View Single Post
Old 07-21-10, 02:47 PM   #27
Registered User
Join Date: Jan 2005
Posts: 19
Default Re: is the nvidia driver falling behind?

I just wanted for everyone to know what raster means in Qt along with the other graphicssystem parameters:

Native: for X11, means XRender (usually).

raster: means all drawing is done to main memory by the CPU... more or less it equivalent to drawing to a QImage and then drawing the QImage to the screen.

opengl: use GL1 or GL2 backend with preference to GL2 backend.

Now, Qt gets better performance from raster, which strongly implies one of the two (or both) of the following:

1) QPainter API maps poorly to XRender


2) Qt XRender backend has issues in terms of how it works.

What is truly frightening is that Qt graphics does perform so poorly, the majority of the use patterns for QPainter are drawing the same stuff to screen that has been drawn to GUI for over 10 years (really even more).

I remember years ago about the flame war of that KDE uses Qt... and then later came the "QPL"... in truth the flame war completely missed many of the technical points. One more note on KDE4: it has only been since October or so that KDE4 used Qt 4.6... AFAIK, and someone correct me if I am wrong if you are using KDE4.3 or older it is at best linked against Qt 4.5.x... and guess what people: GL backend of Qt 4.5.x is horrifyingly bad.

For UI tool kits, in the Qt vs GTK/GDK, GTK/GDK are really the way to go, they are better modularized, have C and C++ interfaces and a much better internals than Qt.
kRogue is offline   Reply With Quote