LayerImpl::tryScroll must convert its content-space point to layer space before comparing to the no…

cc/layer_impl.cc

 // Copyright 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "config.h"
 
 #include "cc/layer_impl.h"
 
 #include "base/debug/trace_event.h"
 #include "base/stringprintf.h"
@@ skipping 197 matching lines @@
         return InputHandlerClient::ScrollOnMainThread;
     }
 
     if (!screenSpaceTransform().isInvertible()) {
         TRACE_EVENT0("cc", "LayerImpl::tryScroll: Ignored nonInvertibleTransform");
         return InputHandlerClient::ScrollIgnored;
     }
 
     if (!nonFastScrollableRegion().IsEmpty()) {
         bool clipped = false;
-        gfx::PointF hitTestPointInLocalSpace = MathUtil::projectPoint(screenSpaceTransform().inverse(), screenSpacePoint, clipped);
-        if (!clipped && nonFastScrollableRegion().Contains(gfx::ToFlooredPoint(hitTestPointInLocalSpace))) {
+        gfx::PointF hitTestPointInContentSpace = MathUtil::projectPoint(screenSpaceTransform().inverse(), screenSpacePoint, clipped);
+        gfx::PointF hitTestPointInLayerSpace = hitTestPointInContentSpace.Scale(1 / contentsScaleX(), 1 / contentsScaleY());
+        if (!clipped && nonFastScrollableRegion().Contains(gfx::ToFlooredPoint(hitTestPointInLayerSpace))) {

[enne (OOO), 2012/11/06 23:18:58]

Can you convince me about the use of ToFlooredPoint here?

What if the contents scale of a layer is < 1, do we need to do
Contains(gfx::Rect)?

[danakj, 2012/11/06 23:21:57]

I think I did ToFloored because I wanted no behaviour changes in the gfx::
conversion.

I believe ToRoundedPoint would be better, we want to be as close to their
pointer/finger as possible.
I don't think so. We want to know if it contains the center of the rect, still,
I believe. Just cuz the scale is < 1, doesn't mean we want to make the
pointer/touch point larger.

[danakj, 2012/11/06 23:22:27]

Done.

             TRACE_EVENT0("cc", "LayerImpl::tryScroll: Failed nonFastScrollableRegion");
             return InputHandlerClient::ScrollOnMainThread;
         }
     }
 
     if (type == InputHandlerClient::Wheel && haveWheelEventHandlers()) {
         TRACE_EVENT0("cc", "LayerImpl::tryScroll: Failed wheelEventHandlers");
         return InputHandlerClient::ScrollOnMainThread;
     }
 
@@ skipping 472 matching lines @@
 
 void LayerImpl::setVerticalScrollbarLayer(ScrollbarLayerImpl* scrollbarLayer)
 {
     if (!m_scrollbarAnimationController)
         m_scrollbarAnimationController = ScrollbarAnimationController::create(this);
     m_scrollbarAnimationController->setVerticalScrollbarLayer(scrollbarLayer);
     m_scrollbarAnimationController->updateScrollOffset(this);
 }
 
 }  // namespace cc