AbstractEglBackend: Share initBufferConfigs among its children

The only one that does it differently is the DRM backend and it's just
an extension that takes GBM into account, otherwise it's effectively
copy-pasted code.

src/backends/drm/drm_egl_backend.h

@@ -86,7 +86,7 @@ public:
 
 private:
     bool initializeEgl();
-    bool initBufferConfigs();
+    bool initBufferConfigs() override;
     bool initRenderingContext();
 
     DrmBackend *m_backend;

src/backends/virtual/virtual_egl_backend.cpp

@@ -150,39 +150,6 @@ void VirtualEglBackend::removeOutput(Output *output)
     m_outputs.erase(output);
 }
 
-bool VirtualEglBackend::initBufferConfigs()
-{
-    const EGLint config_attribs[] = {
-        EGL_SURFACE_TYPE,
-        EGL_WINDOW_BIT,
-        EGL_RED_SIZE,
-        1,
-        EGL_GREEN_SIZE,
-        1,
-        EGL_BLUE_SIZE,
-        1,
-        EGL_ALPHA_SIZE,
-        0,
-        EGL_RENDERABLE_TYPE,
-        isOpenGLES() ? EGL_OPENGL_ES2_BIT : EGL_OPENGL_BIT,
-        EGL_CONFIG_CAVEAT,
-        EGL_NONE,
-        EGL_NONE,
-    };
-
-    EGLint count;
-    EGLConfig configs[1024];
-    if (eglChooseConfig(eglDisplay(), config_attribs, configs, 1, &count) == EGL_FALSE) {
-        return false;
-    }
-    if (count != 1) {
-        return false;
-    }
-    setConfig(configs[0]);
-
-    return true;
-}
-
 std::unique_ptr<SurfaceTexture> VirtualEglBackend::createSurfaceTextureInternal(SurfacePixmapInternal *pixmap)
 {
     return std::make_unique<BasicEGLSurfaceTextureInternal>(this, pixmap);

src/backends/virtual/virtual_egl_backend.h

@@ -56,7 +56,6 @@ public:
 
 private:
     bool initializeEgl();
-    bool initBufferConfigs();
     bool initRenderingContext();
 
     void addOutput(Output *output);

src/backends/wayland/wayland_egl_backend.cpp

@@ -384,41 +384,6 @@ bool WaylandEglBackend::initRenderingContext()
     return makeCurrent();
 }
 
-bool WaylandEglBackend::initBufferConfigs()
-{
-    const EGLint config_attribs[] = {
-        EGL_SURFACE_TYPE,
-        EGL_WINDOW_BIT,
-        EGL_RED_SIZE,
-        1,
-        EGL_GREEN_SIZE,
-        1,
-        EGL_BLUE_SIZE,
-        1,
-        EGL_ALPHA_SIZE,
-        0,
-        EGL_RENDERABLE_TYPE,
-        isOpenGLES() ? EGL_OPENGL_ES2_BIT : EGL_OPENGL_BIT,
-        EGL_CONFIG_CAVEAT,
-        EGL_NONE,
-        EGL_NONE,
-    };
-
-    EGLint count;
-    EGLConfig configs[1024];
-    if (eglChooseConfig(eglDisplay(), config_attribs, configs, 1, &count) == EGL_FALSE) {
-        qCCritical(KWIN_WAYLAND_BACKEND) << "choose config failed";
-        return false;
-    }
-    if (count != 1) {
-        qCCritical(KWIN_WAYLAND_BACKEND) << "choose config did not return a config" << count;
-        return false;
-    }
-    setConfig(configs[0]);
-
-    return true;
-}
-
 std::shared_ptr<KWin::GLTexture> WaylandEglBackend::textureForOutput(KWin::Output *output) const
 {
     auto texture = std::make_unique<GLTexture>(GL_RGBA8, output->pixelSize());

src/backends/wayland/wayland_egl_backend.h

@@ -143,7 +143,6 @@ public:
 
 private:
     bool initializeEgl();
-    bool initBufferConfigs();
     bool initRenderingContext();
     bool createEglWaylandOutput(Output *output);
     void cleanupSurfaces() override;

src/platformsupport/scenes/opengl/abstract_egl_backend.cpp

@@ -477,4 +477,39 @@ QHash<uint32_t, QVector<uint64_t>> AbstractEglBackend::supportedFormats() const
         return RenderBackend::supportedFormats();
     }
 }
+
+bool AbstractEglBackend::initBufferConfigs()
+{
+    const EGLint config_attribs[] = {
+        EGL_SURFACE_TYPE,
+        EGL_WINDOW_BIT,
+        EGL_RED_SIZE,
+        1,
+        EGL_GREEN_SIZE,
+        1,
+        EGL_BLUE_SIZE,
+        1,
+        EGL_ALPHA_SIZE,
+        0,
+        EGL_RENDERABLE_TYPE,
+        isOpenGLES() ? EGL_OPENGL_ES2_BIT : EGL_OPENGL_BIT,
+        EGL_CONFIG_CAVEAT,
+        EGL_NONE,
+        EGL_NONE,
+    };
+
+    EGLint count;
+    EGLConfig configs[1024];
+    if (eglChooseConfig(eglDisplay(), config_attribs, configs, 1, &count) == EGL_FALSE) {
+        qCCritical(KWIN_OPENGL) << "choose config failed";
+        return false;
+    }
+    if (count != 1) {
+        qCCritical(KWIN_OPENGL) << "choose config did not return a config" << count;
+        return false;
+    }
+    setConfig(configs[0]);
+
+    return true;
+}
 }

src/platformsupport/scenes/opengl/abstract_egl_backend.h

@@ -87,6 +87,7 @@ protected:
     bool hasClientExtension(const QByteArray &ext) const;
     bool isOpenGLES() const;
     bool createContext();
+    virtual bool initBufferConfigs();
 
 private:
     EGLContext ensureGlobalShareContext();