content/renderer/input/main_thread_event_queue.cc

// Copyright 2016 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/main_thread_event_queue.h"

namespace content {

MainThreadEventQueue::MainThreadEventQueue(int routing_id,
                                           MainThreadEventQueueClient* client)
    : routing_id_(routing_id), client_(client) {}

MainThreadEventQueue::~MainThreadEventQueue() {}

bool MainThreadEventQueue::HandleEvent(
    const blink::WebInputEvent* event,
    const ui::LatencyInfo& latency,
    InputEventDispatchType original_dispatch_type,
    InputEventAckState ack_result) {
  DCHECK(original_dispatch_type == DISPATCH_TYPE_BLOCKING ||
         original_dispatch_type == DISPATCH_TYPE_NON_BLOCKING);
  DCHECK(ack_result == INPUT_EVENT_ACK_STATE_SET_NON_BLOCKING ||
         ack_result == INPUT_EVENT_ACK_STATE_NOT_CONSUMED);

  bool non_blocking = original_dispatch_type == DISPATCH_TYPE_NON_BLOCKING ||
                      ack_result == INPUT_EVENT_ACK_STATE_SET_NON_BLOCKING;

  InputEventDispatchType dispatch_type =
      non_blocking ? DISPATCH_TYPE_NON_BLOCKING_NOTIFY_MAIN
                   : DISPATCH_TYPE_BLOCKING_NOTIFY_MAIN;

  if (event->type == blink::WebInputEvent::MouseWheel) {
    if (wheel_events_.state() == WebInputEventQueueState::ITEM_PENDING) {
      wheel_events_.Queue(PendingMouseWheelEvent(
          *static_cast<const blink::WebMouseWheelEvent*>(event), latency,
          dispatch_type));
    } else {
      if (non_blocking) {
        wheel_events_.set_state(WebInputEventQueueState::ITEM_PENDING);
        client_->SendEventToMainThread(routing_id_, event, latency,
                                       dispatch_type);
      } else {
        // If there is nothing in the event queue and the event is
        // blocking pass the |original_dispatch_type| to avoid
        // having the main thread call us back as an optimization.
        client_->SendEventToMainThread(routing_id_, event, latency,
                                       original_dispatch_type);
      }
    }
  } else if (blink::WebInputEvent::isTouchEventType(event->type)) {
    if (touch_events_.state() == WebInputEventQueueState::ITEM_PENDING) {
      touch_events_.Queue(
          PendingTouchEvent(*static_cast<const blink::WebTouchEvent*>(event),
                            latency, dispatch_type));
    } else {
      if (non_blocking) {
        touch_events_.set_state(WebInputEventQueueState::ITEM_PENDING);
        client_->SendEventToMainThread(routing_id_, event, latency,
                                       dispatch_type);
      } else {
        // If there is nothing in the event queue and the event is
        // blocking pass the |original_dispatch_type| to avoid
        // having the main thread call us back as an optimization.
        client_->SendEventToMainThread(routing_id_, event, latency,
                                       original_dispatch_type);
      }
    }
  } else {
    client_->SendEventToMainThread(routing_id_, event, latency,
                                   original_dispatch_type);
  }

  // send an ack when we are non-blocking.
  return non_blocking;
}

void MainThreadEventQueue::EventHandled(blink::WebInputEvent::Type type) {
  if (type == blink::WebInputEvent::MouseWheel) {
    if (!wheel_events_.empty()) {
      scoped_ptr<PendingMouseWheelEvent> event = wheel_events_.Pop();
      client_->SendEventToMainThread(routing_id_, &event->event, event->latency,
                                     event->type);
    } else {
      wheel_events_.set_state(WebInputEventQueueState::ITEM_NOT_PENDING);
    }
  } else if (blink::WebInputEvent::isTouchEventType(type)) {
    if (!touch_events_.empty()) {
      scoped_ptr<PendingTouchEvent> event = touch_events_.Pop();
      client_->SendEventToMainThread(routing_id_, &event->event, event->latency,
                                     event->type);
    } else {
      touch_events_.set_state(WebInputEventQueueState::ITEM_NOT_PENDING);
    }
  } else {
    NOTREACHED() << "Invalid passive event type";
  }
}

}  // namespace content