Reduce hit test on ShowPress by moving event targeting to WebViewImpl

Source/core/page/EventHandler.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2012 Digia Plc. and/or its subsidiary(-ies)
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
@@ skipping 51 matching lines @@
 #include "core/inspector/InspectorController.h"
 #include "core/loader/FrameLoader.h"
 #include "core/loader/FrameLoaderClient.h"
 #include "core/page/AutoscrollController.h"
 #include "core/page/BackForwardClient.h"
 #include "core/page/Chrome.h"
 #include "core/page/ChromeClient.h"
 #include "core/page/DragController.h"
 #include "core/page/DragState.h"
 #include "core/page/EditorClient.h"
-#include "core/page/EventWithHitTestResults.h"
 #include "core/page/FocusController.h"
 #include "core/page/FrameTree.h"
 #include "core/page/Page.h"
 #include "core/page/SpatialNavigation.h"
 #include "core/page/TouchAdjustment.h"
 #include "core/rendering/HitTestRequest.h"
 #include "core/rendering/HitTestResult.h"
 #include "core/rendering/RenderFlowThread.h"
 #include "core/rendering/RenderLayer.h"
 #include "core/rendering/RenderTextControlSingleLine.h"
@@ skipping 1973 matching lines @@
         ScrollableArea* sa = *it;
         ScrollAnimator* animator = sa->existingScrollAnimator();
         if (animator)
             animator->cancelAnimations();
     }
     return false;
 }
 
 bool EventHandler::handleGestureEvent(const PlatformGestureEvent& gestureEvent)
 {
     TRACE_EVENT0("input", "EventHandler::handleGestureEvent");

[Rick Byers, 2014/08/22 14:49:57]

How about we remove this trace (since it's normally redundant with the one in
handleGestureScrollEvent/handleGestureEvent), and add one to targetGestureEvent?
 This is just a little wrapper helper that's not always used, so probably
doesn't need it's own trace.  But I expect more and more places to call
targetGestureEvent and it has some non-trivial work (like applying touch
adjustment) so we really should trace it directly...

[Zeeshan Qureshi, 2014/08/22 15:30:50]

Agreed, I only added here because I was thinking about the targeting cost, but
tracing that directly is better.

 
     // Propagation to inner frames is handled below this function.
     ASSERT(m_frame == m_frame->localFrameRoot());
 
     // Scrolling-related gesture events invoke EventHandler recursively for each frame down
     // the chain, doing a single-frame hit-test per frame. This matches handleWheelEvent.
-    // Perhaps we could simplify things by rewriting scroll handling to work inner frame
-    // out, and then unify with other gesture events.
     if (gestureEvent.isScrollEvent())
-        return handleGestureScrollEvent(gestureEvent);
-
-    // Non-scrolling related gesture events instead do a single cross-frame hit-test and
-    // jump directly to the inner most frame. This matches handleMousePressEvent etc.
+        handleGestureScrollEvent(gestureEvent);

[Rick Byers, 2014/08/22 14:49:57]

you still need the return here, right?

[Zeeshan Qureshi, 2014/08/22 15:30:50]

Oh yes, and all the tests passed!

 
     // Hit test across all frames and do touch adjustment as necessary for the event type.
     GestureEventWithHitTestResults targetedEvent = targetGestureEvent(gestureEvent);
 
+    return handleGestureEvent(targetedEvent);
+}
+
+bool EventHandler::handleGestureEvent(const GestureEventWithHitTestResults& targetedEvent)
+{
+    TRACE_EVENT0("input", "EventHandler::handleGestureEvent");
+
+    // Propagation to inner frames is handled below this function.
+    ASSERT(m_frame == m_frame->localFrameRoot());
+
+    // Non-scrolling related gesture events do a single cross-frame hit-test and jump
+    // directly to the inner most frame. This matches handleMousePressEvent etc.
+    ASSERT(!targetedEvent.event().isScrollEvent());
+
     // Route to the correct frame.
     if (LocalFrame* innerFrame = targetedEvent.hitTestResult().innerNodeFrame())
         return innerFrame->eventHandler().handleGestureEventInFrame(targetedEvent);
 
     // No hit test result, handle in root instance. Perhaps we should just return false instead?
     return handleGestureEventInFrame(targetedEvent);
 }
 
 bool EventHandler::handleGestureEventInFrame(const GestureEventWithHitTestResults& targetedEvent)
 {
@@ skipping 39 matching lines @@
         break;
     default:
         ASSERT_NOT_REACHED();
     }
 
     return false;
 }
 
 bool EventHandler::handleGestureScrollEvent(const PlatformGestureEvent& gestureEvent)
 {
+    TRACE_EVENT0("input", "EventHandler::handleGestureScrollEvent");
+
     RefPtrWillBeRawPtr<Node> eventTarget = nullptr;
     RefPtr<Scrollbar> scrollbar;
     if (gestureEvent.type() != PlatformEvent::GestureScrollBegin) {
         scrollbar = m_scrollbarHandlingScrollGesture.get();
         eventTarget = m_scrollGestureHandlingNode.get();
     }
 
     if (!eventTarget) {
         Document* document = m_frame->document();
         if (!document->renderView())
@@ skipping 1707 matching lines @@
 unsigned EventHandler::accessKeyModifiers()
 {
 #if OS(MACOSX)
     return PlatformEvent::CtrlKey | PlatformEvent::AltKey;
 #else
     return PlatformEvent::AltKey;
 #endif
 }
 
 } // namespace blink