Handle TouchCancel events in QQuickPinchArea

QQuickPinchArea did not handle TouchCancel events and would recursively
call QQuickItem::event(). Cancel the pinch gesture by restoring the
pinch state to the start state. Don't recursively call
QQuickItem::event(), instead call QQuickItem::touchEvent() for
unhandled touch events.

[ChangeLog][QtQuick][PinchArea] Fix infinite recursion when TouchCancel
events are received.

Change-Id: Ifce4af91aec4285873cb701069e007bcee180851
Reviewed-by: Martin Jones <martin.jones@qinetic.com.au>

1 files changed, 45 insertions, 1 deletions

diff --git a/src/quick/items/qquickpincharea.cpp b/src/quick/items/qquickpincharea.cpp
index 33f4bade3a..8a391b7aea 100644
--- a/src/quick/items/qquickpincharea.cpp
+++ b/src/quick/items/qquickpincharea.cpp
@@ -346,8 +346,11 @@ void QQuickPinchArea::touchEvent(QTouchEvent *event)
     case QEvent::TouchEnd:
         clearPinch();
         break;
+    case QEvent::TouchCancel:
+        cancelPinch();
+        break;
     default:
-        QQuickItem::event(event);
+        QQuickItem::touchEvent(event);
     }
 }
 
@@ -384,6 +387,47 @@ void QQuickPinchArea::clearPinch()
     setKeepMouseGrab(false);
 }
 
+void QQuickPinchArea::cancelPinch()
+{
+    Q_D(QQuickPinchArea);
+
+    d->touchPoints.clear();
+    if (d->inPinch) {
+        d->inPinch = false;
+        QPointF pinchCenter = mapFromScene(d->sceneLastCenter);
+        QQuickPinchEvent pe(d->pinchStartCenter, d->pinchStartScale, d->pinchStartAngle, d->pinchStartRotation);
+        pe.setStartCenter(d->pinchStartCenter);
+        pe.setPreviousCenter(pinchCenter);
+        pe.setPreviousAngle(d->pinchLastAngle);
+        pe.setPreviousScale(d->pinchLastScale);
+        pe.setStartPoint1(mapFromScene(d->sceneStartPoint1));
+        pe.setStartPoint2(mapFromScene(d->sceneStartPoint2));
+        pe.setPoint1(pe.startPoint1());
+        pe.setPoint2(pe.startPoint2());
+        emit pinchFinished(&pe);
+
+        d->pinchLastScale = d->pinchStartScale;
+        d->sceneLastCenter = d->sceneStartCenter;
+        d->pinchLastAngle = d->pinchStartAngle;
+        d->lastPoint1 = pe.startPoint1();
+        d->lastPoint2 = pe.startPoint2();
+        updatePinchTarget();
+
+        if (d->pinch && d->pinch->target())
+            d->pinch->setActive(false);
+    }
+    d->pinchStartDist = 0;
+    d->pinchActivated = false;
+    d->initPinch = false;
+    d->pinchRejected = false;
+    d->stealMouse = false;
+    d->id1 = -1;
+    QQuickWindow *win = window();
+    if (win && win->mouseGrabberItem() == this)
+        ungrabMouse();
+    setKeepMouseGrab(false);
+}
+
 void QQuickPinchArea::updatePinch()
 {
     Q_D(QQuickPinchArea);