Allow MouseArea to prevent mouse grab begin stolen by Flickable.

Placing a MouseArea in a Flickable (or PinchArea, or PathView) allows
the Flickable to steal mouse events when it detects a flick/drag event.
In some cases this is not desireable and MouseArea should be able to
retain its grab.  Added a 'preventStealing' property to prevent
an ancestor item from stealing the MouseArea's grab.

Change-Id: I6277fbb76919b2b35d4e32a247b38a90e305dbdf
Task-number: QTBUG-17285
Reviewed-by: Joona Petrell

6 files changed, 203 insertions, 3 deletions

diff --git a/src/declarative/graphicsitems/qdeclarativeitemsmodule.cpp b/src/declarative/graphicsitems/qdeclarativeitemsmodule.cpp
index bc4a2d0..3c8f64e 100644
--- a/src/declarative/graphicsitems/qdeclarativeitemsmodule.cpp
+++ b/src/declarative/graphicsitems/qdeclarativeitemsmodule.cpp
@@ -180,6 +180,7 @@ void QDeclarativeItemModule::defineModule()
     qmlRegisterType<QDeclarativePinch>("QtQuick",1,1,"Pinch");
     qmlRegisterType<QDeclarativePinchEvent>();
     qmlRegisterType<QDeclarativeItem,1>("QtQuick",1,1,"Item");
+    qmlRegisterType<QDeclarativeMouseArea,1>("QtQuick",1,1,"MouseArea");
     qmlRegisterType<QDeclarativeFlickable,1>("QtQuick",1,1,"Flickable");
     qmlRegisterType<QDeclarativeListView,1>("QtQuick",1,1,"ListView");
     qmlRegisterType<QDeclarativeGridView,1>("QtQuick",1,1,"GridView");
diff --git a/src/declarative/graphicsitems/qdeclarativemousearea.cpp b/src/declarative/graphicsitems/qdeclarativemousearea.cpp
index 0aa0c1b..1308e73 100644
--- a/src/declarative/graphicsitems/qdeclarativemousearea.cpp
+++ b/src/declarative/graphicsitems/qdeclarativemousearea.cpp
@@ -416,6 +416,40 @@ void QDeclarativeMouseArea::setEnabled(bool a)
         emit enabledChanged();
     }
 }
+
+/*!
+    \qmlproperty bool MouseArea::preventStealing
+    \since Quick 1.1
+    This property holds whether the mouse events may be stolen from this
+    MouseArea.
+
+    If a MouseArea is placed within an item that filters child mouse
+    events, such as Flickable, the mouse
+    events may be stolen from the MouseArea if a gesture is recognized
+    by the parent element, e.g. a flick gesture.  If preventStealing is
+    set to true, no element will steal the mouse events.
+
+    Note that setting preventStealing to true once an element has started
+    stealing events will have no effect until the next press event.
+
+    By default this property is false.
+*/
+bool QDeclarativeMouseArea::preventStealing() const
+{
+    Q_D(const QDeclarativeMouseArea);
+    return d->preventStealing;
+}
+
+void QDeclarativeMouseArea::setPreventStealing(bool prevent)
+{
+    Q_D(QDeclarativeMouseArea);
+    if (prevent != d->preventStealing) {
+        d->preventStealing = prevent;
+        setKeepMouseGrab(d->preventStealing && d->absorb);
+        emit preventStealingChanged();
+    }
+}
+
 /*!
     \qmlproperty MouseButtons MouseArea::pressedButtons
     This property holds the mouse buttons currently pressed.
@@ -443,7 +477,7 @@ void QDeclarativeMouseArea::mousePressEvent(QGraphicsSceneMouseEvent *event)
 {
     Q_D(QDeclarativeMouseArea);
     d->moved = false;
-    d->stealMouse = false;
+    d->stealMouse = d->preventStealing;
     if (!d->absorb)
         QDeclarativeItem::mousePressEvent(event);
     else {
@@ -460,7 +494,7 @@ void QDeclarativeMouseArea::mousePressEvent(QGraphicsSceneMouseEvent *event)
         // we should only start timer if pressAndHold is connected to.
         if (d->isPressAndHoldConnected())
             d->pressAndHoldTimer.start(PressAndHoldDelay, this);
-        setKeepMouseGrab(false);
+        setKeepMouseGrab(d->stealMouse);
         event->setAccepted(setPressed(true));
     }
 }
diff --git a/src/declarative/graphicsitems/qdeclarativemousearea_p.h b/src/declarative/graphicsitems/qdeclarativemousearea_p.h
index 937ac78..985f27e 100644
--- a/src/declarative/graphicsitems/qdeclarativemousearea_p.h
+++ b/src/declarative/graphicsitems/qdeclarativemousearea_p.h
@@ -129,6 +129,7 @@ class Q_AUTOTEST_EXPORT QDeclarativeMouseArea : public QDeclarativeItem
     Q_PROPERTY(Qt::MouseButtons acceptedButtons READ acceptedButtons WRITE setAcceptedButtons NOTIFY acceptedButtonsChanged)
     Q_PROPERTY(bool hoverEnabled READ hoverEnabled WRITE setHoverEnabled NOTIFY hoverEnabledChanged)
     Q_PROPERTY(QDeclarativeDrag *drag READ drag CONSTANT) //### add flicking to QDeclarativeDrag or add a QDeclarativeFlick ???
+    Q_PROPERTY(bool preventStealing READ preventStealing WRITE setPreventStealing NOTIFY preventStealingChanged REVISION 1)
 
 public:
     QDeclarativeMouseArea(QDeclarativeItem *parent=0);
@@ -153,6 +154,9 @@ public:
 
     QDeclarativeDrag *drag();
 
+    bool preventStealing() const;
+    void setPreventStealing(bool prevent);
+
 Q_SIGNALS:
     void hoveredChanged();
     void pressedChanged();
@@ -161,6 +165,7 @@ Q_SIGNALS:
     void hoverEnabledChanged();
     void positionChanged(QDeclarativeMouseEvent *mouse);
     void mousePositionChanged(QDeclarativeMouseEvent *mouse);
+    Q_REVISION(1) void preventStealingChanged();
 
     void pressed(QDeclarativeMouseEvent *mouse);
     void pressAndHold(QDeclarativeMouseEvent *mouse);
diff --git a/src/declarative/graphicsitems/qdeclarativemousearea_p_p.h b/src/declarative/graphicsitems/qdeclarativemousearea_p_p.h
index 2a327af..67694fb 100644
--- a/src/declarative/graphicsitems/qdeclarativemousearea_p_p.h
+++ b/src/declarative/graphicsitems/qdeclarativemousearea_p_p.h
@@ -68,7 +68,7 @@ class QDeclarativeMouseAreaPrivate : public QDeclarativeItemPrivate
 public:
     QDeclarativeMouseAreaPrivate()
       : absorb(true), hovered(false), pressed(false), longPress(false),
-      moved(false), stealMouse(false), doubleClick(false), drag(0)
+      moved(false), stealMouse(false), doubleClick(false), preventStealing(false), drag(0)
     {
     }
 
@@ -110,6 +110,7 @@ public:
     bool dragY : 1;
     bool stealMouse : 1;
     bool doubleClick : 1;
+    bool preventStealing : 1;
     QDeclarativeDrag *drag;
     QPointF startScene;
     qreal startX;
diff --git a/tests/auto/declarative/qdeclarativemousearea/data/preventstealing.qml b/tests/auto/declarative/qdeclarativemousearea/data/preventstealing.qml
new file mode 100644
index 0000000..11553fa
--- /dev/null
+++ b/tests/auto/declarative/qdeclarativemousearea/data/preventstealing.qml
@@ -0,0 +1,24 @@
+import QtQuick 1.1
+
+Flickable {
+    property bool stealing: true
+    width: 200
+    height: 200
+    contentWidth: 400
+    contentHeight: 400
+    Rectangle {
+        color: "black"
+        width: 400
+        height: 400
+        Rectangle {
+            x: 50; y: 50
+            width: 100; height: 100
+            color: "steelblue"
+            MouseArea {
+                objectName: "mousearea"
+                anchors.fill: parent
+                preventStealing: stealing
+            }
+        }
+    }
+}
diff --git a/tests/auto/declarative/qdeclarativemousearea/tst_qdeclarativemousearea.cpp b/tests/auto/declarative/qdeclarativemousearea/tst_qdeclarativemousearea.cpp
index 845d6bb..60d51c6 100644
--- a/tests/auto/declarative/qdeclarativemousearea/tst_qdeclarativemousearea.cpp
+++ b/tests/auto/declarative/qdeclarativemousearea/tst_qdeclarativemousearea.cpp
@@ -43,8 +43,10 @@
 #include <QtTest/QSignalSpy>
 #include <private/qdeclarativemousearea_p.h>
 #include <private/qdeclarativerectangle_p.h>
+#include <private/qdeclarativeflickable_p.h>
 #include <QtDeclarative/qdeclarativeview.h>
 #include <QtDeclarative/qdeclarativecontext.h>
+#include <QtDeclarative/qdeclarativeengine.h>
 
 #ifdef Q_OS_SYMBIAN
 // In Symbian OS test data is located in applications private dir
@@ -65,6 +67,9 @@ private slots:
     void doubleClick();
     void clickTwice();
     void pressedOrdering();
+    void preventStealing();
+    void testQtQuick11Attributes();
+    void testQtQuick11Attributes_data();
 
 private:
     QDeclarativeView *createView();
@@ -356,6 +361,8 @@ void tst_QDeclarativeMouseArea::noOnClickedWithPressAndHold()
 
     QVERIFY(!canvas->rootObject()->property("clicked").toBool());
     QVERIFY(canvas->rootObject()->property("held").toBool());
+
+    delete canvas;
 }
 
 void tst_QDeclarativeMouseArea::onMousePressRejected()
@@ -399,6 +406,8 @@ void tst_QDeclarativeMouseArea::onMousePressRejected()
     QVERIFY(canvas->rootObject()->property("mr1_released").toBool());
     QVERIFY(!canvas->rootObject()->property("mr1_canceled").toBool());
     QVERIFY(!canvas->rootObject()->property("mr2_released").toBool());
+
+    delete canvas;
 }
 
 void tst_QDeclarativeMouseArea::doubleClick()
@@ -436,6 +445,7 @@ void tst_QDeclarativeMouseArea::doubleClick()
     QCOMPARE(canvas->rootObject()->property("doubleClicked").toInt(), 1);
     QCOMPARE(canvas->rootObject()->property("released").toInt(), 2);
 
+    delete canvas;
 }
 
 // QTBUG-14832
@@ -476,6 +486,8 @@ void tst_QDeclarativeMouseArea::clickTwice()
     QCOMPARE(canvas->rootObject()->property("pressed").toInt(), 2);
     QCOMPARE(canvas->rootObject()->property("released").toInt(), 2);
     QCOMPARE(canvas->rootObject()->property("clicked").toInt(), 2);
+
+    delete canvas;
 }
 
 void tst_QDeclarativeMouseArea::pressedOrdering()
@@ -512,6 +524,129 @@ void tst_QDeclarativeMouseArea::pressedOrdering()
     delete canvas;
 }
 
+void tst_QDeclarativeMouseArea::preventStealing()
+{
+    QDeclarativeView *canvas = createView();
+
+    canvas->setSource(QUrl::fromLocalFile(SRCDIR "/data/preventstealing.qml"));
+    canvas->show();
+    canvas->setFocus();
+    QVERIFY(canvas->rootObject() != 0);
+
+    QDeclarativeFlickable *flickable = qobject_cast<QDeclarativeFlickable*>(canvas->rootObject());
+    QVERIFY(flickable != 0);
+
+    QDeclarativeMouseArea *mouseArea = canvas->rootObject()->findChild<QDeclarativeMouseArea*>("mousearea");
+    QVERIFY(mouseArea != 0);
+
+    QSignalSpy mousePositionSpy(mouseArea, SIGNAL(positionChanged(QDeclarativeMouseEvent*)));
+
+    QGraphicsScene *scene = canvas->scene();
+    QGraphicsSceneMouseEvent pressEvent(QEvent::GraphicsSceneMousePress);
+    pressEvent.setScenePos(QPointF(80, 80));
+    pressEvent.setButton(Qt::LeftButton);
+    pressEvent.setButtons(Qt::LeftButton);
+    QApplication::sendEvent(scene, &pressEvent);
+
+    // Without preventStealing, mouse movement over MouseArea would
+    // cause the Flickable to steal mouse and trigger content movement.
+    QGraphicsSceneMouseEvent moveEvent(QEvent::GraphicsSceneMouseMove);
+    moveEvent.setScenePos(QPointF(70, 70));
+    moveEvent.setButton(Qt::LeftButton);
+    moveEvent.setButtons(Qt::LeftButton);
+    QApplication::sendEvent(scene, &moveEvent);
+
+    moveEvent.setScenePos(QPointF(60, 60));
+    moveEvent.setButton(Qt::LeftButton);
+    moveEvent.setButtons(Qt::LeftButton);
+    QApplication::sendEvent(scene, &moveEvent);
+
+    moveEvent.setScenePos(QPointF(50, 50));
+    moveEvent.setButton(Qt::LeftButton);
+    moveEvent.setButtons(Qt::LeftButton);
+    QApplication::sendEvent(scene, &moveEvent);
+
+    // We should have received all three move events
+    QCOMPARE(mousePositionSpy.count(), 3);
+    QVERIFY(mouseArea->pressed());
+
+    // Flickable content should not have moved.
+    QCOMPARE(flickable->contentX(), 0.);
+    QCOMPARE(flickable->contentY(), 0.);
+
+    QGraphicsSceneMouseEvent releaseEvent(QEvent::GraphicsSceneMouseRelease);
+    releaseEvent.setScenePos(QPointF(50, 50));
+    releaseEvent.setButton(Qt::LeftButton);
+    releaseEvent.setButtons(Qt::LeftButton);
+    QApplication::sendEvent(scene, &releaseEvent);
+
+    // Now allow stealing and confirm Flickable does its thing.
+    canvas->rootObject()->setProperty("stealing", false);
+
+    pressEvent.setScenePos(QPointF(80, 80));
+    QApplication::sendEvent(scene, &pressEvent);
+
+    // Without preventStealing, mouse movement over MouseArea would
+    // cause the Flickable to steal mouse and trigger content movement.
+    moveEvent.setScenePos(QPointF(70, 70));
+    QApplication::sendEvent(scene, &moveEvent);
+
+    moveEvent.setScenePos(QPointF(60, 60));
+    QApplication::sendEvent(scene, &moveEvent);
+
+    moveEvent.setScenePos(QPointF(50, 50));
+    QApplication::sendEvent(scene, &moveEvent);
+
+    // We should only have received the first move event
+    QCOMPARE(mousePositionSpy.count(), 4);
+    // Our press should be taken away
+    QVERIFY(!mouseArea->pressed());
+
+    // Flickable content should have moved.
+    QCOMPARE(flickable->contentX(), 10.);
+    QCOMPARE(flickable->contentY(), 10.);
+
+    releaseEvent.setScenePos(QPointF(50, 50));
+    QApplication::sendEvent(scene, &releaseEvent);
+
+    delete canvas;
+}
+
+void tst_QDeclarativeMouseArea::testQtQuick11Attributes()
+{
+    QFETCH(QString, code);
+    QFETCH(QString, warning);
+    QFETCH(QString, error);
+
+    QDeclarativeEngine engine;
+    QObject *obj;
+
+    QDeclarativeComponent valid(&engine);
+    valid.setData("import QtQuick 1.1; MouseArea { " + code.toUtf8() + " }", QUrl(""));
+    obj = valid.create();
+    QVERIFY(obj);
+    QVERIFY(valid.errorString().isEmpty());
+    delete obj;
+
+    QDeclarativeComponent invalid(&engine);
+    invalid.setData("import QtQuick 1.0; MouseArea { " + code.toUtf8() + " }", QUrl(""));
+    QTest::ignoreMessage(QtWarningMsg, warning.toUtf8());
+    obj = invalid.create();
+    QCOMPARE(invalid.errorString(), error);
+    delete obj;
+}
+
+void tst_QDeclarativeMouseArea::testQtQuick11Attributes_data()
+{
+    QTest::addColumn<QString>("code");
+    QTest::addColumn<QString>("warning");
+    QTest::addColumn<QString>("error");
+
+    QTest::newRow("preventStealing") << "preventStealing: true"
+        << "QDeclarativeComponent: Component is not ready"
+        << ":1 \"MouseArea.preventStealing\" is not available in QtQuick 1.0.\n";
+}
+
 QTEST_MAIN(tst_QDeclarativeMouseArea)
 
 #include "tst_qdeclarativemousearea.moc"