[Development] iMX6 EGLGS 2D (QtWidgets) painting acceleration
Uwe Rathmann
Uwe.Rathmann at tigertal.de
Tue Sep 4 14:31:26 CEST 2018
On Tue, 04 Sep 2018 14:38:47 +0300, Denis Shienkov wrote:
> How I can do it for Qt4? Do you mean, I need to specify an appropriate
> '-platform' option before starting of my application on Qt4?
https://doc.qt.io/archives/qt-4.8/qapplication.html#setGraphicsSystem
You can even run opengl as backend for all widgets this way, what might
be an option for non X11 platforms. I should pay more attention to this
option for future Qwt releases.
The vertical lines of the rubberbands are clipped away because of the 1
pixel left shift of the OpenGL paint engine, but the ticks of the axes
and the grid lines of the canvas are correctly aligned - in opposite to
the Qt5/QOpenGLWidget combination.
But please allow me to repeat the hint about trying the
QwtPlotCanvas::OpenGLBuffer option. It introduces some overhead, but at
least avoids doing the rasterization of the vector data with the CPU. It
works with Qt5 ( even with EGLFS ) without having to fiddle around with
QOpenGLWidget.
All you need to do is to add one line to your code:
plot->canvas()->setPaintAttribute( QwtPlotCanvas::OpenGLBuffer );
Uwe
PS: this starts to become too offtopic for this list
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