Add public and QPA APIs for adapting existing OpenGL contexts

For now only xcb on GLX is supported. Other platforms will follow later.

Add also some missing documentation for the platform OpenGL context factory
functions.

[ChangeLog] QOpenGLContext is now able to adopt existing native contexts.

Task-number: QTBUG-37552
Change-Id: I5dd959f102df178f646b2df5989203b5dc6de376
Reviewed-by: Jørgen Lind <jorgen.lind@digia.com>

1 files changed, 68 insertions, 0 deletions

diff --git a/src/platformheaders/doc/src/qtplatformheaders.qdoc b/src/platformheaders/doc/src/qtplatformheaders.qdoc
new file mode 100644
index 0000000000..4ed740d296
--- /dev/null
+++ b/src/platformheaders/doc/src/qtplatformheaders.qdoc
@@ -0,0 +1,68 @@
+/****************************************************************************
+**
+** Copyright (C) 2014 Digia Plc and/or its subsidiary(-ies).
+** Contact: http://www.qt-project.org/legal
+**
+** This file is part of the documentation of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:FDL$
+** 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 Digia.  For licensing terms and
+** conditions see http://qt.digia.com/licensing.  For further information
+** use the contact form at http://qt.digia.com/contact-us.
+**
+** GNU Free Documentation License Usage
+** Alternatively, this file may be used under the terms of the GNU Free
+** Documentation License version 1.3 as published by the Free Software
+** Foundation and appearing in the file included in the packaging of
+** this file.  Please review the following information to ensure
+** the GNU Free Documentation License version 1.3 requirements
+** will be met: http://www.gnu.org/copyleft/fdl.html.
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+/*!
+    \module QtPlatformHeaders
+    \title Qt Platform Headers C++ Classes
+    \ingroup modules
+
+    \brief The Qt Platform Headers module offers header-only inline classes that
+    encapsulate platform-specific information that is tied to a given runtime
+    configuration of a platform plugin.
+*/
+
+/*!
+    \page qtplatformheaders-index.html
+    \title Qt Platform Headers
+
+    \brief The Qt Platform Headers module offers header-only inline classes that
+    encapsulate platform-specific information that is tied to a given runtime
+    configuration of a platform plugin.
+
+    Some applications may need to interface Qt with other frameworks. This often
+    means using graphics contexts or other types of native handles created by
+    one framework with another. For example, on some platforms, QOpenGLContext
+    offers the ability to wrap an existing native OpenGL context, instead of
+    creating a new one. This existing native context can be created by some
+    other third-party code.
+
+    The type of such native handles is highly platform specific and in some
+    cases the platform plugin will need more information to adopt a handle, just
+    the handle in itself will not be sufficient. Therefore the public API
+    consists of functions taking or returning a QVariant that contains a
+    platform-specific value type. See for example
+    QOpenGLContext::setNativeHandle() and QOpenGLContext::nativeHandle(). When
+    running on Linux/X11, using the xcb platform plugin and the GLX windowing
+    system interface, the variant contains a QGLXNativeContext. On other
+    platforms a different class will be used. These classes are all placed in
+    the Qt Platform Headers module.
+
+    \note Similar to the other QPA APIs, there are no binary compatibility
+    guarantees for these classes, meaning that an application using these
+    classes is only guaranteed to work with the Qt version it was developed
+    against. Unlike QPA however, source compatibility is guaranteed.
+ */