Folio properties: auto-add a title block's custom variables (#271)

When a title block template uses custom variables (e.g. %{department},
%{owner}), the user previously had to declare each one by hand in the
folio properties 'Custom' tab before a value could be entered. Now the
template's undefined custom variables are added automatically, so the
user only fills in the values.

- listOfVariables() now extracts %{name} placeholders with a regex
  (deduplicated) instead of a crude '%' strip that returned '{name}'.
- The folio properties widget merges the template's custom variables into
  the Custom tab both on open (setProperties) and when the template is
  changed, preserving any values already entered and skipping the
  standard fields (title, author, date, ...) which have their own inputs.

Fixes #271 (variable auto-population; the revision-history request in the
thread is a separate feature).

sources/ui/titleblockpropertieswidget.cpp

@@ -24,6 +24,7 @@
 #include "ui_titleblockpropertieswidget.h"
 
 #include <QMenu>
+#include <QSet>
 #include <utility>
 
 /**
@@ -162,7 +163,11 @@ void TitleBlockPropertiesWidget::setProperties(
 	}
 	ui -> m_tbt_cb -> setCurrentIndex(index);
 
-	m_dcw -> setContext(properties.context);
+	// Show the saved custom values, plus any of the template's custom variables
+	// that aren't defined yet, so the user only fills in the missing ones (#271).
+	DiagramContext context = properties.context;
+	addTemplateVariables(context, index);
+	m_dcw -> setContext(context);
 }
 
 /**
@@ -435,12 +440,15 @@ void TitleBlockPropertiesWidget::updateTemplateList()
 }
 
 /**
-	@brief TitleBlockPropertiesWidget::changeCurrentTitleBlockTemplate
-	Load the additional field of title block "text"
+	@brief TitleBlockPropertiesWidget::templateForIndex
+	@param index : index in the collection-type map (= the template combo index)
+	@return the TitleBlockTemplate currently selected for that collection, or
+	nullptr.
 */
-void TitleBlockPropertiesWidget::changeCurrentTitleBlockTemplate(int index)
+TitleBlockTemplate *TitleBlockPropertiesWidget::templateForIndex(int index) const
 {
-	m_dcw -> clear();
+	if (index < 0 || index >= m_map_index_to_collection_type.count())
+		return nullptr;
 
 	QET::QetCollection qc = m_map_index_to_collection_type.at(index);
 	TitleBlockTemplatesCollection *collection = nullptr;
@@ -448,21 +456,55 @@ void TitleBlockPropertiesWidget::changeCurrentTitleBlockTemplate(int index)
 		if (c -> collection() == qc)
 			collection = c;
 
-	if (!collection) return;
+	if (!collection) return nullptr;
+	return collection -> getTemplate(ui -> m_tbt_cb -> currentText());
+}
 
-		// get template
-	TitleBlockTemplate *tpl = collection -> getTemplate(ui -> m_tbt_cb -> currentText());
-	if(tpl != nullptr) {
-			// get all template fields
-		QStringList fields = tpl -> listOfVariables();
-			// set fields to additional_fields_ widget
-		DiagramContext templateContext;
-		for(int i =0; i<fields.count(); i++)
-			templateContext.addValue(fields.at(i), "");
-		m_dcw -> setContext(templateContext);
+/**
+	@brief TitleBlockPropertiesWidget::addTemplateVariables
+	Add to @p context every CUSTOM variable used by the currently selected
+	template that is not already present, with an empty value — so the user
+	only has to fill in the values instead of declaring the variables (#271).
+	The standard fields (title, author, date, …) are handled by their own
+	widgets and are skipped. Existing values in @p context are preserved.
+*/
+void TitleBlockPropertiesWidget::addTemplateVariables(
+		DiagramContext &context, int index) const
+{
+	TitleBlockTemplate *tpl = templateForIndex(index);
+	if (!tpl) return;
+
+	// Variables rendered from the dedicated standard-field widgets; they must
+	// not appear in the "Custom" tab.
+	static const QSet<QString> reserved {
+		QStringLiteral("author"), QStringLiteral("date"),
+		QStringLiteral("title"), QStringLiteral("filename"),
+		QStringLiteral("plant"), QStringLiteral("locmach"),
+		QStringLiteral("indexrev"), QStringLiteral("version"),
+		QStringLiteral("folio"), QStringLiteral("folio-id"),
+		QStringLiteral("folio-total"), QStringLiteral("auto_page_num"),
+		QStringLiteral("previous-folio-num"), QStringLiteral("next-folio-num")
+	};
+
+	const QStringList variables = tpl -> listOfVariables();
+	for (const QString &name : variables) {
+		if (name.isEmpty() || reserved.contains(name)) continue;
+		if (!context.contains(name)) context.addValue(name, "");
 	}
 }
 
+/**
+	@brief TitleBlockPropertiesWidget::changeCurrentTitleBlockTemplate
+	When the user picks a template, append its missing custom variables to the
+	"Custom" tab while keeping the values already entered (#271).
+*/
+void TitleBlockPropertiesWidget::changeCurrentTitleBlockTemplate(int index)
+{
+	DiagramContext context = m_dcw -> context();
+	addTemplateVariables(context, index);
+	m_dcw -> setContext(context);
+}
+
 /**
 	@brief TitleBlockPropertiesWidget::on_m_date_now_pb_clicked
 	Set the date to current date

sources/ui/titleblockpropertieswidget.h

@@ -30,6 +30,7 @@ class NumerotationContext;
 class QETProject;
 class QMenu;
 class TitleBlockTemplatesCollection;
+class TitleBlockTemplate;
 
 namespace Ui {
 	class TitleBlockPropertiesWidget;
@@ -77,6 +78,8 @@ class TitleBlockPropertiesWidget : public QWidget
 		void initDialog(const bool &current_date, QETProject *project);
 		int getIndexFor (const QString &tbt_name,
 				 const QET::QetCollection collection) const;
+		TitleBlockTemplate *templateForIndex (int index) const;
+		void addTemplateVariables (DiagramContext &context, int index) const;
 
 	private slots:
 		void editCurrentTitleBlockTemplate();