Postpone rail application for touch scrolling - chrome side.

content/renderer/input/input_handler_proxy.cc

 // Copyright 2013 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 "content/renderer/input/input_handler_proxy.h"
 
 #include "base/auto_reset.h"
 #include "base/command_line.h"
 #include "base/logging.h"
 #include "base/metrics/histogram.h"
@@ skipping 438 matching lines @@
 InputHandlerProxy::HandleGestureScrollUpdate(
   const WebGestureEvent& gesture_event) {
 #ifndef NDEBUG
   DCHECK(expect_scroll_update_end_);
 #endif
 
   if (!gesture_scroll_on_impl_thread_ && !gesture_pinch_on_impl_thread_)
     return DID_NOT_HANDLE;
 
   gfx::Point scroll_point(gesture_event.x, gesture_event.y);
-  gfx::Vector2dF scroll_delta(-gesture_event.data.scrollUpdate.deltaX,
-                              -gesture_event.data.scrollUpdate.deltaY);
+
+  // TODO(tdresser): The rail information should be pushed down into
+  // InputHandler.

[ccameron, 2015/04/01 17:20:25]

Oh, crap, I didn't do my TODO for this that I'd promised.

I'll do that right now, and then you can just pass the rails mode into the
InputHandler.

[tdresser, 2015/04/01 17:22:45]

Sounds good, thanks.

+  const float dx = gesture_event.data.scrollUpdate.deltaX;
+  const float dy = gesture_event.data.scrollUpdate.deltaY;
+  const WebInputEvent::RailsMode railsMode =
+      gesture_event.data.scrollUpdate.railsMode;
+
+  gfx::Vector2dF scroll_delta(
+      railsMode != WebInputEvent::RailsModeVertical ? -dx : 0,
+      railsMode != WebInputEvent::RailsModeHorizontal ? -dy : 0);
+
   cc::InputHandlerScrollResult scroll_result = input_handler_->ScrollBy(
       scroll_point, scroll_delta);
   HandleOverscroll(scroll_point, scroll_result);
   return scroll_result.did_scroll ? DID_HANDLE : DROP_EVENT;
 }
 
 InputHandlerProxy::EventDisposition InputHandlerProxy::HandleGestureScrollEnd(
   const WebGestureEvent& gesture_event) {
 #ifndef NDEBUG
   DCHECK(expect_scroll_update_end_);
@@ skipping 23 matching lines @@
 
 #ifndef NDEBUG
   expect_scroll_update_end_ = false;
 #endif
 
   switch (scroll_status) {
     case cc::InputHandler::SCROLL_STARTED: {
       if (gesture_event.sourceDevice == blink::WebGestureDeviceTouchpad)
         input_handler_->ScrollEnd();
 
-      const float vx = gesture_event.data.flingStart.velocityX;
-      const float vy = gesture_event.data.flingStart.velocityY;
-      current_fling_velocity_ = gfx::Vector2dF(vx, vy);
+      // TODO(tdresser): The rail information should be pushed down into
+      // InputHandler.
+      const WebInputEvent::RailsMode railsMode =
+          gesture_event.data.flingStart.railsMode;
+
+      float vx = railsMode != WebInputEvent::RailsModeVertical
+                     ? gesture_event.data.flingStart.velocityX
+                     : 0;
+      float vy = railsMode != WebInputEvent::RailsModeHorizontal
+                     ? gesture_event.data.flingStart.velocityY
+                     : 0;
+
+      current_fling_velocity_.set_x(vx);
+      current_fling_velocity_.set_y(vy);
+
       DCHECK(!current_fling_velocity_.IsZero());
       fling_curve_.reset(client_->CreateFlingAnimationCurve(
           gesture_event.sourceDevice,
           WebFloatPoint(vx, vy),
           blink::WebSize()));
       disallow_horizontal_fling_scroll_ = !vx;
       disallow_vertical_fling_scroll_ = !vy;
       TRACE_EVENT_ASYNC_BEGIN2("input",
                                "InputHandlerProxy::HandleGestureFling::started",
                                this,
@@ skipping 434 matching lines @@
   // trigger a scroll, e.g., with a trivial time delta between fling updates.
   // Return true in this case to prevent early fling termination.
   if (std::abs(clipped_increment.width) < kScrollEpsilon &&
       std::abs(clipped_increment.height) < kScrollEpsilon)
     return true;
 
   return did_scroll;
 }
 
 }  // namespace content