Allow flick on press-move-release in Flickable.

Right now it needs at least a press-move-move-release to start a flick
which is not ideal for touchscreens because a quick, short flick may
result in reporting only a single move.

Change-Id: I9bf2b4fea23b0eea9d9d00f0e79ce34f4d964bea
Reviewed-by: Martin Jones <martin.jones@nokia.com>

2 files changed, 36 insertions, 25 deletions

diff --git a/src/quick/items/qquickflickable.cpp b/src/quick/items/qquickflickable.cpp
index f0eadc0daa..62d0e4aa41 100644
--- a/src/quick/items/qquickflickable.cpp
+++ b/src/quick/items/qquickflickable.cpp
@@ -887,11 +887,11 @@ void QQuickFlickablePrivate::handleMouseMoveEvent(QMouseEvent *event)
     bool stealY = stealMouse;
     bool stealX = stealMouse;
 
-    qint64 elapsed = computeCurrentTime(event) - lastPressTime;
+    qint64 elapsedSincePress = computeCurrentTime(event) - lastPressTime;
 
     if (q->yflick()) {
         qreal dy = event->localPos().y() - pressPos.y();
-        if (qAbs(dy) > qApp->styleHints()->startDragDistance() || elapsed > 200) {
+        if (qAbs(dy) > qApp->styleHints()->startDragDistance() || elapsedSincePress > 200) {
             if (!vMoved)
                 vData.dragStartOffset = dy;
             qreal newY = dy + vData.pressPos - vData.dragStartOffset;
@@ -924,7 +924,7 @@ void QQuickFlickablePrivate::handleMouseMoveEvent(QMouseEvent *event)
 
     if (q->xflick()) {
         qreal dx = event->localPos().x() - pressPos.x();
-        if (qAbs(dx) > qApp->styleHints()->startDragDistance() || elapsed > 200) {
+        if (qAbs(dx) > qApp->styleHints()->startDragDistance() || elapsedSincePress > 200) {
             if (!hMoved)
                 hData.dragStartOffset = dx;
             qreal newX = dx + hData.pressPos - hData.dragStartOffset;
@@ -974,28 +974,26 @@ void QQuickFlickablePrivate::handleMouseMoveEvent(QMouseEvent *event)
         q->movementStarting();
     }
 
-    if (!lastPos.isNull()) {
-        qint64 currentTimestamp = computeCurrentTime(event);
-        qreal elapsed = qreal(currentTimestamp - lastPosTime) / 1000.;
-        if (elapsed <= 0)
-            return;
-        lastPosTime = currentTimestamp;
-        QQuickMouseEventEx *extended = QQuickMouseEventEx::extended(event);
-        if (q->yflick() && !rejectY) {
-            if (extended && extended->capabilities().testFlag(QTouchDevice::Velocity)) {
-                vData.addVelocitySample(extended->velocity().y(), maxVelocity);
-            } else {
-                qreal dy = event->localPos().y()-lastPos.y();
-                vData.addVelocitySample(dy/elapsed, maxVelocity);
-            }
+    qint64 currentTimestamp = computeCurrentTime(event);
+    qreal elapsed = qreal(currentTimestamp - (lastPos.isNull() ? lastPressTime : lastPosTime)) / 1000.;
+    if (elapsed <= 0)
+        return;
+    lastPosTime = currentTimestamp;
+    QQuickMouseEventEx *extended = QQuickMouseEventEx::extended(event);
+    if (q->yflick() && !rejectY) {
+        if (extended && extended->capabilities().testFlag(QTouchDevice::Velocity)) {
+            vData.addVelocitySample(extended->velocity().y(), maxVelocity);
+        } else {
+            qreal dy = event->localPos().y() - (lastPos.isNull() ? pressPos.y() : lastPos.y());
+            vData.addVelocitySample(dy/elapsed, maxVelocity);
         }
-        if (q->xflick() && !rejectX) {
-            if (extended && extended->capabilities().testFlag(QTouchDevice::Velocity)) {
-                hData.addVelocitySample(extended->velocity().x(), maxVelocity);
-            } else {
-                qreal dx = event->localPos().x()-lastPos.x();
-                hData.addVelocitySample(dx/elapsed, maxVelocity);
-            }
+    }
+    if (q->xflick() && !rejectX) {
+        if (extended && extended->capabilities().testFlag(QTouchDevice::Velocity)) {
+            hData.addVelocitySample(extended->velocity().x(), maxVelocity);
+        } else {
+            qreal dx = event->localPos().x() - (lastPos.isNull() ? pressPos.x() : lastPos.x());
+            hData.addVelocitySample(dx/elapsed, maxVelocity);
         }
     }
 
diff --git a/tests/auto/quick/qquickflickable/tst_qquickflickable.cpp b/tests/auto/quick/qquickflickable/tst_qquickflickable.cpp
index 9f5bd46864..2ed42e7f0f 100644
--- a/tests/auto/quick/qquickflickable/tst_qquickflickable.cpp
+++ b/tests/auto/quick/qquickflickable/tst_qquickflickable.cpp
@@ -441,6 +441,19 @@ void tst_qquickflickable::movingAndDragging()
     // wait for any motion to end
     QTRY_VERIFY(flickable->isMoving() == false);
 
+    // Vertical with a quick press-move-release: should cause a flick in release.
+    QSignalSpy vFlickSpy(flickable, SIGNAL(flickingVerticallyChanged()));
+
+    QTest::mousePress(canvas, Qt::LeftButton, 0, QPoint(50, 90));
+    QTest::qWait(10);
+    QTest::mouseMove(canvas, QPoint(50, 40));
+    QTest::mouseRelease(canvas, Qt::LeftButton, 0, QPoint(50, 40));
+
+    QCOMPARE(vFlickSpy.count(), 1);
+
+    // wait for any motion to end
+    QTRY_VERIFY(flickable->isMoving() == false);
+
     //Horizontal
     vDragSpy.clear();
     hDragSpy.clear();
@@ -493,7 +506,7 @@ void tst_qquickflickable::movingAndDragging()
     vMoveSpy.clear();
     hMoveSpy.clear();
     moveSpy.clear();
-    QSignalSpy vFlickSpy(flickable, SIGNAL(flickingVerticallyChanged()));
+    vFlickSpy.clear();
     QSignalSpy hFlickSpy(flickable, SIGNAL(flickingHorizontallyChanged()));
     QSignalSpy flickSpy(flickable, SIGNAL(flickingChanged()));