Em Segunda-feira 09 Fevereiro 2009, às 13:47:09, Philippe escreveu: > > > 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.
There is no native engine on Windows. The engine we used in Qt 4.4 is the
raster engine. So when you see "native", it actually is the raster engine on
Windows.
That's why you got the same results with QImage and QPainter:
>Under Windows:
>With QImage as paint device: 78 ms
>With direct QPainter device: 78 ms
We did some research in GDI, but it's horribly slow and limited.
--
Thiago Macieira - thiago.macieira (AT) nokia.com
Senior Product Manager - Nokia, Qt Software
Sandakerveien 116, NO-0402 Oslo, Norway
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