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, 27 insertions, 2 deletions

diff --git a/src/opengl/qglpixelbuffer.cpp b/src/opengl/qglpixelbuffer.cpp
index a5e748a1e7..dd13ef24eb 100644
--- a/src/opengl/qglpixelbuffer.cpp
+++ b/src/opengl/qglpixelbuffer.cpp
@@ -100,6 +100,7 @@
 
 #include "gl2paintengineex/qpaintengineex_opengl2_p.h"
 
+#include <qglframebufferobject.h>
 #include <qglpixelbuffer.h>
 #include <private/qglpixelbuffer_p.h>
 #include <private/qfont_p.h>
@@ -115,11 +116,23 @@ QGLContext* QGLPBufferGLPaintDevice::context() const
     return pbuf->d_func()->qctx;
 }
 
-void QGLPBufferGLPaintDevice::endPaint() {
+void QGLPBufferGLPaintDevice::beginPaint()
+{
+    pbuf->makeCurrent();
+    QGLPaintDevice::beginPaint();
+}
+
+void QGLPBufferGLPaintDevice::endPaint()
+{
     glFlush();
     QGLPaintDevice::endPaint();
 }
 
+void QGLPBufferGLPaintDevice::setFbo(GLuint fbo)
+{
+    m_thisFBO = fbo;
+}
+
 void QGLPBufferGLPaintDevice::setPBuffer(QGLPixelBuffer* pb)
 {
     pbuf = pb;
@@ -221,6 +234,7 @@ bool QGLPixelBuffer::makeCurrent()
             format.setSamples(d->req_format.samples());
         d->fbo = new QOpenGLFramebufferObject(d->req_size, format);
         d->fbo->bind();
+        d->glDevice.setFbo(d->fbo->handle());
         glViewport(0, 0, d->req_size.width(), d->req_size.height());
     }
     return true;
@@ -242,6 +256,15 @@ bool QGLPixelBuffer::doneCurrent()
 }
 
 /*!
+    Returns the context of this pixelbuffer.
+*/
+QGLContext *QGLPixelBuffer::context() const
+{
+    Q_D(const QGLPixelBuffer);
+    return d->qctx;
+}
+
+/*!
     \fn GLuint QGLPixelBuffer::generateDynamicTexture() const
 
     Generates and binds a 2D GL texture that is the same size as the
@@ -366,6 +389,8 @@ QImage QGLPixelBuffer::toImage() const
         return QImage();
 
     const_cast<QGLPixelBuffer *>(this)->makeCurrent();
+    if (d->fbo)
+        d->fbo->bind();
     return qt_gl_read_framebuffer(d->req_size, d->format.alpha(), true);
 }
 
@@ -615,7 +640,7 @@ GLuint QGLPixelBuffer::generateDynamicTexture() const
 
 bool QGLPixelBuffer::hasOpenGLPbuffers()
 {
-    return QOpenGLFramebufferObject::hasOpenGLFramebufferObjects();
+    return QGLFramebufferObject::hasOpenGLFramebufferObjects();
 }
 
 QT_END_NAMESPACE