kwin/plugins/platforms/x11/windowed/egl_x11_backend.cpp
Vlad Zahorodnii 0ceff5fd24 Swap buffers after finishing a compositing cycle
The compositing timing algorithm assumes that glXSwapBuffers() and
eglSwapBuffers() block. While this was true long time ago with NVIDIA
drivers, nowadays, it's not the case. The NVIDIA driver queues
several buffers in advance and if the application runs out of them,
it will block. With Mesa driver, swapping buffer was never blocking.

This change makes the render backends swap buffers right after ending
a compositing cycle. This may potentially block, but it shouldn't be
an issue with modern drivers. In case it gets proven, we can move
glXSwapBuffers() and eglSwapBuffers() in a separate thread.

Note that this change breaks the compositing timing algorithm, but
it's already sort of broken with Mesa drivers.
2021-01-06 16:59:29 +00:00

81 lines
2.1 KiB
C++

/*
KWin - the KDE window manager
This file is part of the KDE project.
SPDX-FileCopyrightText: 2015 Martin Gräßlin <mgraesslin@kde.org>
SPDX-License-Identifier: GPL-2.0-or-later
*/
#include "egl_x11_backend.h"
// kwin
#include "screens.h"
#include "x11windowed_backend.h"
// kwin libs
#include <kwinglplatform.h>
namespace KWin
{
EglX11Backend::EglX11Backend(X11WindowedBackend *backend)
: EglOnXBackend(backend->connection(), backend->display(), backend->rootWindow(), backend->screenNumer(), XCB_WINDOW_NONE)
, m_backend(backend)
{
setX11TextureFromPixmapSupported(false);
}
EglX11Backend::~EglX11Backend() = default;
void EglX11Backend::cleanupSurfaces()
{
for (auto it = m_surfaces.begin(); it != m_surfaces.end(); ++it) {
eglDestroySurface(eglDisplay(), *it);
}
}
bool EglX11Backend::createSurfaces()
{
for (int i = 0; i < screens()->count(); ++i) {
EGLSurface s = createSurface(m_backend->windowForScreen(i));
if (s == EGL_NO_SURFACE) {
return false;
}
m_surfaces << s;
}
if (m_surfaces.isEmpty()) {
return false;
}
setSurface(m_surfaces.first());
return true;
}
bool EglX11Backend::usesOverlayWindow() const
{
return false;
}
QRegion EglX11Backend::beginFrame(int screenId)
{
makeContextCurrent(m_surfaces.at(screenId));
setupViewport(screenId);
return screens()->geometry(screenId);
}
void EglX11Backend::setupViewport(int screenId)
{
// TODO: ensure the viewport is set correctly each time
const QSize &overall = screens()->size();
const QRect &v = screens()->geometry(screenId);
// TODO: are the values correct?
qreal scale = screens()->scale(screenId);
glViewport(-v.x(), v.height() - overall.height() + v.y(), overall.width() * scale, overall.height() * scale);
}
void EglX11Backend::endFrame(int screenId, const QRegion &renderedRegion, const QRegion &damagedRegion)
{
Q_UNUSED(damagedRegion)
const QRect &outputGeometry = screens()->geometry(screenId);
presentSurface(m_surfaces.at(screenId), renderedRegion, outputGeometry);
}
} // namespace