#2074 note-relations: allow zooming

Signed-off-by: Patrizio Bekerle <[email protected]>

Author: pbek

Diff for: CHANGELOG.md

@@ -1,5 +1,9 @@
 # QOwnNotes Changelog
 
+## 25.3.3
+- You can now **zoom** in the **note relation panel** with the mouse wheel
+  (for [#2074](https://github.com/pbek/QOwnNotes/issues/2074))
+
 ## 25.3.2
 - In the **note relation panel**, notes can now have **circular relations**
   between each other, no new note items will be drawn for notes that are already

Diff for: src/mainwindow.ui

@@ -698,7 +698,7 @@
               </widget>
              </item>
              <item>
-              <widget class="QGraphicsView" name="noteGraphicsView"/>
+              <widget class="ZoomableGraphicsView" name="noteGraphicsView"/>
              </item>
             </layout>
            </widget>
@@ -2897,6 +2897,11 @@ li.checked::marker { content: &quot;\2612&quot;; }
    <extends>QTreeWidget</extends>
    <header>widgets/notesubfoldertree.h</header>
   </customwidget>
+  <customwidget>
+   <class>ZoomableGraphicsView</class>
+   <extends>QGraphicsView</extends>
+   <header location="global">widgets/noterelationscene.h</header>
+  </customwidget>
  </customwidgets>
  <tabstops>
   <tabstop>noteSubFolderLineEdit</tabstop>

Diff for: src/widgets/noterelationscene.cpp

@@ -282,3 +282,22 @@ QPointF NoteRelationScene::calculateRadialPosition(QPointF center, int index, in
 
     return {x, y};
 }
+
+ZoomableGraphicsView::ZoomableGraphicsView(QWidget *parent) : QGraphicsView(parent) {
+    // Set view properties
+    setRenderHint(QPainter::Antialiasing);
+    setDragMode(QGraphicsView::ScrollHandDrag);
+    setTransformationAnchor(QGraphicsView::AnchorUnderMouse);
+    setResizeAnchor(QGraphicsView::AnchorUnderMouse);
+}
+
+void ZoomableGraphicsView::wheelEvent(QWheelEvent *event) {
+    // Zoom in or out depending on wheel direction
+    if (event->angleDelta().y() > 0) {
+        // Zoom in
+        scale(scaleFactor, scaleFactor);
+    } else {
+        // Zoom out
+        scale(1.0 / scaleFactor, 1.0 / scaleFactor);
+    }
+}

Diff for: src/widgets/noterelationscene.h

@@ -18,7 +18,9 @@
 #include <QGraphicsRectItem>
 #include <QGraphicsScene>
 #include <QGraphicsSceneMouseEvent>
+#include <QGraphicsView>
 #include <QPainter>
+#include <QWheelEvent>
 #include <vector>
 
 #include "entities/note.h"
@@ -90,3 +92,14 @@ class NoteRelationScene : public QGraphicsScene {
     // This will run in the GUI thread
     void addItemToScene(QGraphicsItem *item);
 };
+
+class ZoomableGraphicsView : public QGraphicsView {
+   public:
+    explicit ZoomableGraphicsView(QWidget *parent = nullptr);
+
+   protected:
+    void wheelEvent(QWheelEvent *event) override;
+
+   private:
+    double scaleFactor = 1.15;    // Zoom factor when scrolling
+};