content/browser/renderer_host/smooth_scroll_gesture_controller.cc

   1 // Copyright (c) 2013 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/smooth_scroll_gesture_controller.h"
   6
   7 #include "base/debug/trace_event.h"
   8 #include "base/message_loop.h"
   9 #include "content/common/view_messages.h"
  10 #include "content/port/browser/render_widget_host_view_port.h"
  11 #include "content/port/browser/smooth_scroll_gesture.h"
  12 #include "content/public/browser/render_widget_host.h"
  13
  14 namespace content {
  15
  16 namespace {
  17
  18 // How many milliseconds apart synthetic scroll messages should be sent.
  19 const int kSyntheticScrollMessageIntervalMs = 7;
  20
  21 }  // namespace
  22
  23 SmoothScrollGestureController::SmoothScrollGestureController()
  24     : rwh_(NULL) {
  25 }
  26
  27 SmoothScrollGestureController::~SmoothScrollGestureController() {
  28 }
  29
  30 void SmoothScrollGestureController::BeginSmoothScroll(
  31     RenderWidgetHostViewPort* view,
  32     const ViewHostMsg_BeginSmoothScroll_Params& params) {
  33   if (pending_smooth_scroll_gesture_.get())
  34     return;
  35
  36   rwh_ = view->GetRenderWidgetHost();
  37   pending_smooth_scroll_gesture_ = view->CreateSmoothScrollGesture(
  38       params.scroll_down,
  39       params.pixels_to_scroll,
  40       params.mouse_event_x,
  41       params.mouse_event_y);
  42
  43   timer_.Start(FROM_HERE, GetSyntheticScrollMessageInterval(), this,
  44                &SmoothScrollGestureController::OnTimer);
  45 }
  46
  47 base::TimeDelta
  48     SmoothScrollGestureController::GetSyntheticScrollMessageInterval() const {
  49   return base::TimeDelta::FromMilliseconds(kSyntheticScrollMessageIntervalMs);
  50 }
  51
  52 void SmoothScrollGestureController::OnTimer() {
  53   base::TimeTicks now = base::TimeTicks::Now();
  54   if (!pending_smooth_scroll_gesture_->ForwardInputEvents(now, rwh_)) {
  55     timer_.Stop();
  56     pending_smooth_scroll_gesture_ = NULL;
  57     rwh_->Send(new ViewMsg_SmoothScrollCompleted(rwh_->GetRoutingID()));
  58   }
  59 }
  60
  61 }  // namespace content