b8a70e62d5
At the moment, our frame scheduling infrastructure is still heavily based on Xinerama-style rendering. Specifically, we assume that painting is driven by a single timer, etc. This change introduces a new type - RenderLoop. Its main purpose is to drive compositing on a specific output, or in case of X11, on the overlay window. With RenderLoop, compositing is synchronized to vblank events. It exposes the last and the next estimated presentation timestamp. The expected presentation timestamp can be used by effects to ensure that animations are synchronized with the upcoming vblank event. On Wayland, every outputs has its own render loop. On X11, per screen rendering is not possible, therefore the platform exposes the render loop for the overlay window. Ideally, the Scene has to expose the RenderLoop, but as the first step towards better compositing scheduling it's good as is for the time being. The RenderLoop tries to minimize the latency by delaying compositing as close as possible to the next vblank event. One tricky thing about it is that if compositing is too close to the next vblank event, animations may become a little bit choppy. However, increasing the latency reduces the choppiness. Given that, there is no any "silver bullet" solution for the choppiness issue, a new option has been added in the Compositing KCM to specify the amount of latency. By default, it's "Medium," but if a user is not satisfied with the upstream default, they can tweak it.
120 lines
2.7 KiB
C++
120 lines
2.7 KiB
C++
/*
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KWin - the KDE window manager
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This file is part of the KDE project.
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SPDX-FileCopyrightText: 2015 Martin Gräßlin <mgraesslin@kde.org>
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SPDX-FileCopyrightText: 2019 Roman Gilg <subdiff@gmail.com>
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SPDX-License-Identifier: GPL-2.0-or-later
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*/
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#ifndef KWIN_FB_BACKEND_H
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#define KWIN_FB_BACKEND_H
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#include "abstract_wayland_output.h"
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#include "platform.h"
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#include <QImage>
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#include <QSize>
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namespace KWin
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{
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class FramebufferBackend;
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class VsyncMonitor;
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class FramebufferOutput : public AbstractWaylandOutput
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{
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Q_OBJECT
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public:
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explicit FramebufferOutput(FramebufferBackend *backend, QObject *parent = nullptr);
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~FramebufferOutput() override = default;
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RenderLoop *renderLoop() const override;
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VsyncMonitor *vsyncMonitor() const;
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void init(const QSize &pixelSize, const QSize &physicalSize);
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private:
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void vblank(std::chrono::nanoseconds timestamp);
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RenderLoop *m_renderLoop = nullptr;
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VsyncMonitor *m_vsyncMonitor = nullptr;
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};
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class KWIN_EXPORT FramebufferBackend : public Platform
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{
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Q_OBJECT
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Q_INTERFACES(KWin::Platform)
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Q_PLUGIN_METADATA(IID "org.kde.kwin.Platform" FILE "fbdev.json")
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public:
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explicit FramebufferBackend(QObject *parent = nullptr);
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~FramebufferBackend() override;
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QPainterBackend *createQPainterBackend() override;
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QSize screenSize() const override;
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void init() override;
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int fileDescriptor() const;
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bool isValid() const {
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return m_fd >= 0;
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}
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void map();
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void unmap();
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void *mappedMemory() const {
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return m_memory;
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}
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int bytesPerLine() const {
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return m_bytesPerLine;
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}
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int bufferSize() const {
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return m_bufferLength;
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}
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quint32 bitsPerPixel() const {
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return m_bitsPerPixel;
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}
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QImage::Format imageFormat() const;
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/**
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* @returns whether the imageFormat is BGR instead of RGB.
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*/
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bool isBGR() const {
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return m_bgr;
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}
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Outputs outputs() const override;
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Outputs enabledOutputs() const override;
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QVector<CompositingType> supportedCompositors() const override {
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return QVector<CompositingType>{QPainterCompositing};
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}
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private:
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void openFrameBuffer();
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bool handleScreenInfo();
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void initImageFormat();
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QVector<FramebufferOutput*> m_outputs;
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QByteArray m_id;
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struct Color {
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quint32 offset;
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quint32 length;
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};
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Color m_red;
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Color m_green;
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Color m_blue;
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Color m_alpha;
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quint32 m_bitsPerPixel = 0;
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int m_fd = -1;
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quint32 m_bufferLength = 0;
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int m_bytesPerLine = 0;
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void *m_memory = nullptr;
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QImage::Format m_imageFormat = QImage::Format_Invalid;
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bool m_bgr = false;
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};
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}
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#endif
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