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, 5 insertions, 2 deletions

diff --git a/src/opengl/qpixmapdata_gl_p.h b/src/opengl/qpixmapdata_gl_p.h
index b1b31f7029..7dda653235 100644
--- a/src/opengl/qpixmapdata_gl_p.h
+++ b/src/opengl/qpixmapdata_gl_p.h
@@ -97,8 +97,9 @@ public:
 
     QGLFramebufferObject *fbo() const;
 
-    void beginPaint();
-    void endPaint();
+    void makeCurrent();
+    void doneCurrent();
+    void swapBuffers();
 
 protected:
     int metric(QPaintDevice::PaintDeviceMetric metric) const;
@@ -107,6 +108,8 @@ private:
     QGLPixmapData(const QGLPixmapData &other);
     QGLPixmapData &operator=(const QGLPixmapData &other);
 
+    void copyBackFromRenderFbo(bool keepCurrentFboBound) const;
+
     static bool useFramebufferObjects();
 
     int m_width;