[Development] QT_XCB_NATIVE_PAINTING makes worse that without of it

Uwe Rathmann Uwe.Rathmann at tigertal.de
Sun Mar 24 15:39:08 CET 2019

On 3/24/19 2:53 PM, Allan Sandfeld Jensen wrote:

> ... and I also advocate for the OpenGL engine.

Agreed as this is one is available on Windows as well.

But unfortunately OpenGL and X11 have been dropped with Qt5 and while 
X11 had returned with Qt 5.10 I'm not aware of a replacement for 
"-graphicssystem opengl".

Being a member of the Qt Company you have the chance to change the 
situation ...

> I am just trying to
> explain why it isn't default and why switching to using the native engine
> isn't an automatic win.

No, you wrote: "for most applications Qt raster engine is faster".

This was exactly the argument I heard, for making raster the default 
graphics system on X11 with Qt 4.8 and finally removing the X11 paint 
engine with Qt5. Not being an "automatic win" is not even close to 
explain these decisions.

Please note, that my system has some onboard Intel GPU - guess nothing 
could be more average than this. When adding NVIDIA and Radeon chips you 
are close to 100% of what is running on desktop systems nowadays and I 
never heard, that many of them are lacking X11 support.

I would agree, that drawing a polyline of so many points is a corner 
case - IMHO running remote X11 is more often used. But without naming a 
more relevant use case, where the raster paint engine shows a 
significant better performance, your statement is coming out of nowhere.


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