On Tue, 04 Sep 2018 12:21:29 +0300, Denis Shienkov wrote: > Uwe, > what if I try to back-port my application from Qt5 to Qt4 with X11 > support (on iMX6).
This is what I would try first in a situation like yours. Don't forget to set the graphic system to "native" - the default since 4.8 is raster. > As I understand, then I do not need to specify the OpenGL Widgets with > Qt4. Right and you might even see a lower CPU load depending on what happens in the various paint engines before calling the native libs. > Is it will help? Or do I need to use the QtQuick anyway? When looking at Arnos blog it looks like he has a stable coordinate system, where he only updates the curves with each frame ( please correct me if I'm wrong ). I would recommend to do this for your application too - having different tick labels with each frame will be an issue with all backends. In this situation you would have a positive effect for drawing the decoration of the plot canvas ( background/grid/... ) with using the scene graph. As the axes are different widgets with Qwt, they would not been updated with each frame - so the performance for rendering axes and tick labels does not matter here. But you could do something similar with QPainter by drawing these parts to a QPixmap once and reusing it for each frame. If you are interested - contact me at one of the Qwt support channels. For drawing the curves itself I wouldn't see many benefits from using Qt/ Quick as they do change with each frame. You might even have unwanted effects as you might need more memory - anyone who knows better, please correct me. IMHO I would expect, that you could get the optimal performance by doing native OpenGL with QOpenGLWidget::paintGL. But drawing a polyline of 400 points with 10fps should also be no problem on an iMX6 with QPainter/X11. But also note that Qt/Quick is much more than the scene graph. It is a technology, that includes a JavaScript experience and you always have a run time environment processing this code: if this matters is something only you can decide. Uwe _______________________________________________ Development mailing list Development@qt-project.org http://lists.qt-project.org/mailman/listinfo/development
