[backends/x11] Add a dedicated EGL backend for multi-surface rendering

Based on the existing EglOnXBackend. Main difference is that this
subclass implements perScreenRendering with support for one EGLSurface
per output.

backends/x11/CMakeLists.txt

@@ -1,5 +1,6 @@
 set(X11BACKEND_SOURCES
     logging.cpp
+    egl_x11_backend.cpp
     scene_qpainter_x11_backend.cpp
     x11windowed_backend.cpp
 )

backends/x11/egl_x11_backend.cpp

@@ -0,0 +1,118 @@
+/********************************************************************
+ KWin - the KDE window manager
+ This file is part of the KDE project.
+
+Copyright (C) 2015 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 "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)
+{
+}
+
+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;
+}
+
+void EglX11Backend::present()
+{
+    for (int i = 0; i < screens()->count(); ++i) {
+        EGLSurface s = m_surfaces.at(i);
+        makeContextCurrent(s);
+        setupViewport(i);
+        presentSurface(s, screens()->geometry(i), screens()->geometry(i));
+    }
+    eglWaitGL();
+    xcb_flush(m_backend->connection());
+}
+
+QRegion EglX11Backend::prepareRenderingFrame()
+{
+    startRenderTimer();
+    return QRegion();
+}
+
+void EglX11Backend::endRenderingFrame(const QRegion &renderedRegion, const QRegion &damagedRegion)
+{
+    Q_UNUSED(renderedRegion)
+    Q_UNUSED(damagedRegion)
+}
+
+bool EglX11Backend::usesOverlayWindow() const
+{
+    return false;
+}
+
+bool EglX11Backend::perScreenRendering() const
+{
+    return true;
+}
+
+QRegion EglX11Backend::prepareRenderingForScreen(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?
+    glViewport(-v.x(), v.height() - overall.height() - v.y(), overall.width(), overall.height());
+}
+
+void EglX11Backend::endRenderingFrameForScreen(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

backends/x11/egl_x11_backend.h

@@ -0,0 +1,57 @@
+/********************************************************************
+ KWin - the KDE window manager
+ This file is part of the KDE project.
+
+Copyright (C) 2015 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/>.
+*********************************************************************/
+#ifndef KWIN_EGL_X11_BACKEND_H
+#define KWIN_EGL_X11_BACKEND_H
+#include "eglonxbackend.h"
+
+namespace KWin
+{
+
+class X11WindowedBackend;
+
+/**
+ * @brief OpenGL Backend using Egl windowing system over an X overlay window.
+ **/
+class EglX11Backend : public EglOnXBackend
+{
+public:
+    explicit EglX11Backend(X11WindowedBackend *backend);
+    virtual ~EglX11Backend();
+    virtual QRegion prepareRenderingFrame();
+    virtual void endRenderingFrame(const QRegion &damage, const QRegion &damagedRegion);
+    virtual bool usesOverlayWindow() const override;
+    bool perScreenRendering() const override;
+    QRegion prepareRenderingForScreen(int screenId) override;
+    void endRenderingFrameForScreen(int screenId, const QRegion &damage, const QRegion &damagedRegion) override;
+
+protected:
+    virtual void present();
+    void cleanupSurfaces() override;
+    bool createSurfaces() override;
+
+private:
+    void setupViewport(int screenId);
+    QVector<EGLSurface> m_surfaces;
+    X11WindowedBackend *m_backend;
+};
+
+} // namespace
+
+#endif

backends/x11/x11windowed_backend.cpp

@@ -22,7 +22,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include "logging.h"
 #include "wayland_server.h"
 #include "xcbutils.h"
-#include "eglonxbackend.h"
+#include "egl_x11_backend.h"
 #include "screens.h"
 #include <kwinxrenderutils.h>
 // KDE
@@ -441,7 +441,7 @@ Screens *X11WindowedBackend::createScreens(QObject *parent)
 
 OpenGLBackend *X11WindowedBackend::createOpenGLBackend()
 {
-    return  new EglOnXBackend(connection(), display(), rootWindow(), screenNumer(), window());
+    return  new EglX11Backend(this);
 }
 
 QPainterBackend *X11WindowedBackend::createQPainterBackend()