no route to host Chromium网页输入事件捕捉和手势检测过程分析(23)

RenderWidgetHostImpl类的成员函数ForwardTouchEventWithLatencyInfo首先将参数touch_event描写叙述的Touch事件封装在一个TouchEventWithLatencyInfo对象中，然后再调用成员变量input_router_指向的一个InputRouterImpl对象的成员函数SendTouchEvent将这个TouchEventWithLatencyInfo对象发送给Render进程。

InputRouterImpl类的成员函数SendTouchEvent的实现例如以下所看到的：

void InputRouterImpl::SendTouchEvent(
    const TouchEventWithLatencyInfo& touch_event) {
  ......
  touch_event_queue_.QueueEvent(touch_event);
}

这个函数定义在文件external/chromium_org/content/browser/renderer_host/input/input_router_impl.cc中。

InputRouterImpl类的成员变量touch_event_queue_描写叙述的是一个TouchEventQueue对象，InputRouterImpl类的成员函数SendTouchEvent调用这个TouchEventQueue对象的成员函数QueueEvent将参数touch_event描写叙述的Touch事件发送给Render进程。

TouchEventQueue类的成员函数QueueEvent的实现例如以下所看到的：

void TouchEventQueue::QueueEvent(const TouchEventWithLatencyInfo& event) {
  ......

  // If the queueing of |event| was triggered by an ack dispatch, defer
  // processing the event until the dispatch has finished.
  if (touch_queue_.empty() && !dispatching_touch_ack_) {
    ......

    // There is no touch event in the queue. Forward it to the renderer
    // immediately.
    touch_queue_.push_back(new CoalescedWebTouchEvent(event, false));
    ForwardNextEventToRenderer();
    return;
  }

  // If the last queued touch-event was a touch-move, and the current event is
  // also a touch-move, then the events can be coalesced into a single event.
  if (touch_queue_.size() > 1) {
    CoalescedWebTouchEvent* last_event = touch_queue_.back();
    if (last_event->CoalesceEventIfPossible(event))
      return;
  }
  touch_queue_.push_back(new CoalescedWebTouchEvent(event, false));
}

这个函数定义在文件external/chromium_org/content/browser/renderer_host/input/touch_event_queue.cc中。

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