Introduce QGesture::GestureCancelPolicy, a way to auto-cancel gestures

On accepting one gesture Qt can automatically cancel other gestures
that belong to other targets. The policy is normally set to not cancel
any other gestures and can be set to cancel all active gestures in the
context. For example for all child widgets.

Reviewed-By: Denis Dzyubenko

1 files changed, 62 insertions, 0 deletions

diff --git a/tests/auto/gestures/tst_gestures.cpp b/tests/auto/gestures/tst_gestures.cpp
index 6acfe70..39cdf63 100644
--- a/tests/auto/gestures/tst_gestures.cpp
+++ b/tests/auto/gestures/tst_gestures.cpp
@@ -331,6 +331,7 @@ private slots:
     void ungrabGesture();
     void consumeEventHint();
     void unregisterRecognizer();
+    void autoCancelGestures();
 };
 
 tst_Gestures::tst_Gestures()
@@ -1292,5 +1293,66 @@ void tst_Gestures::unregisterRecognizer() // a method on QApplication
 
 }
 
+void tst_Gestures::autoCancelGestures()
+{
+    class MockRecognizer : public QGestureRecognizer {
+      public:
+        QGestureRecognizer::Result filterEvent(QGesture *gesture, QObject *watched, QEvent *event)
+        {
+            Q_UNUSED(gesture);
+            Q_UNUSED(watched);
+            if (event->type() == QEvent::MouseButtonPress)
+                return QGestureRecognizer::GestureTriggered;
+            if (event->type() == QEvent::MouseButtonRelease)
+                return QGestureRecognizer::GestureFinished;
+            return QGestureRecognizer::Ignore;
+        }
+    };
+
+    class MockWidget : public GestureWidget {
+      public:
+        MockWidget(const char *name) : GestureWidget(name) { }
+
+        bool event(QEvent *event)
+        {
+            if (event->type() == QEvent::Gesture) {
+                QGestureEvent *ge = static_cast<QGestureEvent*>(event);
+                Q_ASSERT(ge->allGestures().count() == 1); // can't use QCOMPARE here...
+                ge->allGestures().first()->setGestureCancelPolicy(QGesture::CancelAllInContext);
+            }
+            return GestureWidget::event(event);
+        }
+    };
+
+    MockWidget parent("parent"); // this one sets the cancel policy to CancelAllInContext
+    parent.resize(300, 100);
+    GestureWidget *child = new GestureWidget("child", &parent);
+    child->setGeometry(10, 10, 100, 80);
+
+    Qt::GestureType type = qApp->registerGestureRecognizer(new MockRecognizer());
+    parent.grabGesture(type, Qt::WidgetWithChildrenGesture);
+    child->grabGesture(type, Qt::WidgetWithChildrenGesture);
+
+    /*
+      An event is send to both the child and the parent, when the child gets it a gesture is triggered
+      and send to the child.
+      When the parent gets the event a new gesture is triggered and delivered to the parent. When the
+      parent gets it he accepts it and that causes the cancel policy to activate.
+      The cause of that is the gesture for the child is cancelled and send to the child as such.
+    */
+    QMouseEvent event(QEvent::MouseButtonPress, QPoint(20,20), Qt::LeftButton, Qt::LeftButton, Qt::NoModifier);
+    QApplication::sendEvent(child, &event);
+    QCOMPARE(child->events.started.count(), 1);
+    QCOMPARE(child->events.all.count(), 1);
+    QCOMPARE(parent.events.all.count(), 0);
+    child->reset();
+    QApplication::sendEvent(&parent, &event);
+    QCOMPARE(parent.events.all.count(), 1);
+    QCOMPARE(parent.events.started.count(), 1);
+    QCOMPARE(child->events.started.count(), 0);
+    QCOMPARE(child->events.all.count(), 1);
+    QCOMPARE(child->events.canceled.count(), 1);
+}
+
 QTEST_MAIN(tst_Gestures)
 #include "tst_gestures.moc"