From 6385a182f0f93820c96cf274e50a56492491ee10 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Samuel=20R=C3=B8dal?= Date: Mon, 26 Nov 2012 12:57:09 +0100 Subject: 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 Reviewed-by: Gunnar Sletta --- src/opengl/qgl.cpp | 45 ++++++++++++++++++++++++++++++++++----------- 1 file changed, 34 insertions(+), 11 deletions(-) (limited to 'src/opengl/qgl.cpp') diff --git a/src/opengl/qgl.cpp b/src/opengl/qgl.cpp index c94c8f550e..583ecb69a8 100644 --- a/src/opengl/qgl.cpp +++ b/src/opengl/qgl.cpp @@ -3126,6 +3126,19 @@ void QGLContextPrivate::setCurrentContext(QGLContext *context) Q_UNUSED(context); } +/*! + Moves the QGLContext to the given \a thread. + + Enables calling swapBuffers() and makeCurrent() on the context in + the given thread. +*/ +void QGLContext::moveToThread(QThread *thread) +{ + Q_D(QGLContext); + if (d->guiGlContext) + d->guiGlContext->moveToThread(thread); +} + /*! \fn bool QGLContext::chooseContext(const QGLContext* shareContext = 0) @@ -3195,16 +3208,18 @@ void QGLContextPrivate::setCurrentContext(QGLContext *context) In some very rare cases the underlying call may fail. If this occurs an error message is output to stderr. + + If you call this from a thread other than the main UI thread, + make sure you've first pushed the context to the relevant thread + from the UI thread using moveToThread(). */ /*! \fn void QGLContext::swapBuffers() const - Swaps the screen contents with an off-screen buffer. Only works if - the context is in double buffer mode. - - \sa QGLFormat::setDoubleBuffer() + Call this to finish a frame of OpenGL rendering, and make sure to + call makeCurrent() again before you begin a new frame. */ @@ -3362,13 +3377,18 @@ void QGLContextPrivate::setCurrentContext(QGLContext *context) 1. Call doneCurrent() in the main thread when the rendering is finished. - 2. Notify the swapping thread that it can grab the context. + 2. Call QGLContext::moveToThread(swapThread) to transfer ownership + of the context to the swapping thread. - 3. Make the rendering context current in the swapping thread with + 3. Notify the swapping thread that it can grab the context. + + 4. Make the rendering context current in the swapping thread with makeCurrent() and then call swapBuffers(). - 4. Call doneCurrent() in the swapping thread and notify the main - thread that swapping is done. + 5. Call doneCurrent() in the swapping thread. + + 6. Call QGLContext::moveToThread(qApp->thread()) and notify the + main thread that swapping is done. Doing this will free up the main thread so that it can continue with, for example, handling UI events or network requests. Even if @@ -3400,7 +3420,10 @@ void QGLContextPrivate::setCurrentContext(QGLContext *context) QGLWidgets can only be created in the main GUI thread. This means a call to doneCurrent() is necessary to release the GL context from the main thread, before the widget can be drawn into by - another thread. Also, the main GUI thread will dispatch resize and + another thread. You then need to call QGLContext::moveToThread() + to transfer ownership of the context to the thread in which you + want to make it current. + Also, the main GUI thread will dispatch resize and paint events to a QGLWidget when the widget is resized, or parts of it becomes exposed or needs redrawing. It is therefore necessary to handle those events because the default @@ -3749,7 +3772,7 @@ void QGLWidget::setFormat(const QGLFormat &format) /*! - \fn const QGLContext *QGLWidget::context() const + \fn QGLContext *QGLWidget::context() const Returns the context of this widget. @@ -4483,7 +4506,7 @@ QGLFormat QGLWidget::format() const return d->glcx->format(); } -const QGLContext *QGLWidget::context() const +QGLContext *QGLWidget::context() const { Q_D(const QGLWidget); return d->glcx; -- cgit v1.2.3