[Development] QT_XCB_NATIVE_PAINTING makes worse that without of it

Allan Sandfeld Jensen kde at carewolf.com
Sat Mar 23 23:09:51 CET 2019

On Samstag, 23. März 2019 19:00:47 CET Uwe Rathmann wrote:
> Ön Fri, 22 Mar 2019 17:06:32 +0100, Allan Sandfeld Jensen wrote:
> > Sounds like XCB isn't as well optimized as Qt is
> Nice joke - but only when X11 falls back on some software emulation it
> might be the case, that the Qt implementation is better than that one.
Software implementation is the default for X11 painting, with accelerated 
paths being addons. Most rendering is done by a software library called 
pixman. A few parts are accelerated but not much. But yes, if you do scaling 
of images a lot, it is hardware accelerated, and can be faster than Qt raster 
if you manage your QPixmaps well. 

But for most applications Qt raster engine is faster. Making full use of the 
native X11 engine is a more delicate process. And typically using the OpenGL 
backed will be even faster unless you need to run X11 remotely.


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