Allow repeated fling boosting for accelerated scrolling
Scrolling long documents on Android is a laborious, sad affair. Native Android
view's address this with a "flywheel" fling mechanism, whereby successive flings
in similar directions accumulative velocity. Add such a feature to
InputHandlerProxy, allowing compositor-driven flings on all platforms to
quickly accelerate to infinity and beyond.
Flings will accumulate if the following conditions are met:
- The active and new flings target the same layer, are in a similar direction,
and are both of sufficient velocity.
- All scroll update events received during the active fling and preceding the
new fling are in a similar direction and of sufficient velocity.
Note: This approach is not suitable to WebView; it relies heavily on the fling
accumulator living "close" to the fling driver. It also does not affect
main-thread driven flings.
BUG=164116
Review URL: https://codereview.chromium.org/239433010
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@268363 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/cc/trees/layer_tree_host_impl.h b/cc/trees/layer_tree_host_impl.h
index 2488eda8..ae69b01 100644
--- a/cc/trees/layer_tree_host_impl.h
+++ b/cc/trees/layer_tree_host_impl.h
@@ -145,8 +145,11 @@
float page_scale,
base::TimeDelta duration) OVERRIDE;
virtual void SetNeedsAnimate() OVERRIDE;
- virtual bool HaveTouchEventHandlersAt(const gfx::Point& viewport_port)
- OVERRIDE;
+ virtual bool IsCurrentlyScrollingLayerAt(
+ const gfx::Point& viewport_point,
+ InputHandler::ScrollInputType type) OVERRIDE;
+ virtual bool HaveTouchEventHandlersAt(
+ const gfx::Point& viewport_port) OVERRIDE;
virtual scoped_ptr<SwapPromiseMonitor> CreateLatencyInfoSwapPromiseMonitor(
ui::LatencyInfo* latency) OVERRIDE;
@@ -523,7 +526,7 @@
InputHandler::ScrollInputType type,
LayerImpl* layer_hit_by_point,
bool* scroll_on_main_thread,
- bool* has_ancestor_scroll_handler) const;
+ bool* optional_has_ancestor_scroll_handler) const;
float DeviceSpaceDistanceToLayer(const gfx::PointF& device_viewport_point,
LayerImpl* layer_impl);
void StartScrollbarFadeRecursive(LayerImpl* layer);
