#166 QwtLog10ScaleEngine doesn't work with Histogram

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nobody
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5
2012-07-11
2012-07-11
Anonymous
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Version: qwt 6.0.1
I've tried to develop logarithmic scaling for Histogram (As it works fine for curve, actually).
But the error is that the data are not drawn, so the plot is empty.

I've used simple line to enable scaling plot->setAxisScaleEngine(QwtPlot::yLeft, new QwtLog10ScaleEngine); (look throw the code in attachment).
In result I have

Discussion

  • Nobody/Anonymous

     
  • Uwe Rathmann

    Uwe Rathmann - 2012-07-11

    In vertical direction the histogram draws bars from the baseline to the value for each sample. The default value for the baseline is 0.0, what is an invalid value for a logarithmic scale - that's why no bars are displayed at all.

    After setting a valid baseline ( f.e. histogram->setBaseline( LOG_MIN ) ) you will see the missing bars.

     
  • Uwe Rathmann

    Uwe Rathmann - 2012-07-11
    • status: open --> closed-invalid
     

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