Move Scene::isPerScreenRenderingEnabled() to Platform

This way the Compositor can know if per screen rendering is enabled
before creating the Scene.

composite.cpp

@@ -685,7 +685,7 @@ void Compositor::performCompositing()
         kwinApp()->platform()->createOpenGLSafePoint(Platform::OpenGLSafePoint::PreFrame);
     }
     m_renderTimer.start();
-    if (m_scene->isPerScreenRenderingEnabled()) {
+    if (kwinApp()->platform()->isPerScreenRenderingEnabled()) {
         for (int screenId = 0; screenId < screens()->count(); ++screenId) {
             m_scene->paint(screenId, repaints, windows);
         }

platform.cpp

@@ -434,6 +434,16 @@ void Platform::setReady(bool ready)
     emit readyChanged(m_ready);
 }
 
+bool Platform::isPerScreenRenderingEnabled() const
+{
+    return m_isPerScreenRenderingEnabled;
+}
+
+void Platform::setPerScreenRenderingEnabled(bool enabled)
+{
+    m_isPerScreenRenderingEnabled = enabled;
+}
+
 void Platform::warpPointer(const QPointF &globalPos)
 {
     Q_UNUSED(globalPos)

platform.h

@@ -454,6 +454,11 @@ public:
         m_selectedCompositor = type;
     }
 
+    /**
+     * Returns @c true if rendering is split per screen; otherwise returns @c false.
+     */
+    bool isPerScreenRenderingEnabled() const;
+
 public Q_SLOTS:
     void pointerMotion(const QPointF &position, quint32 time);
     void pointerButtonPressed(quint32 button, quint32 time);
@@ -500,6 +505,7 @@ protected:
     void setSoftwareCursorForced(bool forced);
     void repaint(const QRect &rect);
     void setReady(bool ready);
+    void setPerScreenRenderingEnabled(bool enabled);
     QSize initialWindowSize() const {
         return m_initialWindowSize;
     }
@@ -566,6 +572,7 @@ private:
     int m_hideCursorCounter = 0;
     bool m_supportsGammaControl = false;
     bool m_supportsOutputChanges = false;
+    bool m_isPerScreenRenderingEnabled = false;
     CompositingType m_selectedCompositor = NoCompositing;
 };
 

platformsupport/scenes/opengl/backend.cpp

@@ -74,11 +74,6 @@ OverlayWindow* OpenGLBackend::overlayWindow() const
     return nullptr;
 }
 
-bool OpenGLBackend::perScreenRendering() const
-{
-    return false;
-}
-
 void OpenGLBackend::copyPixels(const QRegion &region)
 {
     const int height = screens()->size().height();

platformsupport/scenes/opengl/backend.h

@@ -59,11 +59,6 @@ public:
     virtual bool makeCurrent() = 0;
     virtual void doneCurrent() = 0;
     virtual bool usesOverlayWindow() const = 0;
-    /**
-     * Whether the rendering needs to be split per screen.
-     * Default implementation returns @c false.
-     */
-    virtual bool perScreenRendering() const;
     virtual QRegion beginFrame(int screenId) = 0;
     virtual void endFrame(int screenId, const QRegion &damage, const QRegion &damagedRegion) = 0;
     /**

platformsupport/scenes/qpainter/backend.cpp

@@ -34,9 +34,4 @@ void QPainterBackend::setFailed(const QString &reason)
     m_failed = true;
 }
 
-bool QPainterBackend::perScreenRendering() const
-{
-    return false;
-}
-
 }

platformsupport/scenes/qpainter/backend.h

@@ -50,11 +50,6 @@ public:
      */
     virtual QImage *bufferForScreen(int screenId) = 0;
     virtual bool needsFullRepaint(int screenId) const = 0;
-    /**
-     * Whether the rendering needs to be split per screen.
-     * Default implementation returns @c false.
-     */
-    virtual bool perScreenRendering() const;
 
 protected:
     QPainterBackend();

plugins/platforms/drm/abstract_egl_drm_backend.cpp

@@ -39,8 +39,3 @@ bool AbstractEglDrmBackend::usesOverlayWindow() const
 {
     return false;
 }
-
-bool AbstractEglDrmBackend::perScreenRendering() const
-{
-    return true;
-}

plugins/platforms/drm/abstract_egl_drm_backend.h

@@ -25,7 +25,6 @@ public:
     ~AbstractEglDrmBackend();
 
     bool usesOverlayWindow() const override;
-    bool perScreenRendering() const override;
     void screenGeometryChanged(const QSize &size) override;
 
     virtual int screenCount() const = 0;

plugins/platforms/drm/drm_backend.cpp

@@ -69,6 +69,7 @@ DrmBackend::DrmBackend(QObject *parent)
     , m_dpmsFilter()
 {
     setSupportsGammaControl(true);
+    setPerScreenRenderingEnabled(true);
     supportsOutputChanges();
 }
 

plugins/platforms/drm/egl_multi_backend.cpp

@@ -111,11 +111,6 @@ bool EglMultiBackend::usesOverlayWindow() const
     return false;
 }
 
-bool EglMultiBackend::perScreenRendering() const
-{
-    return true;
-}
-
 void EglMultiBackend::screenGeometryChanged(const QSize &size)
 {
     Q_UNUSED(size)

plugins/platforms/drm/egl_multi_backend.h

@@ -33,7 +33,6 @@ public:
     QSharedPointer<GLTexture> textureForOutput(AbstractOutput *requestedOutput) const override;
 
     bool usesOverlayWindow() const override;
-    bool perScreenRendering() const override;
 
     void screenGeometryChanged(const QSize &size) override;
 

plugins/platforms/drm/scene_qpainter_drm_backend.cpp

@@ -118,9 +118,4 @@ void DrmQPainterBackend::endFrame(int screenId, int mask, const QRegion &damage)
     m_backend->present(rendererOutput.buffer[rendererOutput.index], rendererOutput.output);
 }
 
-bool DrmQPainterBackend::perScreenRendering() const
-{
-    return true;
-}
-
 }

plugins/platforms/drm/scene_qpainter_drm_backend.h

@@ -31,7 +31,6 @@ public:
     bool needsFullRepaint(int screenId) const override;
     void beginFrame(int screenId) override;
     void endFrame(int screenId, int mask, const QRegion &damage) override;
-    bool perScreenRendering() const override;
 
 private:
     void initOutput(DrmOutput *output);

plugins/platforms/fbdev/fb_backend.cpp

@@ -45,6 +45,7 @@ void FramebufferOutput::init(const QSize &pixelSize, const QSize &physicalSize)
 FramebufferBackend::FramebufferBackend(QObject *parent)
     : Platform(parent)
 {
+    setPerScreenRenderingEnabled(true);
 }
 
 FramebufferBackend::~FramebufferBackend()

plugins/platforms/fbdev/scene_qpainter_fb_backend.cpp

@@ -80,9 +80,4 @@ void FramebufferQPainterBackend::endFrame(int screenId, int mask, const QRegion
     p.drawImage(QPoint(0, 0), m_backend->isBGR() ? m_renderBuffer.rgbSwapped() : m_renderBuffer);
 }
 
-bool FramebufferQPainterBackend::perScreenRendering() const
-{
-    return true;
-}
-
 }

plugins/platforms/fbdev/scene_qpainter_fb_backend.h

@@ -28,7 +28,6 @@ public:
     bool needsFullRepaint(int screenId) const override;
     void beginFrame(int screenId) override;
     void endFrame(int screenId, int mask, const QRegion &damage) override;
-    bool perScreenRendering() const override;
 
 private:
     /**

plugins/platforms/hwcomposer/hwcomposer_backend.cpp

@@ -140,6 +140,7 @@ HwcomposerBackend::HwcomposerBackend(QObject *parent)
                                               SLOT(screenBrightnessChanged(int)))) {
         qCWarning(KWIN_HWCOMPOSER) << "Failed to connect to brightness control";
     }
+    setPerScreenRenderingEnabled(false);
 }
 
 HwcomposerBackend::~HwcomposerBackend()

plugins/platforms/virtual/scene_qpainter_virtual_backend.cpp

@@ -60,9 +60,4 @@ void VirtualQPainterBackend::endFrame(int screenId, int mask, const QRegion &dam
     }
 }
 
-bool VirtualQPainterBackend::perScreenRendering() const
-{
-    return true;
-}
-
 }

plugins/platforms/virtual/scene_qpainter_virtual_backend.h

@@ -30,7 +30,6 @@ public:
     bool needsFullRepaint(int screenId) const override;
     void beginFrame(int screenId) override;
     void endFrame(int screenId, int mask, const QRegion &damage) override;
-    bool perScreenRendering() const override;
 
 private:
     void createOutputs();

plugins/platforms/virtual/virtual_backend.cpp

@@ -38,6 +38,7 @@ VirtualBackend::VirtualBackend(QObject *parent)
     }
     setSupportsPointerWarping(true);
     setSupportsGammaControl(true);
+    setPerScreenRenderingEnabled(true);
 }
 
 VirtualBackend::~VirtualBackend()

plugins/platforms/wayland/egl_wayland_backend.cpp

@@ -418,11 +418,6 @@ bool EglWaylandBackend::usesOverlayWindow() const
     return false;
 }
 
-bool EglWaylandBackend::perScreenRendering() const
-{
-    return true;
-}
-
 /************************************************
  * EglTexture
  ************************************************/

plugins/platforms/wayland/egl_wayland_backend.h

@@ -73,7 +73,6 @@ public:
     QRegion beginFrame(int screenId) override;
     void endFrame(int screenId, const QRegion &damage, const QRegion &damagedRegion) override;
     bool usesOverlayWindow() const override;
-    bool perScreenRendering() const override;
     void init() override;
 
     bool havePlatformBase() const {

plugins/platforms/wayland/scene_qpainter_wayland_backend.cpp

@@ -156,11 +156,6 @@ WaylandQPainterBackend::~WaylandQPainterBackend()
 {
 }
 
-bool WaylandQPainterBackend::perScreenRendering() const
-{
-    return true;
-}
-
 void WaylandQPainterBackend::createOutput(AbstractOutput *waylandOutput)
 {
     auto *output = new WaylandQPainterOutput(static_cast<WaylandOutput *>(waylandOutput), this);

plugins/platforms/wayland/scene_qpainter_wayland_backend.h

@@ -77,7 +77,6 @@ public:
     void beginFrame(int screenId) override;
 
     bool needsFullRepaint(int screenId) const override;
-    bool perScreenRendering() const override;
 
 private:
     void createOutput(AbstractOutput *waylandOutput);

plugins/platforms/wayland/wayland_backend.cpp

@@ -444,6 +444,7 @@ WaylandBackend::WaylandBackend(QObject *parent)
     , m_connectionThreadObject(new ConnectionThread(nullptr))
     , m_connectionThread(nullptr)
 {
+    setPerScreenRenderingEnabled(true);
     supportsOutputChanges();
     connect(this, &WaylandBackend::connectionFailed, this, &WaylandBackend::initFailed);
 

plugins/platforms/x11/standalone/x11_platform.cpp

@@ -64,6 +64,7 @@ X11StandalonePlatform::X11StandalonePlatform(QObject *parent)
 #endif
 
     setSupportsGammaControl(true);
+    setPerScreenRenderingEnabled(false);
 }
 
 X11StandalonePlatform::~X11StandalonePlatform()

plugins/platforms/x11/windowed/egl_x11_backend.cpp

@@ -65,11 +65,6 @@ bool EglX11Backend::usesOverlayWindow() const
     return false;
 }
 
-bool EglX11Backend::perScreenRendering() const
-{
-    return true;
-}
-
 QRegion EglX11Backend::beginFrame(int screenId)
 {
     makeContextCurrent(m_surfaces.at(screenId));

plugins/platforms/x11/windowed/egl_x11_backend.h

@@ -24,7 +24,6 @@ public:
     explicit EglX11Backend(X11WindowedBackend *backend);
     ~EglX11Backend() override;
     bool usesOverlayWindow() const override;
-    bool perScreenRendering() const override;
     QRegion beginFrame(int screenId) override;
     void endFrame(int screenId, const QRegion &damage, const QRegion &damagedRegion) override;
 

plugins/platforms/x11/windowed/scene_qpainter_x11_backend.cpp

@@ -81,9 +81,4 @@ void X11WindowedQPainterBackend::endFrame(int screenId, int mask, const QRegion
     rendererOutput->needsFullRepaint = false;
 }
 
-bool X11WindowedQPainterBackend::perScreenRendering() const
-{
-    return true;
-}
-
 }

plugins/platforms/x11/windowed/scene_qpainter_x11_backend.h

@@ -33,7 +33,6 @@ public:
     bool needsFullRepaint(int screenId) const override;
     void beginFrame(int screenId) override;
     void endFrame(int screenId, int mask, const QRegion &damage) override;
-    bool perScreenRendering() const override;
 
 private:
     void createOutputs();

plugins/platforms/x11/windowed/x11windowed_backend.cpp

@@ -44,6 +44,7 @@ X11WindowedBackend::X11WindowedBackend(QObject *parent)
     : Platform(parent)
 {
     setSupportsPointerWarping(true);
+    setPerScreenRenderingEnabled(true);
     connect(this, &X11WindowedBackend::sizeChanged, this, &X11WindowedBackend::screenSizeChanged);
 }
 

plugins/scenes/opengl/scene_opengl.cpp

@@ -350,8 +350,6 @@ SceneOpenGL::SceneOpenGL(OpenGLBackend *backend, QObject *parent)
             qCDebug(KWIN_OPENGL) << "Explicit synchronization with the X command stream disabled by environment variable";
         }
     }
-
-    setPerScreenRenderingEnabled(m_backend->perScreenRendering());
 }
 
 SceneOpenGL::~SceneOpenGL()

plugins/scenes/qpainter/scene_qpainter.cpp

@@ -55,7 +55,6 @@ SceneQPainter::SceneQPainter(QPainterBackend *backend, QObject *parent)
     , m_backend(backend)
     , m_painter(new QPainter())
 {
-    setPerScreenRenderingEnabled(m_backend->perScreenRendering());
 }
 
 SceneQPainter::~SceneQPainter()
@@ -83,7 +82,7 @@ void SceneQPainter::paintGenericScreen(int mask, const ScreenPaintData &data)
 
 void SceneQPainter::paint(int screenId, const QRegion &_damage, const QList<Toplevel *> &toplevels)
 {
-    Q_ASSERT(m_backend->perScreenRendering());
+    Q_ASSERT(kwinApp()->platform()->isPerScreenRenderingEnabled());
     painted_screen = screenId;
 
     createStackingOrder(toplevels);

scene.cpp

@@ -56,6 +56,7 @@
 */
 
 #include "scene.h"
+#include "platform.h"
 
 #include <QQuickWindow>
 #include <QVector2D>
@@ -93,16 +94,6 @@ Scene::~Scene()
     Q_ASSERT(m_windows.isEmpty());
 }
 
-bool Scene::isPerScreenRenderingEnabled() const
-{
-    return m_isPerScreenRenderingEnabled;
-}
-
-void Scene::setPerScreenRenderingEnabled(bool enabled)
-{
-    m_isPerScreenRenderingEnabled = enabled;
-}
-
 // returns mask and possibly modified region
 void Scene::paintScreen(int* mask, const QRegion &damage, const QRegion &repaint,
                         QRegion *updateRegion, QRegion *validRegion, const QMatrix4x4 &projection, const QRect &outputGeometry, const qreal screenScale)
@@ -718,8 +709,7 @@ Scene::Window::Window(Toplevel *client, QObject *parent)
     , disable_painting(0)
     , cached_quad_list(nullptr)
 {
-    const Scene *scene = Compositor::self()->scene();
-    if (scene->isPerScreenRenderingEnabled()) {
+    if (kwinApp()->platform()->isPerScreenRenderingEnabled()) {
         connect(screens(), &Screens::countChanged, this, &Window::reallocRepaints);
     }
     reallocRepaints();
@@ -1183,8 +1173,7 @@ void Scene::Window::resetRepaints(int screen)
 
 void Scene::Window::reallocRepaints()
 {
-    const Scene *scene = Compositor::self()->scene();
-    if (scene->isPerScreenRenderingEnabled()) {
+    if (kwinApp()->platform()->isPerScreenRenderingEnabled()) {
         m_repaints.resize(screens()->count());
         m_layerRepaints.resize(screens()->count());
     } else {

scene.h

@@ -137,7 +137,6 @@ public:
     virtual bool blocksForRetrace() const;
     virtual bool syncsToVBlank() const;
     virtual OverlayWindow* overlayWindow() const = 0;
-    bool isPerScreenRenderingEnabled() const;
 
     virtual bool makeOpenGLContextCurrent();
     virtual void doneOpenGLContextCurrent();
@@ -204,7 +203,6 @@ public Q_SLOTS:
     void windowClosed(KWin::Toplevel* c, KWin::Deleted* deleted);
 protected:
     virtual Window *createWindow(Toplevel *toplevel) = 0;
-    void setPerScreenRenderingEnabled(bool enabled);
     void createStackingOrder(const QList<Toplevel *> &toplevels);
     void clearStackingOrder();
     // shared implementation, starts painting the screen
@@ -275,7 +273,6 @@ private:
     QVector< Window* > stacking_order;
     // how many times finalPaintScreen() has been called
     int m_paintScreenCount = 0;
-    bool m_isPerScreenRenderingEnabled = false;
 };
 
 /**