Achieving better graphics quality in Qwt charts

Dear Forum,

I've been happily using Qwt in C++ for some time. Though, the quality of the graphics (plot lines etc.) in Qwt doesn't visually satisfy me as much as say Matlab or Matplotlib (Python) does. If you take a look at this video, where Matplotlib and PyQwt are showcased side by side, you'll notice that the graphics quality of the lines in Matplotlib is somewhat better than Qwt's. I've played around with anti-aliasing, line thicknesses, cap styles and such, but I've been unable to get a look closer to what Matplotlib or Matlab can offer out of the box. What I want to achieve is smooth, quality-looking lines in Qwt.

I'd appreciate any input on the subject.

Best regards.

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PyQwt is pretty outdated and completely unmaintained - I would recommend to use https://github.com/GauiStori/PyQt-Qwt instead.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

Quote:

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Originally Posted by Uwe

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

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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.