Move backing store OpenGL support to the platformcompositor module

QPlatformBackingStore had a dependency on the QOpenGLTextureBlitter, which is a
problem because we want to get rid of all the public QOpenGL* classes in the
gui module.

This splits the heavily QOpenGL dependent parts of the backing store
implementation into a separate class and moves it to the platformcompositor
module.

qplatformbackingstore.cpp is now mostly free from OpenGL implementation
details.

Platform integrations now have to explicitly request backing store OpenGL
support. This has been done for:

- xcb
- windows
- cocoa
- winrt
- android
- wasm
- ios

QPlatformGraphicsBufferHelper::lockAndBindToTexture is now exported so it can
be used from other modules.

Task-number: QTBUG-74409
Change-Id: I42ad9250e5a424939cf751a8ad880c7381ede2ae
Reviewed-by: Laszlo Agocs <laszlo.agocs@qt.io>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>

1 files changed, 14 insertions, 2 deletions

diff --git a/src/gui/painting/qplatformbackingstore.h b/src/gui/painting/qplatformbackingstore.h
index 7aa054f1e2..2a3d7d20b5 100644
--- a/src/gui/painting/qplatformbackingstore.h
+++ b/src/gui/painting/qplatformbackingstore.h
@@ -67,11 +67,10 @@ class QRect;
 class QPoint;
 class QImage;
 class QPlatformBackingStorePrivate;
-class QPlatformWindow;
 class QPlatformTextureList;
 class QPlatformTextureListPrivate;
-class QOpenGLContext;
 class QPlatformGraphicsBuffer;
+class QPlatformBackingStoreOpenGLSupportBase;
 
 #ifndef QT_NO_OPENGL
 class Q_GUI_EXPORT QPlatformTextureList : public QObject
@@ -118,6 +117,8 @@ 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;
@@ -154,6 +155,17 @@ private:
 };
 
 #ifndef QT_NO_OPENGL
+class Q_GUI_EXPORT QPlatformBackingStoreOpenGLSupportBase // pure interface
+{
+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() {}
+};
+#endif // QT_NO_OPENGL
+
+#ifndef QT_NO_OPENGL
 Q_DECLARE_OPERATORS_FOR_FLAGS(QPlatformBackingStore::TextureFlags)
 #endif