From af1e32426c50694c0e4c1c292aa5eeee3b38c7bc Mon Sep 17 00:00:00 2001
From: Laszlo Agocs <laszlo.agocs@digia.com>
Date: Mon, 17 Mar 2014 10:35:35 +0100
Subject: Add public and QPA APIs for adapting existing OpenGL contexts
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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>
---
 src/gui/kernel/qopenglcontext.cpp | 62 ++++++++++++++++++++++++++++++++++++++-
 1 file changed, 61 insertions(+), 1 deletion(-)

(limited to 'src/gui/kernel/qopenglcontext.cpp')

diff --git a/src/gui/kernel/qopenglcontext.cpp b/src/gui/kernel/qopenglcontext.cpp
index 7382d63a06..7fa0452fe5 100644
--- a/src/gui/kernel/qopenglcontext.cpp
+++ b/src/gui/kernel/qopenglcontext.cpp
@@ -479,6 +479,64 @@ void QOpenGLContext::setScreen(QScreen *screen)
         d->screen = QGuiApplication::primaryScreen();
 }
 
+/*!
+    Set the native handles for this context. When create() is called and a
+    native handle is set, configuration settings, like format(), are ignored
+    since this QOpenGLContext will wrap an already created native context
+    instead of creating a new one from scratch.
+
+    On some platforms the native context handle is not sufficient and other
+    related handles (for example, for a window or display) have to be provided
+    in addition. Therefore \a handle is variant containing a platform-specific
+    value type. These classes can be found in the QtPlatformHeaders module.
+
+    When create() is called with native handles set, the handles' ownership are
+    not taken, meaning that destroy() will not destroy the native context.
+
+    \note Some frameworks track the current context and surfaces internally.
+    Making the adopted QOpenGLContext current via Qt will have no effect on such
+    other frameworks' internal state. Therefore a subsequent makeCurrent done
+    via the other framework may have no effect. It is therefore advisable to
+    make explicit calls to make no context and surface current to reset the
+    other frameworks' internal state after performing OpenGL operations via Qt.
+
+    \note Using foreign contexts with Qt windows and Qt contexts with windows
+    and surfaces created by other frameworks may give unexpected results,
+    depending on the platform, due to potential mismatches in context and window
+    pixel formats. To make sure this does not happen, avoid making contexts and
+    surfaces from different frameworks current together. Instead, prefer
+    approaches based on context sharing where OpenGL resources like textures are
+    accessible both from Qt's and the foreign framework's contexts.
+
+    \since 5.4
+    \sa nativeHandle()
+*/
+void QOpenGLContext::setNativeHandle(const QVariant &handle)
+{
+    Q_D(QOpenGLContext);
+    d->nativeHandle = handle;
+}
+
+/*!
+    Returns the native handle for the context.
+
+    This function provides access to the QOpenGLContext's underlying native
+    context. The returned variant contains a platform-specific value type. These
+    classes can be found in the module QtPlatformHeaders.
+
+    On platforms where retrieving the native handle is not supported, or if
+    neither create() nor setNativeHandle() was called, a null variant is
+    returned.
+
+    \since 5.4
+    \sa setNativeHandle()
+ */
+QVariant QOpenGLContext::nativeHandle() const
+{
+    Q_D(const QOpenGLContext);
+    return d->nativeHandle;
+}
+
 /*!
     Attempts to create the OpenGL context with the current configuration.
 
@@ -500,7 +558,8 @@ void QOpenGLContext::setScreen(QScreen *screen)
 */
 bool QOpenGLContext::create()
 {
-    destroy();
+    if (isValid())
+        destroy();
 
     Q_D(QOpenGLContext);
     d->platformGLContext = QGuiApplicationPrivate::platformIntegration()->createPlatformOpenGLContext(this);
@@ -550,6 +609,7 @@ void QOpenGLContext::destroy()
     d->versionFunctionsBackend.clear();
     delete d->textureFunctions;
     d->textureFunctions = 0;
+    d->nativeHandle = QVariant();
 }
 
 /*!
-- 
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