DragHandler active property replaces dragging; same as grabbing

If a QQuickPointerSingleHandler grabs a point, it's definitely in the
active state: doing something with the point.  (The converse is not
always true though: e.g. TapHandler can sometimes detect a tap without
ever grabbing.)
In DragHandler, the "dragging" property means the same as "active":
we always grab when dragging, to be sure to get the updates.  So the
"dragging" property is removed because it's redundant.
In QQuickPointerHandler we don't say that "wanting" an event is the
same as being active, because 1) it won't necessarily grab right away
and 2) every handler which was active should "want" the release event,
yet it needs to setActive(false) as soon as it's done processing it.

Change-Id: Ie010db54714a7914109da6469e79865f9a0a18e4
Reviewed-by: Jan Arve Sæther <jan-arve.saether@qt.io>

8 files changed, 20 insertions, 20 deletions

diff --git a/src/quick/handlers/qquickdraghandler.cpp b/src/quick/handlers/qquickdraghandler.cpp
index a1c3486bd0..dc3116e300 100644
--- a/src/quick/handlers/qquickdraghandler.cpp
+++ b/src/quick/handlers/qquickdraghandler.cpp
@@ -59,7 +59,6 @@ QT_BEGIN_NAMESPACE
 
 QQuickDragHandler::QQuickDragHandler(QObject *parent)
     : QQuickPointerSingleHandler(parent)
-    , m_dragging(false)
 {
 }
 
@@ -88,7 +87,7 @@ void QQuickDragHandler::handleEventPoint(QQuickEventPoint *point)
             delta.setX(0);
         if (!m_yAxis.enabled())
             delta.setY(0);
-        if (m_dragging) {
+        if (active()) {
             if (target() && target()->parentItem()) {
                 QPointF pos = target()->parentItem()->mapFromScene(m_startPos + delta);
                 enforceAxisConstraints(&pos);
@@ -96,17 +95,9 @@ void QQuickDragHandler::handleEventPoint(QQuickEventPoint *point)
             }
         } else if ((m_xAxis.enabled() && QQuickWindowPrivate::dragOverThreshold(delta.x(), Qt::XAxis, point)) ||
                    (m_yAxis.enabled() && QQuickWindowPrivate::dragOverThreshold(delta.y(), Qt::YAxis, point))) {
-            m_dragging = true;
             setGrab(point, true);
-            emit draggingChanged();
         }
     } break;
-    case QQuickEventPoint::Released:
-        if (m_dragging) {
-            m_dragging = false;
-            emit draggingChanged();
-        }
-        break;
     default:
         break;
     }
diff --git a/src/quick/handlers/qquickdraghandler_p.h b/src/quick/handlers/qquickdraghandler_p.h
index e7cb675025..8f27d51b4f 100644
--- a/src/quick/handlers/qquickdraghandler_p.h
+++ b/src/quick/handlers/qquickdraghandler_p.h
@@ -90,7 +90,6 @@ class Q_AUTOTEST_EXPORT QQuickDragHandler : public QQuickPointerSingleHandler
     Q_OBJECT
     Q_PROPERTY(QQuickDragAxis * xAxis READ xAxis CONSTANT)
     Q_PROPERTY(QQuickDragAxis * yAxis READ yAxis CONSTANT)
-    Q_PROPERTY(bool dragging READ dragging NOTIFY draggingChanged)
 
 public:
     QQuickDragHandler(QObject *parent = 0);
@@ -101,13 +100,10 @@ public:
     QQuickDragAxis *xAxis() { return &m_xAxis; }
     QQuickDragAxis *yAxis() { return &m_yAxis; }
 
-    bool dragging() const { return m_dragging; }
-
     Q_INVOKABLE void enforceConstraints();
 
 Q_SIGNALS:
 //    void gestureStarted(QQuickGestureEvent *gesture);
-    void draggingChanged();
 
 protected:
     bool wantsEventPoint(QQuickEventPoint *point) override;
@@ -117,7 +113,6 @@ private:
     void enforceAxisConstraints(QPointF *localPos);
 
 private:
-    bool m_dragging;
     QPointF m_startPos;
     QQuickDragAxis m_xAxis;
     QQuickDragAxis m_yAxis;
diff --git a/src/quick/handlers/qquickpinchhandler.cpp b/src/quick/handlers/qquickpinchhandler.cpp
index 45d8235dff..4832d300c2 100644
--- a/src/quick/handlers/qquickpinchhandler.cpp
+++ b/src/quick/handlers/qquickpinchhandler.cpp
@@ -224,6 +224,10 @@ void QQuickPinchHandler::onActiveChanged()
 void QQuickPinchHandler::handlePointerEventImpl(QQuickPointerEvent *event)
 {
     Q_UNUSED(event)
+    // TODO wait for the drag threshold before setting active
+    // but the old behavior was that whenever we "want" all the points, we're active
+    // so that behavior is retained here temporarily
+    setActive(m_currentPoints.count() > 0 && m_currentPoints.at(0)->state() != QQuickEventPoint::Released);
 
     if (Q_UNLIKELY(lcPinchHandler().isDebugEnabled())) {
         for (QQuickEventPoint *point : qAsConst(m_currentPoints))
diff --git a/src/quick/handlers/qquickpointerhandler.cpp b/src/quick/handlers/qquickpointerhandler.cpp
index d51835a24b..ed08eed93e 100644
--- a/src/quick/handlers/qquickpointerhandler.cpp
+++ b/src/quick/handlers/qquickpointerhandler.cpp
@@ -140,9 +140,7 @@ QQuickItem *QQuickPointerHandler::target() const
 
 void QQuickPointerHandler::handlePointerEvent(QQuickPointerEvent *event)
 {
-    const bool wants = wantsPointerEvent(event);
-    setActive(wants);
-    if (wants)
+    if (wantsPointerEvent(event))
         handlePointerEventImpl(event);
     else
         setActive(false);
diff --git a/src/quick/handlers/qquickpointersinglehandler.cpp b/src/quick/handlers/qquickpointersinglehandler.cpp
index 5b2d6b0801..3a67d66e8c 100644
--- a/src/quick/handlers/qquickpointersinglehandler.cpp
+++ b/src/quick/handlers/qquickpointersinglehandler.cpp
@@ -101,6 +101,11 @@ void QQuickPointerSingleHandler::handlePointerEventImpl(QQuickPointerEvent *even
     } else {
         setPressedButtons(event->buttons());
         handleEventPoint(currentPoint);
+        if (currentPoint->state() == QQuickEventPoint::Released) {
+            m_currentPointId = 0;
+            setPressedButtons(Qt::NoButton);
+            setGrab(currentPoint, false);
+        }
     }
     bool grab = currentPoint->isAccepted() && currentPoint->state() != QQuickEventPoint::Released;
     setGrab(currentPoint, grab);
@@ -120,6 +125,12 @@ void QQuickPointerSingleHandler::handleGrabCancel(QQuickEventPoint *point)
     setPressedButtons(Qt::NoButton);
 }
 
+void QQuickPointerSingleHandler::onGrabChanged(QQuickEventPoint *point)
+{
+    bool grabbing = (point->grabber() == this);
+    setActive(grabbing);
+}
+
 void QQuickPointerSingleHandler::setPressedButtons(Qt::MouseButtons buttons)
 {
     if (buttons != m_pressedButtons) {
diff --git a/src/quick/handlers/qquickpointersinglehandler_p.h b/src/quick/handlers/qquickpointersinglehandler_p.h
index 69a3263271..e3c6bfaddf 100644
--- a/src/quick/handlers/qquickpointersinglehandler_p.h
+++ b/src/quick/handlers/qquickpointersinglehandler_p.h
@@ -77,6 +77,7 @@ protected:
     quint64 currentPointId() const { return m_currentPointId; }
     QQuickEventPoint *currentPoint(QQuickPointerEvent *ev) { return ev->pointById(m_currentPointId); }
     void handleGrabCancel(QQuickEventPoint *point) override;
+    void onGrabChanged(QQuickEventPoint *point) override;
 
 private:
     void setPressedButtons(Qt::MouseButtons buttons);
diff --git a/tests/manual/pointer/content/Slider.qml b/tests/manual/pointer/content/Slider.qml
index 363f6911d4..cd52dfac80 100644
--- a/tests/manual/pointer/content/Slider.qml
+++ b/tests/manual/pointer/content/Slider.qml
@@ -70,7 +70,7 @@ Item {
         anchors.horizontalCenterOffset: 1
         radius: 5
         color: "#4400FFFF"
-        visible: dragHandler.dragging
+        opacity: dragHandler.active ? 1 : 0
     }
     Image {
         id: knob
diff --git a/tests/manual/pointer/joystick.qml b/tests/manual/pointer/joystick.qml
index 7959eaea42..bcc4564471 100644
--- a/tests/manual/pointer/joystick.qml
+++ b/tests/manual/pointer/joystick.qml
@@ -58,7 +58,7 @@ Rectangle {
         }
         states: [
             State {
-                when: dragHandler.dragging
+                when: dragHandler.active
                 AnchorChanges {
                     target: knob
                     anchors.horizontalCenter: undefined