QwtScaleWidget: problem with drawing a ColorMap

The problem I am having is that whenever I create and then draw a QwtScaleWidget with my defined color map it doesn't render properly. If I give it a range of 0 - 1 it renders fine but when ever I hand it any other range it does not render properly.

I have listed my code below and some sample screenshots.

Thanks for your time,
Jon Jones

Code:

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QwtLinearColorMap colorMap(Qt::darkBlue, Qt::red);
    colorMap.addColorStop(0.25, Qt::cyan);
    colorMap.addColorStop(0.75, Qt::yellow);
 
  QWidget *widget = canvas();
 
  QwtScaleWidget *colorBar = new QwtScaleWidget(widget);
  colorBar->setColorMap(QwtDoubleInterval(0, 10), colorMap);
  colorBar->setColorBarEnabled(true);
  colorBar->drawColorBar(&painter, QRect(10,10, 25, 100));

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Assuming you want to use the right axis for your color bar:

Code:

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QwtDoubleInterval range(0, 10);
 
QwtScaleWidget *scale = plot->axisWidget(QwtPlot::yRight);
scale->setColorBarEnabled(true);
scale->setColorMap(range, colorMap);
 
plot->setAxisScale(QwtPlot::yRight,
        range().minValue(), range().maxValue() );
plot->enableAxis(QwtPlot::yRight);
plot->replot();

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The spectrogram example shows a colorbar in the range [0, 10].

Uwe