ModelEditor: Improve panning

Change-Id: Iacb3e2bb9006d306852f18b50bbec322abb5acdf
Reviewed-by: Alessandro Portale <alessandro.portale@qt.io>
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>

2 files changed, 45 insertions, 1 deletions

diff --git a/src/libs/modelinglib/qmt/diagram_widgets_ui/diagramview.cpp b/src/libs/modelinglib/qmt/diagram_widgets_ui/diagramview.cpp
index 5634c4eb7f..eba246676d 100644
--- a/src/libs/modelinglib/qmt/diagram_widgets_ui/diagramview.cpp
+++ b/src/libs/modelinglib/qmt/diagram_widgets_ui/diagramview.cpp
@@ -14,9 +14,14 @@
 #include <QDragLeaveEvent>
 #include <QDropEvent>
 #include <QMimeData>
+#include <QScrollBar>
 
 namespace qmt {
 
+namespace {
+const qreal ADJUSTMENT = 80;
+};
+
 DiagramView::DiagramView(QWidget *parent)
     : QGraphicsView(parent)
 {
@@ -25,6 +30,9 @@ DiagramView::DiagramView(QWidget *parent)
     setDragMode(QGraphicsView::RubberBandDrag);
     setFrameShape(QFrame::NoFrame);
     setRenderHints(QPainter::Antialiasing | QPainter::SmoothPixmapTransform);
+    m_panTimer.setInterval(200);
+    m_panTimer.setSingleShot(false);
+    connect(&m_panTimer, &QTimer::timeout, this, &DiagramView::onPanTimeout);
 }
 
 DiagramView::~DiagramView()
@@ -130,12 +138,41 @@ void DiagramView::dropEvent(QDropEvent *event)
     }
 }
 
+void DiagramView::mousePressEvent(QMouseEvent *event)
+{
+    m_panTimer.start();
+    QGraphicsView::mousePressEvent(event);
+}
+
+void DiagramView::mouseReleaseEvent(QMouseEvent *event)
+{
+    m_panTimer.stop();
+    QGraphicsView::mouseReleaseEvent(event);
+}
+
+void DiagramView::mouseMoveEvent(QMouseEvent *event)
+{
+    QGraphicsView::mouseMoveEvent(event);
+    m_lastMouse = event->pos();
+}
+
 void DiagramView::onSceneRectChanged(const QRectF &sceneRect)
 {
     // add some adjustment to all 4 sides
-    static const qreal ADJUSTMENT = 80;
     QRectF rect = sceneRect.adjusted(-ADJUSTMENT, -ADJUSTMENT, ADJUSTMENT, ADJUSTMENT);
     setSceneRect(rect);
 }
 
+void DiagramView::onPanTimeout()
+{
+    if (m_lastMouse.x() < ADJUSTMENT)
+        horizontalScrollBar()->triggerAction(QScrollBar::SliderSingleStepSub);
+    else if (m_lastMouse.x() > viewport()->size().width() - ADJUSTMENT)
+        horizontalScrollBar()->triggerAction(QScrollBar::SliderSingleStepAdd);
+    if (m_lastMouse.y() < ADJUSTMENT)
+        verticalScrollBar()->triggerAction(QScrollBar::SliderSingleStepSub);
+    else if (m_lastMouse.y() > viewport()->size().height() - ADJUSTMENT)
+        verticalScrollBar()->triggerAction(QScrollBar::SliderSingleStepAdd);
+}
+
 } // namespace qmt
diff --git a/src/libs/modelinglib/qmt/diagram_widgets_ui/diagramview.h b/src/libs/modelinglib/qmt/diagram_widgets_ui/diagramview.h
index 41386f09bd..4eee60ff44 100644
--- a/src/libs/modelinglib/qmt/diagram_widgets_ui/diagramview.h
+++ b/src/libs/modelinglib/qmt/diagram_widgets_ui/diagramview.h
@@ -7,6 +7,7 @@
 #include "qmt/infrastructure/qmt_global.h"
 
 #include <QPointer>
+#include <QTimer>
 
 namespace qmt {
 
@@ -27,11 +28,17 @@ protected:
     void dragLeaveEvent(QDragLeaveEvent *event) override;
     void dragMoveEvent(QDragMoveEvent *event) override;
     void dropEvent(QDropEvent *event) override;
+    void mousePressEvent(QMouseEvent *event) override;
+    void mouseReleaseEvent(QMouseEvent *event) override;
+    void mouseMoveEvent(QMouseEvent *event) override;
 
 private:
     void onSceneRectChanged(const QRectF &sceneRect);
+    void onPanTimeout();
 
     QPointer<DiagramSceneModel> m_diagramSceneModel;
+    QPointF m_lastMouse;
+    QTimer m_panTimer;
 };
 
 } // namespace qmt