no route to host Chromium网页输入事件捕捉和手势检测过程分析(7)

FilteredGestureProvider类的成员函数OnTouchEvent接下来调用GestureEventDataPacket类的静态成员函数FromTouch创建一个用来保存手势操作的Gesture Event Data Packet。例如以下所看到的：

GestureEventDataPacket GestureEventDataPacket::FromTouch(
    const ui::MotionEvent& touch) {
  return GestureEventDataPacket(touch.GetEventTime(),
                                ToGestureSource(touch),
                                gfx::PointF(touch.GetX(), touch.GetY()),
                                gfx::PointF(touch.GetRawX(), touch.GetRawY()));
}

这个函数定义在文件external/chromium_org/ui/events/gesture_detection/gesture_event_data_packet.cc中。

GestureEventDataPacket类的静态成员函数FromTouch首先调用函数ToGestureSource获得接下来要创建的Gesture Event Data Packet的类型，接着创建一个该类型的Gesture Event Data Packet返回给调用者。

函数ToGestureSource的实现例如以下所看到的：

GestureEventDataPacket::GestureSource ToGestureSource(
    const ui::MotionEvent& event) {
  switch (event.GetAction()) {
    case ui::MotionEvent::ACTION_DOWN:
      return GestureEventDataPacket::TOUCH_SEQUENCE_START;
    case ui::MotionEvent::ACTION_UP:
      return GestureEventDataPacket::TOUCH_SEQUENCE_END;
    case ui::MotionEvent::ACTION_MOVE:
      return GestureEventDataPacket::TOUCH_MOVE;
    case ui::MotionEvent::ACTION_CANCEL:
      return GestureEventDataPacket::TOUCH_SEQUENCE_CANCEL;
    case ui::MotionEvent::ACTION_POINTER_DOWN:
      return GestureEventDataPacket::TOUCH_START;
    case ui::MotionEvent::ACTION_POINTER_UP:
      return GestureEventDataPacket::TOUCH_END;
  };
  NOTREACHED() << "Invalid ui::MotionEvent action: " << event.GetAction();
  return GestureEventDataPacket::INVALID;
}

这个函数定义在文件external/chromium_org/ui/events/gesture_detection/gesture_event_data_packet.cc中。

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