src/content/browser/renderer_host/basic_mouse_wheel_smooth_scroll_gesture.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "content/browser/renderer_host/basic_mouse_wheel_smooth_scroll_gesture.h"
   6
   7 #include "base/debug/trace_event.h"
   8 #include "content/browser/renderer_host/render_widget_host_impl.h"
   9
  10 namespace content {
  11
  12 BasicMouseWheelSmoothScrollGesture::BasicMouseWheelSmoothScrollGesture(
  13     bool scroll_down, int pixels_to_scroll,
  14     int mouse_event_x, int mouse_event_y)
  15     : scroll_down_(scroll_down),
  16       pixels_scrolled_(0),
  17       pixels_to_scroll_(pixels_to_scroll),
  18       mouse_event_x_(mouse_event_x),
  19       mouse_event_y_(mouse_event_y) { }
  20
  21 BasicMouseWheelSmoothScrollGesture::~BasicMouseWheelSmoothScrollGesture() { }
  22
  23 bool BasicMouseWheelSmoothScrollGesture::ForwardInputEvents(
  24     base::TimeTicks now, RenderWidgetHost* host) {
  25
  26   if (pixels_scrolled_ >= pixels_to_scroll_)
  27     return false;
  28
  29   float position_delta = synthetic_gesture_calculator_.GetDelta(
  30       now,
  31       RenderWidgetHostImpl::From(host)->GetSyntheticGestureMessageInterval());
  32
  33
  34   WebKit::WebMouseWheelEvent event;
  35   event.type = WebKit::WebInputEvent::MouseWheel;
  36   event.hasPreciseScrollingDeltas = 0;
  37   event.deltaY = scroll_down_ ? -position_delta : position_delta;
  38   // TODO(vollick): find a proper way to access
  39   // WebCore::WheelEvent::tickMultiplier.
  40   event.wheelTicksY = event.deltaY / 120;
  41   event.modifiers = 0;
  42
  43   // TODO(nduca): Figure out plausible x and y values.
  44   event.globalX = 0;
  45   event.globalY = 0;
  46   event.x = mouse_event_x_;
  47   event.y = mouse_event_y_;
  48   event.windowX = event.x;
  49   event.windowY = event.y;
  50   host->ForwardWheelEvent(event);
  51
  52   pixels_scrolled_ += abs(event.deltaY);
  53
  54   TRACE_COUNTER_ID1(
  55       "gpu", "smooth_scroll_by_pixels_scrolled", this, pixels_scrolled_);
  56
  57   return true;
  58 }
  59
  60 }  // content
  61