kwin/platformsupport/scenes/opengl/backend.cpp
Roman Gilg 8d13729031 [platforms/x11] Never block on retrace, always present after paint
Summary:
Compositing in X11 was done time shifted, meaning that we paint first, then
wait one vblank interval length and present on prepareRenderingFrame the
previous paint result. This is supposed to make sure we don't miss the vblank
and in case of block till retrace be able to continue issuing commands and
only shortly before next vblank present.

This is counter-intuitiv, not how we do it on Wayland or even on MESA with X.
The reason seems to be that the GLX backend was in the beginning written
against Nvidia proprietary driver which needed this but nowadays even this
driver defaults to non-blocking behavior on buffer swap.

Therefore remove this legacy anomaly fully and directly present after paint.
We then wait one refresh cycle and in the future can optimize this by delaying
the paint and present till shortly before vsync.

Test Plan: kwin_x11 tested on i915 and Nvidia proprietary driver.

Reviewers: #kwin

Subscribers: zzag, alexeymin, kwin

Tags: #kwin

Maniphest Tasks: T11071

Differential Revision: https://phabricator.kde.org/D23514
2019-11-14 09:03:44 +01:00

117 lines
3 KiB
C++

/********************************************************************
KWin - the KDE window manager
This file is part of the KDE project.
Copyright (C) 2006 Lubos Lunak <l.lunak@kde.org>
Copyright (C) 2009, 2010, 2011 Martin Gräßlin <mgraesslin@kde.org>
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*********************************************************************/
#include "backend.h"
#include <kwineffects.h>
#include <logging.h>
#include "screens.h"
#include <epoxy/gl.h>
namespace KWin
{
OpenGLBackend::OpenGLBackend()
: m_directRendering(false)
, m_haveBufferAge(false)
, m_failed(false)
{
}
OpenGLBackend::~OpenGLBackend()
{
}
void OpenGLBackend::setFailed(const QString &reason)
{
qCWarning(KWIN_OPENGL) << "Creating the OpenGL rendering failed: " << reason;
m_failed = true;
}
void OpenGLBackend::idle()
{
if (hasPendingFlush()) {
effects->makeOpenGLContextCurrent();
present();
}
}
void OpenGLBackend::addToDamageHistory(const QRegion &region)
{
if (m_damageHistory.count() > 10)
m_damageHistory.removeLast();
m_damageHistory.prepend(region);
}
QRegion OpenGLBackend::accumulatedDamageHistory(int bufferAge) const
{
QRegion region;
// Note: An age of zero means the buffer contents are undefined
if (bufferAge > 0 && bufferAge <= m_damageHistory.count()) {
for (int i = 0; i < bufferAge - 1; i++)
region |= m_damageHistory[i];
} else {
const QSize &s = screens()->size();
region = QRegion(0, 0, s.width(), s.height());
}
return region;
}
OverlayWindow* OpenGLBackend::overlayWindow() const
{
return nullptr;
}
QRegion OpenGLBackend::prepareRenderingForScreen(int screenId)
{
// fallback to repaint complete screen
return screens()->geometry(screenId);
}
void OpenGLBackend::endRenderingFrameForScreen(int screenId, const QRegion &damage, const QRegion &damagedRegion)
{
Q_UNUSED(screenId)
Q_UNUSED(damage)
Q_UNUSED(damagedRegion)
}
bool OpenGLBackend::perScreenRendering() const
{
return false;
}
void OpenGLBackend::copyPixels(const QRegion &region)
{
const int height = screens()->size().height();
for (const QRect &r : region) {
const int x0 = r.x();
const int y0 = height - r.y() - r.height();
const int x1 = r.x() + r.width();
const int y1 = height - r.y();
glBlitFramebuffer(x0, y0, x1, y1, x0, y0, x1, y1, GL_COLOR_BUFFER_BIT, GL_NEAREST);
}
}
}