qt graphics performance on qt4 or qt5

[PICCORO McKAY Lenz]

i found ho to improve the Qt graphics system backend without recompiling Qt. In Qt 4.7 this is finally available.

You can configure the backend using the environment variable QT_GRAPHICSSYSTEM.-- 

theres two real available options, raster and system, theres a new available option in qt5 as opengl

opengl only work if moduls of xorg are DRI enabled.

in the razorqt application can be doe for improvements.. 

thi could be a nice preference.. make a interface to this.. the codumentation are here:

http://doc.qt.digia.com/4.7/qapplication.html#setGraphicsSystem

i set the env variable and get some performances if put onto opengl over intel platfors.. but for VIA and Nvidia must set to system or rasterizer if not GPL modles are available or VIA module are opengl older based.

Lenz McKAY Gerardo (PICCORO)

http://qglochekone.blogspot.com

[Kevin Krammer]

On Friday, 2013-01-11, PICCORO McKAY Lenz wrote:
> i found ho to improve the Qt graphics system backend without recompiling
> Qt. In Qt 4.7 this is finally available.
>
> You can configure the backend using the environment variable
> QT_GRAPHICSSYSTEM.--
>
> theres two real available options, raster and system, theres a new
> available option in qt5 as opengl

opengl was already available in Qt4 but experimental.

In Q5 this works a bit different though.

Graphics system access is provided by QPA plugins (Qt Platform Abstraction).
For widgets the loaded plugin is asked for a backing store implementation for
each native window which in turn is asked for a QPaintDevice.

For the default QPA on linux, XCB, this QPaintDevice is currently[1] a QImage,
thus the equivalent to "raster".
For GL based painting you'll need to switch to a GL based QPA, for example
EGLFS.

Similar to graphics system in Qt4 this is controllable through commandline
switch and environment variable.

Cheers,
Kevin

[1] I am currently not aware of anyone working on something different, e.g. an
XCB based QPaintDevice which would be the equivalent for "native"

--
Kevin Krammer, KDE developer, xdg-utils developer
KDE user support, developer mentoring