Fix path preview and selection mask bounds

They now add a margin depending on the zoom level, which fixes rendering
glitches on some systems.

ChangeLog

@@ -1,4 +1,5 @@
 Unreleased Version 2.2.2-pre
+ * Fix: Solve rendering glitches with selection outlines that happen on some systems. Thanks xxxx for reporting.
 
 2024-08-09 Version 2.2.2-beta.3
  * Fix: Use more accurate timers for performance profiles if the platform supports it.

src/desktop/scene/canvasscene.cpp

@@ -149,6 +149,12 @@ void CanvasScene::setZoom(qreal zoom)
 {
 	if(zoom != m_zoom) {
 		m_zoom = zoom;
+		if(m_pathPreview) {
+			m_pathPreview->setZoom(zoom);
+		}
+		if(m_selection) {
+			m_selection->setZoom(zoom);
+		}
 		if(m_transform) {
 			m_transform->setZoom(zoom);
 		}
@@ -441,7 +447,7 @@ void CanvasScene::setSelection(
 	if(valid) {
 		if(!m_selection) {
 			m_selection = new SelectionItem(
-				m_selectionIgnored, m_showSelectionMask, m_group);
+				m_selectionIgnored, m_showSelectionMask, m_zoom, m_group);
 			m_selection->setUpdateSceneOnRefresh(true);
 		}
 		m_selection->setModel(bounds, mask);
@@ -779,7 +785,7 @@ void CanvasScene::setPathPreview(const QPainterPath &path)
 	} else if(m_pathPreview) {
 		m_pathPreview->setPath(path);
 	} else {
-		m_pathPreview = new PathPreviewItem(path, m_group);
+		m_pathPreview = new PathPreviewItem(path, m_zoom, m_group);
 	}
 }
 

src/desktop/scene/pathpreviewitem.cpp

@@ -3,19 +3,22 @@
 #include <QMarginsF>
 #include <QPaintEngine>
 #include <QPainter>
+#include <cmath>
 
 namespace drawingboard {
 
 PathPreviewItem::PathPreviewItem(
-	const QPainterPath &path, QGraphicsItem *parent)
+	const QPainterPath &path, qreal zoom, QGraphicsItem *parent)
 	: BaseItem(parent)
 	, m_path(path)
+	, m_zoom(zoom)
 {
 }
 
 QRectF PathPreviewItem::boundingRect() const
 {
-	return m_path.boundingRect().marginsAdded(QMarginsF(1.0, 1.0, 1.0, 1.0));
+	qreal m = m_zoom > 0.0 ? std::ceil(1.0 / m_zoom) : 1.0;
+	return m_path.boundingRect().marginsAdded(QMarginsF(m, m, m, m));
 }
 
 void PathPreviewItem::setPath(const QPainterPath &path)
@@ -24,6 +27,14 @@ void PathPreviewItem::setPath(const QPainterPath &path)
 	m_path = path;
 }
 
+void PathPreviewItem::setZoom(qreal zoom)
+{
+	if(zoom != m_zoom) {
+		refreshGeometry();
+		m_zoom = zoom;
+	}
+}
+
 void PathPreviewItem::paint(
 	QPainter *painter, const QStyleOptionGraphicsItem *options, QWidget *widget)
 {

src/desktop/scene/pathpreviewitem.h

@@ -10,13 +10,15 @@ class PathPreviewItem final : public BaseItem {
 public:
 	enum { Type = PathPreviewType };
 
-	PathPreviewItem(const QPainterPath &path, QGraphicsItem *parent = nullptr);
+	PathPreviewItem(
+		const QPainterPath &path, qreal zoom, QGraphicsItem *parent = nullptr);
 
 	QRectF boundingRect() const override;
 
 	int type() const override { return Type; }
 
 	void setPath(const QPainterPath &path);
+	void setZoom(qreal zoom);
 
 protected:
 	void paint(
@@ -25,6 +27,7 @@ class PathPreviewItem final : public BaseItem {
 
 private:
 	QPainterPath m_path;
+	qreal m_zoom;
 };
 
 }

src/desktop/scene/selectionitem.cpp

@@ -1,14 +1,17 @@
 // SPDX-License-Identifier: GPL-3.0-or-later
 #include "desktop/scene/selectionitem.h"
 #include "libclient/utils/selectionoutlinegenerator.h"
+#include <QMarginsF>
 #include <QPainter>
 #include <QThreadPool>
 #include <cmath>
 
 namespace drawingboard {
 
-SelectionItem::SelectionItem(bool ignored, bool showMask, QGraphicsItem *parent)
+SelectionItem::SelectionItem(
+	bool ignored, bool showMask, qreal zoom, QGraphicsItem *parent)
 	: BaseObject(parent)
+	, m_zoom(zoom)
 	, m_ignored(ignored)
 	, m_showMask(showMask)
 {
@@ -29,6 +32,7 @@ void SelectionItem::setModel(const QRect &bounds, const QImage &mask)
 	m_maskOpacity = 0.0;
 	m_haveTemporaryMask = true;
 	updateBoundingRectFromBounds();
+	setPos(m_bounds.topLeft());
 	if(m_bounds.isEmpty()) {
 		qWarning("Selection mask is empty");
 	} else if(canShowOutline()) {
@@ -69,6 +73,14 @@ void SelectionItem::setShowMask(bool showMask)
 	}
 }
 
+void SelectionItem::setZoom(qreal zoom)
+{
+	if(zoom != m_zoom) {
+		m_zoom = zoom;
+		updateBoundingRectFromBounds();
+	}
+}
+
 void SelectionItem::animationStep(qreal dt)
 {
 	bool havePath = !m_path.isEmpty();
@@ -173,8 +185,9 @@ void SelectionItem::setOutline(
 void SelectionItem::updateBoundingRectFromBounds()
 {
 	refreshGeometry();
-	m_boundingRect = QRectF(QPointF(0.0, 0.0), QSizeF(m_bounds.size()));
-	setPos(m_bounds.topLeft());
+	qreal m = m_zoom > 0.0 ? std::ceil(1.0 / m_zoom) : 1.0;
+	m_boundingRect = QRectF(QPointF(0.0, 0.0), QSizeF(m_bounds.size()))
+						 .marginsAdded(QMarginsF(m, m, m, m));
 }
 
 }

src/desktop/scene/selectionitem.h

@@ -18,7 +18,9 @@ class SelectionItem final : public BaseObject {
 public:
 	enum { Type = SelectionType };
 
-	SelectionItem(bool ignored, bool showMask, QGraphicsItem *parent = nullptr);
+	SelectionItem(
+		bool ignored, bool showMask, qreal zoom,
+		QGraphicsItem *parent = nullptr);
 
 	int type() const override { return Type; }
 
@@ -30,6 +32,7 @@ class SelectionItem final : public BaseObject {
 
 	void setIgnored(bool ignored);
 	void setShowMask(bool showMask);
+	void setZoom(qreal zoom);
 
 	void animationStep(qreal dt);
 
@@ -50,6 +53,7 @@ class SelectionItem final : public BaseObject {
 	QRect m_bounds;
 	QPainterPath m_path;
 	QImage m_mask;
+	qreal m_zoom;
 	qreal m_marchingAnts = 0.0;
 	qreal m_maskOpacity = 0.0;
 	qreal m_transparentDelay = 0.0;

src/desktop/view/canvasscene.cpp

@@ -116,6 +116,12 @@ void CanvasScene::setZoom(qreal zoom)
 {
 	if(zoom != m_zoom) {
 		m_zoom = zoom;
+		if(m_pathPreview) {
+			m_pathPreview->setZoom(zoom);
+		}
+		if(m_selection) {
+			m_selection->setZoom(zoom);
+		}
 		if(m_transform) {
 			m_transform->setZoom(zoom);
 		}
@@ -304,7 +310,7 @@ void CanvasScene::setPathPreview(const QPainterPath &path)
 	} else if(m_pathPreview) {
 		m_pathPreview->setPath(path);
 	} else {
-		m_pathPreview = new PathPreviewItem(path, m_canvasGroup);
+		m_pathPreview = new PathPreviewItem(path, m_zoom, m_canvasGroup);
 		m_pathPreview->setUpdateSceneOnRefresh(true);
 	}
 }
@@ -625,7 +631,7 @@ void CanvasScene::setSelection(
 	if(valid) {
 		if(!m_selection) {
 			m_selection = new SelectionItem(
-				m_selectionIgnored, m_showSelectionMask, m_canvasGroup);
+				m_selectionIgnored, m_showSelectionMask, m_zoom, m_canvasGroup);
 			m_selection->setUpdateSceneOnRefresh(true);
 		}
 		m_selection->setModel(bounds, mask);