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, 87 insertions, 0 deletions

diff --git a/src/platformsupport/platformcompositor/qplatformbackingstoreopenglsupport.h b/src/platformsupport/platformcompositor/qplatformbackingstoreopenglsupport.h
new file mode 100644
index 0000000000..5523b18f76
--- /dev/null
+++ b/src/platformsupport/platformcompositor/qplatformbackingstoreopenglsupport.h
@@ -0,0 +1,87 @@
+/****************************************************************************
+**
+** Copyright (C) 2020 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the QtGui module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 3 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL3 included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 3 requirements
+** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 2.0 or (at your option) the GNU General
+** Public license version 3 or any later version approved by the KDE Free
+** Qt Foundation. The licenses are as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-2.0.html and
+** https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef QPLATFORMBACKINGSTOREOPENGLSUPPORT_H
+#define QPLATFORMBACKINGSTOREOPENGLSUPPORT_H
+
+//
+//  W A R N I N G
+//  -------------
+//
+// This file is part of the QPA API and is not meant to be used
+// in applications. Usage of this API may make your code
+// source and binary incompatible with future versions of Qt.
+//
+
+#ifndef QT_NO_OPENGL
+
+#include <QtGui/qtguiglobal.h>
+#include <qpa/qplatformbackingstore.h>
+
+#include <QtGui/QOpenGLContext>
+
+QT_BEGIN_NAMESPACE
+
+class QOpenGLTextureBlitter;
+class QOpenGLBackingStore;
+
+class QPlatformBackingStoreOpenGLSupport : public QPlatformBackingStoreOpenGLSupportBase
+{
+public:
+    explicit QPlatformBackingStoreOpenGLSupport(QPlatformBackingStore *backingStore) : backingStore(backingStore) {}
+    ~QPlatformBackingStoreOpenGLSupport() override;
+    void composeAndFlush(QWindow *window, const QRegion &region, const QPoint &offset,
+                         QPlatformTextureList *textures, bool translucentBackground) override;
+    GLuint toTexture(const QRegion &dirtyRegion, QSize *textureSize, QPlatformBackingStore::TextureFlags *flags) const override;
+
+private:
+    QPlatformBackingStore *backingStore = nullptr;
+    QScopedPointer<QOpenGLContext> context;
+    mutable GLuint textureId = 0;
+    mutable QSize textureSize;
+    mutable bool needsSwizzle = false;
+    mutable bool premultiplied = false;
+    QOpenGLTextureBlitter *blitter = nullptr;
+};
+
+QT_END_NAMESPACE
+
+#endif // QT_NO_OPENGL
+
+#endif // QPLATFORMBACKINGSTOREOPENGLSUPPORT_H