Preserve imported image colours by default in dark mode

sources/darkimagerendering.h

@@ -0,0 +1,42 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+#ifndef DARK_IMAGE_RENDERING_H
+#define DARK_IMAGE_RENDERING_H
+
+#include <QPainter>
+#include <QPixmap>
+#include <functional>
+
+namespace DarkImageRendering {
+// View-local raster composition boundary. Qt still paints the scene in
+// its native order, with its own transforms, clipping and opacity.
+// A different painter (printing, export, another view or an item cache)
+// cannot consume this display-only context.
+struct Context {
+	QPainter *painter;
+	bool invertScene;
+	std::function<void(bool, const QRect &)> flush;
+};
+inline thread_local Context *current = nullptr;
+class Scope {
+	Context *previous;
+public:
+	explicit Scope(Context *context) : previous(current) { current = context; }
+	~Scope() { current = previous; }
+	Scope(const Scope &) = delete;
+	Scope &operator=(const Scope &) = delete;
+};
+inline void paintPixmap(QPainter *painter, const QPixmap &pixmap, bool adapt)
+{
+	Context *context = current;
+	const bool boundary = context && context->painter == painter && adapt != context->invertScene;
+	if (boundary) context->flush(context->invertScene, QRect());
+	painter->drawPixmap(pixmap.rect(), pixmap);
+	if (boundary) {
+		// Only the raster was drawn since the preceding flush. Avoid a
+		// whole-viewport copy for a small logo; include filtering/AA edges.
+		const QRect area = painter->worldTransform().mapRect(QRectF(pixmap.rect())).toAlignedRect().adjusted(-2,-2,2,2);
+		context->flush(adapt, area);
+	}
+}
+}
+#endif

sources/palettegraphicsview.cpp

@@ -18,6 +18,7 @@
 #include "palettegraphicsview.h"
 
 #include "qetpalette.h"
+#include "darkimagerendering.h"
 
 #include <QApplication>
 #include <QEvent>
@@ -99,12 +100,13 @@ bool PaletteGraphicsView::eventFilter(QObject *watched, QEvent *event)
 */
 void PaletteGraphicsView::paintEvent(QPaintEvent *event)
 {
-	if (invertsLightness() && !customBackgroundColor())
+	if (invertsLightness())
 	{
 		paintInverted(event);
 		return;
 	}
 	m_buffer = QImage();
+	m_composite = QImage();
 	QGraphicsView::paintEvent(event);
 }
 
@@ -130,7 +132,7 @@ void PaletteGraphicsView::paintInverted(QPaintEvent *event)
 	const QSize size(qCeil(viewport()->width() * ratio), qCeil(viewport()->height() * ratio));
 	if (m_buffer.size() != size || m_buffer.devicePixelRatio() != ratio)
 	{
-		m_buffer = QImage(size, QImage::Format_RGB32);
+		m_buffer = QImage(size, QImage::Format_ARGB32_Premultiplied);
 		m_buffer.setDevicePixelRatio(ratio);
 	}
 
@@ -141,9 +143,13 @@ void PaletteGraphicsView::paintInverted(QPaintEvent *event)
 	m_buffer_painter.setClipRect(exposed);
 	m_buffer_painter.setRenderHints(renderHints());
 	m_buffer_painter.setWorldTransform(viewportTransform());
+	m_exposed = exposed;
+	m_layered = false;
+	DarkImageRendering::Context context{&m_buffer_painter, !customBackgroundColor(), [this](bool invert, const QRect &bounds) { flushLayer(invert, bounds); }};
+	DarkImageRendering::Scope rasterScope(&context);
 
 	m_inverting = true;
-	paintingInverted(true);
+	paintingInverted(!customBackgroundColor());
 	const OptimizationFlags flags = optimizationFlags();
 	setOptimizationFlag(QGraphicsView::IndirectPainting, true);
 	QGraphicsView::paintEvent(event);
@@ -151,10 +157,44 @@ void PaletteGraphicsView::paintInverted(QPaintEvent *event)
 	paintingInverted(false);
 	m_inverting = false;
 
+	if (m_layered) flushLayer(!customBackgroundColor());
 	m_buffer_painter.end();
 	blitInverted(exposed);
 }
 
+void PaletteGraphicsView::flushLayer(bool invert, const QRect &bounds)
+{
+	const QRect area = bounds.isNull() ? m_exposed : bounds.intersected(m_exposed);
+	if (area.isEmpty()) return;
+	const qreal ratio = m_buffer.devicePixelRatio();
+	const QRect pixels = QRectF(area.topLeft() * ratio, area.size() * ratio).toAlignedRect();
+	QImage layer = m_buffer.copy(pixels);
+	layer.setDevicePixelRatio(ratio);
+	if (invert) {
+		const QPalette palette = QApplication::palette();
+		QET::Palette::invertLightnessLayer(layer, palette.color(QPalette::Base), palette.color(QPalette::Text));
+	}
+	if (!m_layered) {
+		if (m_composite.size() != m_buffer.size() || m_composite.devicePixelRatio() != ratio) {
+			m_composite = QImage(m_buffer.size(), QImage::Format_ARGB32_Premultiplied);
+			m_composite.setDevicePixelRatio(ratio);
+		}
+		m_composite.fill(Qt::transparent);
+		m_layered = true;
+	}
+	QPainter composite(&m_composite);
+	composite.drawImage(QPointF(pixels.topLeft()) / ratio, layer);
+	// Keep Qt's active painter and its saved state stack intact. Replacing
+	// or restarting it here would lose ancestor clipping and opacity.
+	m_buffer_painter.save();
+	m_buffer_painter.resetTransform();
+	m_buffer_painter.setClipping(false);
+	m_buffer_painter.setOpacity(1.0);
+	m_buffer_painter.setCompositionMode(QPainter::CompositionMode_Source);
+	m_buffer_painter.fillRect(QRectF(QPointF(pixels.topLeft()) / ratio, QSizeF(pixels.size()) / ratio), Qt::transparent);
+	m_buffer_painter.restore();
+}
+
 /**
 	@brief PaletteGraphicsView::drawBackground
 	Into the off-screen image while painting inverted, else as
@@ -199,15 +239,16 @@ void PaletteGraphicsView::drawForeground(QPainter *painter, const QRectF &rect)
 void PaletteGraphicsView::blitInverted(const QRect &area)
 {
 	const qreal ratio = m_buffer.devicePixelRatio();
-	QImage part = m_buffer.copy(QRectF(area.topLeft() * ratio, area.size() * ratio).toAlignedRect());
+	const QRect pixels = QRectF(area.topLeft() * ratio, area.size() * ratio).toAlignedRect();
+	QImage part = (m_layered ? m_composite : m_buffer).copy(pixels);
 	part.setDevicePixelRatio(ratio);
 	// The application palette, for the reason given in invertsLightness().
 	const QPalette application_palette = QApplication::palette();
-	QET::Palette::invertLightness(part, application_palette.color(QPalette::Base),
+	if (!m_layered && !customBackgroundColor()) QET::Palette::invertLightness(part, application_palette.color(QPalette::Base),
 	                              application_palette.color(QPalette::Text));
 
 	QPainter painter(viewport());
-	painter.drawImage(area.topLeft(), part);
+	painter.drawImage(QPointF(pixels.topLeft()) / ratio, part);
 	drawRubberBand(painter);
 }
 

sources/palettegraphicsview.h

@@ -90,11 +90,15 @@ class PaletteGraphicsView : public QGraphicsView
 		void paintInverted(QPaintEvent *event);
 		void blitInverted(const QRect &area);
 		void drawRubberBand(QPainter &painter);
+		void flushLayer(bool invert, const QRect &bounds = QRect());
 
 		/// The off-screen image the hooks paint into while m_inverting:
 		/// the viewport's size, in its coordinates. Kept between paints,
 		/// dropped when the view paints on a light palette again.
 		QImage m_buffer;
+		QImage m_composite;
+		QRect m_exposed;
+		bool m_layered = false;
 		QPainter m_buffer_painter;
 		/// True while paintEvent() paints for an inverted display.
 		bool m_inverting = false;

sources/qetgraphicsitem/diagramimageitem.cpp

@@ -16,6 +16,7 @@
 	along with QElectroTech.  If not, see <http://www.gnu.org/licenses/>.
 */
 #include "diagramimageitem.h"
+#include "../darkimagerendering.h"
 #include "../shownkinds.h"
 
 #include "../PropertiesEditor/propertieseditordialog.h"
@@ -97,7 +98,7 @@ DiagramImageItem::~DiagramImageItem()
 	@param widget the QWidget where we draw the pixmap
 */
 void DiagramImageItem::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget) {
-	painter -> drawPixmap(pixmap_.rect(),pixmap_);
+	DarkImageRendering::paintPixmap(painter, pixmap_, m_adapt_to_dark_theme);
 
 	Q_UNUSED(option); Q_UNUSED(widget);
 
@@ -155,6 +156,14 @@ void DiagramImageItem::setLabel(const QString &label)
 	emit labelChanged();
 }
 
+void DiagramImageItem::setAdaptToDarkTheme(bool adapt)
+{
+	if (m_adapt_to_dark_theme == adapt) return;
+	m_adapt_to_dark_theme = adapt;
+	update();
+	emit adaptToDarkThemeChanged();
+}
+
 /**
 	@brief DiagramImageItem::editProperty
 	Open the appropriate dialog to edit this image
@@ -1479,6 +1488,7 @@ bool DiagramImageItem::fromXml(const QDomElement &e)
 	if (e.tagName() != "image") {
 		return (false);
 	}
+	setAdaptToDarkTheme(e.attribute("adapt_to_dark_theme", "false") == "true");
 
 	const QUuid uuid(e.attribute(QStringLiteral("uuid")));
 	if (!uuid.isNull() && uuid != m_uuid) setUuid(uuid);
@@ -1623,6 +1633,7 @@ QDomElement DiagramImageItem::toXml(QDomDocument &document) const
 {
 	QDomElement result = document.createElement("image");
 	result.setAttribute("uuid", m_uuid.toString());
+	if (m_adapt_to_dark_theme) result.setAttribute("adapt_to_dark_theme", "true");
 	//write some attribute
 	result.setAttribute("x", QString::number(pos().x()));
 	result.setAttribute("y", QString::number(pos().y()));

sources/qetgraphicsitem/diagramimageitem.h

@@ -53,6 +53,7 @@ class DiagramImageItem : public QetGraphicsItem {
 	// colours -- as one value, so that every edit of it (crop, colour
 	// key, mirror, replace) is undone together with the displayed pixmap.
 	Q_PROPERTY(QVariant imageSource READ imageSourceVariant WRITE setImageSourceVariant)
+	Q_PROPERTY(bool adaptToDarkTheme READ adaptToDarkTheme WRITE setAdaptToDarkTheme NOTIFY adaptToDarkThemeChanged)
 	// A second, deliberately non-compensating property on the SAME
 	// underlying value -- setPivot() (above) intentionally adjusts
 	// pos() to keep the image visually in place, which is exactly
@@ -149,12 +150,15 @@ class DiagramImageItem : public QetGraphicsItem {
 	void setPivotRaw(const QPointF &pivot);
 	QString label() const { return m_label; }
 	void setLabel(const QString &label);
+	bool adaptToDarkTheme() const { return m_adapt_to_dark_theme; }
+	void setAdaptToDarkTheme(bool adapt);
 
 	signals:
 	void pixmapChanged();
 	void transformChanged();
 	void uuidChanged();
 	void labelChanged();
+	void adaptToDarkThemeChanged();
 
 	protected:
 	void paint(QPainter *, const QStyleOptionGraphicsItem *, QWidget *) override;
@@ -258,6 +262,7 @@ class DiagramImageItem : public QetGraphicsItem {
 	// Empty by default, and then neither saved nor painted, so a picture
 	// without one costs exactly what it did before.
 	QString m_label;
+	bool m_adapt_to_dark_theme = false;
 	QFont m_label_font;
 	QSizeF m_label_size;   // in scene units, measured once in setLabel()
 	QPointF m_label_scale{1.0, 1.0};   // scale the label rect was last computed for -- see updateLabelScale()

sources/qetpalette.cpp

@@ -83,8 +83,14 @@ bool QET::Palette::isDark(const QPalette &palette)
 void QET::Palette::invertLightness(QImage &image, const QColor &sheet,
                                    const QColor &ink)
 {
-	if (image.format() != QImage::Format_RGB32)
-		image.convertTo(QImage::Format_RGB32);
+	if (image.format() != QImage::Format_RGB32) image.convertTo(QImage::Format_RGB32);
+	invertLightnessLayer(image, sheet, ink);
+}
+
+void QET::Palette::invertLightnessLayer(QImage &image, const QColor &sheet, const QColor &ink)
+{
+	if (image.format() != QImage::Format_RGB32 && image.format() != QImage::Format_ARGB32)
+		image.convertTo(QImage::Format_ARGB32);
 
 	// One table per channel maps the inverted value (0 = was white,
 	// 255 = was black) onto the sheet..ink span.
@@ -106,6 +112,7 @@ void QET::Palette::invertLightness(QImage &image, const QColor &sheet,
 		quint32 *line = reinterpret_cast<quint32 *>(image.scanLine(y));
 		for (int x = 0, width = image.width(); x < width; ++x) {
 			const quint32 pixel = line[x];
+			if ((pixel & 0xff000000u) == 0) continue;
 			const int red   = (pixel >> 16) & 0xff;
 			const int green = (pixel >> 8) & 0xff;
 			const int blue  = pixel & 0xff;
@@ -114,7 +121,7 @@ void QET::Palette::invertLightness(QImage &image, const QColor &sheet,
 			if (blue > highest) highest = blue;
 			if (blue < lowest)  lowest  = blue;
 			const int offset = 255 - highest - lowest;
-			line[x] = 0xff000000u
+			line[x] = (pixel & 0xff000000u)
 			        | (quint32(red_of[red + offset]) << 16)
 			        | (quint32(green_of[green + offset]) << 8)
 			        | quint32(blue_of[blue + offset]);

sources/qetpalette.h

@@ -66,6 +66,9 @@ namespace QET {
 		*/
 		void invertLightness(QImage &image, const QColor &sheet = Qt::black,
 		                     const QColor &ink = Qt::white);
+		/// The same colour mapping for a transparent composition layer.
+		/// Retains alpha; premultiplied input is converted to straight ARGB32.
+		void invertLightnessLayer(QImage &image, const QColor &sheet, const QColor &ink);
 
 		/**
 			The color of the grid dots on a sheet of color \a sheet: black,

sources/ui/imagepropertieswidget.cpp

@@ -22,6 +22,9 @@
 #include "../qetgraphicsitem/diagramimageitem.h"
 #include "../qeticons.h"
 #include "../ui_imagepropertieswidget.h"
+#include <QSignalBlocker>
+#include <QDialog>
+#include <QEvent>
 
 /**
 	@brief ImagePropertiesWidget::ImagePropertiesWidget
@@ -53,6 +56,19 @@ ImagePropertiesWidget::~ImagePropertiesWidget()
 	delete ui;
 }
 
+bool ImagePropertiesWidget::event(QEvent *event)
+{
+	// The generic properties dialog resets on its Cancel button, but its
+	// title-bar close and Escape reach reject() directly. Roll back the
+	// same preview in all rejection paths, without changing other editors.
+	if (event->type() == QEvent::ParentChange) {
+		if (auto *dialog = qobject_cast<QDialog *>(parentWidget())) {
+			connect(dialog, &QDialog::rejected, this, &ImagePropertiesWidget::reset, Qt::UniqueConnection);
+		}
+	}
+	return PropertiesEditorWidget::event(event);
+}
+
 /**
 	@brief ImagePropertiesWidget::setImageItem
 	Set the image to edit properties
@@ -67,12 +83,15 @@ void ImagePropertiesWidget::setImageItem(DiagramImageItem *image)
 	{
 		disconnect(m_image, &DiagramImageItem::transformChanged, this, &ImagePropertiesWidget::updateUi);
 		disconnect(m_image, &DiagramImageItem::labelChanged, this, &ImagePropertiesWidget::updateUi);
+		disconnect(m_image, &DiagramImageItem::adaptToDarkThemeChanged, this, &ImagePropertiesWidget::updateUi);
 	}
 
 	m_image = image;
 	connect(m_image, &DiagramImageItem::transformChanged, this, &ImagePropertiesWidget::updateUi);
 	connect(m_image, &DiagramImageItem::labelChanged, this, &ImagePropertiesWidget::updateUi);
+	connect(m_image, &DiagramImageItem::adaptToDarkThemeChanged, this, &ImagePropertiesWidget::updateUi);
 	m_movable = image->isMovable();
+	m_adapt_to_dark_theme = image->adaptToDarkTheme();
 	m_scaleX = m_image->scaleFactorX();
 	m_scaleY = m_image->scaleFactorY();
 	m_rotation = m_image->rotationAngle();
@@ -107,6 +126,7 @@ void ImagePropertiesWidget::apply()
 	m_skewX = m_image->skewX();
 	m_skewY = m_image->skewY();
 	m_label = m_image->label();
+	m_adapt_to_dark_theme = m_image->adaptToDarkTheme();
 }
 
 /**
@@ -124,6 +144,9 @@ void ImagePropertiesWidget::reset()
 	m_image->setSkewY(m_skewY);
 	m_image->setLabel(m_label);
 	m_image->setMovable(m_movable);
+	m_preview_dark_theme = true;
+	m_image->setAdaptToDarkTheme(m_adapt_to_dark_theme);
+	m_preview_dark_theme = false;
 	updateUi();
 }
 
@@ -146,6 +169,7 @@ bool ImagePropertiesWidget::setLiveEdit(bool live_edit)
 		connect (ui->m_skew_x_sb, &QDoubleSpinBox::editingFinished, this, &ImagePropertiesWidget::apply);
 		connect (ui->m_skew_y_sb, &QDoubleSpinBox::editingFinished, this, &ImagePropertiesWidget::apply);
 		connect (ui->m_label_le, &QLineEdit::editingFinished, this, &ImagePropertiesWidget::apply);
+		connect (ui->m_adapt_to_dark_theme_cb, &QCheckBox::clicked, this, &ImagePropertiesWidget::apply);
 	}
 	else
 	{
@@ -155,6 +179,7 @@ bool ImagePropertiesWidget::setLiveEdit(bool live_edit)
 		disconnect (ui->m_skew_x_sb, &QDoubleSpinBox::editingFinished, this, &ImagePropertiesWidget::apply);
 		disconnect (ui->m_skew_y_sb, &QDoubleSpinBox::editingFinished, this, &ImagePropertiesWidget::apply);
 		disconnect (ui->m_label_le, &QLineEdit::editingFinished, this, &ImagePropertiesWidget::apply);
+		disconnect (ui->m_adapt_to_dark_theme_cb, &QCheckBox::clicked, this, &ImagePropertiesWidget::apply);
 	}
 
 	return true;
@@ -179,7 +204,7 @@ QUndoCommand* ImagePropertiesWidget::associatedUndo() const
 	const qreal newSkewX = ui->m_skew_x_sb->value();
 	const qreal newSkewY = ui->m_skew_y_sb->value();
 
-	QPropertyUndoCommand *undo = nullptr;
+	QUndoCommand *undo = nullptr;
 	auto chain = [&](const char *property, qreal oldValue, qreal newValue, const QString &text)
 	{
 		if (qFuzzyCompare(oldValue, newValue))
@@ -188,9 +213,10 @@ QUndoCommand* ImagePropertiesWidget::associatedUndo() const
 			new QPropertyUndoCommand(m_image, property, oldValue, newValue, undo);
 		else
 		{
-			undo = new QPropertyUndoCommand(m_image, property, oldValue, newValue);
-			undo->enableAnimation();
-			undo->setText(text);
+			auto *change = new QPropertyUndoCommand(m_image, property, oldValue, newValue);
+			change->enableAnimation();
+			change->setText(text);
+			undo = change;
 		}
 	};
 
@@ -213,6 +239,14 @@ QUndoCommand* ImagePropertiesWidget::associatedUndo() const
 		}
 	}
 
+	const bool adapt = ui->m_adapt_to_dark_theme_cb->isChecked();
+	if (adapt != m_adapt_to_dark_theme) {
+		if (undo) new QPropertyUndoCommand(m_image, "adaptToDarkTheme", m_adapt_to_dark_theme, adapt, undo);
+		else {
+			undo = new QUndoCommand(tr("Modifier l'adaptation d'une image au thème sombre"));
+			new QPropertyUndoCommand(m_image, "adaptToDarkTheme", m_adapt_to_dark_theme, adapt, undo);
+		}
+	}
 	return undo;
 }
 
@@ -233,6 +267,9 @@ void ImagePropertiesWidget::updateUi()
 	// signal from a resize handle used directly on the canvas while
 	// this dialog is open).
 	if (!m_image || m_updating_ratio) return;
+	if (m_live_edit && !m_preview_dark_theme) m_adapt_to_dark_theme = m_image->adaptToDarkTheme();
+	const QSignalBlocker darkThemeBlocker(ui->m_adapt_to_dark_theme_cb);
+	ui->m_adapt_to_dark_theme_cb->setChecked(m_image->adaptToDarkTheme());
 
 	m_updating_ratio = true;
 	ui->m_width_sb->setValue(m_image->scaleFactorX() * 100.0);
@@ -395,3 +432,11 @@ void ImagePropertiesWidget::on_m_lock_pos_cb_clicked()
 {
 	m_image->setMovable(!ui->m_lock_pos_cb->isChecked());
 }
+
+void ImagePropertiesWidget::on_m_adapt_to_dark_theme_cb_toggled(bool checked)
+{
+	if (!m_image) return;
+	m_preview_dark_theme = true;
+	m_image->setAdaptToDarkTheme(checked);
+	m_preview_dark_theme = false;
+}

sources/ui/imagepropertieswidget.h

@@ -43,6 +43,8 @@ class ImagePropertiesWidget : public PropertiesEditorWidget
 		void reset() override;
 		bool setLiveEdit(bool live_edit) override;
 		QUndoCommand* associatedUndo() const override;
+	protected:
+		bool event(QEvent *event) override;
 
 	private:
 		void updateUi() override;
@@ -56,11 +58,14 @@ class ImagePropertiesWidget : public PropertiesEditorWidget
 		void on_m_lock_ratio_tb_toggled(bool checked);
 		void on_m_restore_ratio_pb_clicked();
 		void on_m_lock_pos_cb_clicked();
+		void on_m_adapt_to_dark_theme_cb_toggled(bool checked);
 
 	private:
 		Ui::ImagePropertiesWidget *ui;
 		DiagramImageItem *m_image;
 		bool m_movable;
+		bool m_adapt_to_dark_theme = false;
+		bool m_preview_dark_theme = false;
 		// All tracked independently -- the image may already be
 		// non-uniformly scaled, rotated, and/or skewed via the resize/
 		// rotate/skew handles before this dialog is even opened, and

sources/ui/imagepropertieswidget.ui

@@ -173,7 +173,17 @@
      </property>
     </widget>
    </item>
-   <item row="8" column="0">
+   <item row="8" column="0" colspan="3">
+    <widget class="QCheckBox" name="m_adapt_to_dark_theme_cb">
+     <property name="text">
+      <string>Adapter l’image au thème sombre</string>
+     </property>
+     <property name="toolTip">
+      <string>Adapte les couleurs à l’affichage sombre uniquement. L’image originale, les exports et les impressions restent inchangés.</string>
+     </property>
+    </widget>
+   </item>
+   <item row="9" column="0">
     <spacer name="verticalSpacer">
      <property name="orientation">
       <enum>Qt::Vertical</enum>

tests/qttest/CMakeLists.txt

@@ -66,6 +66,22 @@ include(../../cmake/fetch_pugixml.cmake)
 
 enable_testing()
 
+add_executable(tst_darkimagelayers tst_darkimagelayers.cpp
+  ${QET_DIR}/sources/palettegraphicsview.cpp ${QET_DIR}/sources/palettegraphicsview.h
+  ${QET_DIR}/sources/qetpalette.cpp)
+add_test(NAME tst_darkimagelayers COMMAND tst_darkimagelayers)
+target_include_directories(tst_darkimagelayers PRIVATE ${QET_DIR}/sources)
+target_link_libraries(tst_darkimagelayers PRIVATE Qt::Test Qt::Widgets)
+find_package(Python3 QUIET COMPONENTS Interpreter)
+if(Python3_Interpreter_FOUND AND CMAKE_GENERATOR STREQUAL "Ninja")
+  add_test(NAME tst_darkimageintegration
+    COMMAND ${Python3_EXECUTABLE} ${CMAKE_CURRENT_SOURCE_DIR}/run_image_dark_probe.py
+      --build ${CMAKE_BINARY_DIR} --binary $<TARGET_FILE:qelectrotech>
+      --source ${CMAKE_CURRENT_SOURCE_DIR}/image_dark_integration_probe.cpp
+      --fixture ${CMAKE_CURRENT_SOURCE_DIR}/fixtures/unlinked_contact_label.qet)
+  set_tests_properties(tst_darkimageintegration PROPERTIES TIMEOUT 300 RUN_SERIAL TRUE)
+endif()
+
 add_executable(${PROJECT_NAME} tst_mytest.cpp)
 add_test(NAME ${PROJECT_NAME} COMMAND ${PROJECT_NAME})
 

tests/qttest/image_dark_integration_probe.cpp

@@ -0,0 +1,124 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+// Linked by run_image_dark_probe.py against the application's own objects.
+#include <QApplication>
+#include <QBuffer>
+#include <QCheckBox>
+#include <QDialogButtonBox>
+#include <QDomDocument>
+#include <QFile>
+#include <QFontDatabase>
+#include <QPrinter>
+#include <QPushButton>
+#include <QSettings>
+#include <QSvgGenerator>
+#include <QTemporaryDir>
+#include <cstdio>
+#include <stdexcept>
+#include "../../sources/diagram.h"
+#include "../../sources/qetproject.h"
+#include "../../sources/qetresult.h"
+#include "../../sources/qetmessagebox.h"
+#include "../../sources/qetpalette.h"
+#include "../../sources/palettegraphicsview.h"
+#include "../../sources/qetgraphicsitem/diagramimageitem.h"
+#include "../../sources/ui/imagepropertieswidget.h"
+#include "../../sources/PropertiesEditor/propertieseditordialog.h"
+
+static void check(bool value, const char *message) { if (!value) throw std::runtime_error(message); }
+static QByteArray png(const QPixmap &pixmap) {
+	QByteArray bytes; QBuffer buffer(&bytes); buffer.open(QIODevice::WriteOnly); pixmap.save(&buffer,"PNG"); return bytes;
+}
+static QByteArray read(const QString &path) { QFile file(path); check(file.open(QIODevice::ReadOnly),"read export"); return file.readAll(); }
+static DiagramImageItem *findImage(Diagram *diagram) {
+	for (auto *item : diagram->items()) if (auto *image = dynamic_cast<DiagramImageItem *>(item)) return image;
+	return nullptr;
+}
+int main(int argc, char **argv)
+{
+	QApplication app(argc,argv);
+	std::freopen(argv[2],"w",stdout); std::freopen(argv[2],"a",stderr);
+	QTemporaryDir settings;
+	QSettings::setDefaultFormat(QSettings::IniFormat);
+	QSettings::setPath(QSettings::IniFormat,QSettings::UserScope,settings.path());
+	QCoreApplication::setOrganizationName("QETImageDarkRegression");
+	QETProject::setBackupEnabled(false); QET::QetMessageBox::setNonInteractive(true);
+	QFontDatabase::addApplicationFont(":/fonts/LiberationSans-Regular.ttf");
+	try {
+		const QString output=QString::fromLocal8Bit(argv[3]);
+		QETProject project(QString::fromLocal8Bit(argv[1])); check(project.state()==QETProject::Ok,"load fixture");
+		auto *diagram=project.diagrams().first();
+		QImage original(40,30,QImage::Format_ARGB32); original.fill(QColor(197,81,33));
+		for(int y=0;y<30;++y) for(int x=10;x<20;++x) original.setPixelColor(x,y,QColor(197,81,33,128));
+		for(int y=10;y<16;++y) for(int x=24;x<30;++x) original.setPixelColor(x,y,Qt::transparent);
+		QPixmap source=QPixmap::fromImage(original);
+		auto *image=new DiagramImageItem(source); diagram->addItem(image);
+		image->setPos(55,55); image->setLabel("Image test"); image->setRotationAngle(17); image->setScaleFactorX(1.3); image->setSkewX(8);
+		check(!image->adaptToDarkTheme(),"new image defaults to original colours");
+		QDomDocument xml; auto legacy=image->toXml(xml);
+		check(!legacy.hasAttribute("adapt_to_dark_theme"),"default does not add an attribute to old files");
+		const QRect crop(4,3,24,20);
+		legacy.firstChild().setNodeValue(QString::fromLatin1(png(source.copy(crop)).toBase64()));
+		auto base=xml.createElement("image_base"); base.appendChild(xml.createTextNode(QString::fromLatin1(png(source).toBase64()))); legacy.appendChild(base);
+		auto cropElement=xml.createElement("crop"); cropElement.setAttribute("x",4); cropElement.setAttribute("y",3); cropElement.setAttribute("w",24); cropElement.setAttribute("h",20); legacy.appendChild(cropElement);
+		image->setAdaptToDarkTheme(true); check(image->fromXml(legacy),"load cropped legacy image");
+		check(!image->adaptToDarkTheme(),"missing attribute resets an existing image to original colours");
+		check(image->pixmap().size()==crop.size(),"crop survives");
+		const QByteArray pristine=png(image->pixmap()); const auto transform=image->transform(); const auto bounds=image->boundingRect();
+		ImagePropertiesWidget widget(image); auto *box=widget.findChild<QCheckBox *>("m_adapt_to_dark_theme_cb");
+		check(box && !box->isChecked(),"unchecked properties default");
+		check(box->text()==QString::fromUtf8("Adapter l’image au thème sombre"),"checkbox wording");
+		check(box->toolTip()==QString::fromUtf8("Adapte les couleurs à l’affichage sombre uniquement. L’image originale, les exports et les impressions restent inchangés."),"tooltip wording");
+		box->setChecked(true); check(image->adaptToDarkTheme(),"preview"); widget.reset(); check(!image->adaptToDarkTheme(),"reset cancels preview");
+		diagram->undoStack().clear(); box->setChecked(true); widget.apply(); check(image->adaptToDarkTheme(),"apply");
+		diagram->undoStack().undo(); check(!image->adaptToDarkTheme()&&!box->isChecked(),"undo updates checkbox");
+		diagram->undoStack().redo(); check(image->adaptToDarkTheme()&&box->isChecked(),"redo updates checkbox");
+		widget.setLiveEdit(true); box->click(); check(!image->adaptToDarkTheme(),"live edit");
+		check(diagram->undoStack().count()==2,"deliberate toggles do not merge");
+		diagram->undoStack().undo(); check(image->adaptToDarkTheme(),"live undo");
+		diagram->undoStack().redo(); check(!image->adaptToDarkTheme(),"live redo");
+		box->click(); check(image->adaptToDarkTheme()&&diagram->undoStack().count()==3,"edit after undo has current baseline");
+		for (auto role : {QDialogButtonBox::Cancel,QDialogButtonBox::Reset,QDialogButtonBox::Apply}) {
+			image->setAdaptToDarkTheme(false);
+			auto *editor=new ImagePropertiesWidget(image); PropertiesEditorDialog dialog(editor);
+			editor->findChild<QCheckBox *>("m_adapt_to_dark_theme_cb")->setChecked(true);
+			dialog.findChild<QDialogButtonBox *>()->button(role)->click();
+			check(image->adaptToDarkTheme()==(role==QDialogButtonBox::Apply),"actual dialog button semantics");
+		}
+		check(png(image->pixmap())==pristine && image->transform()==transform && image->boundingRect()==bounds && image->label()=="Image test","choice cannot modify pixels, transform, crop or caption");
+		image->setAdaptToDarkTheme(false);
+		{
+			auto *editor=new ImagePropertiesWidget(image); PropertiesEditorDialog dialog(editor);
+			editor->findChild<QCheckBox *>("m_adapt_to_dark_theme_cb")->setChecked(true);
+			dialog.reject(); check(!image->adaptToDarkTheme(),"Escape/title-bar rejection cancels preview");
+		}
+		PaletteGraphicsView view(diagram); view.setSceneRect(0,0,180,180); view.setFrameShape(QFrame::NoFrame);
+		view.setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff); view.setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
+		view.setAlignment(Qt::AlignLeft|Qt::AlignTop); view.resize(180,180); view.setAttribute(Qt::WA_DontShowOnScreen); view.show();
+		for (bool dark : {false,true}) for(bool adapt : {false,true}) {
+			const auto palette=dark?QET::Palette::fusionDark():QET::Palette::fusionLight(); QApplication::setPalette(palette);
+			image->setAdaptToDarkTheme(adapt); QApplication::processEvents(); const auto shown=view.viewport()->grab().toImage();
+			shown.save(output+QString("/screen-%1-%2.png").arg(dark).arg(adapt));
+			const auto point=view.mapFromScene(image->mapToScene(QPointF(2,2))); const auto ratio=shown.devicePixelRatio();
+			QImage expected(1,1,QImage::Format_RGB32); expected.fill(QColor(197,81,33));
+			if(dark&&adapt) QET::Palette::invertLightness(expected,palette.color(QPalette::Base),palette.color(QPalette::Text));
+			check(shown.pixelColor(qRound(point.x()*ratio),qRound(point.y()*ratio))==expected.pixelColor(0,0),"actual rotated/cropped image display colour");
+			project.setFilePath(output+QString("/project-%1-%2.qet").arg(dark).arg(adapt)); check(project.write().isOk(),"project save");
+			QETProject reopened(project.filePath()); check(reopened.state()==QETProject::Ok,"project reopen");
+			auto *loaded=findImage(reopened.diagrams().first()); check(loaded && loaded->adaptToDarkTheme()==adapt,"per-image persisted choice");
+			check(png(loaded->pixmap())==pristine && loaded->transform()==transform && loaded->label()=="Image test","reopen keeps original image/crop/transform/caption");
+		}
+		QApplication::setPalette(QET::Palette::fusionDark()); QImage exports[2];
+		for(int i=0;i<2;++i) {
+			image->setAdaptToDarkTheme(i); exports[i]=QImage(180,180,QImage::Format_RGB32); exports[i].fill(Qt::white);
+			{QPainter painter(&exports[i]); diagram->render(&painter,QRectF(0,0,180,180),QRectF(0,0,180,180));}
+			exports[i].save(output+QString("/export-%1.png").arg(i));
+			QSvgGenerator svg; svg.setFileName(output+QString("/export-%1.svg").arg(i)); svg.setSize(QSize(180,180)); svg.setViewBox(QRect(0,0,180,180));
+			{QPainter painter(&svg); diagram->render(&painter,QRectF(0,0,180,180),QRectF(0,0,180,180));}
+			QPrinter printer; printer.setOutputFormat(QPrinter::PdfFormat); printer.setOutputFileName(output+QString("/print-%1.pdf").arg(i)); printer.setResolution(72);
+			{QPainter painter(&printer); check(painter.isActive(),"PDF print painter"); diagram->render(&painter,QRectF(0,0,180,180),QRectF(0,0,180,180));}
+		}
+		check(exports[0]==exports[1],"raster export unchanged"); check(read(output+"/export-0.svg")==read(output+"/export-1.svg"),"SVG export unchanged");
+		std::puts("PASS: image defaults, XML crop/alpha/transform/label, properties preview/apply/reset/cancel, undo/redo and live edit, four display modes, project save/reopen, raster/SVG export, PDF print generation");
+	} catch(const std::exception &error) {std::fprintf(stderr,"FAIL: %s\n",error.what());return 1;}
+	return 0;
+}

tests/qttest/run_image_dark_probe.py

@@ -0,0 +1,96 @@
+#!/usr/bin/env python3
+"""Link the real image/widget integration probe using an existing Ninja app build.
+
+Reuses app objects without duplicating the app or introducing a core-library
+refactor. No application source or existing executable is replaced. The
+generated manifest, probe binary, reports and export fixtures stay in build/.
+"""
+import argparse
+import pathlib
+import re
+import shutil
+import subprocess
+import sys
+import zlib
+
+parser = argparse.ArgumentParser()
+parser.add_argument('--build', required=True)
+parser.add_argument('--binary', required=True)
+parser.add_argument('--source', required=True)
+parser.add_argument('--fixture', required=True)
+args = parser.parse_args()
+build = pathlib.Path(args.build).resolve()
+binary = pathlib.Path(args.binary).resolve()
+source = pathlib.Path(args.source).resolve()
+fixture = pathlib.Path(args.fixture).resolve()
+manifest = (build / 'build.ninja').read_text(encoding='utf-8')
+match = re.search(r'^build (\S*?/sources/main\.cpp\.(?:obj|o)):', manifest, re.MULTILINE)
+if not match:
+    sys.exit('Cannot find the application main object in the Ninja build.')
+main_object = match.group(1)
+probe_object = main_object.replace('main.cpp.', 'image_dark_integration_probe.cpp.')
+probe_binary = binary.with_name('image_dark_integration_probe' + binary.suffix)
+def escape(path):
+    return pathlib.Path(path).as_posix().replace('$', '$$').replace(':', '$:').replace(' ', '$ ')
+main_source = source.parents[2] / 'sources' / 'main.cpp'
+manifest = manifest.replace(main_object, probe_object)
+manifest = manifest.replace(escape(main_source), escape(source))
+if binary.suffix:
+    manifest = manifest.replace(binary.name, probe_binary.name)
+else:
+    old_target = escape(binary.name if binary.parent == build else binary)
+    new_target = escape(probe_binary.name if probe_binary.parent == build else probe_binary)
+    manifest = manifest.replace('build ' + old_target + ':', 'build ' + new_target + ':')
+    old_file = binary.name if binary.parent == build else binary.as_posix()
+    new_file = probe_binary.name if probe_binary.parent == build else probe_binary.as_posix()
+    manifest = re.sub(r'^  TARGET_FILE = ' + re.escape(old_file) + r'$',
+                      '  TARGET_FILE = ' + new_file, manifest, flags=re.MULTILINE)
+probe_manifest = build / 'image-dark-probe.ninja'
+probe_manifest.write_text(manifest, encoding='utf-8')
+ninja = shutil.which('ninja')
+if not ninja:
+    sys.exit('Ninja is required for the integration probe.')
+target = probe_binary.name if probe_binary.parent == build else str(probe_binary)
+subprocess.run([ninja, '-C', str(build), '-f', probe_manifest.name, target], check=True)
+output = build / 'image-dark-integration'
+output.mkdir(exist_ok=True)
+report = output / 'results.txt'
+result = subprocess.run([str(probe_binary), str(fixture), str(report), str(output)], timeout=90)
+if report.exists():
+    print(report.read_text(encoding='utf-8', errors='replace'))
+if result.returncode == 0:
+    def print_streams(path):
+        streams = re.findall(rb'\nstream\r?\n(.*?)\nendstream', path.read_bytes(), re.DOTALL)
+        decoded = []
+        for stream in streams:
+            try:
+                data = zlib.decompress(stream)
+            except zlib.error:
+                data = stream
+            # Qt assigns every PDF a fresh XMP DocumentID (and dates).
+            # Metadata is not printing content and must not be compared
+            # as if it were a graphics/image/font stream.
+            if b'<x:xmpmeta' not in data:
+                decoded.append(data)
+        return decoded
+    first = print_streams(output / 'print-0.pdf')
+    second = print_streams(output / 'print-1.pdf')
+    if not first or first != second:
+        sys.exit('PDF printing changed the decoded graphics/image/font streams.')
+    print('PASS: PDF print graphics/image/font streams identical for both choices.')
+    try:
+        import pymupdf
+    except ImportError:
+        print('PDF raster comparison not run: optional PyMuPDF is unavailable.')
+    else:
+        documents = [pymupdf.open(output / f'print-{i}.pdf') for i in range(2)]
+        if len(documents[0]) != len(documents[1]):
+            sys.exit('PDF page counts differ.')
+        for page in range(len(documents[0])):
+            pixels = [doc[page].get_pixmap(dpi=144, alpha=False) for doc in documents]
+            if (pixels[0].width, pixels[0].height, pixels[0].samples) != (pixels[1].width, pixels[1].height, pixels[1].samples):
+                sys.exit('Rasterized PDF print pages differ.')
+            for i, image in enumerate(pixels):
+                image.save(output / f'print-{i}-page-{page}.png')
+        print('PASS: PDF print pages rendered at 144 dpi are pixel-identical.')
+sys.exit(result.returncode)

tests/qttest/tst_darkimagelayers.cpp

@@ -0,0 +1,129 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+#include <QtTest>
+#include <QGraphicsRectItem>
+#include <QGraphicsScene>
+#include "darkimagerendering.h"
+#include "palettegraphicsview.h"
+#include "qetpalette.h"
+
+class Raster : public QGraphicsItem {
+public:
+	QPixmap pixmap;
+	bool adapt = false;
+	explicit Raster(QGraphicsItem *parent = nullptr) : QGraphicsItem(parent) {
+		QImage image(40, 30, QImage::Format_ARGB32);
+		image.fill(QColor(197, 81, 33));
+		for (int y = 0; y < 30; ++y)
+			for (int x = 10; x < 20; ++x) image.setPixelColor(x, y, QColor(197,81,33,128));
+		for (int y = 0; y < 30; ++y)
+			for (int x = 30; x < 40; ++x) image.setPixelColor(x, y, Qt::transparent);
+		pixmap = QPixmap::fromImage(image);
+	}
+	QRectF boundingRect() const override { return QRectF(0,0,40,40); }
+	void paint(QPainter *p, const QStyleOptionGraphicsItem *, QWidget *) override {
+		DarkImageRendering::paintPixmap(p, pixmap, adapt);
+		p->fillRect(QRectF(0,34,8,4), Qt::black); // caption/decorations remain adapted
+	}
+};
+
+class tst_darkimagelayers : public QObject {
+	Q_OBJECT
+	static QColor sample(const QImage &image, const PaletteGraphicsView &view, QPointF scene) {
+		const QPoint point = view.mapFromScene(scene);
+		const qreal dpr = image.devicePixelRatio();
+		return image.pixelColor(qRound(point.x()*dpr), qRound(point.y()*dpr));
+	}
+	static void setup(PaletteGraphicsView &view) {
+		view.setFrameShape(QFrame::NoFrame);
+		view.setAlignment(Qt::AlignLeft | Qt::AlignTop);
+		view.setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
+		view.setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
+		view.resize(100,80); view.show();
+	}
+private slots:
+	void cleanup() {
+		QApplication::setPalette(QET::Palette::fusionLight());
+		PaletteGraphicsView::setCustomBackgroundColor(false);
+	}
+	void modes_data() {
+		QTest::addColumn<bool>("dark"); QTest::addColumn<bool>("adapt"); QTest::addColumn<bool>("custom");
+		QTest::newRow("light-original") << false << false << false;
+		QTest::newRow("light-adapt") << false << true << false;
+		QTest::newRow("dark-original") << true << false << false;
+		QTest::newRow("dark-adapt") << true << true << false;
+		QTest::newRow("light-custom-original") << false << false << true;
+		QTest::newRow("light-custom-adapt") << false << true << true;
+		QTest::newRow("dark-custom-original") << true << false << true;
+		QTest::newRow("dark-custom-adapt") << true << true << true;
+	}
+	void modes() {
+		QFETCH(bool,dark); QFETCH(bool,adapt); QFETCH(bool,custom);
+		PaletteGraphicsView::setCustomBackgroundColor(custom);
+		const QPalette palette = dark ? QET::Palette::fusionDark() : QET::Palette::fusionLight();
+		QApplication::setPalette(palette);
+		const QColor background = custom ? QColor(80,90,100) : QColor(Qt::white);
+		QGraphicsScene scene(0,0,100,80); scene.setBackgroundBrush(background);
+		auto *raster = new Raster; raster->adapt = adapt; raster->setPos(10,10); scene.addItem(raster);
+		scene.addRect(32,10,5,20,QPen(Qt::NoPen),QBrush(Qt::black))->setZValue(1);
+		PaletteGraphicsView view(&scene); setup(view);
+		QVERIFY(QTest::qWaitForWindowExposed(&view));
+		const QImage shown = view.viewport()->grab().toImage();
+		QImage expected(100,80,QImage::Format_RGB32);
+		expected.fill(custom ? background : (dark && !adapt ? palette.color(QPalette::Base) : QColor(Qt::white)));
+		QPainter p(&expected);
+		if (dark && custom && adapt) {
+			QImage adapted = raster->pixmap.toImage();
+			QET::Palette::invertLightnessLayer(adapted,palette.color(QPalette::Base),palette.color(QPalette::Text));
+			p.drawImage(QPoint(10,10),adapted);
+		} else p.drawPixmap(QPoint(10,10),raster->pixmap);
+		p.fillRect(QRect(32,10,5,20), dark && !adapt && !custom ? palette.color(QPalette::Text) : QColor(Qt::black));
+		p.end();
+		if (dark && adapt && !custom) QET::Palette::invertLightness(expected,palette.color(QPalette::Base),palette.color(QPalette::Text));
+		for (const QPoint point : {QPoint(15,15),QPoint(25,15),QPoint(45,15),QPoint(34,15)})
+			QCOMPARE(sample(shown,view,point), expected.pixelColor(point));
+		QCOMPARE(sample(shown,view,QPoint(13,45)), dark && !custom ? palette.color(QPalette::Text) : QColor(Qt::black));
+	}
+	void parentClippingRotationOpacityAndOverlap() {
+		const auto palette = QET::Palette::fusionDark(); QApplication::setPalette(palette);
+		QGraphicsScene scene(0,0,100,80); scene.setBackgroundBrush(Qt::white);
+		auto *parent = scene.addRect(0,0,25,40,QPen(Qt::NoPen),QBrush(Qt::NoBrush));
+		parent->setFlag(QGraphicsItem::ItemClipsChildrenToShape); parent->setPos(35,15); parent->setRotation(12);
+		auto *first = new Raster(parent); first->setOpacity(0.5);
+		auto *second = new Raster; second->setPos(36,30); scene.addItem(second); second->setZValue(2);
+		QImage blue(40,30,QImage::Format_ARGB32); blue.fill(QColor(20,80,210,128)); second->pixmap=QPixmap::fromImage(blue);
+		PaletteGraphicsView view(&scene); setup(view); QVERIFY(QTest::qWaitForWindowExposed(&view));
+		const auto shown = view.viewport()->grab().toImage();
+		// Original pixels blend once over the dark sheet, then the upper
+		// original image blends once over those pixels. No inverse transform.
+		QImage reference(1,1,QImage::Format_RGB32); reference.fill(palette.color(QPalette::Base));
+		QPainter p(&reference); p.setOpacity(0.5); p.fillRect(reference.rect(),QColor(197,81,33)); p.end();
+		QCOMPARE(sample(shown,view,first->mapToScene(QPointF(5,5))),reference.pixelColor(0,0));
+		QPainter upper(&reference); upper.fillRect(reference.rect(),QColor(20,80,210,128)); upper.end();
+		QCOMPARE(sample(shown,view,first->mapToScene(QPointF(5,20))),reference.pixelColor(0,0));
+		// Pixel in the child's transparent stripe / beyond the parent's clip.
+		QCOMPARE(sample(shown,view,first->mapToScene(QPointF(28,5))),palette.color(QPalette::Base));
+		first->setPos(3,0); scene.update(); QApplication::processEvents();
+		QVERIFY(!view.viewport()->grab().isNull());
+	}
+	void alphaMapping() {
+		QImage image(2,1,QImage::Format_ARGB32_Premultiplied);
+		image.setPixelColor(0,0,QColor(0,0,0,128)); image.setPixelColor(1,0,Qt::transparent);
+		QET::Palette::invertLightnessLayer(image,QColor(30,30,30),QColor(220,220,220));
+		QCOMPARE(image.pixelColor(0,0),QColor(220,220,220,128));
+		QCOMPARE(image.pixelColor(1,0).alpha(),0);
+	}
+	void exportUnaffected() {
+		QApplication::setPalette(QET::Palette::fusionDark());
+		QGraphicsScene scene(0,0,100,80); scene.setBackgroundBrush(Qt::white);
+		auto *raster=new Raster; raster->setPos(10,10); scene.addItem(raster);
+		QImage results[2];
+		for(int i=0;i<2;++i) {
+			raster->adapt=i; results[i]=QImage(100,80,QImage::Format_RGB32); results[i].fill(Qt::white);
+			QPainter p(&results[i]); scene.render(&p,QRectF(0,0,100,80),scene.sceneRect());
+		}
+		QCOMPARE(results[0],results[1]);
+		QCOMPARE(results[0].pixelColor(15,15),QColor(197,81,33));
+	}
+};
+QTEST_MAIN(tst_darkimagelayers)
+#include "tst_darkimagelayers.moc"