Support multiple touch targets in QGraphicsView

This required a larger change to the kernel and graphicsview directories to
make this as efficient as possible:

1. QTouchEvent::TouchPoint becomes the base for
QGraphicsSceneTouchEvent::TouchPoint - this means there is one private for
every touch point, and we can store both the screen and scene coordinates
in one place. Converting a QTouchEvent to QGraphicsSceneTouchEvent becomes
nothing more than casting the QTouchEvent::TouchPoints to
QGraphicsSceneTouchEvent::TouchPoints.

2. The logic that we use in QApplication to convert WM_TOUCH* messages to
QTouchEvents is essentially duplicated (with some minor changes) to
QGraphicsScene so that it can support mulitple touch item targets. I
will have to investigate how I can perhaps merge some of the duplicated
code.

QEvent::GraphicsSceneTouchBegin propagation is not implemented yet, and will
come in a later commit

1 files changed, 41 insertions, 89 deletions

diff --git a/src/gui/graphicsview/qgraphicsview.cpp b/src/gui/graphicsview/qgraphicsview.cpp
index 6f142e3..1d801cd 100644
--- a/src/gui/graphicsview/qgraphicsview.cpp
+++ b/src/gui/graphicsview/qgraphicsview.cpp
@@ -306,6 +306,30 @@ inline int q_round_bound(qreal d) //### (int)(qreal) INT_MAX != INT_MAX for sing
     return d >= 0.0 ? int(d + 0.5) : int(d - int(d-1) + 0.5) + int(d-1);
 }
 
+static void qt_convertTouchEventToGraphicsSceneTouchEvent(QGraphicsViewPrivate *d,
+                                                          QTouchEvent *originalEvent,
+                                                          QGraphicsSceneTouchEvent *touchEvent)
+{
+    QList<QTouchEvent::TouchPoint *> originalTouchPoints = originalEvent->touchPoints();
+    QList<QGraphicsSceneTouchEvent::TouchPoint *> touchPoints;
+    for (int i = 0; i < originalTouchPoints.count(); ++i) {
+        QGraphicsSceneTouchEvent::TouchPoint *touchPoint =
+            static_cast<QGraphicsSceneTouchEvent::TouchPoint *>(originalTouchPoints.at(i));
+        // the scene will set the pos before delivering to an item
+        touchPoint->setScenePos(d->mapToScene(touchPoint->pos()));
+        // the scene will set the startPos before delivering to an item
+        touchPoint->setStartScenePos(d->mapToScene(touchPoint->startPos()));
+        // the scene will set the lastPos before delivering to an item
+        touchPoint->setLastScenePos(d->mapToScene(touchPoint->lastScreenPos()));
+        // lastScreenPos is already set in the originalTouchPoint
+
+        touchPoints.append(touchPoint);
+    }
+
+    touchEvent->setTouchPoints(touchPoints);
+    touchEvent->setModifiers(originalEvent->modifiers());
+}
+
 /*!
     \internal
 */
@@ -2962,20 +2986,24 @@ bool QGraphicsView::viewportEvent(QEvent *event)
     {
         if (!isEnabled())
             return false;
-        QTouchEvent *touchEvent = static_cast<QTouchEvent *>(event);
-        switch (touchEvent->type()) {
-        case QEvent::TouchBegin:
-            d->touchBeginEvent(touchEvent);
-            break;
-        case QEvent::TouchUpdate:
-            d->touchUpdateEvent(touchEvent);
-            break;
-        case QEvent::TouchEnd:
-            d->touchEndEvent(touchEvent);
-            break;
-        default:
-            break;
+
+        if (d->scene && d->sceneInteractionAllowed) {
+            // Convert and deliver the touch event to the scene.
+            QEvent::Type eventType = event->type() == QEvent::TouchBegin
+                                     ? QEvent::GraphicsSceneTouchBegin
+                                     : event->type() == QEvent::TouchEnd
+                                     ? QEvent::GraphicsSceneTouchEnd
+                                     : QEvent::GraphicsSceneTouchUpdate;
+            QGraphicsSceneTouchEvent touchEvent(eventType);
+            touchEvent.setWidget(viewport());
+            qt_convertTouchEventToGraphicsSceneTouchEvent(d,
+                                                          static_cast<QTouchEvent *>(event),
+                                                          &touchEvent);
+            touchEvent.setAccepted(false);
+            QApplication::sendEvent(d->scene, &touchEvent);
+            event->setAccepted(touchEvent.isAccepted());
         }
+
         return true;
     }
     default:
@@ -3916,34 +3944,6 @@ void QGraphicsView::resetTransform()
     setTransform(QTransform());
 }
 
-static void qt_convertTouchEventToGraphicsSceneTouchEvent(QGraphicsViewPrivate *d, QTouchEvent *originalEvent, QGraphicsSceneTouchEvent *touchEvent)
-{
-    QList<QTouchEvent::TouchPoint *> originalTouchPoints = originalEvent->touchPoints();
-    QList<QGraphicsSceneTouchEvent::TouchPoint *> touchPoints;
-    for (int i = 0; i < originalTouchPoints.count(); ++i) {
-        QTouchEvent::TouchPoint *originalTouchPoint = originalTouchPoints.at(i);
-
-        QGraphicsSceneTouchEvent::TouchPoint *touchPoint = new QGraphicsSceneTouchEvent::TouchPoint();
-        touchPoint->setId(originalTouchPoint->id());
-        touchPoint->setState(originalTouchPoint->state());
-        // the scene will set the pos before delivering to an item
-        touchPoint->setScenePos(d->mapToScene(originalTouchPoint->pos()));
-        touchPoint->setScreenPos(originalTouchPoint->globalPos());
-        // the scene will set the startPos before delivering to an item
-        touchPoint->setStartScenePos(d->mapToScene(originalTouchPoint->startPos()));
-        touchPoint->setStartScreenPos(originalTouchPoint->startGlobalPos());
-        // the scene will set the lastPos before delivering to an item
-        touchPoint->setLastScenePos(d->mapToScene(originalTouchPoint->lastPos()));
-        touchPoint->setLastScreenPos(originalTouchPoint->lastGlobalPos());
-        touchPoint->setPressure(originalTouchPoint->pressure());
-
-        touchPoints.append(touchPoint);
-    }
-
-    touchEvent->setTouchPoints(touchPoints);
-    touchEvent->setModifiers(originalEvent->modifiers());
-}
-
 QPointF QGraphicsViewPrivate::mapToScene(const QPointF &point) const
 {
     QPointF p = point;
@@ -3952,54 +3952,6 @@ QPointF QGraphicsViewPrivate::mapToScene(const QPointF &point) const
     return identityMatrix ? p : matrix.inverted().map(p);
 }
 
-void QGraphicsViewPrivate::touchBeginEvent(QTouchEvent *event)
-{
-    Q_Q(QGraphicsView);
-
-    if (!scene || !sceneInteractionAllowed)
-        return;
-
-    // Convert and deliver the touch event to the scene.
-    QGraphicsSceneTouchEvent touchEvent(QEvent::GraphicsSceneTouchBegin);
-    touchEvent.setWidget(q->viewport());
-    qt_convertTouchEventToGraphicsSceneTouchEvent(this, event, &touchEvent);
-    touchEvent.setAccepted(false);
-    QApplication::sendEvent(scene, &touchEvent);
-    event->setAccepted(touchEvent.isAccepted());
-}
-
-void QGraphicsViewPrivate::touchUpdateEvent(QTouchEvent *event)
-{
-    Q_Q(QGraphicsView);
-
-    if (!scene || !sceneInteractionAllowed)
-        return;
-
-    // Convert and deliver the touch event to the scene.
-    QGraphicsSceneTouchEvent touchEvent(QEvent::GraphicsSceneTouchUpdate);
-    touchEvent.setWidget(q->viewport());
-    qt_convertTouchEventToGraphicsSceneTouchEvent(this, event, &touchEvent);
-    touchEvent.setAccepted(false);
-    QApplication::sendEvent(scene, &touchEvent);
-    event->setAccepted(touchEvent.isAccepted());
-}
-
-void QGraphicsViewPrivate::touchEndEvent(QTouchEvent *event)
-{
-    Q_Q(QGraphicsView);
-
-    if (!scene || !sceneInteractionAllowed)
-        return;
-
-    // Convert and deliver the touch event to the scene.
-    QGraphicsSceneTouchEvent touchEvent(QEvent::GraphicsSceneTouchEnd);
-    touchEvent.setWidget(q->viewport());
-    qt_convertTouchEventToGraphicsSceneTouchEvent(this, event, &touchEvent);
-    touchEvent.setAccepted(false);
-    QApplication::sendEvent(scene, &touchEvent);
-    event->setAccepted(touchEvent.isAccepted());
-}
-
 QT_END_NAMESPACE
 
 #include "moc_qgraphicsview.cpp"