gecko-dev/layout/ipc/PVsync.ipdl

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

include protocol PBackground;
include "mozilla/layers/LayersMessageUtils.h";

using class mozilla::TimeStamp from "mozilla/TimeStamp.h";

namespace mozilla {
namespace layout {

/*
 * The PVsync is a sub-protocol in PBackground and it is used to notify
 * the vsync event from chrome to content process. It also provides the
 * interfaces for content to observe/unobserve vsync event notifications.
 */
async protocol PVsync
{
  manager PBackground;

child:
  // Send vsync event from chrome to content process.
  prio(high) async Notify(TimeStamp aVsyncTimestamp) compress;

  // Send the vsync rate to the content process.
  async VsyncRate(float aVsyncRate);

parent:
  // Content process use these messages to acquire the vsync event.
  async Observe();
  async Unobserve();
  async RequestVsyncRate();

  // This message is never sent. Each PVsync actor will stay alive as long as
  // its PBackground manager.
  async __delete__();
};

} // namespace layout
} // namespace mozilla