSmallPictures = false)
 {
 	const QList<Diagram *> diagrams = project.diagrams();
 	if (diagrams.isEmpty()) {
@@ -306,8 +307,10 @@ int exportImages(QETProject &project, const QString &format,
 			gen.setViewBox(QRect(0, 0, r.width(), r.height()));
 			gen.setTitle(diagram->title());
 			QPainter painter(&gen);
+			diagram->setSmallPictures(svgSmallPictures);
 			renderDiagram(diagram, painter, QRectF(QPointF(0, 0), r.size()),
 						 showTerminals);
+			diagram->setSmallPictures(false);
 			painter.end();
 		} else { // png
 			QImage image(r.size(), QImage::Format_ARGB32);
@@ -1014,6 +1017,7 @@ int run(const QStringList &args)
 	const bool showTerminals = filtered.removeAll("--show-terminals") > 0;
 	const bool dxfBlocks = filtered.removeAll("--dxf-blocks") > 0;
 	const bool dxfAttributes = filtered.removeAll("--dxf-attributes") > 0;
+	const bool svgSmallPictures = filtered.removeAll("--svg-small-pictures") > 0;
 	// --no-slaves and --no-junctions leave rows out of --export-bom.
 	const bool includeSlaves = filtered.removeAll("--no-slaves") == 0;
 	const bool includeJunctions = filtered.removeAll("--no-junctions") == 0;
@@ -1085,7 +1089,8 @@ int run(const QStringList &args)
 		return resaveProject(project, output);
 	if (format == "settb")
 		return setTitleBlock(project, output, rest.mid(2));
-	return exportImages(project, format, output, showTerminals);
+	return exportImages(project, format, output, showTerminals,
+						svgSmallPictures);
 }
 
 } // namespace CLIExport

sources/cli_export.h

@@ -44,7 +44,7 @@ namespace CLIExport {
 		Usage:
 		  qelectrotech --export-pdf     <project.qet> <output.pdf> [--show-terminals]
 		  qelectrotech --export-png     <project.qet> <output_dir> [--show-terminals]
-		  qelectrotech --export-svg     <project.qet> <output_dir> [--show-terminals]
+		  qelectrotech --export-svg     <project.qet> <output_dir> [--show-terminals] [--svg-small-pictures]
 		  qelectrotech --export-dxf     <project.qet> <output_dir> [--show-terminals] [--dxf-blocks] [--dxf-attributes]
 		  qelectrotech --export-cables  <project.qet> <output.csv>
 		  qelectrotech --export-wires   <project.qet> <output.csv>
@@ -71,6 +71,9 @@ namespace CLIExport {
 		--dxf-attributes: as --dxf-blocks, and a symbol's texts (its label,
 		      function...) are attributes of its INSERT. LibreCAD does not
 		      show attributes.
+		--svg-small-pictures: in an SVG, each picture at most four times the
+		      size it is drawn at instead of its full resolution: a much
+		      smaller file, still sharp when printed.
 		cables: wiring list (one row per conductor) as CSV.
 		wires: list of distinct wire numbers as CSV.
 		bom: bill of materials (one row per element) as CSV.

sources/conductormultiedit.h

@@ -62,33 +62,80 @@ namespace ConductorMultiEdit
 		@brief targets
 		@param selected : the edited conductors
 		@param apply_all : true to add every conductor of their potentials
+		@param function_separated : set to the conductors that share the
+		potential of an edited one only by crossing a function separated
+		terminal element -- conductors undo() then gives the voltage /
+		protocol only, and no other property. nullptr, the default, leaves
+		those conductors out of the returned list entirely.
+
+		A conductor the user picked themselves is never part of it: the
+		selection is the edit reaching that conductor, so it takes the
+		full edit however remote it is from the other selected ones --
+		picking a wire on each side of a separation and editing them is
+		exactly that. Nor is a conductor that belongs to a potential, on
+		any path, however far that potential is reached.
 		@return each conductor an edit reaches, once
 	*/
 	template <typename T>
-	QList<T *> targets(const QList<T *> &selected, bool apply_all)
+	QList<T *> targets(const QList<T *> &selected, bool apply_all,
+			   QSet<T *> *function_separated = nullptr)
 	{
 		QList<T *> list;
 		QSet<T *> seen;
+			//The explicitly picked ones, so a separation met while walking
+			//the list cannot demote a wire the user asked to edit.
+		QSet<T *> chosen;
+		for (T *conductor : selected)
+			if (conductor)
+				chosen.insert(conductor);
+			//What the potentials reach, and what only a function separation
+			//reaches. A conductor can be in both -- wired normally on one
+			//path and across a separation on another -- and then belongs to
+			//the potential.
+		QSet<T *> potential_reached, separated_reached;
+
 		for (T *conductor : selected)
 		{
-				//Already reached through an earlier conductor's potential:
+			if (!conductor)
-				//its own potential is the same one.
-			if (!conductor || seen.contains(conductor))
 				continue;
-			seen.insert(conductor);
+				//Already reached through an earlier conductor's potential or
-			list << conductor;
+				//separation: its own potential adds nothing new to walk over
-			if (!apply_all)
+				//-- unless the user picked it, because a separation may have
+				//put it in the list before its potential was ever reached.
+			const bool fresh = !seen.contains(conductor);
+			if (fresh)
+			{
+				seen.insert(conductor);
+				list << conductor;
+			}
+			if (!apply_all || (!fresh && !chosen.contains(conductor)))
 				continue;
 			const QSet<T *> potential = conductor->relatedPotentialConductors();
 			for (T *other : potential)
 			{
+				potential_reached.insert(other);
 				if (!seen.contains(other))
 				{
 					seen.insert(other);
 					list << other;
 				}
 			}
+			if (function_separated)
+			{
+				const QSet<T *> separated = conductor->functionSeparatedConductors();
+				for (T *other : separated)
+				{
+					separated_reached.insert(other);
+					if (!seen.contains(other))
+					{
+						seen.insert(other);
+						list << other;
+					}
+				}
+			}
 		}
+		if (function_separated)
+			*function_separated = separated_reached - potential_reached - chosen;
 		return list;
 	}
 
@@ -97,13 +144,18 @@ namespace ConductorMultiEdit
 		@param targets : the conductors to change, see targets()
 		@param shown : the properties as the panel showed them
 		@param edited : the properties after the user's edit
+		@param function_separated : the targets of targets() that only a
+		function separated terminal element links to the edited
+		conductors: they get the voltage / protocol and nothing else
+		(@see ConductorProperties::applyTensionProtocolChange)
 		@return one undo step giving each target the fields that differ
 		between shown and edited, or nullptr if no conductor changes
 	*/
 	template <typename T>
 	QUndoCommand *undo(const QList<T *> &targets,
 			   const ConductorProperties &shown,
-			   const ConductorProperties &edited)
+			   const ConductorProperties &edited,
+			   const QSet<T *> &function_separated = QSet<T *>())
 	{
 		if (edited == shown)
 			return nullptr;
@@ -114,7 +166,10 @@ namespace ConductorMultiEdit
 		{
 			const ConductorProperties old_properties = conductor->properties();
 			ConductorProperties properties = old_properties;
-			properties.applyChanges(shown, edited);
+			if (function_separated.contains(conductor))
+				properties.applyTensionProtocolChange(shown, edited);
+			else
+				properties.applyChanges(shown, edited);
 			if (properties == old_properties)
 				continue;
 

sources/conductorproperties.cpp

@@ -851,6 +851,32 @@ void ConductorProperties::applyChanges(const ConductorProperties &before,
 		singleLineProperties.setPhasesCount(slp_after.phasesCount());
 }
 
+/**
+	@brief ConductorProperties::applyTensionProtocolChange
+	Copy into this the voltage / protocol when it differs between before
+	and after, and leave every other attribute as it is. This is the one
+	property a function separated terminal element lets through
+	(@see Conductor::functionSeparatedConductors): the voltage /
+	protocol describes the electrical node itself, while the text, the
+	function, the wire color... describe one side of the separation and
+	stay local to it.
+
+	Both arguments describe one edit -- what was shown to the user, and
+	what the user made of it -- so that only an edit which really
+	changed the voltage / protocol passes it on. Passing the far wire's
+	own properties as @a before instead would make every edit overwrite
+	its voltage: the two sides differ on that field just as often as
+	not, so the comparison would hold no matter what was edited.
+	@param before : the properties as they were shown to the user
+	@param after : the properties after the user's edit
+*/
+void ConductorProperties::applyTensionProtocolChange(const ConductorProperties &before,
+						     const ConductorProperties &after)
+{
+	if (before.m_tension_protocol != after.m_tension_protocol)
+		m_tension_protocol = after.m_tension_protocol;
+}
+
 /**
 	@brief ConductorProperties::defaultProperties
 	@return the default properties stored in the setting file

sources/conductorproperties.h

@@ -139,6 +139,8 @@ class ConductorProperties
 		void applyForEqualAttributes(QList<ConductorProperties> list);
 		void applyChanges(const ConductorProperties &before,
 				  const ConductorProperties &after);
+		void applyTensionProtocolChange(const ConductorProperties &before,
+					      const ConductorProperties &after);
 
 		static ConductorProperties defaultProperties();
 

sources/container/QETZ-FORMAT.md

@@ -0,0 +1,182 @@
+# The `.qetz` project file, format 3
+
+A `.qetz` is a QElectroTech project saved as a zip archive: the same project
+a `.qet` holds, split into files, with the engineering data in an SQLite
+database. This document describes format 3. `tst_qetcontainer` checks that
+the schema below is the one QElectroTech writes.
+
+The code is `qetcontainer.cpp` (the zip and its files), `qetcontainerdb.cpp`
+(the database) and `qetzip.cpp` (reading and writing zip archives).
+
+## 1. Principles
+
+- **One writer.** A `.qet` and a `.qetz` are written from the same project
+  document. Saving a `.qetz` splits that document into files and a database;
+  opening one puts it back together, and the program reads it exactly as a
+  `.qet`. Opening a `.qetz` and saving it as `.qet` gives the file a plain
+  `.qet` save gives.
+- **Each fact once.** A value moved into the database is taken out of the
+  folio file. Nothing is stored in both.
+- **What a thing is, against where it is drawn.** The database holds the
+  engineering data; the folio files hold the drawing:
+
+  | | database | folio file |
+  |---|---|---|
+  | Symbol | its information (label, comment, …), prefix, links | which symbol it is (`type`), position, rotation |
+  | Label shown on a folio | the value | the text item: position, font, rotation |
+  | Wire | its ends, number, function, voltage, colour, section | its path, the number's text position and font |
+  | Folio | title-block fields and custom variables | everything drawn on it |
+  | Terminal strip | its terminals, their order and bridges | the strip drawn on a folio |
+
+  Cables are kept in `project.xml` in this format.
+- **Nothing is lost.** Anything the database does not model stays in the
+  XML as it was. A block is moved only if it can be rebuilt exactly.
+
+## 2. The archive
+
+| Entry | Content |
+|---|---|
+| `mimetype` | `application/x-qelectrotech-project+zip`, the first entry, stored uncompressed |
+| `manifest.xml` | `<qetz format="3" min-reader="3" writer="QElectroTech …"/>` |
+| `project.xml` | the project document, each part replaced by `<qetz-part file="…"/>` |
+| `project.sqlite` | the engineering data (section 4) |
+| `folios/<uuid>.xml` | one `<diagram>` per folio, named by the folio's uuid (or its position when it has none) |
+| `elements/<categories>/<name>` | the project's symbol definitions, as in the symbol collection |
+| `titleblocks/<name>.titleblock` | the project's title-block templates |
+| `images/<sha256>.png` | each folio picture once, as a file instead of base64 text (`.bin` if it is not a PNG) |
+
+Names that would collide get `~2`, `~3`… before the extension. A picture
+in a folio file keeps the name of its file in the attribute `qetz-file`.
+
+A reader refuses the whole archive if an entry is encrypted, uses a
+compression method it cannot read, has a name that is absolute, holds `..`,
+`\` or `:`, or repeats another entry's name, or if the archive holds more
+than 100 000 entries or more than 2 GiB once unpacked. Entries the format
+does not name are ignored.
+
+## 3. Versions
+
+`manifest.xml` gives two numbers: `format`, the format written, and
+`min-reader`, the oldest format allowed to read the file.
+
+- A reader opens a file whose `min-reader` is not above its own format.
+- If `format` is above its own, the project opens **read-only**, with a
+  message: saving it could drop what that reader does not know. *Save As*
+  writes a copy in the reader's own format.
+- If `min-reader` is above its own format, the file is refused with a
+  message.
+
+The database repeats the format in `meta` (key `format`) and in
+`PRAGMA user_version`.
+
+**Rules for a new format:**
+
+1. New data goes in a new column or table. An older reader skips both.
+2. A change an older reader would misread raises `min-reader`.
+3. Every format keeps a saved file in `tests/qttest/fixtures` that must
+   keep opening.
+
+| Format | Written by | Reading |
+|---|---|---|
+| 2 | QElectroTech 0.200.1 development builds (#1462) | read: rows keyed by position (`f1`, `e1`, `c1`) where an item had no uuid of its own, every value as text |
+| 3 | this document | read and written |
+
+## 4. The database
+
+### 4.1 Schema
+
+<!-- schema: tst_qetcontainer checks it against the database written -->
+```sql
+CREATE TABLE meta (key TEXT PRIMARY KEY, value TEXT);
+CREATE TABLE project_property (ord INTEGER PRIMARY KEY, name TEXT, value TEXT, show INTEGER, attrs TEXT);
+CREATE TABLE folio (uuid TEXT PRIMARY KEY, pos INTEGER NOT NULL UNIQUE,
+    "title" TEXT, "author" TEXT, "date" TEXT, "folio" TEXT, "indexrev" TEXT, "filename" TEXT,
+    "locmach" TEXT, "plant" TEXT, "auto_page_num" TEXT, props_attrs TEXT);
+CREATE TABLE folio_property (folio_uuid TEXT NOT NULL REFERENCES folio, ord INTEGER NOT NULL,
+    name TEXT, value TEXT, show INTEGER, attrs TEXT, PRIMARY KEY (folio_uuid, ord));
+CREATE TABLE element (uuid TEXT PRIMARY KEY, folio_uuid TEXT NOT NULL REFERENCES folio,
+    "prefix" TEXT, "freezeLabel" INTEGER, info_attrs TEXT, links_attrs TEXT);
+CREATE TABLE element_info (element_uuid TEXT NOT NULL REFERENCES element, ord INTEGER NOT NULL,
+    name TEXT, value TEXT, show INTEGER, attrs TEXT, PRIMARY KEY (element_uuid, ord));
+CREATE TABLE link (element_uuid TEXT NOT NULL REFERENCES element, ord INTEGER NOT NULL,
+    linked_uuid TEXT, attrs TEXT, PRIMARY KEY (element_uuid, ord));
+CREATE TABLE conductor (uuid TEXT PRIMARY KEY, folio_uuid TEXT NOT NULL REFERENCES folio,
+    "element1" TEXT, "terminal1" TEXT, "element2" TEXT, "terminal2" TEXT, "num" TEXT,
+    "formula" TEXT, "function" TEXT, "tension_protocol" TEXT, "conductor_color" TEXT,
+    "conductor_section" TEXT, "cable" TEXT, "bus" TEXT, "freezeLabel" INTEGER);
+CREATE TABLE terminal_strip (uuid TEXT PRIMARY KEY, ord INTEGER NOT NULL UNIQUE,
+    installation TEXT, location TEXT, name TEXT, comment TEXT, description TEXT);
+CREATE TABLE strip_terminal (strip_uuid TEXT NOT NULL REFERENCES terminal_strip,
+    pos INTEGER NOT NULL, level INTEGER NOT NULL, element_uuid TEXT,
+    PRIMARY KEY (strip_uuid, pos, level));
+CREATE TABLE strip_bridge (uuid TEXT PRIMARY KEY, strip_uuid TEXT NOT NULL REFERENCES terminal_strip,
+    ord INTEGER NOT NULL, color TEXT);
+CREATE TABLE strip_bridge_terminal (bridge_uuid TEXT NOT NULL REFERENCES strip_bridge,
+    ord INTEGER NOT NULL, element_uuid TEXT, PRIMARY KEY (bridge_uuid, ord));
+```
+
+### 4.2 What each table holds
+
+| Table | One row per | Comes from |
+|---|---|---|
+| `meta` | setting of the file | `format`; `props_attrs` (attributes of the project's `<properties>`); `terminal_strips` = `1` when the strips are in the database |
+| `project_property` | project property (project-wide variable) | `<project><properties><property>` |
+| `folio` | folio, in folio order (`pos` from 1) | the title-block attributes of `<diagram>` |
+| `folio_property` | custom title-block variable of a folio | `<diagram><properties><property>` |
+| `element` | symbol placed on a folio | `<element>`: its label prefix and frozen-label flag |
+| `element_info` | piece of symbol information, in order | `<elementInformations><elementInformation>` |
+| `link` | cross-reference link of a symbol, in order | `<links_uuids><link_uuid>` |
+| `conductor` | wire | `<conductor>`: its two ends (symbol uuid and terminal), number, formula, function, voltage/protocol, colour, section, cable, bus, frozen-label flag |
+| `terminal_strip`, `strip_terminal`, `strip_bridge`, `strip_bridge_terminal` | terminal strip, terminal, bridge, bridged terminal | `<terminal_strips>` |
+
+A value is NULL when the XML has no such attribute.
+
+- `freezeLabel` is 1 for `true`, 0 for `false`. Any other text stays as an
+  attribute in the folio file.
+- `show` is 0 or 1. Any other text goes in `attrs`.
+- `attrs`, `props_attrs`, `info_attrs` and `links_attrs` are JSON objects of
+  the attributes that have no column, and the entry's tag when it is not the
+  usual one. In a project QElectroTech saves they are all NULL. They hold
+  something only for older or hand-edited files. Whitespace between
+  entries, which only a hand-edited file has, is kept in them as
+  `qetz-ws`.
+
+### 4.3 Keys
+
+Every row is keyed by its item's **uuid**, which stays in the folio file:
+that is how a folio file's item finds its row. Folios, symbols and wires
+are keyed this way.
+
+An item with no uuid of its own (none, or one another item of the same kind
+shares) gets a key made from the item itself: a version 5 uuid in the
+namespace `{3f0c6c1e-5b8e-4b8a-9d55-6b2f5f0f9a41}` from its XML text, how
+many identical items came before it, and a counter that avoids taken keys.
+The key is the same on every save and never depends on where the item is.
+It is written on the item as `qetz-key` (a symbol or wire) or `qetz-folio`
+(a folio).
+
+### 4.4 Markers
+
+A block moved into the database leaves `<qetz-db block="…"/>` where it was:
+`properties`, `elementInformations`, `links_uuids` or `terminal_strips`.
+Reading puts the block back where its marker is; a block without a marker
+was never moved.
+
+Only a block that can be rebuilt exactly is moved: entries of the expected
+tag with plain text values. Terminal strips are moved only if their rows
+rebuild the same XML. Anything else stays in the folio file or
+`project.xml` unchanged.
+
+## 5. Reading a file safely
+
+A `.qetz` is untrusted. A reader:
+
+- runs nothing from the database's schema (`PRAGMA trusted_schema = OFF`,
+  read-only) and refuses a database where any table of section 4.1 is not a
+  plain table (a view, say);
+- refuses the file, with a message saying what is wrong, if the database
+  and the folio files disagree: an item whose row is missing or on another
+  folio, an item twice, a row no item has, or information, links or
+  properties of a symbol or folio that does not exist.
+
+A damaged archive is caught by the zip format's own checksums.

sources/container/qetcontainer.cpp

@@ -153,15 +153,23 @@ bool QetContainer::isZip(const QByteArray &content)
 /**
 	@brief QetContainer::readDocument
 	The project document held in @p content: unzipped and joined for a
-	.qetz, parsed for a .qet.
+	.qetz, parsed for a .qet. @p format, if any: the .qetz's format, 0
+	for a .qet.
 */
-bool QetContainer::readDocument(const QByteArray &content, QDomDocument *document, QString *error)
+bool QetContainer::readDocument(const QByteArray &content, QDomDocument *document,
+								QString *error, Pictures *pictures, int *format)
 {
+	if (format) *format = 0;
 	if (!isZip(content))
 		return parse(content, document, error);
 	QList<QetZip::Entry> entries;
 	return QetZip::fromBytes(content, &entries, error)
-			&& join(entries, document, error);
+			&& join(entries, document, error, pictures, format);
+}
+
+QString QetContainer::pictureFile(const QDomElement &image)
+{
+	return image.attribute(ImageFileAttribute);
 }
 
 /**
@@ -264,8 +272,13 @@ QList<QetZip::Entry> QetContainer::split(const QDomDocument &project, const QStr
 	Refused, with @p error set: not a .qetz, made for a later QElectroTech
 	(the manifest's min-reader), or a part missing or unreadable. Entries
 	nothing names are ignored, so a later format may add some.
+	With @p pictures, the pictures stay out of the document: see the
+	namespace.
+	@p format, if any: the format the file says it is, above Format for a
+	later one this may read (its min-reader allows it)
 */
-bool QetContainer::join(const QList<QetZip::Entry> &entries, QDomDocument *project, QString *error)
+bool QetContainer::join(const QList<QetZip::Entry> &entries, QDomDocument *project, QString *error,
+						Pictures *pictures, int *format)
 {
 	QHash<QString, QByteArray> files;
 	for (const QetZip::Entry &entry : entries)
@@ -286,6 +299,8 @@ bool QetContainer::join(const QList<QetZip::Entry> &entries, QDomDocument *proje
 				 .arg(Format));
 		return false;
 	}
+	if (format)
+		*format = manifest.documentElement().attribute(QStringLiteral("format")).toInt();
 
 	if (!parse(files.value(QStringLiteral("project.xml")), project, error))
 		return false;
@@ -310,7 +325,8 @@ bool QetContainer::join(const QList<QetZip::Entry> &entries, QDomDocument *proje
 		part.parentNode().replaceChild(project->importNode(document.documentElement(), true), part);
 	}
 
-		//Pictures back to base64, as the image's first child
+		//Pictures back to base64, as the image's first child, or into
+		//pictures
 	const QDomNodeList images = project->elementsByTagName(QStringLiteral("image"));
 	for (int i = 0 ; i < images.size() ; ++i)
 	{
@@ -321,6 +337,10 @@ bool QetContainer::join(const QList<QetZip::Entry> &entries, QDomDocument *proje
 			setError(error, QStringLiteral("picture \"%1\" is missing").arg(file));
 			return false;
 		}
+		if (pictures) {
+			pictures->insert(file, files.value(file));
+			continue;
+		}
 		image.removeAttribute(ImageFileAttribute);
 		image.insertBefore(project->createTextNode(QString::fromLatin1(files.value(file).toBase64())),
 						   image.firstChild());

sources/container/qetcontainer.h

@@ -21,6 +21,7 @@
 #include "qetzip.h"
 
 #include <QDomDocument>
+#include <QHash>
 
 /**
 	@brief The QetContainer namespace
@@ -31,7 +32,7 @@
 	  manifest.xml             format and oldest format allowed to read it
 	  project.xml              the project, each part replaced by
 	                           <qetz-part file="..."/>
-	  project.sqlite           the engineering data (format 2,
+	  project.sqlite           the engineering data (format 2 on,
 	                           QetContainerDb): title-block fields, symbol
 	                           information, links, wires
 	  folios/<uuid>.xml        one per folio
@@ -41,26 +42,45 @@
 
 	join(split(d)) is d. Nothing here knows what the parts mean: the
 	project is read and written by the same code as a .qet file.
+
+	Given a Pictures map, join() leaves the pictures out of the document:
+	each <image> keeps the name of its file, pictureFile(), and the bytes
+	go in the map. Turning them back into base64 text costs seconds on a
+	project with large pictures, and the folio would only decode it again.
+
+	The format is written down in QETZ-FORMAT.md, beside this file.
 */
 namespace QetContainer
 {
 	extern const char MimeType[];
+		/// Picture bytes by file name, see join()
+	using Pictures = QHash<QString, QByteArray>;
 		/// The format written; files of a later format are refused by join()
 		/// unless their min-reader allows this one.
-	constexpr int Format = 2;
+	constexpr int Format = 3;
+		/// 3: the database's rows keyed by the items' uuids, true/false and
+		/// show flags as 1/0, its PRAGMA user_version the format, the symbols' type left
+		/// in the folio files, no column for where a block sat. Format 2 is
+		/// still read; a later format whose min-reader allows this one is
+		/// read too, and said so through join()'s @p format.
 
 	QList<QetZip::Entry> split(const QDomDocument &project,
 							   const QString &writer = QString(),
 							   QString *error = nullptr);
 	bool join(const QList<QetZip::Entry> &entries, QDomDocument *project,
-			  QString *error = nullptr);
+			  QString *error = nullptr, Pictures *pictures = nullptr,
+			  int *format = nullptr);
+		/// The file join() left the picture of @p image in, or an empty string
+	QString pictureFile(const QDomElement &image);
 
 		/// Parse @p xml as a .qet is read (QETProject::openFile)
 	bool parse(const QByteArray &xml, QDomDocument *document, QString *error = nullptr);
 		/// true if @p content is a zip, so a .qetz rather than a .qet
 	bool isZip(const QByteArray &content);
 		/// The project document in @p content, a .qet or a .qetz
-	bool readDocument(const QByteArray &content, QDomDocument *document, QString *error = nullptr);
+	bool readDocument(const QByteArray &content, QDomDocument *document,
+					  QString *error = nullptr, Pictures *pictures = nullptr,
+					  int *format = nullptr);
 }
 
 #endif // QETCONTAINER_H

sources/container/qetcontainerdb.cpp

@@ -17,11 +17,15 @@
 */
 #include "qetcontainerdb.h"
 
+#include "qetcontainer.h"
+
 #include <QHash>
 #include <QJsonArray>
 #include <QJsonDocument>
 #include <QJsonObject>
 #include <QSet>
+#include <QTextStream>
+#include <QUuid>
 #include <QVariant>
 
 #include <sqlite3.h>
@@ -54,43 +58,81 @@ bool replaceMarker(QDomElement parent, const QDomElement &block)
 	return false;
 }
 
+	//true if @p parent holds the marker of a block @p tag moved out: where
+	//the block goes back, and that it was there at all
+bool hasMarker(const QDomElement &parent, const QString &tag)
+{
+	for (QDomElement m = parent.firstChildElement(MarkerTag) ; !m.isNull() ; m = m.nextSiblingElement(MarkerTag))
+		if (m.attribute(MarkerBlock) == tag) return true;
+	return false;
+}
+
 const QStringList FolioData = {
 	QStringLiteral("title"), QStringLiteral("author"), QStringLiteral("date"),
 	QStringLiteral("folio"), QStringLiteral("indexrev"), QStringLiteral("filename"),
 	QStringLiteral("locmach"), QStringLiteral("plant"), QStringLiteral("auto_page_num")};
+	//From format 3 on an item's uuid is its row's key, not a column of its
+	//own: it stays in the folio file, where it says which row is the item's.
+	//So does a symbol's type, the symbol it is: a folio file read alone
+	//still says what is drawn where
 const QStringList ElementData = {
-	QStringLiteral("uuid"), QStringLiteral("type"), QStringLiteral("prefix"),
+	QStringLiteral("prefix"), QStringLiteral("freezeLabel")};
-	QStringLiteral("freezeLabel")};
+	//Format 2 also moved the type
+const QStringList ElementDataV2 = {
+	QStringLiteral("uuid"), QStringLiteral("type"), QStringLiteral("prefix"), QStringLiteral("freezeLabel")};
 const QStringList ConductorData = {
-	QStringLiteral("uuid"), QStringLiteral("element1"), QStringLiteral("terminal1"),
+	QStringLiteral("element1"), QStringLiteral("terminal1"),
 	QStringLiteral("element2"), QStringLiteral("terminal2"), QStringLiteral("num"),
 	QStringLiteral("formula"), QStringLiteral("function"), QStringLiteral("tension_protocol"),
 	QStringLiteral("conductor_color"), QStringLiteral("conductor_section"),
 	QStringLiteral("cable"), QStringLiteral("bus"), QStringLiteral("freezeLabel")};
 
+	//Attributes held as 0 or 1 (format 3 on). A value QElectroTech does not
+	//write, "yes" say, stays in the folio file as it was.
+const QStringList BooleanData = {QStringLiteral("freezeLabel")};
+
 QString columns(const QStringList &names)
 {
 	QStringList quoted;
-	for (const QString &n : names) quoted << QStringLiteral("\"%1\" TEXT").arg(n);
+	for (const QString &n : names)
+		quoted << QStringLiteral("\"%1\" %2").arg(n, BooleanData.contains(n) ? QStringLiteral("INTEGER")
+																				 : QStringLiteral("TEXT"));
 	return quoted.join(QStringLiteral(", "));
 }
 
+	//@p text as attribute @p name is stored, or invalid if it cannot be
+QVariant stored(const QString &name, const QString &text)
+{
+	if (!BooleanData.contains(name)) return text;
+	if (text == QLatin1String("true")) return 1;
+	if (text == QLatin1String("false")) return 0;
+	return {};
+}
+
+	//A stored value as attribute @p name writes it
+QString attributeText(const QString &name, const QVariant &value)
+{
+	if (BooleanData.contains(name) && value.typeId() == QMetaType::Int)
+		return value.toInt() ? QStringLiteral("true") : QStringLiteral("false");
+	return value.toString();
+}
+
 QString schema()
 {
 	return QStringLiteral(
 		"CREATE TABLE meta (key TEXT PRIMARY KEY, value TEXT);"
-		"CREATE TABLE project_property (ord INTEGER PRIMARY KEY, name TEXT, value TEXT, attrs TEXT);"
+		"CREATE TABLE project_property (ord INTEGER PRIMARY KEY, name TEXT, value TEXT, show INTEGER, attrs TEXT);"
-		"CREATE TABLE folio (id TEXT PRIMARY KEY, pos INTEGER NOT NULL UNIQUE, %1,"
+		"CREATE TABLE folio (uuid TEXT PRIMARY KEY, pos INTEGER NOT NULL UNIQUE, %1,"
-		" props_at INTEGER, props_attrs TEXT);"
+		" props_attrs TEXT);"
-		"CREATE TABLE folio_property (folio_id TEXT NOT NULL REFERENCES folio, ord INTEGER NOT NULL,"
+		"CREATE TABLE folio_property (folio_uuid TEXT NOT NULL REFERENCES folio, ord INTEGER NOT NULL,"
-		" name TEXT, value TEXT, attrs TEXT, PRIMARY KEY (folio_id, ord));"
+		" name TEXT, value TEXT, show INTEGER, attrs TEXT, PRIMARY KEY (folio_uuid, ord));"
-		"CREATE TABLE element (key TEXT PRIMARY KEY, folio_id TEXT NOT NULL REFERENCES folio, %2,"
+		"CREATE TABLE element (uuid TEXT PRIMARY KEY, folio_uuid TEXT NOT NULL REFERENCES folio, %2,"
-		" info_at INTEGER, info_attrs TEXT, links_at INTEGER, links_attrs TEXT);"
+		" info_attrs TEXT, links_attrs TEXT);"
-		"CREATE TABLE element_info (element_key TEXT NOT NULL REFERENCES element, ord INTEGER NOT NULL,"
+		"CREATE TABLE element_info (element_uuid TEXT NOT NULL REFERENCES element, ord INTEGER NOT NULL,"
-		" name TEXT, value TEXT, attrs TEXT, PRIMARY KEY (element_key, ord));"
+		" name TEXT, value TEXT, show INTEGER, attrs TEXT, PRIMARY KEY (element_uuid, ord));"
-		"CREATE TABLE link (element_key TEXT NOT NULL REFERENCES element, ord INTEGER NOT NULL,"
+		"CREATE TABLE link (element_uuid TEXT NOT NULL REFERENCES element, ord INTEGER NOT NULL,"
-		" linked_uuid TEXT, attrs TEXT, PRIMARY KEY (element_key, ord));"
+		" linked_uuid TEXT, attrs TEXT, PRIMARY KEY (element_uuid, ord));"
-		"CREATE TABLE conductor (key TEXT PRIMARY KEY, folio_id TEXT NOT NULL REFERENCES folio, %3);"
+		"CREATE TABLE conductor (uuid TEXT PRIMARY KEY, folio_uuid TEXT NOT NULL REFERENCES folio, %3);"
 		"CREATE TABLE terminal_strip (uuid TEXT PRIMARY KEY, ord INTEGER NOT NULL UNIQUE,"
 		" installation TEXT, location TEXT, name TEXT, comment TEXT, description TEXT);"
 		"CREATE TABLE strip_terminal (strip_uuid TEXT NOT NULL REFERENCES terminal_strip,"
@@ -165,15 +207,16 @@ QString placeholders(int n)
 	return q.join(QLatin1Char(','));
 }
 
-	//The attributes of @p e but @p skip, and its tag, as JSON
+	//The attributes of @p e but @p skip as JSON, and its tag if it is not
-QVariant attributesJson(const QDomElement &e, const QString &skip = QString(), bool with_tag = false)
+	//@p usual_tag
+QVariant attributesJson(const QDomElement &e, const QStringList &skip, const QString &usual_tag)
 {
 	QJsonObject o;
-	if (with_tag) o.insert(QStringLiteral("tag"), e.tagName());
+	if (e.tagName() != usual_tag) o.insert(QStringLiteral("tag"), e.tagName());
 	const QDomNamedNodeMap map = e.attributes();
 	for (int i = 0 ; i < map.count() ; ++i) {
 		const QDomAttr a = map.item(i).toAttr();
-		if (a.name() != skip) o.insert(a.name(), a.value());
+		if (!skip.contains(a.name())) o.insert(a.name(), a.value());
 	}
 	if (o.isEmpty()) return QVariant();
 	return QString::fromUtf8(QJsonDocument(o).toJson(QJsonDocument::Compact));
@@ -257,21 +300,15 @@ bool listBlock(const QDomElement &block, const QString &entry)
 	return true;
 }
 
-int childIndex(const QDomNode &child)
+	//The attributes @p names of @p e, taken out of it; one that cannot be
-{
+	//stored stays, its value null
-	int i = 0;
-	for (QDomNode n = child.parentNode().firstChild() ; !n.isNull() ; n = n.nextSibling(), ++i)
-		if (n == child) return i;
-	return -1;
-}
-
-
 QVariantList take(QDomElement e, const QStringList &names)
 {
 	QVariantList values;
 	for (const QString &n : names) {
-		values << (e.hasAttribute(n) ? QVariant(e.attribute(n)) : QVariant());
+		const QVariant v = e.hasAttribute(n) ? stored(n, e.attribute(n)) : QVariant();
-		e.removeAttribute(n);
+		values << (v.isValid() ? v : QVariant());
+		if (v.isValid()) e.removeAttribute(n);
 	}
 	return values;
 }
@@ -279,7 +316,8 @@ QVariantList take(QDomElement e, const QStringList &names)
 void put(QDomElement e, const QStringList &names, const QVariantList &values, int from)
 {
 	for (int i = 0 ; i < names.size() ; ++i)
-		if (!values.at(from + i).isNull()) e.setAttribute(names.at(i), values.at(from + i).toString());
+		if (!values.at(from + i).isNull())
+			e.setAttribute(names.at(i), attributeText(names.at(i), values.at(from + i)));
 }
 
 	//Same tags, attributes, text and child order
@@ -417,18 +455,55 @@ QList<QDomElement> children(const QDomElement &parent, const QString &tag)
 	return list;
 }
 
-	//uuid when present and unique among @p items, else prefix + count
+	//A list entry -- a <property>, an <elementInformation> -- as its row:
-QStringList keys(const QList<QDomElement> &items, const QString &prefix)
+	//its name, value, show flag (0 or 1, else left in the JSON) and any
+	//other attribute as JSON, its tag too if it is not @p usual_tag
+QVariantList entryRow(const QDomElement &e, const QString &usual_tag)
 {
+	QVariant value;
+	simpleValue(e, &value);
+	const QString show = e.attribute(QStringLiteral("show"));
+	const bool show_stored = show == QLatin1String("0") || show == QLatin1String("1");
+	QStringList kept{QStringLiteral("name")};
+	if (show_stored) kept << QStringLiteral("show");
+	return {e.hasAttribute(QStringLiteral("name")) ? QVariant(e.attribute(QStringLiteral("name"))) : QVariant(),
+			value, show_stored ? QVariant(show.toInt()) : QVariant(), attributesJson(e, kept, usual_tag)};
+}
+
+	//The key of each of @p items: its uuid, when it has one no other of
+	//@p items has, so the uuid the folio file already holds says which row
+	//is the item's (@p own true). Else (F100: symbols copied with their
+	//uuid) a uuid made from the item itself -- the same on every save,
+	//never from where the item is -- kept in the folio file as qetz-key.
+QStringList keys(const QList<QDomElement> &items, QList<bool> *own)
+{
+	static const QUuid key_namespace(QStringLiteral("{3f0c6c1e-5b8e-4b8a-9d55-6b2f5f0f9a41}"));
 	QHash<QString, int> seen;
 	for (const QDomElement &e : items)
-		if (e.hasAttribute(QStringLiteral("uuid"))) ++seen[e.attribute(QStringLiteral("uuid"))];
+		if (!QUuid(e.attribute(QStringLiteral("uuid"))).isNull()) ++seen[e.attribute(QStringLiteral("uuid"))];
+	QSet<QString> taken(seen.keyBegin(), seen.keyEnd());
+	QHash<QString, int> twins;
 	QStringList out;
-	int made_up = 0;
 	for (const QDomElement &e : items) {
 		const QString uuid = e.attribute(QStringLiteral("uuid"));
-		out << ((!uuid.isEmpty() && seen.value(uuid) == 1)
+		if (seen.value(uuid) == 1) {
-				? uuid : prefix + QString::number(++made_up));
+			out << uuid;
+			*own << true;
+			continue;
+		}
+		QString text;
+		QTextStream stream(&text);
+		e.save(stream, -1);
+		stream.flush();
+			//Items alike to the byte: how many came before tells them apart
+		const int twin = twins[text]++;
+		QString key;
+		for (int salt = 0 ; key.isEmpty() || taken.contains(key) ; ++salt)
+			key = QUuid::createUuidV5(key_namespace, QStringLiteral("%1\n%2\n%3").arg(text).arg(twin).arg(salt))
+					.toString();
+		taken.insert(key);
+		out << key;
+		*own << false;
 	}
 	return out;
 }
@@ -450,43 +525,31 @@ QByteArray QetContainerDb::extract(QDomElement project, QString *error)
 	db.exec(QStringLiteral("BEGIN"));
 
 	Statement meta(db.m_db, QStringLiteral("INSERT INTO meta VALUES (?,?)"));
-	Statement project_property(db.m_db, QStringLiteral("INSERT INTO project_property VALUES (?,?,?,?)"));
+	Statement project_property(db.m_db, QStringLiteral("INSERT INTO project_property VALUES (?,?,?,?,?)"));
-	Statement folio(db.m_db, QStringLiteral("INSERT INTO folio VALUES (?,?,%1,?,?)").arg(placeholders(FolioData.size())));
+	Statement folio(db.m_db, QStringLiteral("INSERT INTO folio VALUES (?,?,%1,?)").arg(placeholders(FolioData.size())));
-	Statement folio_property(db.m_db, QStringLiteral("INSERT INTO folio_property VALUES (?,?,?,?,?)"));
+	Statement folio_property(db.m_db, QStringLiteral("INSERT INTO folio_property VALUES (?,?,?,?,?,?)"));
-	Statement element(db.m_db, QStringLiteral("INSERT INTO element VALUES (?,?,%1,?,?,?,?)").arg(placeholders(ElementData.size())));
+	Statement element(db.m_db, QStringLiteral("INSERT INTO element VALUES (?,?,%1,?,?)").arg(placeholders(ElementData.size())));
-	Statement element_info(db.m_db, QStringLiteral("INSERT INTO element_info VALUES (?,?,?,?,?)"));
+	Statement element_info(db.m_db, QStringLiteral("INSERT INTO element_info VALUES (?,?,?,?,?,?)"));
 	Statement link(db.m_db, QStringLiteral("INSERT INTO link VALUES (?,?,?,?)"));
 	Statement conductor(db.m_db, QStringLiteral("INSERT INTO conductor VALUES (?,?,%1)").arg(placeholders(ConductorData.size())));
 	bool ok = meta.ok() && project_property.ok() && folio.ok() && folio_property.ok()
 			&& element.ok() && element_info.ok() && link.ok() && conductor.ok();
 
-	ok = ok && meta.run({QStringLiteral("format"), QStringLiteral("2")});
+	ok = ok && meta.run({QStringLiteral("format"), QString::number(QetContainer::Format)})
+			&& db.exec(QStringLiteral("PRAGMA user_version = %1").arg(QetContainer::Format));
 
 		//<properties> of a block, as rows of @p rows (with @p prefix values)
 	auto moveProperties = [&](QDomElement block, Statement &rows, const QVariantList &prefix) {
 		int ord = 0;
-		for (QDomElement p : children(block, QStringLiteral("property"))) {
+		for (QDomElement p : children(block, QStringLiteral("property")))
-			QVariant value;
+			ok = ok && rows.run(QVariantList(prefix) << ord++ << entryRow(p, QStringLiteral("property")));
-			simpleValue(p, &value);
-			ok = ok && rows.run(QVariantList(prefix) << ord++ << (p.hasAttribute(QStringLiteral("name"))
-													   ? QVariant(p.attribute(QStringLiteral("name"))) : QVariant())
-							   << value << attributesJson(p, QStringLiteral("name"), true));
-		}
 	};
 
 		//Project properties
 	const QDomElement project_props = project.firstChildElement(QStringLiteral("properties"));
 	if (!project_props.isNull() && listBlock(project_props, QStringLiteral("property"))) {
-		ok = ok && meta.run({QStringLiteral("props_at"), QString::number(childIndex(project_props))});
 		ok = ok && meta.run({QStringLiteral("props_attrs"), blockJson(project_props)});
-		int ord = 0;
+		moveProperties(project_props, project_property, {});
-		for (QDomElement p : children(project_props, QStringLiteral("property"))) {
-			QVariant value;
-			simpleValue(p, &value);
-			ok = ok && project_property.run({ord++, p.hasAttribute(QStringLiteral("name"))
-												? QVariant(p.attribute(QStringLiteral("name"))) : QVariant(),
-											 value, attributesJson(p, QStringLiteral("name"), true)});
-		}
 		leaveMarker(project_props);
 	}
 
@@ -498,72 +561,69 @@ QByteArray QetContainerDb::extract(QDomElement project, QString *error)
 		for (const QDomElement &list : children(d, QStringLiteral("conductors")))
 			all_conductors += children(list, QStringLiteral("conductor"));
 	}
-	const QStringList element_keys = keys(all_elements, QStringLiteral("e"));
+	QList<bool> folio_own, element_own, conductor_own;
-	const QStringList conductor_keys = keys(all_conductors, QStringLiteral("c"));
+	const QStringList folio_keys = keys(diagrams, &folio_own);
+	const QStringList element_keys = keys(all_elements, &element_own);
+	const QStringList conductor_keys = keys(all_conductors, &conductor_own);
 	int e_index = 0, c_index = 0;
 
 	int pos = 0;
 	for (QDomElement d : diagrams)
 	{
-		const QString id = QStringLiteral("f%1").arg(++pos);
+		const QString id = folio_keys.at(pos);
+		const bool own_id = folio_own.at(pos);
+		++pos;
 		QVariantList row{id, pos};
 		row += take(d, FolioData);
 		QDomElement props = d.firstChildElement(QStringLiteral("properties"));
 		const bool move_props = !props.isNull() && listBlock(props, QStringLiteral("property"));
-		row << (move_props ? QVariant(childIndex(props)) : QVariant())
+		row << (move_props ? blockJson(props) : QVariant());
-			<< (move_props ? blockJson(props) : QVariant());
 		ok = ok && folio.run(row);
 		if (move_props) {
 			moveProperties(props, folio_property, {id});
 			leaveMarker(props);
 		}
-		d.setAttribute(FolioAttribute, id);
+		if (!own_id) d.setAttribute(FolioAttribute, id);
 
 		for (const QDomElement &list : children(d, QStringLiteral("elements"))) {
 			for (QDomElement e : children(list, QStringLiteral("element"))) {
-				const QString key = element_keys.at(e_index++);
+				const QString key = element_keys.at(e_index);
+				const bool own_key = element_own.at(e_index++);
 				QVariantList erow{key, id};
 				erow += take(e, ElementData);
 				QDomElement info = e.firstChildElement(QStringLiteral("elementInformations"));
 				QDomElement links = e.firstChildElement(QStringLiteral("links_uuids"));
 				if (!info.isNull() && !listBlock(info, QStringLiteral("elementInformation"))) info = QDomElement();
 				if (!links.isNull() && !listBlock(links, QStringLiteral("link_uuid"))) links = QDomElement();
-				const int info_at = info.isNull() ? -1 : childIndex(info);
+				erow << (info.isNull() ? QVariant() : blockJson(info))
-				const int links_at = links.isNull() ? -1 : childIndex(links);
+					 << (links.isNull() ? QVariant() : blockJson(links));
-				erow << (info_at < 0 ? QVariant() : QVariant(info_at))
-					 << (info_at < 0 ? QVariant() : blockJson(info))
-					 << (links_at < 0 ? QVariant() : QVariant(links_at))
-					 << (links_at < 0 ? QVariant() : blockJson(links));
 				ok = ok && element.run(erow);
-				if (info_at >= 0) {
+				if (!info.isNull()) {
 					int ord = 0;
-					for (QDomElement i : children(info, QStringLiteral("elementInformation"))) {
+					for (QDomElement i : children(info, QStringLiteral("elementInformation")))
-						QVariant value;
+						ok = ok && element_info.run(QVariantList{key, ord++}
-						simpleValue(i, &value);
+													<< entryRow(i, QStringLiteral("elementInformation")));
-						ok = ok && element_info.run({key, ord++, i.hasAttribute(QStringLiteral("name"))
-														? QVariant(i.attribute(QStringLiteral("name"))) : QVariant(),
-													 value, attributesJson(i, QStringLiteral("name"), true)});
-					}
 				}
-				if (links_at >= 0) {
+				if (!links.isNull()) {
 					int ord = 0;
 					for (QDomElement l : children(links, QStringLiteral("link_uuid")))
 						ok = ok && link.run({key, ord++, l.hasAttribute(QStringLiteral("uuid"))
 												? QVariant(l.attribute(QStringLiteral("uuid"))) : QVariant(),
-											 attributesJson(l, QStringLiteral("uuid"), true)});
+											 attributesJson(l, {QStringLiteral("uuid")}, QStringLiteral("link_uuid"))});
 				}
-				if (info_at >= 0) leaveMarker(info);
+				if (!info.isNull()) leaveMarker(info);
-				if (links_at >= 0) leaveMarker(links);
+				if (!links.isNull()) leaveMarker(links);
-				e.setAttribute(KeyAttribute, key);
+				if (!own_key) e.setAttribute(KeyAttribute, key);
 			}
 		}
 		for (const QDomElement &list : children(d, QStringLiteral("conductors"))) {
 			for (QDomElement c : children(list, QStringLiteral("conductor"))) {
-				const QString key = conductor_keys.at(c_index++);
+				const QString key = conductor_keys.at(c_index);
+				const bool own_key = conductor_own.at(c_index++);
 				QVariantList crow{key, id};
 				crow += take(c, ConductorData);
 				ok = ok && conductor.run(crow);
-				c.setAttribute(KeyAttribute, key);
+				if (!own_key) c.setAttribute(KeyAttribute, key);
 			}
 		}
 	}
@@ -637,10 +697,11 @@ bool QetContainerDb::restore(QDomElement project, const QByteArray &database, QS
 	}
 
 	auto entry = [&document](const QVariant &name_attr, const QString &name, const QVariant &value,
-							 const QVariant &attrs, const QString &default_tag) {
+							 const QVariant &attrs, const QString &default_tag, const QVariant &show = QVariant()) {
 		const QJsonObject o = QJsonDocument::fromJson(attrs.toString().toUtf8()).object();
 		QDomElement e = document.createElement(o.value(QStringLiteral("tag")).toString(default_tag));
 		if (!name_attr.isNull()) e.setAttribute(name, name_attr.toString());
+		if (!show.isNull()) e.setAttribute(QStringLiteral("show"), show.toString());
 		setAttributesJson(e, attrs);
 		if (!value.isNull()) e.appendChild(document.createTextNode(value.toString()));
 		return e;
@@ -652,13 +713,47 @@ bool QetContainerDb::restore(QDomElement project, const QByteArray &database, QS
 		Statement s(db.m_db, QStringLiteral("SELECT key, value FROM meta"));
 		while (s.next()) meta.insert(s.value(0).toString(), s.value(1));
 	}
-	if (meta.contains(QStringLiteral("props_at"))) {
+		//Format 2 (QElectroTech 0.200.1 development builds) keyed its rows
+		//apart from the items' uuids: "f1", "e1", "c1" where an item had
+		//none of its own, and every item's key in the folio file
+	const int format = meta.value(QStringLiteral("format")).toString().toInt();
+		//A later format is read when the manifest's min-reader allows it
+		//(QetContainer::join()): its writer kept what this reads
+	if (format < 2) {
+		setError(error, QStringLiteral("the project database is of format %1, this reads format 2 on")
+				 .arg(meta.value(QStringLiteral("format")).toString()));
+		return false;
+	}
+	const bool v2 = format == 2;
+	const QString folio_key = v2 ? QStringLiteral("id") : QStringLiteral("uuid");
+	const QString folio_ref = v2 ? QStringLiteral("folio_id") : QStringLiteral("folio_uuid");
+	const QString item_key = v2 ? QStringLiteral("key") : QStringLiteral("uuid");
+	const QString element_ref = v2 ? QStringLiteral("element_key") : QStringLiteral("element_uuid");
+	const QString show_column = v2 ? QStringLiteral("NULL") : QStringLiteral("show");
+	const QStringList element_data = v2 ? ElementDataV2 : ElementData;
+	const QStringList conductor_data = v2 ? QStringList{QStringLiteral("uuid")} + ConductorData : ConductorData;
+	auto quoted = [](const QStringList &names) {
+		return QStringLiteral("\"") + names.join(QStringLiteral("\", \"")) + QStringLiteral("\"");
+	};
+		//An item's key: the one it was given, else (format 3) its uuid
+	auto keyOf = [v2](QDomElement e, const QString &attribute) {
+		if (e.hasAttribute(attribute)) {
+			const QString key = e.attribute(attribute);
+			e.removeAttribute(attribute);
+			return key;
+		}
+		return v2 ? QString() : e.attribute(QStringLiteral("uuid"));
+	};
+		//A moved block goes back where its marker is: the marker says it
+		//was there
+	if (hasMarker(project, QStringLiteral("properties"))) {
 		QDomElement props = document.createElement(QStringLiteral("properties"));
 		setAttributesJson(props, meta.value(QStringLiteral("props_attrs")));
-		Statement s(db.m_db, QStringLiteral("SELECT name, value, attrs FROM project_property ORDER BY ord"));
+		Statement s(db.m_db, QStringLiteral("SELECT name, value, attrs, %1 FROM project_property ORDER BY ord")
+					.arg(show_column));
 		while (s.next())
 			props.appendChild(entry(s.value(0), QStringLiteral("name"), s.value(1), s.value(2),
-									QStringLiteral("property")));
+									QStringLiteral("property"), s.value(3)));
 		restoreWhitespace(props, meta.value(QStringLiteral("props_attrs")));
 		if (!replaceMarker(project, props)) {
 			setError(error, QStringLiteral("the project's properties have no place"));
@@ -686,27 +781,39 @@ bool QetContainerDb::restore(QDomElement project, const QByteArray &database, QS
 		}
 	}
 
+		//Every row must be an item's, once, on the folio the item is on:
+		//nothing enforces it in the file, which is untrusted
+	QSet<QString> folios_used, elements_used, conductors_used;
+	auto use = [error](QSet<QString> &used, const QString &key, const QString &what) {
+		if (used.contains(key)) {
+			setError(error, QStringLiteral("%1 %2 is in the folios twice").arg(what, key));
+			return false;
+		}
+		used.insert(key);
+		return true;
+	};
 	for (QDomElement d : children(project, QStringLiteral("diagram")))
 	{
-		const QString id = d.attribute(FolioAttribute);
+		const QString id = keyOf(d, FolioAttribute);
 		if (id.isEmpty()) continue;
-		d.removeAttribute(FolioAttribute);
+		if (!use(folios_used, id, QStringLiteral("folio"))) return false;
-		Statement f(db.m_db, QStringLiteral("SELECT %1, props_at, props_attrs FROM folio WHERE id = ?")
+		Statement f(db.m_db, QStringLiteral("SELECT %1, props_attrs FROM folio WHERE %2 = ?")
-					.arg(QStringLiteral("\"") + FolioData.join(QStringLiteral("\", \"")) + QStringLiteral("\"")));
+					.arg(quoted(FolioData), folio_key));
 		f.bind({id});
 		if (!f.next()) { setError(error, QStringLiteral("folio %1 is not in the database").arg(id)); return false; }
 		QVariantList values;
-		for (int i = 0 ; i < FolioData.size() + 2 ; ++i) values << f.value(i);
+		for (int i = 0 ; i < FolioData.size() + 1 ; ++i) values << f.value(i);
 		put(d, FolioData, values, 0);
-		if (!values.at(FolioData.size()).isNull()) {
+		if (hasMarker(d, QStringLiteral("properties"))) {
 			QDomElement props = document.createElement(QStringLiteral("properties"));
-			setAttributesJson(props, values.at(FolioData.size() + 1));
+			setAttributesJson(props, values.at(FolioData.size()));
-			Statement p(db.m_db, QStringLiteral("SELECT name, value, attrs FROM folio_property WHERE folio_id = ? ORDER BY ord"));
+			Statement p(db.m_db, QStringLiteral("SELECT name, value, attrs, %1 FROM folio_property WHERE %2 = ? ORDER BY ord")
+						.arg(show_column, folio_ref));
 			p.bind({id});
 			while (p.next())
 				props.appendChild(entry(p.value(0), QStringLiteral("name"), p.value(1), p.value(2),
-										QStringLiteral("property")));
+										QStringLiteral("property"), p.value(3)));
-			restoreWhitespace(props, values.at(FolioData.size() + 1));
+			restoreWhitespace(props, values.at(FolioData.size()));
 			if (!replaceMarker(d, props)) {
 				setError(error, QStringLiteral("folio %1's properties have no place").arg(id));
 				return false;
@@ -715,37 +822,42 @@ bool QetContainerDb::restore(QDomElement project, const QByteArray &database, QS
 
 		for (const QDomElement &list : children(d, QStringLiteral("elements"))) {
 			for (QDomElement e : children(list, QStringLiteral("element"))) {
-				if (!e.hasAttribute(KeyAttribute)) continue;
+				const QString key = keyOf(e, KeyAttribute);
-				const QString key = e.attribute(KeyAttribute);
+				if (key.isEmpty()) continue;
-				e.removeAttribute(KeyAttribute);
+				if (!use(elements_used, key, QStringLiteral("symbol"))) return false;
-				Statement s(db.m_db, QStringLiteral("SELECT %1, info_at, info_attrs, links_at, links_attrs FROM element WHERE key = ?")
+				Statement s(db.m_db, QStringLiteral("SELECT %1, info_attrs, links_attrs, %2 FROM element WHERE %3 = ?")
-							.arg(QStringLiteral("\"") + ElementData.join(QStringLiteral("\", \"")) + QStringLiteral("\"")));
+							.arg(quoted(element_data), folio_ref, item_key));
 				s.bind({key});
 				if (!s.next()) { setError(error, QStringLiteral("symbol %1 is not in the database").arg(key)); return false; }
+				if (s.value(element_data.size() + 2).toString() != id) {
+					setError(error, QStringLiteral("symbol %1 is on folio %2, the database says another").arg(key, id));
+					return false;
+				}
 				QVariantList v;
-				for (int i = 0 ; i < ElementData.size() + 4 ; ++i) v << s.value(i);
+				for (int i = 0 ; i < element_data.size() + 2 ; ++i) v << s.value(i);
-				put(e, ElementData, v, 0);
+				put(e, element_data, v, 0);
-				const int n = ElementData.size();
+				const int n = element_data.size();
 				QDomElement info, links;
-				if (!v.at(n).isNull()) {
+				if (hasMarker(e, QStringLiteral("elementInformations"))) {
 					info = document.createElement(QStringLiteral("elementInformations"));
-					setAttributesJson(info, v.at(n + 1));
+					setAttributesJson(info, v.at(n));
-					Statement i(db.m_db, QStringLiteral("SELECT name, value, attrs FROM element_info WHERE element_key = ? ORDER BY ord"));
+					Statement i(db.m_db, QStringLiteral("SELECT name, value, attrs, %1 FROM element_info WHERE %2 = ? ORDER BY ord")
+								.arg(show_column, element_ref));
 					i.bind({key});
 					while (i.next())
 						info.appendChild(entry(i.value(0), QStringLiteral("name"), i.value(1), i.value(2),
-											   QStringLiteral("elementInformation")));
+											   QStringLiteral("elementInformation"), i.value(3)));
-					restoreWhitespace(info, v.at(n + 1));
+					restoreWhitespace(info, v.at(n));
 				}
-				if (!v.at(n + 2).isNull()) {
+				if (hasMarker(e, QStringLiteral("links_uuids"))) {
 					links = document.createElement(QStringLiteral("links_uuids"));
-					setAttributesJson(links, v.at(n + 3));
+					setAttributesJson(links, v.at(n + 1));
-					Statement l(db.m_db, QStringLiteral("SELECT linked_uuid, attrs FROM link WHERE element_key = ? ORDER BY ord"));
+					Statement l(db.m_db, QStringLiteral("SELECT linked_uuid, attrs FROM link WHERE %1 = ? ORDER BY ord").arg(element_ref));
 					l.bind({key});
 					while (l.next())
 						links.appendChild(entry(l.value(0), QStringLiteral("uuid"), QVariant(), l.value(1),
 												QStringLiteral("link_uuid")));
-					restoreWhitespace(links, v.at(n + 3));
+					restoreWhitespace(links, v.at(n + 1));
 				}
 				if ((!info.isNull() && !replaceMarker(e, info))
 					|| (!links.isNull() && !replaceMarker(e, links))) {
@@ -756,18 +868,47 @@ bool QetContainerDb::restore(QDomElement project, const QByteArray &database, QS
 		}
 		for (const QDomElement &list : children(d, QStringLiteral("conductors"))) {
 			for (QDomElement c : children(list, QStringLiteral("conductor"))) {
-				if (!c.hasAttribute(KeyAttribute)) continue;
+				const QString key = keyOf(c, KeyAttribute);
-				const QString key = c.attribute(KeyAttribute);
+				if (key.isEmpty()) continue;
-				c.removeAttribute(KeyAttribute);
+				if (!use(conductors_used, key, QStringLiteral("wire"))) return false;
-				Statement s(db.m_db, QStringLiteral("SELECT %1 FROM conductor WHERE key = ?")
+				Statement s(db.m_db, QStringLiteral("SELECT %1, %2 FROM conductor WHERE %3 = ?")
-							.arg(QStringLiteral("\"") + ConductorData.join(QStringLiteral("\", \"")) + QStringLiteral("\"")));
+							.arg(quoted(conductor_data), folio_ref, item_key));
 				s.bind({key});
 				if (!s.next()) { setError(error, QStringLiteral("wire %1 is not in the database").arg(key)); return false; }
+				if (s.value(conductor_data.size()).toString() != id) {
+					setError(error, QStringLiteral("wire %1 is on folio %2, the database says another").arg(key, id));
+					return false;
+				}
 				QVariantList v;
-				for (int i = 0 ; i < ConductorData.size() ; ++i) v << s.value(i);
+				for (int i = 0 ; i < conductor_data.size() ; ++i) v << s.value(i);
-				put(c, ConductorData, v, 0);
+				put(c, conductor_data, v, 0);
 			}
 		}
 	}
+
+		//No row left over: each table's rows, counted, are the items read,
+		//and every entry belongs to a row
+	auto count = [&db](const QString &sql) {
+		Statement s(db.m_db, sql);
+		return s.next() ? s.value(0).toInt() : -1;
+	};
+	const struct { QString sql; int expected; QString what; } checks[] = {
+		{QStringLiteral("SELECT count(*) FROM folio"), int(folios_used.size()), QStringLiteral("folio rows")},
+		{QStringLiteral("SELECT count(*) FROM element"), int(elements_used.size()), QStringLiteral("symbol rows")},
+		{QStringLiteral("SELECT count(*) FROM conductor"), int(conductors_used.size()), QStringLiteral("wire rows")},
+		{QStringLiteral("SELECT count(*) FROM folio_property WHERE %1 NOT IN (SELECT %2 FROM folio)")
+				.arg(folio_ref, folio_key), 0, QStringLiteral("folio property rows of no folio")},
+		{QStringLiteral("SELECT count(*) FROM element_info WHERE %1 NOT IN (SELECT %2 FROM element)")
+				.arg(element_ref, item_key), 0, QStringLiteral("information rows of no symbol")},
+		{QStringLiteral("SELECT count(*) FROM link WHERE %1 NOT IN (SELECT %2 FROM element)")
+				.arg(element_ref, item_key), 0, QStringLiteral("link rows of no symbol")}};
+	for (const auto &check : checks) {
+		const int found = count(check.sql);
+		if (found != check.expected) {
+			setError(error, QStringLiteral("the project database does not match its folios: %1 %2, %3 expected")
+					 .arg(found).arg(check.what).arg(check.expected));
+			return false;
+		}
+	}
 	return true;
 }

sources/container/qetcontainerdb.h

@@ -30,8 +30,10 @@
 	drawn. extract() takes them out of the document into a database,
 	restore() puts them back, so that restore(extract(d)) is d.
 
-	Each moved item leaves its key in the document (qetz-key, qetz-folio):
+	A row's key is its item's uuid, which stays in the folio file. An item
-	its uuid where that is unique, else a made-up one. A block of a shape
+	without a uuid of its own -- none, or one another item shares -- gets a
+	uuid made from what it holds, left in the document as qetz-key or
+	qetz-folio. A block of a shape
 	this does not model -- a value holding elements, say -- stays in the
 	document, so nothing can be lost by moving.
 */

sources/container/qetzip.cpp

@@ -22,6 +22,7 @@
 #include <QFile>
 #include <QSaveFile>
 #include <QSet>
+#include <QtEndian>
 
 namespace {
 void setError(QString *error, const QString &text)
@@ -44,6 +45,42 @@ bool safeName(const QString &name)
 	}
 	return true;
 }
+
+	//Built with MINIZ_NO_TIME, miniz leaves each entry's DOS date at 0,
+	//day 0 of month 0, which is no date: unzip shows 30 Nov 1979, other
+	//tools 13 Dec 1901. Give every entry 1 Jan 1980 00:00 instead, the
+	//first valid DOS date, so the bytes still do not depend on the time.
+constexpr quint16 EntryDosDate = (1 << 5) | 1;
+
+bool setEntryDates(QByteArray *bytes)
+{
+	char *data = bytes->data();
+	mz_zip_archive zip;
+	mz_zip_zero_struct(&zip);
+	if (!mz_zip_reader_init_mem(&zip, data, size_t(bytes->size()), 0)) return false;
+
+	bool ok = true;
+	const mz_uint count = mz_zip_reader_get_num_files(&zip);
+	for (mz_uint i = 0 ; i < count && ok ; ++i)
+	{
+		mz_zip_archive_file_stat stat;
+		if (!mz_zip_reader_file_stat(&zip, i, &stat)) {
+			ok = false;
+			break;
+		}
+			//date at offset 12 of the local header, 14 of the central one
+		const quint64 local = stat.m_local_header_ofs + 12;
+		const quint64 central = zip.m_central_directory_file_ofs + stat.m_central_dir_ofs + 14;
+		if (local + 2 > quint64(bytes->size()) || central + 2 > quint64(bytes->size())) {
+			ok = false;
+			break;
+		}
+		qToLittleEndian<quint16>(EntryDosDate, data + local);
+		qToLittleEndian<quint16>(EntryDosDate, data + central);
+	}
+	mz_zip_reader_end(&zip);
+	return ok;
+}
 }
 
 /**
@@ -87,8 +124,12 @@ QByteArray QetZip::toBytes(const QList<Entry> &entries, QString *error)
 		mz_zip_writer_end(&zip);
 		return {};
 	}
-	const QByteArray bytes(static_cast<const char *>(buffer), qsizetype(size));
+	QByteArray bytes(static_cast<const char *>(buffer), qsizetype(size));
 	mz_zip_writer_end(&zip);   //frees buffer
+	if (!setEntryDates(&bytes)) {
+		setError(error, QStringLiteral("cannot date the zip entries"));
+		return {};
+	}
 	return bytes;
 }
 

sources/container/qetzip.h

@@ -30,8 +30,8 @@
 	megabytes, not gigabytes -- and written through QSaveFile, so a failed
 	save leaves the previous file as it was.
 
-	Entries carry no timestamp: saving the same project twice gives the
+	Every entry is dated 1 Jan 1980 00:00, not the time of saving: saving
-	same bytes.
+	the same project twice gives the same bytes.
 */
 namespace QetZip
 {

sources/dataBase/projectdatabase.cpp

@@ -253,6 +253,58 @@ void projectDataBase::updateDB(const QDomDocument &document)
 	updateDB();
 }
 
+/**
+	@brief projectDataBase::documentRefusal
+	@return why populateFromDocument() will refuse @p document, for the
+	reasons it gives that the document alone can tell -- a folio, symbol
+	or wire with no saved uuid, two symbols sharing one, a folio number
+	using %autonum -- or an empty string. The other reasons need the
+	project's definitions or every folio's links; a document refused for
+	one of those is still filled from the folios, only later.
+*/
+QString projectDataBase::documentRefusal(const QDomDocument &document)
+{
+	if (qEnvironmentVariableIntValue("QET_DATABASE_FROM_FOLIOS") == 1) {
+		return QStringLiteral("QET_DATABASE_FROM_FOLIOS is set");
+	}
+	QSet<QUuid> element_uuids;
+	const QDomNodeList diagram_nodes = document.elementsByTagName(QStringLiteral("diagram"));
+	for (int i = 0 ; i < diagram_nodes.size() ; ++i)
+	{
+		QDomElement diagram_xml = diagram_nodes.at(i).toElement();
+		if (QUuid(diagram_xml.attribute(QStringLiteral("uuid"))).isNull()) {
+			return QStringLiteral("a folio has no saved uuid");
+		}
+		if (diagram_xml.attribute(QStringLiteral("folio")).contains(QStringLiteral("%autonum"))) {
+			return QStringLiteral("a folio number uses %autonum");
+		}
+		for (QDomElement element_xml : QET::findInDomElement(
+				 diagram_xml, QStringLiteral("elements"), QStringLiteral("element")))
+		{
+				//Skipped by Diagram::fromXml() as well
+			if (!Element::valideXml(element_xml)) {
+				continue;
+			}
+			const QUuid uuid(element_xml.attribute(QStringLiteral("uuid")));
+			if (uuid.isNull() || element_uuids.contains(uuid)) {
+				return QStringLiteral("an element has no saved uuid, or shares one");
+			}
+			element_uuids.insert(uuid);
+		}
+		for (QDomElement conductor_xml : QET::findInDomElement(
+				 diagram_xml, QStringLiteral("conductors"), QStringLiteral("conductor")))
+		{
+			if (Conductor::valideXml(conductor_xml)
+				&& (QUuid(conductor_xml.attribute(QStringLiteral("uuid"))).isNull()
+					|| !conductor_xml.hasAttribute(QStringLiteral("element1"))
+					|| !conductor_xml.hasAttribute(QStringLiteral("element2")))) {
+				return QStringLiteral("a conductor has no saved uuid, or names its ends the older way");
+			}
+		}
+	}
+	return QString();
+}
+
 namespace {
 struct DocumentTerminal
 {
@@ -2445,7 +2497,7 @@ void projectDataBase::populateElementTable()
 /**
 	@brief projectDataBase::populateElementInfoTable
 	Populate the element info table from the symbol information store
-	(DB-ACCESSORS-PLAN.md stage 4.3), in the order of the element table.
+	in the order of the element table.
 	The label column is the label a symbol shows, which its folio's
 	numbering decides: the symbol holding the uuid gives it.
 

sources/dataBase/projectdatabase.h

@@ -67,6 +67,14 @@ class projectDataBase : public QObject
 				populateFromDocument()), from the built folios otherwise.
 			*/
 		void updateDB(const QDomDocument &document);
+			/**
+				Why updateDB(document) will fill the tables from the folios
+				rather than from @p document, for the reasons the document
+				alone can tell; empty when it knows of none. Read before the
+				folios are: a project whose tables will come from the folios
+				builds every folio as it opens, even with QET_LAZY_FOLIOS.
+			*/
+		static QString documentRefusal(const QDomDocument &document);
 			/**
 				Suppress the full rebuild performed by updateDB().
 
@@ -106,7 +114,7 @@ class projectDataBase : public QObject
 
 			//The information of every symbol placed in the project, by
 			//symbol uuid: the store each symbol's information is written
-			//through (DB-ACCESSORS-PLAN.md stage 4.1). A symbol not placed
+			//through. A symbol not placed
 			//(a preview, the symbol editor) keeps its own.
 		DiagramContext elementInformation(const QUuid &element) const;
 		bool hasElementInformation(const QUuid &element) const;
@@ -124,7 +132,7 @@ class projectDataBase : public QObject
 
 			//The title block properties of every folio of the project, by
 			//folio uuid: the store each folio's title block is written
-			//through (DB-ACCESSORS-PLAN.md stage 4.4). A folio not in a
+			//through. A folio not in a
 			//project keeps its own.
 		TitleBlockProperties folioTitleBlock(const QUuid &folio) const;
 		const TitleBlockProperties *storedFolioTitleBlock(const QUuid &folio) const;
@@ -136,7 +144,7 @@ class projectDataBase : public QObject
 
 			//The properties of every wire placed in the project, by wire
 			//uuid: the store each wire's properties are written through
-			//(DB-ACCESSORS-PLAN.md stage 4.5). A wire not placed keeps its own.
+			//A wire not placed keeps its own.
 		ConductorProperties conductorProperties(const QUuid &conductor) const;
 		bool hasConductorProperties(const QUuid &conductor) const;
 		int placedConductorCount(const QUuid &conductor) const;
@@ -145,7 +153,7 @@ class projectDataBase : public QObject
 		QStringList conductorPropertiesMismatches() const;
 
 			//Fill the three stores from a project's document before its
-			//folios are built (DB-ACCESSORS-PLAN.md stage 4.6), then, once
+			//folios are built, then, once
 			//they are, say how many of those values building agreed with.
 		void prefillFromDocument(const QDomDocument &document);
 		void endPrefill(bool keep_unplaced = false);

sources/diagram.cpp

@@ -49,9 +49,12 @@
 #include "diagramsortkeys.h"
 #include "itemgroups.h"
 #include "textgrid.h"
+#include "container/qetcontainer.h"
 #include "foliogrid.h"
 #include <QGraphicsView>
 #include <QTextStream>
+#include <QThreadPool>
+#include <QtConcurrentMap>
 #include <algorithm>
 #include <climits>
 #include <cassert>
@@ -2005,12 +2008,37 @@ bool Diagram::fromXml(QDomElement &document,
 	}
 
 		// Load image
+		// Decoding is most of the time of a folio with photos (a quarter of
+		// a second each), so the pictures are decoded first, in parallel,
+		// and the items built afterwards in this thread.
+	const QList<QDomElement> images_xml = QET::findInDomElement(
+				root, QStringLiteral("images"), QStringLiteral("image"));
+	QList<DiagramImageItem::Picture> pictures;
+	pictures.reserve(images_xml.size());
+	for (const QDomElement &image_xml : images_xml) {
+		const QString picture_file = QetContainer::pictureFile(image_xml);
+		pictures << DiagramImageItem::pictureOf(
+						image_xml,
+						!picture_file.isEmpty() && project()
+						? project() -> containerPicture(picture_file)
+						: QByteArray());
+	}
+	if (pictures.size() > 1) {
+		QThreadPool pool;
+		pool.setMaxThreadCount(std::min<int>(QThread::idealThreadCount(),
+											 pictures.size()));
+		QtConcurrent::blockingMap(&pool, pictures,
+								  &DiagramImageItem::decodePicture);
+	} else {
+		for (DiagramImageItem::Picture &picture : pictures)
+			DiagramImageItem::decodePicture(picture);
+	}
+
 	QList<DiagramImageItem *> added_images;
-	for (auto image_xml : QET::findInDomElement(root,
+	for (qsizetype i = 0 ; i < images_xml.size() ; ++i) {
-												QStringLiteral("images"),
+		const QDomElement &image_xml = images_xml.at(i);
-												QStringLiteral("image"))) {
 		DiagramImageItem *dii = new DiagramImageItem ();
-		dii -> fromXml(image_xml);
+		dii -> fromXml(image_xml, std::move(pictures[i]));
 		settle_uuid(dii, image_xml, QStringLiteral("image"), added_images.size());
 		ItemGroups::setGroup(dii, ItemGroups::read(image_xml));
 		addItem(dii);

sources/diagram.h

@@ -133,6 +133,7 @@ class Diagram : public QGraphicsScene
 		bool draw_terminals_;
 		bool draw_terminal_names_;
 		bool draw_colored_conductors_;
+		bool m_small_pictures = false;
 
 		QString m_conductors_autonum_name;
 		DiagramEventInterface *m_event_interface;
@@ -211,7 +212,7 @@ class Diagram : public QGraphicsScene
 				 bool = true,
 				 DiagramContent * = nullptr);
 			/// false while this folio's items wait in its XML to be
-			/// built (QET_LAZY_FOLIOS, LAZY-FOLIO-PLAN.md)
+			/// built (QET_LAZY_FOLIOS)
 		bool isLoaded() const {return m_deferred.isNull();}
 		QDomElement deferredXml() const {return m_deferred;}
 		QString headerXml();
@@ -284,6 +285,11 @@ class Diagram : public QGraphicsScene
 		void setDrawTerminalNames(bool);
 		bool drawColoredConductors() const;
 		void setDrawColoredConductors(bool);
+			/// While true, pictures draw a copy of a few times the size
+			/// they are drawn at, not their full resolution (SVG export,
+			/// ExportProperties::svg_small_pictures)
+		bool smallPictures() const {return m_small_pictures;}
+		void setSmallPictures(bool small) {m_small_pictures = small;}
 	
 		QString title() const;
 		bool toPaintDevice(QPaintDevice &, int = -1, int = -1,

sources/editor/ui/elementpropertieseditorwidget.ui

@@ -255,7 +255,7 @@
              <string>margin: 5px; font-weight: bold;</string>
             </property>
             <property name="text">
-             <string>Potential separation</string>
+             <string>Function separation</string>
             </property>
            </widget>
           </item>

sources/exportdialog.cpp

@@ -417,12 +417,14 @@ void ExportDialog::generateSvg(
 	
 	// genere une QPicture a partir du schema
 	QPicture picture;
+	diagram -> setSmallPictures(epw -> exportProperties().svg_small_pictures);
 	diagram -> toPaintDevice(
 		picture,
 		width,
 		height,
 		keep_aspect_ratio ? Qt::KeepAspectRatio : Qt::IgnoreAspectRatio
 	);
+	diagram -> setSmallPictures(false);
 	
 	// "joue" la QPicture sur un QSvgGenerator
 	QSvgGenerator svg_engine;

sources/exportproperties.cpp

@@ -39,6 +39,7 @@ ExportProperties::ExportProperties() :
 	draw_colored_conductors(true),
 	dxf_blocks(false),
 	dxf_attributes(false),
+	svg_small_pictures(false),
 	exported_area(QET::BorderArea)
 {
 }
@@ -83,6 +84,8 @@ void ExportProperties::toSettings(QSettings &settings,
 			  dxf_blocks);
 	settings.setValue(prefix % "dxfattributes",
 			  dxf_attributes);
+	settings.setValue(prefix % "svgsmallpictures",
+			  svg_small_pictures);
 	settings.setValue(prefix % "area",
 			  QET::diagramAreaToString(exported_area));
 }
@@ -125,6 +128,8 @@ void ExportProperties::fromSettings(QSettings &settings,
 				    false).toBool();
 	dxf_attributes = settings.value(prefix % "dxfattributes",
 					false).toBool();
+	svg_small_pictures = settings.value(prefix % "svgsmallpictures",
+					    false).toBool();
 
 	exported_area  = QET::diagramAreaFromString(
 				settings.value(

sources/exportproperties.h

@@ -52,6 +52,7 @@ class ExportProperties {
 	bool draw_colored_conductors;   ///< Whether to render conductors colors
 	bool dxf_blocks;                ///< DXF: each symbol as a block, placed with an INSERT
 	bool dxf_attributes;            ///< DXF, with dxf_blocks: a symbol's texts as attributes of its INSERT
+	bool svg_small_pictures;        ///< SVG: pictures at most 4x the size they are drawn, not full resolution
 	QET::DiagramArea exported_area; ///< Area of diagrams to be rendered
 };
 #endif

sources/exportpropertieswidget.cpp

@@ -68,6 +68,7 @@ ExportProperties ExportPropertiesWidget::exportProperties() const
 	export_properties.draw_colored_conductors = draw_colored_conductors -> isChecked();
 	export_properties.dxf_blocks              = dxf_blocks -> isChecked();
 	export_properties.dxf_attributes          = dxf_attributes -> isChecked();
+	export_properties.svg_small_pictures      = svg_small_pictures -> isChecked();
 	export_properties.exported_area           = export_border -> isChecked() ? QET::BorderArea : QET::ElementsArea;
 	
 	return(export_properties);
@@ -94,6 +95,7 @@ void ExportPropertiesWidget::setExportProperties(const ExportProperties &export_
 	dxf_blocks              -> setChecked(export_properties.dxf_blocks);
 	dxf_attributes          -> setChecked(export_properties.dxf_attributes);
 	dxf_attributes          -> setEnabled(export_properties.dxf_blocks);
+	svg_small_pictures      -> setChecked(export_properties.svg_small_pictures);
 	
 	if (export_properties.exported_area == QET::BorderArea) {
 		export_border -> setChecked(true);
@@ -125,6 +127,7 @@ void ExportPropertiesWidget::setPrintingMode(bool mode) {
 	export_border       -> setVisible(!mode);
 	export_elements     -> setVisible(!mode);
 	draw_bg_transparent -> setVisible(!mode);
+	svg_small_pictures  -> setVisible(!mode);
 }
 
 /**
@@ -235,6 +238,11 @@ void ExportPropertiesWidget::build()
 	dxf_attributes -> setToolTip(tr("A symbol's texts (label, function...) become attributes of its block. LibreCAD does not show attributes."));
 	optionshlayout -> addWidget(dxf_attributes, 5, 1);
 	connect(dxf_blocks, &QCheckBox::toggled, dxf_attributes, &QCheckBox::setEnabled);
+
+	// pictures not at full resolution in an SVG: a much smaller file
+	svg_small_pictures = new QCheckBox(tr("SVG: smaller pictures"), groupbox_options);
+	svg_small_pictures -> setToolTip(tr("Pictures are stored at four times the size they have on the folio instead of their full resolution: a much smaller file, still sharp when printed"));
+	optionshlayout -> addWidget(svg_small_pictures, 5, 0);
 	
 	vboxLayout -> addWidget(groupbox_options);
 	
@@ -252,6 +260,7 @@ void ExportPropertiesWidget::build()
 	setTabOrder(draw_colored_conductors, draw_bg_transparent);
 	setTabOrder(draw_bg_transparent, dxf_blocks);
 	setTabOrder(dxf_blocks, dxf_attributes);
+	setTabOrder(draw_bg_transparent, svg_small_pictures);
 	
 	// connexion du bouton permettant le choix du repertoire
 	connect(button_browse, &QPushButton::released, this, &ExportPropertiesWidget::slot_chooseADirectory);	
@@ -269,6 +278,7 @@ void ExportPropertiesWidget::build()
 	connect(draw_colored_conductors, &QCheckBox::stateChanged, this, &ExportPropertiesWidget::optionChanged);
 	connect(dxf_blocks, &QCheckBox::stateChanged, this, &ExportPropertiesWidget::optionChanged);
 	connect(dxf_attributes, &QCheckBox::stateChanged, this, &ExportPropertiesWidget::optionChanged);
+	connect(svg_small_pictures, &QCheckBox::stateChanged, this, &ExportPropertiesWidget::optionChanged);
 #else
 	connect(draw_grid, &QCheckBox::checkStateChanged, this, &ExportPropertiesWidget::optionChanged);
 	connect(draw_border, &QCheckBox::checkStateChanged, this, &ExportPropertiesWidget::optionChanged);
@@ -279,5 +289,6 @@ void ExportPropertiesWidget::build()
 	connect(draw_colored_conductors, &QCheckBox::checkStateChanged, this, &ExportPropertiesWidget::optionChanged);
 	connect(dxf_blocks, &QCheckBox::checkStateChanged, this, &ExportPropertiesWidget::optionChanged);
 	connect(dxf_attributes, &QCheckBox::checkStateChanged, this, &ExportPropertiesWidget::optionChanged);
+	connect(svg_small_pictures, &QCheckBox::checkStateChanged, this, &ExportPropertiesWidget::optionChanged);
 #endif
 }

sources/exportpropertieswidget.h

@@ -67,6 +67,7 @@ class ExportPropertiesWidget : public QWidget {
 	QCheckBox *draw_colored_conductors;
 	QCheckBox *dxf_blocks;
 	QCheckBox *dxf_attributes;
+	QCheckBox *svg_small_pictures;
 	QRadioButton *export_border;
 	QRadioButton *export_elements;
 	QButtonGroup *exported_content_choices;

sources/properties/terminaldata.h

@@ -107,10 +107,11 @@ class TerminalData : public PropertiesInterface
 			@brief m_potential
 			An optional, symbol-author-chosen grouping identifier shared by
 			terminals that belong to the same physical terminal within
-			a multi-terminal block. When potential_isolating is enabled
+			a multi-terminal block. When the function separation checkbox
+			(element information potential_isolating) is enabled
 			on the parent element, terminals sharing a non-empty,
 			matching m_potential stay linked to each other; terminals
-			with different (or empty) values become isolated from each
+			with different (or empty) values become separated from each
 			other. Empty by default.
 		*/
 		QString m_potential;

sources/qetdiagrameditor.cpp

@@ -1969,6 +1969,16 @@ bool QETDiagramEditor::openAndAddProject(
 	addProject(project);
 	DialogWaiting::dropInstance();
 
+	if (interactive && project->isFromLaterVersion()) {
+		QET::QetMessageBox::warning(
+			this,
+			tr("Opening the file read-only", "message box title"),
+			tr("This project was saved by a later version of QElectroTech. "
+			   "It is opened read-only, so that saving it cannot lose what "
+			   "this version does not know. Use Save As to keep a copy "
+			   "in this version's format."));
+	}
+
 		//Report font descriptions which could not be read as-is (written by
 		//an incompatible Qt version or corrupted), so the user learns about
 		//it from somewhere else than the console. See issue #553.

sources/qetgraphicsitem/conductor.cpp

@@ -1857,7 +1857,7 @@ ConductorProperties Conductor::properties() const
 /**
 	@brief Conductor::placedStore
 	@return the project database holding this wire's properties
-	(DB-ACCESSORS-PLAN.md stage 4.5), or nullptr if it is not placed in a
+	or nullptr if it is not placed in a
 	project, or shares its uuid with another wire for the moment a copy
 	takes to get its own
 */
@@ -2005,9 +2005,16 @@ void Conductor::displayedTextChanged()
 	@param all_diagram : if true search in all diagram of the project,
 	false search only in the parent diagram of this conductor
 	@param t_list : a list of terminal already found for this potential.
+	@param ignore_function_separation : if true, a terminal element whose
+	function separation is enabled does not stop the search, and the
+	conductors of both its sides are returned as one potential. Only
+	functionSeparatedConductors() passes true.
+	@sa functionSeparatedConductors
 	@return  a QSet of conductor at the same potential.
 */
-QSet<Conductor *> Conductor::relatedPotentialConductors(const bool all_diagram, QList <Terminal *> *t_list)
+QSet<Conductor *> Conductor::relatedPotentialConductors(const bool all_diagram,
+							QList <Terminal *> *t_list,
+							const bool ignore_function_separation)
 {
 	bool declar_t_list = false;
 	if (t_list == nullptr)
@@ -2030,7 +2037,8 @@ QSet<Conductor *> Conductor::relatedPotentialConductors(const bool all_diagram,
 
 				//Get the other terminals of the parent element of @terminal, who share the same potential
 				//This is use for element type "folio report" and "terminal element"
-			for (Terminal *t : relatedPotentialTerminal(terminal, all_diagram))
+			for (Terminal *t : relatedPotentialTerminal(terminal, all_diagram,
+								ignore_function_separation))
 			{
 				if (!t_list->contains(t))
 				{
@@ -2042,7 +2050,8 @@ QSet<Conductor *> Conductor::relatedPotentialConductors(const bool all_diagram,
 			other_conductors_list_t.removeAll(this);
 				//Get the conductors at the same potential for each conductors of other_conductors_list_t
 			for (Conductor *c : other_conductors_list_t) {
-				other_conductors += c->relatedPotentialConductors(all_diagram, t_list);
+				other_conductors += c->relatedPotentialConductors(all_diagram, t_list,
+								  ignore_function_separation);
 			}
 
 			other_conductors += QSet<Conductor*>(other_conductors_list_t.begin(),other_conductors_list_t.end());
@@ -2055,6 +2064,36 @@ QSet<Conductor *> Conductor::relatedPotentialConductors(const bool all_diagram,
 	return(other_conductors);
 }
 
+/**
+	@brief Conductor::functionSeparatedConductors
+	Return the conductors that belong to this conductor's potential only
+	by crossing a function separated terminal element -- a terminal
+	element whose function separation checkbox (element information
+	potential_isolating) is enabled, the checkbox the user ticks to stop
+	sharing a terminal's properties with the other side of the terminal.
+
+	Those conductors are deliberately not part of
+	relatedPotentialConductors(): no property may be copied over them
+	by default. One does cross that separation, though: the voltage /
+	protocol, which describes the electrical node itself. Callers that
+	push it over the whole potential use this method to reach the other
+	side (@see ConductorProperties::applyTensionProtocolChange).
+
+	It is simply the potential computed with the separations ignored,
+	minus the potential that respects them.
+	@param all_diagram : if true search in all diagram of the project,
+	false search only in the parent diagram of this conductor
+	@return a QSet of conductor, this conductor excluded
+*/
+QSet<Conductor *> Conductor::functionSeparatedConductors(const bool all_diagram)
+{
+	QSet<Conductor *> separated = relatedPotentialConductors(all_diagram, nullptr, true);
+	separated.subtract(relatedPotentialConductors(all_diagram));
+	separated.remove(this);
+
+	return separated;
+}
+
 /**
 	@brief Conductor::diagramEditor
 	@return The parent diagram editor or nullptr;

sources/qetgraphicsitem/conductor.h

@@ -151,7 +151,10 @@ class Conductor : public QGraphicsObject
 		virtual void setHighlighted(Highlight);
 		QSet<Conductor *> relatedPotentialConductors(
 				const bool all_diagram = true,
-				QList <Terminal *> *t_list=nullptr);
+				QList <Terminal *> *t_list=nullptr,
+				const bool ignore_function_separation = false);
+		QSet<Conductor *> functionSeparatedConductors(
+				const bool all_diagram = true);
 		QETDiagramEditor* diagramEditor() const;
 		void editProperty ();
 

sources/qetgraphicsitem/diagramimageitem.cpp

@@ -167,7 +167,28 @@ void DiagramImageItem::paint(QPainter *painter, const QStyleOptionGraphicsItem *
 		return;
 	}
 
-	DarkImageRendering::paintPixmap(painter, pixmap_, m_adapt_to_dark_theme);
+		// SVG export with smaller pictures: a copy four times the size the
+		// picture is drawn at, when that is smaller than the picture. An
+		// SVG stores what it is given, so a photo shown at a tenth of its
+		// size would otherwise be written whole.
+	const QTransform world = painter -> worldTransform();
+	const qreal drawn_scale = std::sqrt(std::abs(world.determinant()));
+	const QSize small_size = (QSizeF(pixmap_.size()) * drawn_scale * 4).toSize();
+	if (diagram() && diagram() -> smallPictures() && !pixmap_.isNull()
+			&& small_size.width() < pixmap_.width()
+			&& small_size.height() < pixmap_.height()
+			&& !small_size.isEmpty())
+	{
+		const QPixmap small = pixmap_.scaled(small_size, Qt::IgnoreAspectRatio,
+											 Qt::SmoothTransformation);
+		painter -> save();
+		painter -> scale(qreal(pixmap_.width()) / small.width(),
+						 qreal(pixmap_.height()) / small.height());
+		DarkImageRendering::paintPixmap(painter, small, m_adapt_to_dark_theme);
+		painter -> restore();
+	}
+	else
+		DarkImageRendering::paintPixmap(painter, pixmap_, m_adapt_to_dark_theme);
 
 	Q_UNUSED(option); Q_UNUSED(widget);
 
@@ -1787,6 +1808,71 @@ const QByteArray &DiagramImageItem::encodedPng(const QPixmap &pixmap, QByteArray
 	@return true if successfully loaded.
 */
 bool DiagramImageItem::fromXml(const QDomElement &e)
+{
+	return fromXml(e, QByteArray());
+}
+
+/**
+	@brief DiagramImageItem::fromXml
+	Load this image from xml element e, its picture being @p picture, not
+	the base64 text of @p e, unless @p picture is empty. A .qetz keeps its
+	pictures as files (QetContainer::join()).
+*/
+bool DiagramImageItem::fromXml(const QDomElement &e, const QByteArray &picture)
+{
+	Picture p = pictureOf(e, picture);
+	decodePicture(p);
+	return fromXml(e, std::move(p));
+}
+
+/**
+	@brief DiagramImageItem::pictureOf
+	@return the picture of @p e, @p picture unless it is empty, else the
+	base64 text of @p e, still encoded : decodePicture() does the slow part.
+	Reads the DOM, so GUI thread only.
+*/
+DiagramImageItem::Picture DiagramImageItem::pictureOf(const QDomElement &e,
+													  const QByteArray &picture)
+{
+	Picture p;
+	p.bytes = picture;
+	if (p.bytes.isEmpty())
+	{
+		// From the first text node only, not e.text(): that also collects
+		// the text of every child element, so on a cropped or colour-keyed
+		// picture it carries <image_base>'s bytes too.
+		const QDomNode image_node = e.firstChild();
+		if (image_node.isText())
+			p.base64 = image_node.toText().data();
+		else
+			p.found = false;
+	}
+	return p;
+}
+
+/**
+	@brief DiagramImageItem::decodePicture
+	Decodes the base64 text and the picture file of @p picture. Touches
+	nothing else, so it can run in any thread : a large photo takes about
+	a quarter of a second, and Diagram::fromXml() decodes a folio's
+	pictures in parallel.
+*/
+void DiagramImageItem::decodePicture(Picture &picture)
+{
+	if (picture.bytes.isEmpty() && !picture.base64.isEmpty())
+	{
+		picture.bytes = QByteArray::fromBase64(picture.base64.toLatin1());
+		picture.base64.clear();
+	}
+	picture.image = QImage::fromData(picture.bytes);
+}
+
+/**
+	@brief DiagramImageItem::fromXml
+	Load this image from xml element e, its picture already decoded by
+	decodePicture().
+*/
+bool DiagramImageItem::fromXml(const QDomElement &e, Picture picture)
 {
 	if (e.tagName() != "image") {
 		return (false);
@@ -1796,28 +1882,17 @@ bool DiagramImageItem::fromXml(const QDomElement &e)
 	const QUuid uuid(e.attribute(QStringLiteral("uuid")));
 	if (!uuid.isNull() && uuid != m_uuid) setUuid(uuid);
 
-	QDomNode image_node = e.firstChild();
+	if (!picture.found) {
-	if (!image_node.isText()) {
 		return (false);
 	}
+	const QByteArray array = picture.bytes;
 
-	//load xml image to QByteArray
+	//Set QPixmap from the decoded picture
-	QByteArray array;
+	QPixmap pixmap = QPixmap::fromImage(std::move(picture.image));
-	array = QByteArray::fromBase64(e.text().toLatin1());
-
-	//Set QPixmap from the array
-	QPixmap pixmap;
-	pixmap.loadFromData(array);
 	setPixmap(pixmap);
-	// From the first text node only, not e.text(): that also collects the
+	if (isPng(array) && !pixmap_.isNull())
-	// text of every child element, so on a cropped or colour-keyed picture
-	// it carries <image_base>'s bytes too. loadFromData() stops at the end
-	// of the first PNG and never notices; a cache written back verbatim
-	// would.
-	const QByteArray ownArray = QByteArray::fromBase64(image_node.toText().data().toLatin1());
-	if (isPng(ownArray) && !pixmap_.isNull())
 	{
-		m_png_cache = ownArray;
+		m_png_cache = array;
 		m_png_cache_key = pixmap_.cacheKey();
 	}
 

sources/qetgraphicsitem/diagramimageitem.h

@@ -24,6 +24,7 @@
 
 #include <QColor>
 #include <QFont>
+#include <QImage>
 #include <QList>
 #include <QUuid>
 #include <QStyleOptionGraphicsItem>
@@ -119,7 +120,20 @@ class DiagramImageItem : public QetGraphicsItem {
 	*/
 	int type() const override { return Type; }
 	
+	/// A picture as read from its <image> element, before and after
+	/// decodePicture(), which may run outside the GUI thread.
+	struct Picture {
+		QString base64;		///< text of <image>, decoded when bytes is empty
+		QByteArray bytes;	///< the picture file (PNG, JPEG...)
+		QImage image;		///< bytes, decoded
+		bool found = true;	///< false : neither bytes nor text
+	};
+	static Picture pictureOf(const QDomElement &, const QByteArray &picture);
+	static void decodePicture(Picture &picture);
+
 	virtual bool fromXml(const QDomElement &);
+	bool fromXml(const QDomElement &, const QByteArray &picture);
+	bool fromXml(const QDomElement &, Picture picture);
 	virtual QDomElement toXml(QDomDocument &) const;
 	QUuid uuid() const {return m_uuid;}
 	void setUuid(const QUuid &uuid) {m_uuid = uuid; emit uuidChanged();}

sources/qetgraphicsitem/element.cpp

@@ -1859,7 +1859,7 @@ void Element::setUuid(const QUuid &uuid)
 /**
 	@brief Element::storeInformation
 	Write this symbol's information to its project's store, once it is
-	placed (DB-ACCESSORS-PLAN.md stage 4.1): every change of a placed
+	placed: every change of a placed
 	symbol's information comes through here.
 */
 void Element::storeInformation()
@@ -1925,7 +1925,7 @@ ElementData Element::elementData() const
 /**
 	@brief Element::elementInformations
 	@return this symbol's information: for a placed symbol the project's
-	store holds it (DB-ACCESSORS-PLAN.md stage 4.2), for one not placed
+	store holds it, for one not placed
 	(a preview, the symbol editor) its own copy.
 */
 DiagramContext Element::elementInformations() const

sources/qetgraphicsitem/terminal.cpp

@@ -1082,10 +1082,19 @@ void Terminal::setMasterLabelIndex(int index)
 	@param terminal : to start search
 	@param all_diagram :if true return all related terminal,
 	false return only terminal in the same diagram of t
+	@param ignore_function_separation : if true, a parent element whose
+	function separation (element information potential_isolating) is
+	enabled does not keep its terminals apart: they all count as one
+	potential, the way they do when the option is disabled. Only the
+	callers that need the conductors a separation hides -- so that the
+	one property still allowed to cross it, the voltage / protocol, can
+	be applied there (@see Conductor::functionSeparatedConductors) --
+	pass true; every other caller keeps the default.
 	@return the list of terminal at the same potential
 */
 QList<Terminal *> relatedPotentialTerminal (
-		const Terminal *terminal, const bool all_diagram)
+		const Terminal *terminal, const bool all_diagram,
+		const bool ignore_function_separation)
 {
 	// If terminal parent element is a folio report.
 	if (all_diagram && terminal -> parentElement() -> linkType() & Element::AllReport)
@@ -1110,14 +1119,18 @@ QList<Terminal *> relatedPotentialTerminal (
 	// If terminal parent element is a Terminal element.
 	else if (terminal -> parentElement() -> linkType() & Element::Terminale)
 	{
-		// English: Check if the user activated the potential isolation checkbox for this terminal
+		// English: Check if the user activated the function separation
-		if (QET::infoFlagIsTrue(terminal->parentElement()->elementInformations().value(QStringLiteral("potential_isolating")).toString())) {
+		// checkbox for this terminal (the checkbox that used to be called
-			// English: Potential is isolated -- but terminals sharing this
+		// potential separation -- the stored flag is still
-			// terminal's own, non-empty potential-group identifier
+		// "potential_isolating" so existing elements keep their setting).
-			// (@see TerminalData::m_potential, set per-terminal in the
+		if (!ignore_function_separation
-			// element editor) still belong to the same physical terminal
+			&& QET::infoFlagIsTrue(terminal->parentElement()->elementInformations().value(QStringLiteral("potential_isolating")).toString())) {
+			// English: The terminals are function separated -- but terminals
+			// sharing this terminal's own, non-empty potential-group
+			// identifier (@see TerminalData::m_potential, set per-terminal in
+			// the element editor) still belong to the same physical terminal
 			// and stay linked to each other. An empty/unset potential on
-			// every terminal reproduces the previous, fully-isolated
+			// every terminal reproduces the previous, fully-separated
 			// behavior exactly, so existing elements are unaffected.
 			const QString this_potential = terminal->potential();
 			QList<Terminal *> same_potential;

sources/qetgraphicsitem/terminal.h

@@ -168,6 +168,7 @@ inline int Terminal::conductorsCount() const
 }
 
 QList<Terminal *> relatedPotentialTerminal (const Terminal *terminal,
-						const bool all_diagram = true);
+						const bool all_diagram = true,
+						const bool ignore_function_separation = false);
 
 #endif

sources/qetproject.cpp

@@ -46,6 +46,7 @@
 #include "qetversion.h"
 #include "undocommand/adddiagramcommand.h"
 
+#include <QCryptographicHash>
 #include <QElapsedTimer>
 #include <QHash>
 #include <QTimer>
@@ -278,6 +279,20 @@ QUuid QETProject::uuid() const
 	return m_uuid;
 }
 
+/**
+	@brief QETProject::containerPicture
+	The folio pictures of a .qetz are kept as bytes beside the document,
+	not as base64 text in it (QetContainer::join()), for as long as the
+	project is open: a folio built after opening still finds its pictures.
+	They cost almost no memory, sharing their bytes with the pictures
+	built from them.
+	@return the picture in @p file, or an empty array when there is none
+*/
+QByteArray QETProject::containerPicture(const QString &file) const
+{
+	return m_container_pictures.value(file);
+}
+
 /**
 	@brief QETProject::derivedItemUuid
 	A uuid for an item of this project that was saved without one, the same
@@ -398,11 +413,25 @@ QUuid QETProject::derivedUuid(const QByteArray &content)
 	static const QUuid project_namespace(
 				QStringLiteral("{c8c75719-0fea-4b1c-9f4b-2dd179fb2f0c}"));
 
-	QByteArray normalized(content);
+		//Same result as QUuid::createUuidV5(project_namespace,
-	normalized.replace('\r', QByteArray());
+		//"qet-project-legacy\n" + content without '\r'), hashed in place :
-	return QUuid::createUuidV5(project_namespace,
+		//copying the content twice took 2 s of opening a 263 MB project.
-							   QByteArrayLiteral("qet-project-legacy\n")
+	QCryptographicHash hash(QCryptographicHash::Sha1);
-							   + normalized);
+	hash.addData(project_namespace.toRfc4122());
+	hash.addData(QByteArrayView("qet-project-legacy\n"));
+	const QByteArrayView view(content);
+	qsizetype start = 0;
+	while (start < view.size()) {
+		qsizetype cr = view.indexOf('\r', start);
+		if (cr < 0)
+			cr = view.size();
+		hash.addData(view.sliced(start, cr - start));
+		start = cr + 1;
+	}
+	QByteArray bytes = hash.result().left(16);
+	bytes[6] = char((bytes[6] & 0x0F) | 0x50); // version 5
+	bytes[8] = char((bytes[8] & 0x3F) | 0x80); // RFC 4122 variant
+	return QUuid::fromRfc4122(bytes);
 }
 
 /**
@@ -456,9 +485,12 @@ QETProject::ProjectState QETProject::openFile(QFile *file)
 	// QetContainer::parse() does exactly that, for a .qet and for each part
 	// of a .qetz alike.
 	QString read_error;
-	if (!QetContainer::readDocument(content, &xml_project, &read_error))
+	int container_format = 0;
+	if (!QetContainer::readDocument(content, &xml_project, &read_error, &m_container_pictures,
+									&container_format))
 	{
 		qWarning().noquote() << "Unable to read" << fi.fileName() << ":" << read_error;
+		m_container_pictures.clear();
 		if(opened_here) {
 			file->close();
 		}
@@ -489,9 +521,16 @@ QETProject::ProjectState QETProject::openFile(QFile *file)
 			<< xml_parse_ms / 1000.0 << ", content "
 			<< (total_ms - xml_parse_ms) / 1000.0 << ")";
 
-	if (!fi.isWritable()) {
+		//Written by a later QElectroTech that lets this one read it: saving
+		//here would drop what this version does not know
+	m_from_later_version = container_format > QetContainer::Format;
+	if (!fi.isWritable() || m_from_later_version) {
 		setReadOnly(true);
 	}
+	if (m_from_later_version) {
+		qInfo().noquote() << QStringLiteral("Project %1 is of .qetz format %2 (this version writes %3): opened read-only")
+							 .arg(fi.fileName()).arg(container_format).arg(QetContainer::Format);
+	}
 	if(opened_here) {
 		file->close();
 	}
@@ -544,7 +583,7 @@ QETProject::ProjectState QETProject::state() const
 QList<Diagram *> QETProject::diagrams() const
 {
 		//Every caller of diagrams() expects every folio built: those that
-		//do not are moved to folios() one by one (LAZY-FOLIO-PLAN.md)
+		//do not are moved to folios() one by one
 	loadFolios();
 	return(m_diagrams_list);
 }
@@ -2291,8 +2330,7 @@ QDomDocument QETProject::toXml(QHash<int, QByteArray> *kept_folios)
 		loadFolios();
 	}
 		//QET_CHECK_ELEMENT_INFO_STORE=1: say whether the stores of symbol
-		//information, folio title blocks and wire properties
+		//information, folio title blocks and wire properties agree with every placed symbol, folio and
-		//(DB-ACCESSORS-PLAN.md) agree with every placed symbol, folio and
 		//wire, at each save. A test and debugging aid; it changes nothing.
 	if (qEnvironmentVariableIntValue("QET_CHECK_ELEMENT_INFO_STORE") == 1) {
 		const QStringList mismatches = m_data_base.elementInformationMismatches();
@@ -3015,9 +3053,22 @@ void QETProject::readProjectXml(QDomDocument &xml_project)
 
 		//The stores of symbol information, folio title blocks and wire
 		//properties are filled from the document before the folios are
-		//built (DB-ACCESSORS-PLAN.md stage 4.6)
+		//built
 	m_data_base.prefillFromDocument(xml_project);
 
+		//QET_LAZY_FOLIOS leaves the folios to be built when needed only
+		//when the database can be filled from the document: otherwise
+		//filling it from the folios builds every one of them anyway, late
+		//and more slowly than reading them now
+	m_lazy_open = qEnvironmentVariableIntValue("QET_LAZY_FOLIOS") == 1;
+	if (m_lazy_open) {
+		const QString why = projectDataBase::documentRefusal(xml_project);
+		if (!why.isEmpty()) {
+			qInfo().noquote() << "Project opened with every folio built:" << why;
+			m_lazy_open = false;
+		}
+	}
+
 		//Load the diagrams
 	readDiagramsXml(xml_project);
 	const qint64 diagrams_ms = phase_timer.restart();
@@ -3057,7 +3108,6 @@ void QETProject::readProjectXml(QDomDocument &xml_project)
 		//number can hold what a save rewrites (tst_freetextnonfinite,
 		//tst_foliofreezeflags): only with QET_LAZY_SAVE_KEPT=1, until a
 		//.qetz, whose manifest names its writer, does it
-		//(QETZ-DB-TRUTH-PLAN.md D4)
 	m_kept_folios_trusted = qEnvironmentVariableIntValue("QET_LAZY_SAVE_KEPT") == 1
 			&& unloadedFolioCount() > 0
 			&& m_project_qet_version == QetVersion::currentVersion()
@@ -3134,7 +3184,7 @@ void QETProject::readDiagramsXml(QDomDocument &xml_project)
 		//Where each line of the file starts, for a folio's text: lines
 		//[its start, the next element's start) (QETProject::toXml())
 	QList<qsizetype> line_starts;
-	if (qEnvironmentVariableIntValue("QET_LAZY_FOLIOS") == 1 && !m_opened_content.isEmpty()) {
+	if (m_lazy_open && !m_opened_content.isEmpty()) {
 		line_starts << 0;
 		for (qsizetype i = 0 ; i < m_opened_content.size() ; ++i)
 			if (m_opened_content.at(i) == '\n') line_starts << i + 1;
@@ -3181,7 +3231,7 @@ void QETProject::readDiagramsXml(QDomDocument &xml_project)
 			connect(diagram, &Diagram::usedTitleBlockTemplateChanged,
 					this, &QETProject::usedTitleBlockTemplateChanged);
 
-			m_deferring_folios = qEnvironmentVariableIntValue("QET_LAZY_FOLIOS") == 1;
+			m_deferring_folios = m_lazy_open;
 			diagram->initFromXml(diagram_xml_element);
 			m_deferring_folios = false;
 			if (!diagram->isLoaded() && !line_starts.isEmpty())

sources/qetproject.h

@@ -119,10 +119,11 @@ class QETProject : public QObject
 		projectDataBase *dataBase();
 		QUuid uuid() const;
 		QUuid derivedItemUuid(const QString &kind, const QString &key);
+		QByteArray containerPicture(const QString &file) const;
 		ProjectState state() const;
 		QList<Diagram *> diagrams() const;
 			//The folios whether their items are built or not
-			//(QET_LAZY_FOLIOS, LAZY-FOLIO-PLAN.md); diagrams() builds them
+			//(QET_LAZY_FOLIOS); diagrams() builds them
 		QList<Diagram *> folios() const;
 		bool deferringFolios() const {return m_deferring_folios;}
 		int unloadedFolioCount() const;
@@ -318,6 +319,8 @@ class QETProject : public QObject
 		bool close();
 		QETResult write();
 		bool isReadOnly() const;
+			/// Opened from a .qetz of a later format (opened read-only)
+		bool isFromLaterVersion() const {return m_from_later_version;}
 		void setReadOnly(bool);
 		bool isEmpty() const;
 		ElementsLocation importElement(ElementsLocation &location);
@@ -448,6 +451,9 @@ class QETProject : public QObject
 		static bool m_backup_enabled;
 			/// Something changed since the last backup, see writeBackup()
 		bool m_backup_needed = true;
+			/// The pictures of the .qetz this project was opened from, see
+			/// containerPicture()
+		QHash<QString, QByteArray> m_container_pictures;
 			/// File path this project is saved to
 		QString m_file_path;
 			/// Current state of the project
@@ -462,6 +468,7 @@ class QETProject : public QObject
 		bool m_modified = false;
 			/// Whether the project is read only
 		bool m_read_only = false;
+		bool m_from_later_version = false;
 			/// Filepath for which this project is considered read only
 		QString read_only_file_path_;
 			/// Default dimensions and properties for new diagrams created within the project
@@ -512,6 +519,9 @@ class QETProject : public QObject
 				const DiagramContext &information,
 				const QHash<QString, QStringList> &titles_by_formula) const;
 		bool m_deferring_folios = false;
+			/// Opening with folios built only when needed: QET_LAZY_FOLIOS
+			/// is set and the database can be filled from the document
+		bool m_lazy_open = false;
 			/// Saving may write a folio not built as it was read
 			/// (writesKeptFolios()): the file is this version's, its
 			/// database rows came from it, and nothing project-wide that

sources/scripting/qetscriptapi.cpp

@@ -1189,6 +1189,10 @@ QString QetScriptApi::conductorProperty(int folioIndex, const QString &elementUu
 	describes a potential and not one drawn segment. Setting it on one
 	conductor and leaving the rest of the potential disagreeing would
 	produce a file no GUI action could have produced.
+
+	One thing stops at a terminal element with its function separation
+	enabled: every property but the voltage / protocol, which still
+	crosses it (@see Conductor::functionSeparatedConductors).
 	@return true if anything was changed, or if it already held that value
 */
 bool QetScriptApi::setConductorProperty(int folioIndex, const QString &elementUuid,
@@ -1209,13 +1213,17 @@ bool QetScriptApi::setConductorProperty(int folioIndex, const QString &elementUu
 	Conductor *conductor = findConductor(folioIndex, elementUuid, terminalIndex, caller);
 	if (!conductor) return false;
 
-	ConductorProperties properties = conductor->properties();
+	//Captured before the pushes below: QPropertyUndoCommand applies on
+	//push, so reading the properties afterwards would already give back
+	//@a properties.
+	const ConductorProperties before = conductor->properties();
+	ConductorProperties properties = before;
 	if (!setConductorPropertyValue(properties, property, value)) {
 		log(QStringLiteral("qet.%1: '%2' is not a valid value for %3")
 			.arg(caller, value, property));
 		return false;
 	}
-	if (properties == conductor->properties()) return true; // already so
+	if (properties == before) return true; // already so
 
 	QSet<Conductor *> potential = conductor->relatedPotentialConductors(true);
 	potential << conductor;
@@ -1227,6 +1235,25 @@ bool QetScriptApi::setConductorProperty(int folioIndex, const QString &elementUu
 		old_value.setValue(c->properties());
 		new_value.setValue(properties);
 		m_project->undoStack()->push(new QPropertyUndoCommand(c, "properties", old_value, new_value));
+	}
+		//The other side of a function separated terminal element gets the
+		//voltage / protocol only: it is the one property that still
+		//describes the electrical node rather than one side of it. And it
+		//only arrives when this call really changed it -- before / after
+		//is the edit, not the far wire's own value, which differs from it
+		//just as often as not and would then be overwritten by every call,
+		//colour included.
+	for (Conductor *c : conductor->functionSeparatedConductors(true))
+	{
+		ConductorProperties separated_properties = c->properties();
+		separated_properties.applyTensionProtocolChange(before, properties);
+		if (separated_properties == c->properties())
+			continue;
+
+		QVariant old_value, new_value;
+		old_value.setValue(c->properties());
+		new_value.setValue(separated_properties);
+		m_project->undoStack()->push(new QPropertyUndoCommand(c, "properties", old_value, new_value));
 	}
 	m_project->undoStack()->endMacro();
 	return true;

sources/ui/conductorpropertiesdialog.cpp

@@ -88,6 +88,37 @@ void ConductorPropertiesDialog::PropertiesDialog(Conductor *conductor,
 		}
 	}
 
+		//A function separated terminal element (element information
+		//potential_isolating) keeps the two sides of the terminal apart:
+		//every property but one stays local to the side it was edited on.
+		//The voltage / protocol still crosses, because it describes the
+		//electrical node and not one side of it.
+	if (cpd.applyAll())
+	{
+			//Only an edit that really changed the voltage / protocol passes
+			//it on, so the comparison is the edit itself -- what the dialog
+			//was filled with, against what the user left in it -- and never
+			//the far wire's own value, which differs from it just as often
+			//as not (a 24 V side against a 0 V one, say) and would then be
+			//overwritten by every edit, voltage included.
+		const ConductorProperties shown = conductor->properties();
+		foreach (Conductor *separated_conductor, conductor->functionSeparatedConductors())
+		{
+			ConductorProperties separated_properties = separated_conductor->properties();
+			separated_properties.applyTensionProtocolChange(
+						shown,
+						cpd.properties());
+			if (separated_properties == separated_conductor->properties())
+				continue;
+
+			QVariant separated_old_value, separated_new_value;
+			separated_old_value.setValue(separated_conductor->properties());
+			separated_new_value.setValue(separated_properties);
+			new QPropertyUndoCommand (separated_conductor, "properties",
+						  separated_old_value, separated_new_value, undo);
+		}
+	}
+
 	conductor->diagram()->undoStack().push(undo);
 }
 

sources/ui/conductorpropertieseditorwidget.cpp

@@ -346,7 +346,10 @@ void ConductorPropertiesEditorWidget::updateUi()
 	When "apply to all" is ticked, every conductor on the same potential as
 	an edited one is updated too, in the same undo step (one undo reverts
 	them all), as the modal dialog does
-	(ConductorPropertiesDialog::PropertiesDialog).
+	(ConductorPropertiesDialog::PropertiesDialog). A terminal element with
+	its function separation enabled is not crossed by any of that -- its
+	other side keeps its own text, function, color... -- but the voltage /
+	protocol still crosses (@see Conductor::functionSeparatedConductors).
 */
 QUndoCommand *ConductorPropertiesEditorWidget::associatedUndo() const
 {
@@ -360,10 +363,12 @@ QUndoCommand *ConductorPropertiesEditorWidget::associatedUndo() const
 		if (c)
 			selected << c.data();
 
-	return ConductorMultiEdit::undo(
+	QSet<Conductor *> function_separated;
-		ConductorMultiEdit::targets(
+	const QList<Conductor *> targets = ConductorMultiEdit::targets(
-			selected, m_apply_all_cb && m_apply_all_cb->isChecked()),
+		selected, m_apply_all_cb && m_apply_all_cb->isChecked(),
-		m_shown, edited);
+		&function_separated);
+
+	return ConductorMultiEdit::undo(targets, m_shown, edited, function_separated);
 }
 
 /**

sources/ui/elementinfowidget.cpp

@@ -313,8 +313,9 @@ void ElementInfoWidget::buildInterface()
 
 	ui->scroll_vlayout->addStretch();
 
-	// Existing potential isolating checkbox
+	// Existing function separation checkbox (stored as the
-	m_potential_isolating_cb = new QCheckBox(tr("Potential separation"), this);
+	// "potential_isolating" element information)
+	m_potential_isolating_cb = new QCheckBox(tr("Function separation"), this);
 	m_potential_isolating_cb->setStyleSheet(QStringLiteral("margin: 5px; font-weight: bold;"));
 
 	// English: Initialize and style the BOM exclusion checkbox

tests/qttest/CMakeLists.txt

@@ -271,6 +271,19 @@ qet_add_app_test(tst_rotateselectionimage tst_rotateselectionimage.cpp)
 # it selected and records no undo step (#1414); the key goes to the view.
 qet_add_app_test(tst_imagehandleescape tst_imagehandleescape.cpp)
 
+# A folio's pictures, decoded in parallel, each come back with its own
+# pixels and position; an <image> with no picture does not stop the others.
+qet_add_app_test(tst_folioimageload tst_folioimageload.cpp)
+
+# SVG export with smaller pictures (--svg-small-pictures, the export dialog's
+# option): a picture drawn at a tenth of its size is stored at four times
+# that, a small one whole; without the option every picture is whole.
+qet_add_app_test(tst_svgsmallpictures tst_svgsmallpictures.cpp)
+add_dependencies(tst_svgsmallpictures qelectrotech)
+target_link_libraries(tst_svgsmallpictures PRIVATE Qt::Svg)
+target_compile_definitions(tst_svgsmallpictures PRIVATE
+  "QET_TEST_BINARY_PATH=\"$<TARGET_FILE:qelectrotech>\"")
+
 # TextResizeHandles: the corner handles that change the width of a text box,
 # on a plain QGraphicsTextItem with the "textWidth" property QET texts have.
 add_executable(
@@ -1253,4 +1266,6 @@ add_test(NAME tst_qetcontainer COMMAND tst_qetcontainer)
 target_include_directories(tst_qetcontainer PRIVATE ${QET_DIR}/sources)
 target_link_libraries(tst_qetcontainer PRIVATE Qt::Test Qt::Xml SQLite3::SQLite3)
 target_compile_definitions(tst_qetcontainer PRIVATE
-  "QET_EXAMPLES_DIR=\"${QET_DIR}/examples\"")
+  "QET_EXAMPLES_DIR=\"${QET_DIR}/examples\""
+  "QET_FIXTURES_DIR=\"${CMAKE_CURRENT_SOURCE_DIR}/fixtures\""
+  "QET_FORMAT_SPEC=\"${QET_DIR}/sources/container/QETZ-FORMAT.md\"")

tests/qttest/fixtures/svg_small_pictures.qet

@@ -0,0 +1,41 @@
+<project title="A large picture shown small" uuid="{3f6a2c91-8d47-4b5e-a0c3-91e2d7b4f600}" version="0.200.1">
+    <properties>
+        <property name="saveddate" show="1">10/2/26</property>
+        <property name="saveddate-eu" show="1">02-10-2026</property>
+        <property name="saveddate-us" show="1">2026-10-02</property>
+        <property name="savedfilename" show="1">svg_small_pictures</property>
+        <property name="savedtime" show="1">18:39</property>
+    </properties>
+    <usage enabled="true" time_spent="0"/>
+    <newdiagrams>
+        <border cols="17" colsize="60" displaycols="true" displayrows="true" rows="8" rowsize="80"/>
+        <inset author="" auto_page_num="" date="null" displayAt="bottom" filename="" folio="" indexrev="" locmach="" plant="" title="" version=""/>
+        <conductors bicolor="false" bus="" cable="" color2="#000000" condsize="1" conductor_color="" conductor_section="" dash-size="1" displaytext="1" formula="" function="" horizontal-alignment="AlignBottom" horizrotatetext="0" num="_" numsize="7" onetextperfolio="0" tension_protocol="" text_color="#000000" type="multi" vertical-alignment="AlignRight" vertirotatetext="270"/>
+        <report label="%f-%l%c"/>
+        <xrefs>
+            <xref delayprefix="" displayhas="cross" master_label="%f-%l%c" offset="0" powerprefix="" showallconfiguredslaves="false" showpowerctc="true" showterminalname="true" slave_label="(%f-%l%c)" slave_offset="0" snapto="label" switchprefix="" type="coil" xrefpos="AlignBottom"/>
+            <xref delayprefix="" displayhas="cross" master_label="%f-%l%c" offset="0" powerprefix="" showallconfiguredslaves="false" showpowerctc="true" showterminalname="true" slave_label="(%f-%l%c)" slave_offset="0" snapto="label" switchprefix="" type="commutator" xrefpos="AlignBottom"/>
+            <xref delayprefix="" displayhas="cross" master_label="%f-%l%c" offset="0" powerprefix="" showallconfiguredslaves="false" showpowerctc="true" showterminalname="true" slave_label="(%f-%l%c)" slave_offset="0" snapto="label" switchprefix="" type="plc" xrefpos="AlignBottom"/>
+            <xref delayprefix="" displayhas="cross" master_label="%f-%l%c" offset="0" powerprefix="" showallconfiguredslaves="false" showpowerctc="true" showterminalname="true" slave_label="(%f-%l%c)" slave_offset="0" snapto="label" switchprefix="" type="protection" xrefpos="AlignBottom"/>
+        </xrefs>
+        <conductors_autonums auto_break_conductors="false" current_autonum="" freeze_new_conductors="false"/>
+        <folio_autonums/>
+        <element_autonums current_autonum="" freeze_new_elements="false"/>
+        <guides/>
+    </newdiagrams>
+    <diagram author="" auto_page_num="" cols="17" colsize="60" date="null" displayAt="bottom" displaycols="true" displayrows="true" filename="" folio="" freezeNewConductor="false" freezeNewElement="false" height="660" indexrev="" locmach="" order="1" plant="" rows="8" rowsize="80" title="" uuid="{3f6a2c91-8d47-4b5e-a0c3-91e2d7b4f610}" version="0.200.1-dev">
+        <defaultconductor bicolor="false" bus="" cable="" color2="#000000" condsize="1" conductor_color="" conductor_section="" dash-size="1" displaytext="1" formula="" function="" horizontal-alignment="AlignBottom" horizrotatetext="0" num="_" numsize="7" onetextperfolio="0" tension_protocol="" text_color="#000000" type="multi" vertical-alignment="AlignRight" vertirotatetext="270"/>
+        <inputs/>
+        <images>
+            <image z="0" rotation="0" y="100" x="100" size="0.1" is_movable="1">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</image>
+            <image z="0" rotation="0" y="300" x="100" size="1" is_movable="1">iVBORw0KGgoAAAANSUhEUgAAACgAAAAeCAIAAADRv8uKAAAAP0lEQVR42u3PMQoAIAwEwRVC1F/7dFuxFoKwqS7XHNNgJSR0OMP1Pu+DQckFs2pYsWLFihUrVqxYsWLFir8Rb7mhAuQBqxaIAAAAAElFTkSuQmCC</image>
+        </images>
+    </diagram>
+    <collection>
+        <category name="import">
+            <names>
+                <name lang="en">Imported elements</name>
+            </names>
+        </category>
+    </collection>
+</project>

tests/qttest/lazy_folios_probe.cpp

@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: GPL-2.0-or-later
-// Lazy folios (QET_LAZY_FOLIOS, LAZY-FOLIO-PLAN.md stages 5.2 and 5.3),
+// Lazy folios (QET_LAZY_FOLIOS),
 // linked against the application's objects: a folio shown in a project
 // opened without building its folios draws and links as in the project
 // opened as usual, building only it and the folios its links and tables
@@ -37,6 +37,8 @@
 #include "../../sources/undocommand/deleteqgraphicsitemcommand.h"
 #include "../../sources/factory/elementfactory.h"
 #include "../../sources/undocommand/addgraphicsobjectcommand.h"
+#include "../../sources/dataBase/projectdatabase.h"
+#include <QDomDocument>
 
 static void check(bool value, const char *message) { if (!value) throw std::runtime_error(message); }
 
@@ -567,6 +569,44 @@ int main(int argc, char **argv)
 			check(potential(wire) == potential(usual_wire), "a potential followed as when built");
 			std::printf("potential through reports: %d wires, %d folios not built\n",
 						int(potential(wire).size()), followed.unloadedFolioCount());
+		}
+			//Two symbols sharing a uuid: the database is filled from the
+			//folios, which builds every one of them, so the project opens
+			//with every folio built rather than building them all later
+		{
+			QFile file(path);
+			check(file.open(QIODevice::ReadOnly), "fixture read");
+			QDomDocument document;
+			check(bool(document.setContent(&file)), "fixture parsed");
+			file.close();
+			check(projectDataBase::documentRefusal(document).isEmpty(), "the fixture fills the database itself");
+			QDomNodeList elements = document.elementsByTagName(QStringLiteral("element"));
+			QList<QDomElement> placed;
+			for (int i = 0; i < elements.size(); ++i) {
+				QDomElement e = elements.at(i).toElement();
+				if (Element::valideXml(e)) placed << e;
+			}
+			check(placed.size() > 1, "two placed symbols");
+			placed.last().setAttribute(QStringLiteral("uuid"), placed.first().attribute(QStringLiteral("uuid")));
+			check(!projectDataBase::documentRefusal(document).isEmpty(), "a shared uuid is seen before the folios are read");
+			const QString shared = output + "/lazy_folios_shared_uuid.qet";
+			QFile out(shared);
+			check(out.open(QIODevice::WriteOnly), "copy written");
+			out.write(document.toByteArray(4));
+			out.close();
+			qputenv("QET_LAZY_FOLIOS", "1");
+			qputenv("QET_LAZY_FOLIOS_TRACE", "1");
+			static int built_late; built_late = 0;
+			const QtMessageHandler previous = qInstallMessageHandler(
+					[](QtMsgType, const QMessageLogContext &, const QString &message) {
+				if (message.contains(QStringLiteral("built for a caller of diagrams()"))) ++built_late;
+			});
+			QETProject opened(shared);
+			qInstallMessageHandler(previous);
+			qunsetenv("QET_LAZY_FOLIOS_TRACE");
+			check(opened.state() == QETProject::Ok, "a project with a shared uuid opens");
+			check(opened.unloadedFolioCount() == 0, "a project with a shared uuid opens with every folio built");
+			check(built_late == 0, "a project with a shared uuid builds its folios as it reads them, not later");
 		}
 		std::printf("PASS: %d folios\n", int(folios.size()));
 	} catch (const std::exception &error) {

tests/qttest/tst_conductormultiedit.cpp

@@ -29,6 +29,10 @@ class FakeWire : public QObject
 		ConductorProperties properties() const { return m_properties; }
 		void setProperties(const ConductorProperties &p) { m_properties = p; }
 		QSet<FakeWire *> relatedPotentialConductors() const { return m_potential; }
+			// The wires of the other side of a function separated terminal
+			// element: same electrical node, but only the voltage /
+			// protocol crosses.
+		QSet<FakeWire *> functionSeparatedConductors() const { return m_separated; }
 		QPointF pos() const { return m_pos; }
 
 			// Joins wires into one potential; like the real one, a wire's
@@ -41,10 +45,24 @@ class FakeWire : public QObject
 						w->m_potential.insert(o);
 		}
 
+			// Marks two groups as separated by a function separated
+			// terminal element, without joining their potentials.
+		static void separate(const QList<FakeWire *> &one,
+				     const QList<FakeWire *> &other)
+		{
+			for (FakeWire *w : one)
+				for (FakeWire *o : other)
+				{
+					w->m_separated.insert(o);
+					o->m_separated.insert(w);
+				}
+		}
+
 		ConductorProperties m_properties;
 
 	private:
 		QSet<FakeWire *> m_potential;
+		QSet<FakeWire *> m_separated;
 		QPointF m_pos;
 };
 
@@ -102,6 +120,143 @@ class tst_conductormultiedit : public QObject
 				 (QSet<FakeWire *> {&a, &b, &c, &d}));
 		}
 
+			// A function separated terminal element: the other side of the
+			// terminal is reached too, but only the voltage / protocol
+			// crosses it -- not the function, not the number.
+		void functionSeparatedGetsVoltageProtocolOnly()
+		{
+			FakeWire a("1", "fnA", "", {}), b("2", "fnB", "", {}),
+				 c("3", "fnC", "", {});
+			FakeWire::join({&a, &b});
+			FakeWire::separate({&a}, {&c});
+
+			QSet<FakeWire *> separated;
+			const Wires t = ConductorMultiEdit::targets(Wires {&a}, true,
+								      &separated);
+			QCOMPARE(QSet<FakeWire *>(t.begin(), t.end()),
+				 (QSet<FakeWire *> {&a, &b, &c}));
+			QCOMPARE(separated, (QSet<FakeWire *> {&c}));
+				// A caller that does not know about the rule gets the
+				// separated side left out, as before
+			QCOMPARE(ConductorMultiEdit::targets(Wires {&a}, true),
+				 (Wires {&a, &b}));
+
+			const ConductorProperties shown = a.properties();
+			ConductorProperties after = edited(shown,
+				&ConductorProperties::m_function, "PWR");
+			after.m_tension_protocol = "24V";
+
+			QUndoStack stack;
+			stack.push(ConductorMultiEdit::undo(t, shown, after, separated));
+			QCOMPARE(stack.count(), 1);
+
+			for (FakeWire *w : {&a, &b})
+			{
+				QCOMPARE(w->m_properties.m_function, QStringLiteral("PWR"));
+				QCOMPARE(w->m_properties.m_tension_protocol,
+					 QStringLiteral("24V"));
+			}
+			QCOMPARE(c.m_properties.m_function, QStringLiteral("fnC"));
+			QCOMPARE(c.m_properties.text, QStringLiteral("3"));
+			QCOMPARE(c.m_properties.m_tension_protocol, QStringLiteral("24V"));
+
+			stack.undo();
+			QVERIFY(c.properties().m_tension_protocol.isEmpty());
+			QCOMPARE(c.m_properties.m_function, QStringLiteral("fnC"));
+		}
+
+			// The explicitly picked side of a separation: selecting one
+			// wire on each side and editing them edits them both, in
+			// full -- however the selection happens to be walked (#review)
+		void selectedWireIsNeverSeparated()
+		{
+			FakeWire a("1", "fnA", "", {}), c("3", "fnC", "", {});
+			FakeWire::separate({&a}, {&c});
+
+			const ConductorProperties original_a = a.properties();
+			const ConductorProperties original_c = c.properties();
+			const ConductorProperties after = edited(original_a,
+				&ConductorProperties::m_function, "PWR");
+
+			for (const Wires &selection : {Wires {&a, &c}, Wires {&c, &a}})
+			{
+					//Each order starts from the same, unedited state
+				a.setProperties(original_a);
+				c.setProperties(original_c);
+
+				QSet<FakeWire *> separated;
+				const Wires t = ConductorMultiEdit::targets(selection, true,
+								      &separated);
+					//c is picked, so it is not "the far side" of anything
+				QCOMPARE(separated, (QSet<FakeWire *> {}));
+
+				QUndoStack stack;
+				QUndoCommand *undo = ConductorMultiEdit::undo(t, original_a,
+									     after, separated);
+				QVERIFY(undo);
+				stack.push(undo);
+				QCOMPARE(a.m_properties.m_function, QStringLiteral("PWR"));
+				QCOMPARE(c.m_properties.m_function, QStringLiteral("PWR"));
+			}
+		}
+
+			// A wire that belongs to the potential as well -- on any path,
+			// however far that path runs -- takes the full edit, even when a
+			// separation also reaches it. The fake's potential is one hop
+			// deep, unlike the real one, so the shared potential is stated
+			// in full here.
+		void wireReachableBothWaysIsNotSeparated()
+		{
+			FakeWire a("1", "fnA", "", {}), b("2", "fnB", "", {}),
+				 c("3", "fnC", "", {});
+			FakeWire::join({&a, &b, &c});
+			FakeWire::separate({&a}, {&c});
+
+			QSet<FakeWire *> separated;
+			const Wires t = ConductorMultiEdit::targets(Wires {&a}, true,
+								      &separated);
+			QCOMPARE(QSet<FakeWire *>(t.begin(), t.end()),
+				 (QSet<FakeWire *> {&a, &b, &c}));
+			QCOMPARE(separated, (QSet<FakeWire *> {}));
+
+			const ConductorProperties shown = a.properties();
+			QUndoStack stack;
+			stack.push(ConductorMultiEdit::undo(t, shown, edited(shown,
+				&ConductorProperties::m_function, "PWR"), separated));
+			QCOMPARE(c.m_properties.m_function, QStringLiteral("PWR"));
+		}
+
+			// The far side only takes the voltage when the edit changed it:
+			// editing the function of a 24 V wire must leave the 0 V one
+			// at 0 V, not drag it along (#review)
+		void separatedWireKeepsVoltageWhenNotEdited()
+		{
+			FakeWire a("1", "fnA", "", {}), c("3", "fnC", "", {});
+			FakeWire::separate({&a}, {&c});
+			a.m_properties.m_tension_protocol = "24V";
+			c.m_properties.m_tension_protocol = "0V";
+
+			QSet<FakeWire *> separated;
+			const Wires t = ConductorMultiEdit::targets(Wires {&a}, true,
+								      &separated);
+			const ConductorProperties shown = a.properties();
+			QUndoStack stack;
+
+				//Only the function changes: the far side changes nothing
+			stack.push(ConductorMultiEdit::undo(t, shown, edited(shown,
+				&ConductorProperties::m_function, "PWR"), separated));
+			QCOMPARE(c.m_properties.m_function, QStringLiteral("fnC"));
+			QCOMPARE(c.m_properties.m_tension_protocol, QStringLiteral("0V"));
+
+				//Now the voltage changes too: it crosses, and only it
+			const ConductorProperties shown_now = a.properties();
+			stack.push(ConductorMultiEdit::undo(t, shown_now, edited(shown_now,
+				&ConductorProperties::m_tension_protocol, "30V"), separated));
+			QCOMPARE(c.m_properties.m_tension_protocol, QStringLiteral("30V"));
+			QCOMPARE(c.m_properties.m_function, QStringLiteral("fnC"));
+			QCOMPARE(a.m_properties.m_tension_protocol, QStringLiteral("30V"));
+		}
+
 			// One edit of three wires: each takes the function, keeps its
 			// own number and cable; one undo restores all three exactly
 		void undoRedoThreeWires()

tests/qttest/tst_folioimageload.cpp

@@ -0,0 +1,132 @@
+/*
+	Copyright 2006-2026 The QElectroTech Team
+	This file is part of QElectroTech.
+
+	QElectroTech is free software: you can redistribute it and/or modify
+	it under the terms of the GNU General Public License as published by
+	the Free Software Foundation, either version 2 of the License, or
+	(at your option) any later version.
+
+	QElectroTech is distributed in the hope that it will be useful,
+	but WITHOUT ANY WARRANTY; without even the implied warranty of
+	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+	GNU General Public License for more details.
+
+	You should have received a copy of the GNU General Public License
+	along with QElectroTech.  If not, see <http://www.gnu.org/licenses/>.
+*/
+#include "qetapptest.h"
+#include "diagramcontent.h"
+#include "qetgraphicsitem/diagramimageitem.h"
+
+#include <QDomDocument>
+#include <QRandomGenerator>
+
+/**
+	Diagram::fromXml() decodes a folio's pictures in parallel, then builds
+	the items in file order. Every picture must come back with its own
+	pixels and position, whatever thread decoded it.
+*/
+class tst_folioimageload : public QObject
+{
+	Q_OBJECT
+
+	Diagram *m_diagram = nullptr;
+
+	/// A picture no other one equals: its own size and noise.
+	static QImage distinctImage(int n)
+	{
+		QImage image(40 + 7 * n, 30 + 3 * n, QImage::Format_ARGB32);
+		QRandomGenerator random(quint32(n + 1));
+		for (int y = 0 ; y < image.height() ; ++y)
+			for (int x = 0 ; x < image.width() ; ++x)
+				image.setPixel(x, y, random.generate() | 0xFF000000);
+		return image;
+	}
+
+	static QImage pixelsOf(const DiagramImageItem *item)
+	{
+		return item->pixmap().toImage()
+				.convertToFormat(QImage::Format_ARGB32);
+	}
+
+	void removePictures()
+	{
+			// A selected picture's handles are its children, in items()
+			// too: deleting the picture first would leave them dangling.
+		m_diagram->clearSelection();
+		for (QGraphicsItem *item : m_diagram->items())
+			if (item->type() == DiagramImageItem::Type)
+				delete item;
+	}
+
+private slots:
+	void initTestCase()
+	{
+		QVERIFY(QetAppTest::editor());
+		m_diagram = QetAppTest::diagram();
+		QVERIFY(m_diagram);
+	}
+
+	void cleanup()
+	{
+		m_diagram->clearSelection();
+		removePictures();
+		m_diagram->undoStack().clear();
+	}
+
+	void everyPictureComesBackWithItsPixels()
+	{
+		QHash<int, QImage> expected;	// by x position, each its own
+		for (int n = 0 ; n < 6 ; ++n) {
+			const QImage image = distinctImage(n);
+			auto *picture = new DiagramImageItem(QPixmap::fromImage(image));
+			m_diagram->addItem(picture);
+			picture->setPos(100 + 150 * n, 200);
+			picture->setSelected(true);
+			expected.insert(qRound(picture->pos().x()), image);
+		}
+		QDomDocument document = m_diagram->toXml(false);
+		removePictures();
+
+		DiagramContent content;
+		QVERIFY(m_diagram->fromXml(document, QPointF(), false, &content));
+
+		QCOMPARE(content.m_images.size(), expected.size());
+		for (const DiagramImageItem *picture : std::as_const(content.m_images)) {
+			const int x = qRound(picture->pos().x());
+			QVERIFY2(expected.contains(x), "picture moved");
+			QCOMPARE(picture->pos().y(), 200.0);
+			QCOMPARE(pixelsOf(picture), expected.value(x));
+		}
+	}
+
+	void anImageWithoutPictureDoesNotStopTheOthers()
+	{
+		for (int n = 0 ; n < 3 ; ++n) {
+			auto *picture = new DiagramImageItem(
+						QPixmap::fromImage(distinctImage(n)));
+			m_diagram->addItem(picture);
+			picture->setSelected(true);
+		}
+		QDomDocument document = m_diagram->toXml(false);
+		removePictures();
+		QDomElement images = document.documentElement()
+				.firstChildElement(QStringLiteral("images"));
+		QVERIFY(!images.isNull());
+		QDomElement empty = document.createElement(QStringLiteral("image"));
+		images.insertBefore(empty, images.firstChild());
+
+		DiagramContent content;
+		QVERIFY(m_diagram->fromXml(document, QPointF(), false, &content));
+
+		int with_pixels = 0;
+		for (const DiagramImageItem *picture : std::as_const(content.m_images))
+			if (!picture->pixmap().isNull())
+				++with_pixels;
+		QCOMPARE(with_pixels, 3);
+	}
+};
+
+QET_APP_TEST_MAIN(tst_folioimageload)
+#include "tst_folioimageload.moc"

tests/qttest/tst_qetcontainer.cpp

@@ -69,6 +69,57 @@ class tst_qetcontainer : public QObject
 		return QetContainer::split(*original, QStringLiteral("tst_qetcontainer"), &error);
 	}
 
+	static QByteArray entry(const QList<QetZip::Entry> &entries, const QString &name)
+	{
+		for (const QetZip::Entry &e : entries)
+			if (e.name == name) return e.data;
+		return {};
+	}
+
+	static QByteArray folioFiles(const QList<QetZip::Entry> &entries)
+	{
+		QByteArray all;
+		for (const QetZip::Entry &e : entries)
+			if (e.name.startsWith(QStringLiteral("folios/"))) all += e.data;
+		return all;
+	}
+
+		// The first column of the first row @p sql gives, from @p database
+	static QString query(const QByteArray &database, const char *sql)
+	{
+		sqlite3 *db = nullptr;
+		sqlite3_open(":memory:", &db);
+		unsigned char *copy = static_cast<unsigned char *>(sqlite3_malloc64(sqlite3_uint64(database.size())));
+		memcpy(copy, database.constData(), size_t(database.size()));
+		sqlite3_deserialize(db, "main", copy, database.size(), database.size(), SQLITE_DESERIALIZE_FREEONCLOSE);
+		sqlite3_stmt *st = nullptr;
+		QString out;
+		if (sqlite3_prepare_v2(db, sql, -1, &st, nullptr) == SQLITE_OK && sqlite3_step(st) == SQLITE_ROW)
+			out = QString::fromUtf8(reinterpret_cast<const char *>(sqlite3_column_text(st, 0)));
+		sqlite3_finalize(st);
+		sqlite3_close(db);
+		return out;
+	}
+
+		// grafcet.qet as QElectroTech saves it: every folio, symbol and wire
+		// with a uuid of its own, which the examples' wires and folios lack
+	static QDomDocument savedProject()
+	{
+		QList<QetZip::Entry> entries;
+		QDomDocument project;
+		QetZip::fromBytes(read(QStringLiteral(QET_FIXTURES_DIR "/qetz_format2.qetz")), &entries);
+		QetContainer::join(entries, &project);
+		return project;
+	}
+
+	static QString backDifference(const QDomDocument &original, const QList<QetZip::Entry> &entries)
+	{
+		QDomDocument back;
+		QString error;
+		if (!QetContainer::join(entries, &back, &error)) return error;
+		return difference(original.documentElement(), back.documentElement(), QString());
+	}
+
 private slots:
 	void sameDocumentBack_data()
 	{
@@ -242,7 +293,145 @@ private slots:
 		QVERIFY(pictures < 121);   // the 121 placed pictures repeat a few files
 	}
 
+	// Given a map, join() hands the pictures over as bytes instead of
+	// putting them back in the document as base64
+	void picturesKeptAside()
+	{
+		QDomDocument original;
+		QList<QetZip::Entry> entries = splitFile(
+					QStringLiteral(QET_EXAMPLES_DIR "/weneedpolonez-Polonez_MR89_wiring_diagram.qet"), &original);
+		QVERIFY(!entries.isEmpty());
+		QHash<QString, QByteArray> files;
+		for (const QetZip::Entry &e : entries) files.insert(e.name, e.data);
+
+		QDomDocument back;
+		QetContainer::Pictures pictures;
+		QString error;
+		QVERIFY2(QetContainer::join(entries, &back, &error, &pictures), qPrintable(error));
+		const QDomNodeList images = back.elementsByTagName(QStringLiteral("image"));
+		const QDomNodeList original_images = original.elementsByTagName(QStringLiteral("image"));
+		QCOMPARE(images.size(), 121);
+		QCOMPARE(images.size(), original_images.size());
+		for (int i = 0 ; i < images.size() ; ++i) {
+			const QDomElement image = images.at(i).toElement();
+			const QString file = QetContainer::pictureFile(image);
+			QVERIFY(!file.isEmpty());
+			QVERIFY(!image.firstChild().isText());
+			QCOMPARE(pictures.value(file), files.value(file));
+			QCOMPARE(pictures.value(file),
+					 QByteArray::fromBase64(original_images.at(i).firstChild().toText().data().toLatin1()));
+		}
+
+		// still refused when a picture is missing
+		for (int i = 0 ; i < entries.size() ; ++i)
+			if (entries.at(i).name.startsWith(QStringLiteral("images/"))) { entries.removeAt(i); break; }
+		QDomDocument broken;
+		QVERIFY(!QetContainer::join(entries, &broken, &error, &pictures));
+		QVERIFY2(error.contains(QStringLiteral("missing")), qPrintable(error));
+	}
+
 	// A file whose manifest needs a later reader is refused, not half read
+	// A later format whose min-reader allows this one opens, and join() says
+	// it is later: QElectroTech opens it read-only
+	void laterFormatAllowedRead()
+	{
+		QDomDocument original;
+		QList<QetZip::Entry> entries = splitFile(QStringLiteral(QET_EXAMPLES_DIR "/industrial.qet"), &original);
+		QVERIFY(!entries.isEmpty());
+		const int later = QetContainer::Format + 1;
+		for (QetZip::Entry &e : entries)
+			if (e.name == QLatin1String("manifest.xml"))
+				e.data = QString::fromUtf8(e.data).replace(QRegularExpression(QStringLiteral(" format=\"\\d+\"")),
+														   QStringLiteral(" format=\"%1\"").arg(later)).toUtf8();
+		alterDatabase(entries, QStringLiteral("UPDATE meta SET value = '%1' WHERE key = 'format'")
+					  .arg(later).toUtf8().constData());
+		QDomDocument back;
+		QString error;
+		int format = 0;
+		QVERIFY2(QetContainer::join(entries, &back, &error, nullptr, &format), qPrintable(error));
+		QCOMPARE(format, later);
+		const QString d = difference(original.documentElement(), back.documentElement(), QString());
+		QVERIFY2(d.isEmpty(), qPrintable(d));
+	}
+
+	// The database holds data, not where a block sat in the XML: the folio
+	// file's marker says where it goes back
+	void noPositionColumns()
+	{
+		QDomDocument original;
+		const QList<QetZip::Entry> entries = splitFile(QStringLiteral(QET_EXAMPLES_DIR "/industrial.qet"), &original);
+		const QByteArray database = entry(entries, QStringLiteral("project.sqlite"));
+		QCOMPARE(query(database, "SELECT group_concat(name) FROM pragma_table_info('element')"),
+				 QStringLiteral("uuid,folio_uuid,prefix,freezeLabel,info_attrs,links_attrs"));
+		QCOMPARE(query(database, "SELECT count(*) FROM pragma_table_info('folio') WHERE name LIKE '%_at'"),
+				 QStringLiteral("0"));
+		QCOMPARE(query(database, "SELECT count(*) FROM meta WHERE key = 'props_at'"), QStringLiteral("0"));
+	}
+
+	// A project as QElectroTech saves it needs no JSON: every attribute it
+	// writes has a column, the show flag of a property too
+	void savedProjectNeedsNoJson()
+	{
+		QString error;
+		const QList<QetZip::Entry> entries = QetContainer::split(savedProject(), QString(), &error);
+		QVERIFY2(!entries.isEmpty(), qPrintable(error));
+		const QByteArray database = entry(entries, QStringLiteral("project.sqlite"));
+		QVERIFY(query(database, "SELECT count(*) FROM project_property").toInt() > 0);
+		QCOMPARE(query(database, "SELECT count(*) FROM project_property WHERE show IS NOT NULL"),
+				 query(database, "SELECT count(*) FROM project_property"));
+		for (const char *sql : {"SELECT count(*) FROM project_property WHERE attrs IS NOT NULL",
+								"SELECT count(*) FROM folio_property WHERE attrs IS NOT NULL",
+								"SELECT count(*) FROM element_info WHERE attrs IS NOT NULL",
+								"SELECT count(*) FROM link WHERE attrs IS NOT NULL",
+								"SELECT count(*) FROM folio WHERE props_attrs IS NOT NULL",
+								"SELECT count(*) FROM element WHERE info_attrs IS NOT NULL OR links_attrs IS NOT NULL"})
+			QVERIFY2(query(database, sql) == QLatin1String("0"), sql);
+	}
+
+	// The schema in QETZ-FORMAT.md is the one written: same tables, same
+	// columns in the same order, same types and keys
+	void specMatchesSchema()
+	{
+		const QString spec = QString::fromUtf8(read(QStringLiteral(QET_FORMAT_SPEC)));
+		const int from = spec.indexOf(QStringLiteral("```sql\n"));
+		const int to = spec.indexOf(QStringLiteral("```"), from + 7);
+		QVERIFY2(from >= 0 && to > from, "no schema in QETZ-FORMAT.md");
+		const QByteArray sql = spec.mid(from + 7, to - from - 7).toUtf8();
+
+		QDomDocument original;
+		const QList<QetZip::Entry> entries = splitFile(QStringLiteral(QET_EXAMPLES_DIR "/industrial.qet"), &original);
+		const QByteArray written = entry(entries, QStringLiteral("project.sqlite"));
+
+		auto describe = [](sqlite3 *db) {
+			QStringList out;
+			sqlite3_stmt *st = nullptr;
+			sqlite3_prepare_v2(db, "SELECT m.name, p.name, p.type, p.pk, p.\"notnull\" FROM sqlite_master m, "
+									"pragma_table_info(m.name) p WHERE m.type = 'table' ORDER BY m.name, p.cid",
+							   -1, &st, nullptr);
+			while (st && sqlite3_step(st) == SQLITE_ROW) {
+				QStringList row;
+				for (int i = 0 ; i < 5 ; ++i)
+					row << QString::fromUtf8(reinterpret_cast<const char *>(sqlite3_column_text(st, i)));
+				out << row.join(QLatin1Char(' '));
+			}
+			sqlite3_finalize(st);
+			return out;
+		};
+		sqlite3 *from_spec = nullptr;
+		sqlite3_open(":memory:", &from_spec);
+		QCOMPARE(sqlite3_exec(from_spec, sql.constData(), nullptr, nullptr, nullptr), SQLITE_OK);
+		sqlite3 *from_file = nullptr;
+		sqlite3_open(":memory:", &from_file);
+		unsigned char *copy = static_cast<unsigned char *>(sqlite3_malloc64(sqlite3_uint64(written.size())));
+		memcpy(copy, written.constData(), size_t(written.size()));
+		sqlite3_deserialize(from_file, "main", copy, written.size(), written.size(), SQLITE_DESERIALIZE_FREEONCLOSE);
+		const QStringList spec_tables = describe(from_spec), file_tables = describe(from_file);
+		sqlite3_close(from_spec);
+		sqlite3_close(from_file);
+		QVERIFY(!spec_tables.isEmpty());
+		QCOMPARE(spec_tables, file_tables);
+	}
+
 	void laterFormatRefused()
 	{
 		QDomDocument original;
@@ -272,6 +461,86 @@ private slots:
 
 	// A crafted project.sqlite whose "element" is a view, not a table, is
 	// refused: nothing in a file's schema is trusted.
+	// project.sqlite changed by @p sql in @p entries
+	static void alterDatabase(QList<QetZip::Entry> &entries, const char *sql)
+	{
+		for (QetZip::Entry &e : entries) {
+			if (e.name != QLatin1String("project.sqlite")) continue;
+			sqlite3 *db = nullptr;
+			sqlite3_open(":memory:", &db);
+			unsigned char *copy = static_cast<unsigned char *>(sqlite3_malloc64(sqlite3_uint64(e.data.size())));
+			memcpy(copy, e.data.constData(), size_t(e.data.size()));
+			sqlite3_deserialize(db, "main", copy, e.data.size(), e.data.size(),
+								SQLITE_DESERIALIZE_FREEONCLOSE | SQLITE_DESERIALIZE_RESIZEABLE);
+			QCOMPARE(sqlite3_exec(db, sql, nullptr, nullptr, nullptr), SQLITE_OK);
+			sqlite3_int64 size = 0;
+			unsigned char *bytes = sqlite3_serialize(db, "main", &size, 0);
+			e.data = QByteArray(reinterpret_cast<const char *>(bytes), qsizetype(size));
+			sqlite3_free(bytes);
+			sqlite3_close(db);
+		}
+	}
+
+	// A database that does not match its folio files -- a row no item has,
+	// an item's row on another folio, entries of no symbol -- is refused
+	// with what is wrong, not read as far as it goes
+	void mismatchRefused_data()
+	{
+		QTest::addColumn<QByteArray>("sql");
+		QTest::addColumn<QString>("said");
+		QTest::newRow("symbol row of no symbol")
+				<< QByteArray("INSERT INTO element SELECT 'x', folio_uuid, prefix, freezeLabel, info_attrs,"
+							  " links_attrs FROM element LIMIT 1")
+				<< QStringLiteral("symbol rows");
+		QTest::newRow("wire row of no wire")
+				<< QByteArray("INSERT INTO conductor SELECT 'x', folio_uuid, element1, terminal1, element2, terminal2,"
+							  " num, formula, function, tension_protocol, conductor_color, conductor_section, cable,"
+							  " bus, freezeLabel FROM conductor LIMIT 1")
+				<< QStringLiteral("wire rows");
+		QTest::newRow("symbol on another folio")
+				<< QByteArray("UPDATE element SET folio_uuid = (SELECT uuid FROM folio WHERE pos = 2)"
+							  " WHERE folio_uuid = (SELECT uuid FROM folio WHERE pos = 1)")
+				<< QStringLiteral("the database says another");
+		QTest::newRow("information of no symbol")
+				<< QByteArray("UPDATE element_info SET element_uuid = 'x' WHERE rowid = 1")
+				<< QStringLiteral("information rows of no symbol");
+	}
+	void mismatchRefused()
+	{
+		QFETCH(QByteArray, sql);
+		QFETCH(QString, said);
+		QDomDocument original;
+		QList<QetZip::Entry> entries = splitFile(QStringLiteral(QET_EXAMPLES_DIR "/industrial.qet"), &original);
+		QVERIFY(!entries.isEmpty());
+		{
+			QDomDocument back;
+			QString error;
+			QVERIFY2(QetContainer::join(entries, &back, &error), qPrintable(error));
+		}
+		alterDatabase(entries, sql.constData());
+		QDomDocument back;
+		QString error;
+		QVERIFY(!QetContainer::join(entries, &back, &error));
+		QVERIFY2(error.contains(said), qPrintable(error));
+	}
+
+	// A folio file says which symbol each item is (its type), read alone
+	void folioSaysWhichSymbol()
+	{
+		QDomDocument original;
+		const QList<QetZip::Entry> entries = splitFile(QStringLiteral(QET_EXAMPLES_DIR "/industrial.qet"), &original);
+		QVERIFY(!entries.isEmpty());
+		int typed = 0, symbols = 0;
+		for (const QetZip::Entry &e : entries) {
+			if (!e.name.startsWith(QStringLiteral("folios/"))) continue;
+			const QString text = QString::fromUtf8(e.data);
+			symbols += int(text.count(QStringLiteral("<element ")));
+			typed += int(text.count(QRegularExpression(QStringLiteral("<element [^>]*type=\"embed://"))));
+		}
+		QVERIFY(symbols > 0);
+		QCOMPARE(typed, symbols);
+	}
+
 	void viewInsteadOfTableRefused()
 	{
 		QDomDocument original;
@@ -300,6 +569,104 @@ private slots:
 		QVERIFY2(error.contains(QStringLiteral("element")), qPrintable(error));
 	}
 
+	// A row's key is its item's uuid, which the folio file keeps: no key
+	// made up from where an item is (format 2 had f1, f2...), no key
+	// attribute in the folio files of a project as QElectroTech saves it,
+	// true/false held as 1/0, and the format in the database's
+	// user_version.
+	void keysAreTheUuids()
+	{
+		const QDomDocument original = savedProject();
+		original.elementsByTagName(QStringLiteral("conductor")).at(0).toElement()
+				.setAttribute(QStringLiteral("freezeLabel"), QStringLiteral("true"));
+		QString error;
+		const QList<QetZip::Entry> entries = QetContainer::split(original, QString(), &error);
+		QVERIFY2(!entries.isEmpty(), qPrintable(error));
+		const QByteArray database = entry(entries, QStringLiteral("project.sqlite"));
+		const QByteArray folios = folioFiles(entries);
+		QVERIFY(!folios.contains("qetz-key"));
+		QVERIFY(!folios.contains("qetz-folio"));
+		QCOMPARE(query(database, "PRAGMA user_version"), QString::number(QetContainer::Format));
+		const QString first = original.elementsByTagName(QStringLiteral("diagram")).at(0).toElement()
+				.attribute(QStringLiteral("uuid"));
+		QCOMPARE(query(database, "SELECT uuid FROM folio WHERE pos = 1"), first);
+		QCOMPARE(query(database, "SELECT count(*) FROM folio WHERE uuid NOT LIKE '{%}'"), QStringLiteral("0"));
+		QCOMPARE(query(database, "SELECT count(*) FROM element WHERE uuid NOT LIKE '{%}'"), QStringLiteral("0"));
+		QCOMPARE(query(database, "SELECT count(*) FROM conductor WHERE uuid NOT LIKE '{%}'"), QStringLiteral("0"));
+		QCOMPARE(query(database, "SELECT count(*) FROM element WHERE typeof(freezeLabel) <> 'integer'"),
+				 QStringLiteral("0"));
+		QCOMPARE(query(database, "SELECT count(*) FROM conductor WHERE typeof(freezeLabel) <> 'integer'"),
+				 QStringLiteral("0"));
+		QCOMPARE(query(database, "SELECT sum(freezeLabel) FROM conductor"), QStringLiteral("1"));
+		const QString d = backDifference(original, entries);
+		QVERIFY2(d.isEmpty(), qPrintable(d));
+		QCOMPARE(query(database, "SELECT count(*) FROM element_info WHERE typeof(show) <> 'integer'"),
+				 QStringLiteral("0"));
+		QCOMPARE(query(database, "SELECT count(*) FROM element_info WHERE attrs LIKE '%\"tag\"%'"),
+				 QStringLiteral("0"));
+	}
+
+	// Two symbols sharing a uuid (F100) each get a key made from what they
+	// hold, the same on every save, and come back as they were.
+	void sharedUuidKeyed()
+	{
+		QDomDocument original = savedProject();
+		const QDomNodeList elements = original.elementsByTagName(QStringLiteral("element"));
+		QDomElement a, b;
+		for (int i = 0 ; i < elements.size() && b.isNull() ; ++i) {
+			const QDomElement e = elements.at(i).toElement();
+			if (e.parentNode().nodeName() != QLatin1String("elements")) continue;
+			if (a.isNull()) a = e; else b = e;
+		}
+		QVERIFY(!b.isNull());
+		b.setAttribute(QStringLiteral("uuid"), a.attribute(QStringLiteral("uuid")));
+		QString error;
+		const QList<QetZip::Entry> once = QetContainer::split(original, QString(), &error);
+		const QList<QetZip::Entry> twice = QetContainer::split(original, QString(), &error);
+		QVERIFY2(!once.isEmpty(), qPrintable(error));
+		QCOMPARE(folioFiles(once).count("qetz-key"), 2);
+		QCOMPARE(entry(once, QStringLiteral("project.sqlite")), entry(twice, QStringLiteral("project.sqlite")));
+		const QString d = backDifference(original, once);
+		QVERIFY2(d.isEmpty(), qPrintable(d));
+	}
+
+	// A true/false attribute QElectroTech would not write stays in the
+	// folio file as it was.
+	void oddBooleanKept()
+	{
+		QDomDocument original;
+		QVERIFY(QetContainer::parse(read(QStringLiteral(QET_EXAMPLES_DIR "/perceuse.qet")), &original));
+		const QDomNodeList conductors = original.elementsByTagName(QStringLiteral("conductor"));
+		QVERIFY(conductors.size() > 0);
+		conductors.at(0).toElement().setAttribute(QStringLiteral("freezeLabel"), QStringLiteral("yes"));
+		QString error;
+		const QList<QetZip::Entry> entries = QetContainer::split(original, QString(), &error);
+		QVERIFY2(!entries.isEmpty(), qPrintable(error));
+		QVERIFY(folioFiles(entries).contains("freezeLabel=\"yes\""));
+		const QString d = backDifference(original, entries);
+		QVERIFY2(d.isEmpty(), qPrintable(d));
+	}
+
+	// A format 2 file, as QElectroTech 0.200.1 development builds wrote it
+	// (grafcet.qet saved as .qetz), still opens, and saved again as the
+	// current format comes back the same.
+	void format2Read()
+	{
+		QList<QetZip::Entry> entries;
+		QString error;
+		QVERIFY2(QetZip::fromBytes(read(QStringLiteral(QET_FIXTURES_DIR "/qetz_format2.qetz")), &entries, &error),
+				 qPrintable(error));
+		QVERIFY(entry(entries, QStringLiteral("manifest.xml")).contains("format=\"2\""));
+		QDomDocument project;
+		QVERIFY2(QetContainer::join(entries, &project, &error), qPrintable(error));
+		QVERIFY(project.toString().contains(QStringLiteral("<elementInformation ")));
+		QVERIFY(!project.toString().contains(QStringLiteral("qetz-")));
+		const QList<QetZip::Entry> resaved = QetContainer::split(project, QString(), &error);
+		QVERIFY2(!resaved.isEmpty(), qPrintable(error));
+		const QString d = backDifference(project, resaved);
+		QVERIFY2(d.isEmpty(), qPrintable(d));
+	}
+
 	void notAProjectRefused()
 	{
 		QDomDocument back;

tests/qttest/tst_qetzip.cpp

@@ -2,6 +2,7 @@
 #include <QtTest>
 
 #include <QTemporaryDir>
+#include <QtEndian>
 
 #include "container/qetzip.h"
 #include "container/miniz/miniz.h"
@@ -72,6 +73,33 @@ private slots:
 		QCOMPARE(QetZip::toBytes(sample()), QetZip::toBytes(sample()));
 	}
 
+	// every entry carries a valid date in both of its headers, not the
+	// 0 miniz writes without a clock (shown as 1979 or 1901 by unzip tools)
+	void entriesHaveValidDate()
+	{
+		const QByteArray zip = QetZip::toBytes(sample());
+		QVERIFY(!zip.isEmpty());
+		mz_zip_archive archive;
+		mz_zip_zero_struct(&archive);
+		QVERIFY(mz_zip_reader_init_mem(&archive, zip.constData(), size_t(zip.size()), 0));
+		const mz_uint count = mz_zip_reader_get_num_files(&archive);
+		QCOMPARE(int(count), sample().size());
+		for (mz_uint i = 0 ; i < count ; ++i) {
+			mz_zip_archive_file_stat stat;
+			QVERIFY(mz_zip_reader_file_stat(&archive, i, &stat));
+			const char *local = zip.constData() + stat.m_local_header_ofs;
+			const char *central = zip.constData() + archive.m_central_directory_file_ofs + stat.m_central_dir_ofs;
+			QCOMPARE(qFromLittleEndian<quint16>(local), quint16(0x50 | 0x4b << 8));   // "PK"
+			QCOMPARE(qFromLittleEndian<quint16>(central), quint16(0x50 | 0x4b << 8));
+			// 1 Jan 1980: day 1, month 1, year 0 since 1980; time 00:00:00
+			QCOMPARE(qFromLittleEndian<quint16>(local + 12), quint16(0x21));
+			QCOMPARE(qFromLittleEndian<quint16>(central + 14), quint16(0x21));
+			QCOMPARE(qFromLittleEndian<quint16>(local + 10), quint16(0));
+			QCOMPARE(qFromLittleEndian<quint16>(central + 12), quint16(0));
+		}
+		mz_zip_reader_end(&archive);
+	}
+
 	void refusesUnsafeNamesOnWrite_data()
 	{
 		QTest::addColumn<QString>("name");

tests/qttest/tst_resaveunchanged.cpp

@@ -340,8 +340,8 @@ private slots:
 		return QString::fromUtf8(proc.readAllStandardOutput() + proc.readAllStandardError());
 	}
 
-	// The stores of symbol information and folio title blocks
+	// The stores of symbol information and folio title blocks agree with
-	// (DB-ACCESSORS-PLAN.md stages 4.1, 4.4) agree with every placed symbol
+	// every placed symbol
 	// and folio once a project is open: every example.
 	void elementInfoStoreAgrees_data()
 	{
@@ -361,7 +361,7 @@ private slots:
 	}
 
 	// The stores filled from the document before the folios are built
-	// (DB-ACCESSORS-PLAN.md stage 4.6) hold what building them gives, for a
+	// hold what building them gives, for a
 	// project saved by this version (every symbol, folio and wire carries
 	// a uuid): nothing differs, nothing is left unplaced.
 	void storesFilledBeforeBuilding()

tests/qttest/tst_svgsmallpictures.cpp

@@ -0,0 +1,143 @@
+/*
+	Copyright 2006-2026 The QElectroTech Team
+	This file is part of QElectroTech.
+
+	QElectroTech is free software: you can redistribute it and/or modify
+	it under the terms of the GNU General Public License as published by
+	the Free Software Foundation, either version 2 of the License, or
+	(at your option) any later version.
+
+	QElectroTech is distributed in the hope that it will be useful,
+	but WITHOUT ANY WARRANTY; without even the implied warranty of
+	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+	GNU General Public License for more details.
+
+	You should have received a copy of the GNU General Public License
+	along with QElectroTech.  If not, see <http://www.gnu.org/licenses/>.
+*/
+#include "qetapptest.h"
+#include "qetgraphicsitem/diagramimageitem.h"
+
+#include <QBuffer>
+#include <QDomDocument>
+#include <QPicture>
+#include <QProcess>
+#include <QRegularExpression>
+#include <QSvgGenerator>
+#include <QTemporaryDir>
+
+/**
+	SVG export with "smaller pictures" (ExportProperties::svg_small_pictures,
+	--svg-small-pictures) stores each picture at four times the size it is
+	drawn at when that is smaller than the picture, and at full resolution
+	otherwise. fixtures/svg_small_pictures.qet has an 800x600 picture drawn
+	at a tenth of its size and a 40x30 one at full size.
+*/
+class tst_svgsmallpictures : public QObject
+{
+	Q_OBJECT
+
+	QString m_fixture;
+
+		/// Pixel size of each picture embedded in @p svg, smallest first
+	static QList<QSize> embeddedSizes(const QByteArray &svg)
+	{
+		static const QRegularExpression data(
+					QStringLiteral("data:image/png;base64,([A-Za-z0-9+/=\\s]+)"));
+		QList<QSize> sizes;
+		auto it = data.globalMatch(QString::fromLatin1(svg));
+		while (it.hasNext())
+			sizes << QImage::fromData(QByteArray::fromBase64(
+										  it.next().captured(1).toLatin1())).size();
+		std::sort(sizes.begin(), sizes.end(), [](const QSize &a, const QSize &b) {
+			return a.width() < b.width();
+		});
+		return sizes;
+	}
+
+	QByteArray exportWithCli(const QStringList &extra)
+	{
+		QTemporaryDir dir;
+		QProcessEnvironment env = QProcessEnvironment::systemEnvironment();
+		env.insert(QStringLiteral("QT_QPA_PLATFORM"), QStringLiteral("offscreen"));
+		QProcess proc;
+		proc.setProcessEnvironment(env);
+		proc.start(QStringLiteral(QET_TEST_BINARY_PATH),
+				   QStringList{QStringLiteral("--export-svg"), m_fixture, dir.path()} + extra);
+		if (!proc.waitForFinished(60000) || proc.exitCode() != 0)
+			return {};
+		const QStringList files = QDir(dir.path()).entryList({QStringLiteral("*.svg")});
+		QFile svg(QDir(dir.path()).filePath(files.value(0)));
+		return svg.open(QIODevice::ReadOnly) ? svg.readAll() : QByteArray();
+	}
+
+		/// As ExportDialog::generateSvg(): the folio drawn into a QPicture,
+		/// played into the SVG generator
+	static QByteArray exportLikeTheDialog(Diagram *diagram, bool small)
+	{
+		const QSize size = diagram->imageSize();
+		QPicture picture;
+		diagram->setSmallPictures(small);
+		diagram->toPaintDevice(picture, size.width(), size.height());
+		diagram->setSmallPictures(false);
+
+		QByteArray svg;
+		QBuffer buffer(&svg);
+		buffer.open(QIODevice::WriteOnly);
+		QSvgGenerator generator;
+		generator.setSize(size);
+		generator.setOutputDevice(&buffer);
+		QPainter painter(&generator);
+		picture.play(&painter);
+		painter.end();
+		return svg;
+	}
+
+private slots:
+	void initTestCase()
+	{
+		m_fixture = QFINDTESTDATA("fixtures/svg_small_pictures.qet");
+		QVERIFY2(!m_fixture.isEmpty(), "fixture project not found");
+		QVERIFY(QetAppTest::editor());
+	}
+
+	void cliFullResolutionByDefault()
+	{
+		const QByteArray svg = exportWithCli({});
+		QVERIFY2(!svg.isEmpty(), "--export-svg failed");
+		QCOMPARE(embeddedSizes(svg), (QList<QSize>{QSize(40, 30), QSize(800, 600)}));
+	}
+
+	void cliSmallPictures()
+	{
+		const QByteArray svg = exportWithCli({QStringLiteral("--svg-small-pictures")});
+		QVERIFY2(!svg.isEmpty(), "--export-svg --svg-small-pictures failed");
+			// 800 x 600 drawn at 0.1, times 4; the 40 x 30 one is kept whole
+		QCOMPARE(embeddedSizes(svg), (QList<QSize>{QSize(40, 30), QSize(320, 240)}));
+	}
+
+	void dialogSmallPicturesThenFullAgain()
+	{
+		QFile file(m_fixture);
+		QVERIFY(file.open(QIODevice::ReadOnly));
+		QDomDocument document;
+		QVERIFY(document.setContent(&file));
+		const QDomElement image_xml = document.elementsByTagName(
+					QStringLiteral("image")).at(0).toElement();
+		Diagram *diagram = QetAppTest::diagram();
+		auto *picture = new DiagramImageItem();
+		QVERIFY(picture->fromXml(image_xml));
+		diagram->addItem(picture);
+
+		QCOMPARE(embeddedSizes(exportLikeTheDialog(diagram, true)),
+				 QList<QSize>{QSize(320, 240)});
+			// The option lasts for one export only
+		QVERIFY(!diagram->smallPictures());
+		QCOMPARE(embeddedSizes(exportLikeTheDialog(diagram, false)),
+				 QList<QSize>{QSize(800, 600)});
+		delete picture;
+	}
+};
+
+QET_APP_TEST_MAIN(tst_svgsmallpictures)
+#include "tst_svgsmallpictures.moc"