[Qt4-preview-feedback] Bad drawing speed under OSX

[Philippe]

> > 2) Using QPainter directly (OSX api) to draw is dead slow, 550% slower  
> > that drawing to QImage.
> > I am wondering if there is any interest to this? Is it even normal?
> 
> There are cases where CoreGraphics does better than the usecase you 
> provided, but we are in general not happy with the performance we get 
> from it. This is why we are opening up the option for switching to use 
> different graphics backends on both OSX and X11. You can run 
> applications with -graphicssystem raster (or even configure Qt with it 
> to have enabled for all apps). You can also try with the highly 
> experimental -graphicssystem opengl, but it probably won't look so good ;)

The Qt 4.5 doc says: by default the backends is "Software Rasterizer" for Windows.

But by tracing with the debugger, in API QGraphicsSystemFactory::create,
the default engine is in fact "native", not "raster".

In all cases, I see no difference of speed. In earlier Qt version, native was faster under Windows.