diff options
Diffstat (limited to 'examples/multitouch/pinchzoom/graphicsview.cpp')
| -rw-r--r-- | examples/multitouch/pinchzoom/graphicsview.cpp | 20 |
1 files changed, 15 insertions, 5 deletions
diff --git a/examples/multitouch/pinchzoom/graphicsview.cpp b/examples/multitouch/pinchzoom/graphicsview.cpp index 0c79073..00e620a 100644 --- a/examples/multitouch/pinchzoom/graphicsview.cpp +++ b/examples/multitouch/pinchzoom/graphicsview.cpp @@ -45,7 +45,7 @@ #include <QTouchEvent> GraphicsView::GraphicsView(QGraphicsScene *scene, QWidget *parent) - : QGraphicsView(scene, parent) + : QGraphicsView(scene, parent), totalScaleFactor(1) { viewport()->setAttribute(Qt::WA_AcceptTouchEvents); setDragMode(ScrollHandDrag); @@ -58,14 +58,24 @@ bool GraphicsView::viewportEvent(QEvent *event) case QEvent::TouchUpdate: case QEvent::TouchEnd: { - QList<QTouchEvent::TouchPoint> touchPoints = static_cast<QTouchEvent *>(event)->touchPoints(); + QTouchEvent *touchEvent = static_cast<QTouchEvent *>(event); + QList<QTouchEvent::TouchPoint> touchPoints = touchEvent->touchPoints(); if (touchPoints.count() == 2) { // determine scale factor const QTouchEvent::TouchPoint &touchPoint0 = touchPoints.first(); const QTouchEvent::TouchPoint &touchPoint1 = touchPoints.last(); - const qreal scaleFactor = QLineF(touchPoint0.pos(), touchPoint1.pos()).length() - / QLineF(touchPoint0.startPos(), touchPoint1.startPos()).length(); - setTransform(QTransform().scale(scaleFactor, scaleFactor)); + qreal currentScaleFactor = + QLineF(touchPoint0.pos(), touchPoint1.pos()).length() + / QLineF(touchPoint0.startPos(), touchPoint1.startPos()).length(); + if (touchEvent->touchPointStates() & Qt::TouchPointReleased) { + // 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().scale(totalScaleFactor * currentScaleFactor, + totalScaleFactor * currentScaleFactor)); } return true; } |