6.5.3 clean

tests/manual/examples/widgets/touch/pinchzoom/graphicsview.cpp

@@ -0,0 +1,48 @@
+// Copyright (C) 2016 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
+
+#include "graphicsview.h"
+
+#include <QScrollBar>
+#include <QTouchEvent>
+
+GraphicsView::GraphicsView(QGraphicsScene *scene, QWidget *parent)
+    : QGraphicsView(scene, parent)
+{
+    viewport()->setAttribute(Qt::WA_AcceptTouchEvents);
+    setDragMode(ScrollHandDrag);
+}
+
+bool GraphicsView::viewportEvent(QEvent *event)
+{
+    switch (event->type()) {
+    case QEvent::TouchBegin:
+    case QEvent::TouchUpdate:
+    case QEvent::TouchEnd:
+    {
+        QTouchEvent *touchEvent = static_cast<QTouchEvent *>(event);
+        const auto touchPoints = touchEvent->points();
+        if (touchPoints.count() == 2) {
+            // determine scale factor
+            const QEventPoint &touchPoint0 = touchPoints.first();
+            const QEventPoint &touchPoint1 = touchPoints.last();
+            qreal currentScaleFactor =
+                    QLineF(touchPoint0.position(), touchPoint1.position()).length()
+                    / QLineF(touchPoint0.pressPosition(), touchPoint1.pressPosition()).length();
+            if (touchEvent->touchPointStates() & QEventPoint::Released) {
+                // if one of the fingers is released, remember the current scale
+                // factor so that adding another finger later will continue zooming
+                // by adding new scale factor to the existing remembered value.
+                totalScaleFactor *= currentScaleFactor;
+                currentScaleFactor = 1;
+            }
+            setTransform(QTransform::fromScale(totalScaleFactor * currentScaleFactor,
+                                               totalScaleFactor * currentScaleFactor));
+        }
+        return true;
+    }
+    default:
+        break;
+    }
+    return QGraphicsView::viewportEvent(event);
+}