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Thread: Uwe : How to create real time plot with auto scale axis and zooming functionality.

  1. #1
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    Default Uwe : How to create real time plot with auto scale axis and zooming functionality.

    I have a scenario where i should be plotting real time data for an hour. But first i have to display only first 2 min in x axis, when time reaches 2 min i should expand my scale to 4 min and it should keep on going......

    I tried using QwtPlotDirectPainter which is efficient but after 2 min , i dont know how to rescale it to 4 min ....

    But if i use QwtPlotCurve with replot() and autoaxisscale() feature , i am able to acheive this, but with delay in plotting as time increases ....

    Any help will be appreciated.....


    I feel QwtPlotDirectPainter will be efficient, please give a solution with it.....
    I tried looking at Oscilloscope example , i could not get it....If possible try give source code with explanation......
    Last edited by vinothrajendran; 18th November 2014 at 10:55. Reason: updated contents

  2. #2
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    Default Re: Uwe : How to create real time plot with auto scale axis and zooming functionality

    Quote Originally Posted by vinothrajendran View Post
    I have a scenario where i should be plotting real time data for an hour. But first i have to display only first 2 min in x axis, when time reaches 2 min i should expand my scale to 4 min and it should keep on going......
    Qt Code:
    1. void YourPlot::addPoint( const QPointF &pos )
    2. {
    3. const QwtInterval interval = axisInterval( QwtPlot::xBottom );
    4. if ( pos.x() > interval.maxValue() )
    5. {
    6. setAxisScale( interval.minValue(), interval.maxValue() + ... );
    7. replot();
    8. }
    9.  
    10. ...
    11. }
    To copy to clipboard, switch view to plain text mode 
    Uwe

  3. The following user says thank you to Uwe for this useful post:

    vinothrajendran (20th November 2014)

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