Correctly handle using GL pixmaps that still have an active engine.

In the case where a GL pixmap is used when there it still has an active
engine we need to ensure that the pixmap has been flushed from the
render FBO first. The newly added QGLPixmapData::copyBackFromRenderFbo()
handles this.

In addition, because several GL 2 paint engines can be active on the same
context at the same time, we can't make any assumptions and need to call
the newly added QGL2PaintEngineEx::ensureCreated() in the beginning of
any state-dependent paint engine function.
QGL2PaintEngineEx::ensureCreated() correctly transfers control to the
current engine if a different engine is active.

Running lance with -pixmap and -graphicssystem opengl works correctly
with the GL pixmap backend now.

1 files changed, 4 insertions, 2 deletions

diff --git a/src/opengl/qgl.cpp b/src/opengl/qgl.cpp
index 64048f2..d1cf35d 100644
--- a/src/opengl/qgl.cpp
+++ b/src/opengl/qgl.cpp
@@ -4289,6 +4289,8 @@ void QGLDrawable::swapBuffers()
     if (widget) {
         if (widget->autoBufferSwap())
             widget->swapBuffers();
+    } else if (pixmapData) {
+        pixmapData->swapBuffers();
     } else {
         glFlush();
     }
@@ -4297,7 +4299,7 @@ void QGLDrawable::swapBuffers()
 void QGLDrawable::makeCurrent()
 {
     if (pixmapData)
-        pixmapData->beginPaint();
+        pixmapData->makeCurrent();
     else if (widget)
         widget->makeCurrent();
     else if (buffer)
@@ -4321,7 +4323,7 @@ QGLPixmapData *QGLDrawable::copyOnBegin() const
 void QGLDrawable::doneCurrent()
 {
     if (pixmapData)
-        pixmapData->endPaint();
+        pixmapData->doneCurrent();
     else if (fbo && !wasBound)
         fbo->release();
 }