core: Expose graphics buffer allocator in RenderBackend

It can be used by other components to allocate buffers on the
compositing render device. For example, QPA.

src/backends/drm/drm_egl_backend.cpp

@@ -142,6 +142,11 @@ std::unique_ptr<SurfaceTexture> EglGbmBackend::createSurfaceTextureWayland(Surfa
     return std::make_unique<BasicEGLSurfaceTextureWayland>(this, pixmap);
 }
 
+GraphicsBufferAllocator *EglGbmBackend::graphicsBufferAllocator() const
+{
+    return gpu()->graphicsBufferAllocator();
+}
+
 void EglGbmBackend::present(Output *output)
 {
     static_cast<DrmAbstractOutput *>(output)->present();

src/backends/drm/drm_egl_backend.h

@@ -50,6 +50,8 @@ public:
     std::unique_ptr<SurfaceTexture> createSurfaceTextureInternal(SurfacePixmapInternal *pixmap) override;
     std::unique_ptr<SurfaceTexture> createSurfaceTextureWayland(SurfacePixmapWayland *pixmap) override;
 
+    GraphicsBufferAllocator *graphicsBufferAllocator() const override;
+
     void present(Output *output) override;
     OutputLayer *primaryLayer(Output *output) override;
     OutputLayer *cursorLayer(Output *output) override;

src/backends/drm/drm_qpainter_backend.cpp

@@ -8,6 +8,7 @@
 */
 #include "drm_qpainter_backend.h"
 #include "drm_backend.h"
+#include "drm_gpu.h"
 #include "drm_output.h"
 #include "drm_pipeline.h"
 #include "drm_qpainter_layer.h"
@@ -31,6 +32,11 @@ DrmQPainterBackend::~DrmQPainterBackend()
     m_backend->setRenderBackend(nullptr);
 }
 
+GraphicsBufferAllocator *DrmQPainterBackend::graphicsBufferAllocator() const
+{
+    return m_backend->primaryGpu()->graphicsBufferAllocator();
+}
+
 void DrmQPainterBackend::present(Output *output)
 {
     static_cast<DrmAbstractOutput *>(output)->present();

src/backends/drm/drm_qpainter_backend.h

@@ -28,6 +28,8 @@ public:
     DrmQPainterBackend(DrmBackend *backend);
     ~DrmQPainterBackend();
 
+    GraphicsBufferAllocator *graphicsBufferAllocator() const override;
+
     void present(Output *output) override;
     OutputLayer *primaryLayer(Output *output) override;
     OutputLayer *cursorLayer(Output *output) override;

src/backends/virtual/virtual_egl_backend.h

@@ -59,7 +59,7 @@ public:
     void init() override;
 
     VirtualBackend *backend() const;
-    GraphicsBufferAllocator *graphicsBufferAllocator() const;
+    GraphicsBufferAllocator *graphicsBufferAllocator() const override;
 
 private:
     bool initializeEgl();

src/backends/virtual/virtual_qpainter_backend.h

@@ -50,7 +50,7 @@ public:
     VirtualQPainterBackend(VirtualBackend *backend);
     ~VirtualQPainterBackend() override;
 
-    GraphicsBufferAllocator *graphicsBufferAllocator() const;
+    GraphicsBufferAllocator *graphicsBufferAllocator() const override;
 
     void present(Output *output) override;
     VirtualQPainterLayer *primaryLayer(Output *output) override;

src/backends/wayland/wayland_egl_backend.h

@@ -91,7 +91,7 @@ public:
     ~WaylandEglBackend() override;
 
     WaylandBackend *backend() const;
-    GraphicsBufferAllocator *graphicsBufferAllocator() const;
+    GraphicsBufferAllocator *graphicsBufferAllocator() const override;
 
     std::unique_ptr<SurfaceTexture> createSurfaceTextureInternal(SurfacePixmapInternal *pixmap) override;
     std::unique_ptr<SurfaceTexture> createSurfaceTextureWayland(SurfacePixmapWayland *pixmap) override;

src/backends/wayland/wayland_qpainter_backend.h

@@ -81,7 +81,7 @@ public:
     explicit WaylandQPainterBackend(WaylandBackend *b);
     ~WaylandQPainterBackend() override;
 
-    GraphicsBufferAllocator *graphicsBufferAllocator() const;
+    GraphicsBufferAllocator *graphicsBufferAllocator() const override;
 
     void present(Output *output) override;
     OutputLayer *primaryLayer(Output *output) override;

src/backends/x11/windowed/x11_windowed_egl_backend.h

@@ -73,7 +73,7 @@ public:
     ~X11WindowedEglBackend() override;
 
     X11WindowedBackend *backend() const;
-    GraphicsBufferAllocator *graphicsBufferAllocator() const;
+    GraphicsBufferAllocator *graphicsBufferAllocator() const override;
 
     std::unique_ptr<SurfaceTexture> createSurfaceTextureInternal(SurfacePixmapInternal *pixmap) override;
     std::unique_ptr<SurfaceTexture> createSurfaceTextureWayland(SurfacePixmapWayland *pixmap) override;

src/backends/x11/windowed/x11_windowed_qpainter_backend.h

@@ -69,7 +69,7 @@ public:
     X11WindowedQPainterBackend(X11WindowedBackend *backend);
     ~X11WindowedQPainterBackend() override;
 
-    GraphicsBufferAllocator *graphicsBufferAllocator() const;
+    GraphicsBufferAllocator *graphicsBufferAllocator() const override;
 
     void present(Output *output) override;
     OutputLayer *primaryLayer(Output *output) override;

src/core/renderbackend.cpp

@@ -32,6 +32,11 @@ bool RenderBackend::checkGraphicsReset()
     return false;
 }
 
+GraphicsBufferAllocator *RenderBackend::graphicsBufferAllocator() const
+{
+    return nullptr;
+}
+
 bool RenderBackend::testImportBuffer(GraphicsBuffer *buffer)
 {
     return false;

src/core/renderbackend.h

@@ -17,6 +17,7 @@ namespace KWin
 {
 
 class GraphicsBuffer;
+class GraphicsBufferAllocator;
 class Output;
 class OverlayWindow;
 class OutputLayer;
@@ -44,6 +45,8 @@ public:
     virtual OutputLayer *cursorLayer(Output *output);
     virtual void present(Output *output) = 0;
 
+    virtual GraphicsBufferAllocator *graphicsBufferAllocator() const;
+
     virtual bool testImportBuffer(GraphicsBuffer *buffer);
     virtual QHash<uint32_t, QVector<uint64_t>> supportedFormats() const;