Quote Originally Posted by Uwe View Post
The performance and quality of rendering lines depends on the graphic stack you have set up on your system and the attributes of your pen. So this discussion is about Qt and more or less unrelated to Qwt.

In general Qt offers OpenGL, Raster or X11 as graphic systems. Usually Raster gives nicer results than OpenGL with multisampling, but this is up to you to decide.
X11 has been removed with Qt5, so you need to use Qt4 if you want to check it ( IMHO X11 was the best option ).

X11 and OpenGL are hardware accelerated so the result might also depend on your hardware or drivers, while the raster paint engine is a pure software renderer and you should have the same results on all platforms. See https://doc.qt.io/archives/qt-4.8/qa...GraphicsSystem

PyQwt is pretty outdated and completely unmaintained - I would recommend to use https://github.com/GauiStori/PyQt-Qwt instead.

If you not happy with the quality of the lines being rendered from the raster paint engine you can try to contact the Qt development.

Uwe
Thanks Uwe. I've found in Qt5 docs that "The primary paint engine provided is the raster paint engine..."

But I do understand that this is more on the Qt side than Qwt, as you said. I'll try getting help from the Qt dev team on the matter.