Added explicit threading API to QtOpenGL.

Since QtOpenGL/QGLContext is implemented in terms of
QtGui/QOpenGLContext which has stricter requirements about how it's
supposed to be used, we need to apply these requirements to QGLContext
as well.

This change adds QGLContext::moveToThread(QThread *) and documents it as
a necessity for making a context current on another thread.

Also introduces QGLPixelbuffer::context() to access the QGLContext of a
pixelbuffer, and made QGLWidget::context() return a non-const
QGLContext, since there's no good reason why it shouldn't, and it leads
to less const_cast clutter.

We could have introduced a backdoor in QOpenGLContext instead, making it
loosen its requirements, but that would have made it harder / impossible
to fully support threaded OpenGL in all the platforms.

Task-number: QTBUG-22560
Change-Id: Ibb6f65f342e7c963e80cc42ab5664c5f1cab30b0
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
Reviewed-by: Gunnar Sletta <gunnar.sletta@digia.com>

1 files changed, 8 insertions, 3 deletions

diff --git a/src/opengl/qgl_qpa.cpp b/src/opengl/qgl_qpa.cpp
index f52beceaae..ba07f6121c 100644
--- a/src/opengl/qgl_qpa.cpp
+++ b/src/opengl/qgl_qpa.cpp
@@ -186,9 +186,14 @@ void QGLContext::reset()
     d->initDone = false;
     QGLContextGroup::removeShare(this);
     if (d->guiGlContext) {
-        if (d->ownContext)
-            delete d->guiGlContext;
-        else
+        if (QOpenGLContext::currentContext() == d->guiGlContext)
+            doneCurrent();
+        if (d->ownContext) {
+            if (d->guiGlContext->thread() == QThread::currentThread())
+                delete d->guiGlContext;
+            else
+                d->guiGlContext->deleteLater();
+        } else
             d->guiGlContext->setQGLContextHandle(0,0);
         d->guiGlContext = 0;
     }