Merge 144519 "EventHandler::handleGestureScrollUpdate() should i..."

Source/WebCore/page/EventHandler.cpp

Index: Source/WebCore/page/EventHandler.cpp
===================================================================
--- Source/WebCore/page/EventHandler.cpp	(revision 145820)
+++ Source/WebCore/page/EventHandler.cpp	(working copy)
@@ -403,6 +403,7 @@
 #if ENABLE(GESTURE_EVENTS)
     m_scrollGestureHandlingNode = 0;
     m_lastHitTestResultOverWidget = false;
+    m_previousGestureScrolledNode = 0;
     m_scrollbarHandlingScrollGesture = 0;
 #endif
     m_maxMouseMovedDuration = 0;
@@ -2498,6 +2499,9 @@
     case PlatformEvent::GestureScrollUpdate:
     case PlatformEvent::GestureScrollUpdateWithoutPropagation:
         return handleGestureScrollUpdate(gestureEvent);
+    case PlatformEvent::GestureScrollEnd:
+        clearGestureScrollNodes(); 
+        return true;
     case PlatformEvent::GestureTap:
         return handleGestureTap(gestureEvent);
     case PlatformEvent::GestureTapDown:
@@ -2508,7 +2512,6 @@
         return handleGestureLongTap(gestureEvent);
     case PlatformEvent::GestureTwoFingerTap:
         return handleGestureTwoFingerTap(gestureEvent);
-    case PlatformEvent::GestureScrollEnd:
     case PlatformEvent::GestureDoubleTap:
     case PlatformEvent::GesturePinchBegin:
     case PlatformEvent::GesturePinchEnd:
@@ -2636,18 +2639,6 @@
     return false;
 }
 
-static const Node* closestScrollableNodeCandidate(const Node* node)
-{
-    for (const Node* scrollableNode = node; scrollableNode; scrollableNode = scrollableNode->parentNode()) {
-        if (scrollableNode->isDocumentNode())
-            return scrollableNode;
-        RenderObject* renderer = scrollableNode->renderer();
-        if (renderer && renderer->isBox() && toRenderBox(renderer)->canBeScrolledAndHasScrollableArea())
-            return scrollableNode;
-    }
-    return node;
-}
-
 bool EventHandler::handleGestureScrollBegin(const PlatformGestureEvent& gestureEvent)
 {
     Document* document = m_frame->document();
@@ -2666,6 +2657,7 @@
 
     m_lastHitTestResultOverWidget = result.isOverWidget(); 
     m_scrollGestureHandlingNode = result.innerNode();
+    m_previousGestureScrolledNode = 0;
 
     Node* node = m_scrollGestureHandlingNode.get();
     if (node)
@@ -2676,50 +2668,81 @@
 
 bool EventHandler::handleGestureScrollUpdate(const PlatformGestureEvent& gestureEvent)
 {
-    // Ignore this event if we don't already have a targeted node with a valid renderer.
-    const Node* node = m_scrollGestureHandlingNode.get();
-    if (!node)
+    FloatSize delta(gestureEvent.deltaX(), gestureEvent.deltaY());
+    if (delta.isZero())
         return false;
 
-    RenderObject* latchedRenderer = node->renderer();
-    if (!latchedRenderer)
-        return false;
+    const float scaleFactor = m_frame->pageZoomFactor() * m_frame->frameScaleFactor();
+    delta.scale(1 / scaleFactor, 1 / scaleFactor);
 
-    IntSize delta(-gestureEvent.deltaX(), -gestureEvent.deltaY());
-    if (delta.isZero())
+    Node* node = m_scrollGestureHandlingNode.get();
+    if (!node)
+        return sendScrollEventToView(gestureEvent, delta);
+
+    // Ignore this event if the targeted node does not have a valid renderer.
+    RenderObject* renderer = node->renderer();
+    if (!renderer)
         return false;
 
     RefPtr<FrameView> protector(m_frame->view());
 
     // Try to send the event to the correct view.
-    if (passGestureEventToWidgetIfPossible(gestureEvent, latchedRenderer))
+    if (passGestureEventToWidgetIfPossible(gestureEvent, renderer))
         return true;
 
-    // Otherwise if this is the correct view for the event, find the closest scrollable
-    // ancestor of the targeted node and scroll the layer that contains this node's renderer.
-    node = closestScrollableNodeCandidate(node);
-    if (!node)
-        return false;
+    Node* stopNode = 0;
+    bool scrollShouldNotPropagate = gestureEvent.type() == PlatformEvent::GestureScrollUpdateWithoutPropagation;
+    if (scrollShouldNotPropagate)
+        stopNode = m_previousGestureScrolledNode.get();
 
-    latchedRenderer = node->renderer();
-    if (!latchedRenderer)
-        return false;
+    // First try to scroll the closest scrollable RenderBox ancestor of |node|.
+    ScrollGranularity granularity = ScrollByPixel; 
+    bool horizontalScroll = scrollNode(delta.width(), granularity, ScrollLeft, ScrollRight, node, &stopNode);
+    bool verticalScroll = scrollNode(delta.height(), granularity, ScrollUp, ScrollDown, node, &stopNode);
 
-    RenderLayer::ScrollPropagation shouldPropagate = RenderLayer::ShouldPropagateScroll;
-    if (gestureEvent.type() == PlatformEvent::GestureScrollUpdateWithoutPropagation)
-        shouldPropagate = RenderLayer::DontPropagateScroll;
+    if (scrollShouldNotPropagate)
+        m_previousGestureScrolledNode = stopNode;
 
-    const float scaleFactor = m_frame->pageZoomFactor() * m_frame->frameScaleFactor();
-    delta.scale(1 / scaleFactor, 1 / scaleFactor);
+    if (horizontalScroll || verticalScroll) {
+        setFrameWasScrolledByUser();
+        return true;
+    }
 
-    bool result = latchedRenderer->enclosingLayer()->scrollBy(delta, RenderLayer::ScrollOffsetClamped, shouldPropagate);
+    // Otherwise try to scroll the view.
+    return sendScrollEventToView(gestureEvent, delta);
+}
 
-    if (result)
+bool EventHandler::sendScrollEventToView(const PlatformGestureEvent& gestureEvent, const FloatSize& scaledDelta)
+{
+    FrameView* view = m_frame->view();
+    if (!view)
+        return false;
+
+    const float tickDivisor = static_cast<float>(WheelEvent::TickMultiplier);
+    IntPoint point(gestureEvent.position().x(), gestureEvent.position().y());
+    IntPoint globalPoint(gestureEvent.globalPosition().x(), gestureEvent.globalPosition().y());
+    PlatformWheelEvent syntheticWheelEvent(point, globalPoint,
+        scaledDelta.width(), scaledDelta.height(), 
+        scaledDelta.width() / tickDivisor, scaledDelta.height() / tickDivisor,
+        ScrollByPixelWheelEvent,
+        gestureEvent.shiftKey(), gestureEvent.ctrlKey(), gestureEvent.altKey(), gestureEvent.metaKey());
+#if PLATFORM(MAC) || PLATFORM(CHROMIUM)
+    syntheticWheelEvent.setHasPreciseScrollingDeltas(true);
+#endif
+
+    bool scrolledFrame = view->wheelEvent(syntheticWheelEvent);
+    if (scrolledFrame)
         setFrameWasScrolledByUser();
 
-    return result;
+    return scrolledFrame;
 }
 
+void EventHandler::clearGestureScrollNodes()
+{
+    m_scrollGestureHandlingNode = 0;
+    m_previousGestureScrolledNode = 0;
+}
+
 bool EventHandler::isScrollbarHandlingGestures() const
 {
     return m_scrollbarHandlingScrollGesture.get();