What is the best way to implement digital graph control (QGLWidget Vs QGraphicsScene Vs ??)



  • I have used QGraphicsScene with QGraphicsView for creating an digital graph viewer application. In that, i will be using the PainterPath functions for plotting the digital waveform. This is working fine, when the number of lines to draw is few lakhs. But if the number of lines increased, i am facing a serious performance issue, while drawing/scrolling/zooming.

    I tried to create the same kind of application by using QGLWidget (instead of QGraphicsScene), But the opengl logic requires repeated drawing of the images which is viewed in the screen. Is there any logic for plotting the long digital waveforms with zoom/scroll/scale features in opengl (QGLWidget ) environment? Also using OpenGL (QGLWidget ) has significant performance improvement in comparison with QGraphicsScene?

    Any other library (Other than QGraphicsScene/QGLWidget ) is available with qt for plotting the digital waveforms?



  • Qwt is great for plotting interfaces. I have used it A LOT, and have had great success. The fastest plot refresh rate that I have used is a replot every 10 mS.

    http://qwt.sourceforge.net/class_qwt_plot.html

    It is definitely one of the better graphing libraries for Qt



  • I want to use something which is available as standard in QT Library.



  • [quote author="JothiMurugeswaran" date="1340355033"]I want to use something which is available as standard in QT Library.[/quote]

    1. Qt instead of QT (QuickTime).

    2. It's life, man. Sometimes we need to use 3rd party. Or you can contribute Qt if you want)).



  • Or you can look at the code in QWT, and then write something like it yourself.


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