Merge pull request #799 from ispyisail/fix/element-editor-zoom-clamp

Fix issue #798: element editor crash on scroll-wheel zoom

ChangeLog_full.md

@@ -20,6 +20,7 @@ All notable changes to QElectroTech are documented here.
 
 ### 🐛 Bug Fixes
 
+- Fix #798: clamp element-editor and diagram-view zoom to prevent view-transform overflow crash on scroll-wheel zoom ([3ca5d4a](../../commit/3ca5d4ab2))
 - Fix(windows-msi): inject rev into MSI Version Build field ([e19f523](../../commit/e19f5232277efb37435cb65a83563d73333d62ec))
 - Fix #391: use wide-char path for pugixml on Windows to handle Unicode paths ([31edf30](../../commit/31edf30c619213368e9b592b51be6ca8190db831))
 - Fix(#283): restore center alignment when loading table config ([f55ba56](../../commit/f55ba568f68293e06436899bcc831431e9d27295))

sources/diagramview.cpp

@@ -334,6 +334,13 @@ void DiagramView::setSelectionMode()
 */
 void DiagramView::zoom(const qreal zoom_factor)
 {
+	// clamp the resulting scale so a repeated wheel-zoom cannot drive the view
+	// transform to floating-point overflow and crash the editor (issue #798)
+	const qreal target = transform().m11() * zoom_factor;
+	if (target < m_min_zoom || target > m_max_zoom) {
+		return;
+	}
+
 	if (zoom_factor >= 1){
 		scale(zoom_factor, zoom_factor);
 	}

sources/diagramview.h

@@ -103,6 +103,12 @@ class DiagramView : public QGraphicsView
 		bool mustIntegrateTitleBlockTemplate(const TitleBlockTemplateLocation &) const;
 		bool gestures() const;
 
+		/// Lowest and highest allowed value of the view transform scale (m11).
+		/// Prevents wheel-zoom from driving the transform to overflow, which
+		/// crashes the editor (see GitHub issue #798, same class of bug).
+		static constexpr qreal m_min_zoom = 0.01;
+		static constexpr qreal m_max_zoom = 200.0;
+
 	signals:
 			/// Signal emitted after the selection mode changed
 		void modeChanged();

sources/editor/elementview.cpp

@@ -100,13 +100,30 @@ void ElementView::setSelectionMode()
 	emit(modeChanged());
 }
 
+/**
+	Applique un facteur d'echelle a la vue en bornant l'echelle resultante
+	entre m_min_zoom et m_max_zoom. Sans cette borne, un zoom repete (molette)
+	finit par faire deborder la transformation de la vue et fait planter
+	l'editeur (issue #798).
+	@param factor facteur d'echelle a appliquer
+*/
+void ElementView::scaleClamped(qreal factor)
+{
+	const qreal current = transform().m11();
+	const qreal target = current * factor;
+	if (target < m_min_zoom || target > m_max_zoom) {
+		return;
+	}
+	scale(factor, factor);
+}
+
 /**
 	Agrandit le schema (+33% = inverse des -25 % de zoomMoins())
 */
 void ElementView::zoomIn()
 {
 	adjustSceneRect();
-	scale(4.0/3.0, 4.0/3.0);
+	scaleClamped(4.0/3.0);
 }
 
 /**
@@ -115,7 +132,7 @@ void ElementView::zoomIn()
 void ElementView::zoomOut()
 {
 	adjustSceneRect();
-	scale(0.75, 0.75);
+	scaleClamped(0.75);
 }
 
 /**
@@ -123,7 +140,7 @@ void ElementView::zoomOut()
 */
 void ElementView::zoomInSlowly()
 {
-	scale(1.02, 1.02);
+	scaleClamped(1.02);
 }
 
 /**
@@ -131,7 +148,7 @@ void ElementView::zoomInSlowly()
 */
 void ElementView::zoomOutSlowly()
 {
-	scale(0.98, 0.98);
+	scaleClamped(0.98);
 }
 
 /**

sources/editor/elementview.h

@@ -53,6 +53,13 @@ class ElementView : public QGraphicsView {
 	
 	private:
 	QRectF applyMovement(const QRectF &, const QPointF &);
+	void scaleClamped(qreal factor);
+
+	/// Lowest and highest allowed value of the view transform scale (m11).
+	/// Prevents the wheel-zoom from driving the transform to overflow, which
+	/// crashes the editor (bugtracker / GitHub issue #798).
+	static constexpr qreal m_min_zoom = 0.1;
+	static constexpr qreal m_max_zoom = 200.0;
 	
 	public slots:
 	void setVisualisationMode();