MouseArea: use current value of drag.axis

If the drag.axis is changed while a drag operation is in progress, put
it into action immediately. This allows, for example, start a dragging
operation out of an item in a scrollable ListView to anywhere on the
screen.
See the linked bug number for an example.

Task-number: QTBUG-26440
Change-Id: Id4219d44d1066dd962319086ac1f2a2a75bb2525
Reviewed-by: Damian Jansen <damian.jansen@nokia.com>
Reviewed-by: Martin Jones <martin.jones@nokia.com>

2 files changed, 85 insertions, 0 deletions

diff --git a/tests/auto/quick/qquickmousearea/data/changeAxis.qml b/tests/auto/quick/qquickmousearea/data/changeAxis.qml
new file mode 100644
index 0000000000..cf791df31d
--- /dev/null
+++ b/tests/auto/quick/qquickmousearea/data/changeAxis.qml
@@ -0,0 +1,22 @@
+import QtQuick 2.0
+Rectangle {
+    id: whiteRect
+    width: 200
+    height: 200
+    color: "white"
+    Rectangle {
+        id: blackRect
+        objectName: "blackrect"
+        color: "black"
+        y: 50
+        x: 50
+        width: 100
+        height: 100
+        MouseArea {
+            objectName: "mouseregion"
+            anchors.fill: parent
+            drag.target: blackRect
+            drag.axis: blackRect.x <= 75 ? Drag.XandYAxis : Drag.YAxis
+         }
+     }
+ }
diff --git a/tests/auto/quick/qquickmousearea/tst_qquickmousearea.cpp b/tests/auto/quick/qquickmousearea/tst_qquickmousearea.cpp
index 7d42eb2261..b2ef1909df 100644
--- a/tests/auto/quick/qquickmousearea/tst_qquickmousearea.cpp
+++ b/tests/auto/quick/qquickmousearea/tst_qquickmousearea.cpp
@@ -84,6 +84,7 @@ private slots:
     void transformedMouseArea();
     void pressedMultipleButtons_data();
     void pressedMultipleButtons();
+    void changeAxis();
 
 private:
     void acceptedButton_data();
@@ -1303,6 +1304,68 @@ void tst_QQuickMouseArea::pressedMultipleButtons()
     delete canvas;
 }
 
+void tst_QQuickMouseArea::changeAxis()
+{
+    QQuickView *canvas = createView();
+
+    canvas->setSource(testFileUrl("changeAxis.qml"));
+    canvas->show();
+    canvas->requestActivateWindow();
+    QTRY_VERIFY(canvas->rootObject() != 0);
+
+    QQuickMouseArea *mouseRegion = canvas->rootObject()->findChild<QQuickMouseArea*>("mouseregion");
+    QQuickDrag *drag = mouseRegion->drag();
+    QVERIFY(mouseRegion != 0);
+    QVERIFY(drag != 0);
+
+    mouseRegion->setAcceptedButtons(Qt::LeftButton);
+
+    // target
+    QQuickItem *blackRect = canvas->rootObject()->findChild<QQuickItem*>("blackrect");
+    QVERIFY(blackRect != 0);
+    QVERIFY(blackRect == drag->target());
+
+    QVERIFY(!drag->active());
+
+    // Start a diagonal drag
+    QTest::mousePress(canvas, Qt::LeftButton, 0, QPoint(100, 100));
+
+    QVERIFY(!drag->active());
+    QCOMPARE(blackRect->x(), 50.0);
+    QCOMPARE(blackRect->y(), 50.0);
+
+    QTest::mouseMove(canvas, QPoint(111, 111));
+    QTest::qWait(50);
+    QTest::mouseMove(canvas, QPoint(122, 122));
+
+    QTRY_VERIFY(drag->active());
+    QCOMPARE(blackRect->x(), 72.0);
+    QCOMPARE(blackRect->y(), 72.0);
+    QCOMPARE(drag->axis(), QQuickDrag::XandYAxis);
+
+    /* When blackRect.x becomes bigger than 75, the drag axis is changed to
+     * Drag.YAxis by the QML code. Verify that this happens, and that the drag
+     * movement is effectively constrained to the Y axis. */
+    QTest::mouseMove(canvas, QPoint(133, 133));
+
+    QTRY_COMPARE(blackRect->x(), 83.0);
+    QTRY_COMPARE(blackRect->y(), 83.0);
+    QTRY_COMPARE(drag->axis(), QQuickDrag::YAxis);
+
+    QTest::mouseMove(canvas, QPoint(144, 144));
+
+    QTRY_COMPARE(blackRect->y(), 94.0);
+    QCOMPARE(blackRect->x(), 83.0);
+
+    QTest::mouseRelease(canvas, Qt::LeftButton, 0, QPoint(144, 144));
+
+    QTRY_VERIFY(!drag->active());
+    QCOMPARE(blackRect->x(), 83.0);
+    QCOMPARE(blackRect->y(), 94.0);
+
+    delete canvas;
+}
+
 QTEST_MAIN(tst_QQuickMouseArea)
 
 #include "tst_qquickmousearea.moc"