Move QPlatformBackingStoreOpenGLSupport handling out of platform plugins

Allows them to not depend on QtOpenGL just to provide the default
backing store OpenGL support backend.

Change-Id: I90d6d9247ce76848d9d03e2d512fb736c81488d3
Reviewed-by: Laszlo Agocs <laszlo.agocs@qt.io>

1 files changed, 12 insertions, 3 deletions

diff --git a/src/gui/painting/qplatformbackingstore.h b/src/gui/painting/qplatformbackingstore.h
index 2a3d7d20b5..e0fdca2f21 100644
--- a/src/gui/painting/qplatformbackingstore.h
+++ b/src/gui/painting/qplatformbackingstore.h
@@ -117,8 +117,6 @@ public:
     QWindow *window() const;
     QBackingStore *backingStore() const;
 
-    void setOpenGLSupport(QPlatformBackingStoreOpenGLSupportBase *openGLSupport);
-
     virtual QPaintDevice *paintDevice() = 0;
 
     virtual void flush(QWindow *window, const QRegion &region, const QPoint &offset) = 0;
@@ -155,13 +153,24 @@ private:
 };
 
 #ifndef QT_NO_OPENGL
-class Q_GUI_EXPORT QPlatformBackingStoreOpenGLSupportBase // pure interface
+class Q_GUI_EXPORT QPlatformBackingStoreOpenGLSupportBase
 {
 public:
     virtual void composeAndFlush(QWindow *window, const QRegion &region, const QPoint &offset,
                                  QPlatformTextureList *textures, bool translucentBackground) = 0;
     virtual GLuint toTexture(const QRegion &dirtyRegion, QSize *textureSize, QPlatformBackingStore::TextureFlags *flags) const = 0;
     virtual ~QPlatformBackingStoreOpenGLSupportBase() {}
+
+    using FactoryFunction = QPlatformBackingStoreOpenGLSupportBase *(*)();
+    static void setFactoryFunction(FactoryFunction);
+    static FactoryFunction factoryFunction();
+
+protected:
+    QPlatformBackingStore *backingStore = nullptr;
+    friend class QPlatformBackingStore;
+
+private:
+    static FactoryFunction s_factoryFunction;
 };
 #endif // QT_NO_OPENGL