[Development] iMX6 EGLGS 2D (QtWidgets) painting acceleration

[Uwe Rathmann]

On Thu, 30 Aug 2018 14:26:34 +0300, Denis Shienkov wrote:

> Yeah, seems that Qt5 && X11 && 'xcb' backend with the Qwt 6.2 and
> QwtPlotOpenGLCanvas does help a bit. The iMX6 CPU usage now is ~50%
> (instead of previous 100%).

A small correction for others reading this: trunk is Qwt 6.3. The main 
difference to the code you find in the 6.2 branch is exactly about the 
OpenGL canvases, where I need more time to find workarounds for the 
incompatibilities of the OpenGL paint engines.

I also forgot to mention that Qwt from trunk also has the option 
QwtPlotCanvas::OpenGLBuffer. In this mode rendering is also done hardware 
accelerated - using the OpenGL paint engine to an offscreen FBO. Then the 
FBO gets copied to a QImage being rendered to a normal QWidget.

This combination should also work with EGLFS. But of course copying from 
GPU to CPU and back for each frame might kill your performance 
requirements.

Please let me know what you can achieve with this combination ?

Uwe