kwin/src/renderloop.h
Xaver Hugl 75863454a0 RenderLoop: restrict repaint scheduling with fullscreen windows
With an opaque fullscreen window we can be sure that items under it don't
actually require us to repaint. This should yield some small efficiency
improvements and resolves stutter with adaptive sync.

BUG: 443872
FIXED-IN: 5.23.3
2021-11-07 00:41:38 +01:00

135 lines
3.6 KiB
C++

/*
SPDX-FileCopyrightText: 2020 Vlad Zahorodnii <vlad.zahorodnii@kde.org>
SPDX-License-Identifier: GPL-2.0-or-later
*/
#pragma once
#include "kwinglobals.h"
#include <QObject>
namespace KWin
{
class RenderLoopPrivate;
class Item;
/**
* The RenderLoop class represents the compositing scheduler on a particular output.
*
* The RenderLoop class drives the compositing. The frameRequested() signal is emitted
* when the loop wants a new frame to be rendered. The frameCompleted() signal is
* emitted when a previously rendered frame has been presented on the screen. In case
* you want the compositor to repaint the scene, call the scheduleRepaint() function.
*/
class KWIN_EXPORT RenderLoop : public QObject
{
Q_OBJECT
public:
explicit RenderLoop(QObject *parent = nullptr);
~RenderLoop() override;
/**
* Pauses the render loop. While the render loop is inhibited, scheduleRepaint()
* requests are queued.
*
* Once the render loop is uninhibited, the pending schedule requests are going to
* be re-applied.
*/
void inhibit();
/**
* Uninhibits the render loop.
*/
void uninhibit();
/**
* This function must be called before the Compositor starts rendering the next
* frame.
*/
void beginFrame();
/**
* This function must be called after the Compositor has finished rendering the
* next frame.
*/
void endFrame();
/**
* Returns the refresh rate at which the output is being updated, in millihertz.
*/
int refreshRate() const;
/**
* Sets the refresh rate of this RenderLoop to @a refreshRate, in millihertz.
*/
void setRefreshRate(int refreshRate);
/**
* Schedules a compositing cycle at the next available moment.
*/
void scheduleRepaint(Item *item = nullptr);
/**
* Returns the timestamp of the last frame that has been presented on the screen.
* The returned timestamp is sourced from the monotonic clock.
*/
std::chrono::nanoseconds lastPresentationTimestamp() const;
/**
* If a repaint has been scheduled, this function returns the expected time when
* the next frame will be presented on the screen. The returned timestamp is sourced
* from the monotonic clock.
*/
std::chrono::nanoseconds nextPresentationTimestamp() const;
/**
* Sets the surface that currently gets scanned out,
* so that this RenderLoop can adjust its timing behavior to that surface
*/
void setFullscreenSurface(Item *surface);
enum class VrrPolicy : uint32_t {
Never = 0,
Always = 1,
Automatic = 2,
};
Q_ENUM(VrrPolicy);
/**
* the current policy regarding the use of variable refresh rate
*/
VrrPolicy vrrPolicy() const;
/**
* Set the policy regarding the use of variable refresh rate with RenderLoop
*/
void setVrrPolicy(VrrPolicy vrrPolicy);
Q_SIGNALS:
/**
* This signal is emitted when the refresh rate of this RenderLoop has changed.
*/
void refreshRateChanged();
/**
* This signal is emitted when a frame has been actually presented on the screen.
* @a timestamp indicates the time when it took place.
*/
void framePresented(RenderLoop *loop, std::chrono::nanoseconds timestamp);
/**
* This signal is emitted when the render loop wants a new frame to be composited.
*
* The Compositor should make a connection to this signal using Qt::DirectConnection.
*/
void frameRequested(RenderLoop *loop);
private:
QScopedPointer<RenderLoopPrivate> d;
friend class RenderLoopPrivate;
};
} // namespace KWin