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>

2 files changed, 20 insertions, 7 deletions

diff --git a/src/plugins/platforms/xcb/qxcbintegration.cpp b/src/plugins/platforms/xcb/qxcbintegration.cpp
index 3fd989e1f9..cea0511822 100644
--- a/src/plugins/platforms/xcb/qxcbintegration.cpp
+++ b/src/plugins/platforms/xcb/qxcbintegration.cpp
@@ -61,6 +61,9 @@
 
 #include <QtFontDatabaseSupport/private/qgenericunixfontdatabase_p.h>
 #include <QtServiceSupport/private/qgenericunixservices_p.h>
+#if QT_CONFIG(opengl)
+#include <QtPlatformCompositorSupport/qpa/qplatformbackingstoreopenglsupport.h>
+#endif
 
 #include <stdio.h>
 
@@ -288,16 +291,23 @@ QPlatformOpenGLContext *QXcbIntegration::createPlatformOpenGLContext(QOpenGLCont
 
 QPlatformBackingStore *QXcbIntegration::createPlatformBackingStore(QWindow *window) const
 {
-    const bool isTrayIconWindow = QXcbWindow::isTrayIconWindow(window);
-    if (isTrayIconWindow)
-        return new QXcbSystemTrayBackingStore(window);
+    QPlatformBackingStore *backingStore = nullptr;
 
+    const bool isTrayIconWindow = QXcbWindow::isTrayIconWindow(window);
+    if (isTrayIconWindow) {
+        backingStore = new QXcbSystemTrayBackingStore(window);
 #if QT_CONFIG(xcb_native_painting)
-    if (nativePaintingEnabled())
-        return new QXcbNativeBackingStore(window);
+    } else if (nativePaintingEnabled()) {
+        backingStore = new QXcbNativeBackingStore(window);
 #endif
-
-    return new QXcbBackingStore(window);
+    } else {
+        backingStore = new QXcbBackingStore(window);
+    }
+    Q_ASSERT(backingStore);
+#ifndef QT_NO_OPENGL
+    backingStore->setOpenGLSupport(new QPlatformBackingStoreOpenGLSupport(backingStore));
+#endif
+    return backingStore;
 }
 
 QPlatformOffscreenSurface *QXcbIntegration::createPlatformOffscreenSurface(QOffscreenSurface *surface) const
diff --git a/src/plugins/platforms/xcb/xcb_qpa_lib.pro b/src/plugins/platforms/xcb/xcb_qpa_lib.pro
index a5d05faa9c..1f651e7697 100644
--- a/src/plugins/platforms/xcb/xcb_qpa_lib.pro
+++ b/src/plugins/platforms/xcb/xcb_qpa_lib.pro
@@ -9,6 +9,9 @@ QT += \
     edid_support-private \
     xkbcommon_support-private
 
+qtHaveModule(platformcompositor_support-private): \
+    QT += platformcompositor_support-private
+
 qtHaveModule(linuxaccessibility_support-private): \
     QT += linuxaccessibility_support-private