chromium/ui/compositor/compositor_lock.h

// Copyright 2017 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef UI_COMPOSITOR_COMPOSITOR_LOCK_H_
#define UI_COMPOSITOR_COMPOSITOR_LOCK_H_

#include <vector>

#include "base/functional/callback_forward.h"
#include "base/memory/raw_ptr.h"
#include "base/memory/weak_ptr.h"
#include "base/task/single_thread_task_runner.h"
#include "base/time/time.h"
#include "ui/compositor/compositor_export.h"

namespace ui {

class Compositor;
class CompositorLock;

// Implemented by clients which take compositor lock. Used to notify the client
// when their lock times out.
class CompositorLockClient { … };

// A helper class used to manage compositor locks. Should be created/used by
// classes which want to provide out compositor locking.
class COMPOSITOR_EXPORT CompositorLockManager { … };

// This class represents a lock on the compositor, that can be used to prevent
// commits to the compositor tree while we're waiting for an asynchronous
// event. The typical use case is when waiting for a renderer to produce a frame
// at the right size. The caller keeps a reference on this object, and drops the
// reference once it desires to release the lock.
// By default, the lock will be cancelled after a short timeout to ensure
// responsiveness of the UI, so the compositor tree should be kept in a
// "reasonable" state while the lock is held. The timeout length, or no timeout,
// can be requested at the time the lock is created.
// Don't instantiate this class directly, use Compositor::GetCompositorLock.
class COMPOSITOR_EXPORT CompositorLock { … };

}  // namespace ui

#endif  // UI_COMPOSITOR_COMPOSITOR_LOCK_H_