qwtPlotHistogram negative index

[ech01]

Hi everyone

I am attempting to build Histogram using the qwtlotHistogram class.

However, my source data to generate the histogram contains negative values, therefore I am interested in the bins of the histogram to go from say -100 to +100.

The code below Works as long as my variable "min" us equal or grater to zero since QVector takes no negative indexes.

Is there a way to:

1 - Feed histogram data to qwtPlotHistogram with negative bin index values?
2 - I attempted to change the qwtPlot X axis either by using "setAxisScale" or generating a QwtScaleDiv and QwtScaleDraw but it only shifts the qwtPlot canvas and my histogram does not correspond to the modified axis.

Any suggestions are appreciated.

Thank you,
Sergio

QwtPlotHistogram *eHisto = new QwtPlotHistogram(title);
eHisto->setStyle(QwtPlotHistogram::Columns);

QVector<QwtIntervalSample> samples(size);// vector of interval samples

for ( int i = min; i < max; i++ )
{
QwtInterval interval(double(i), i + 1.0);
interval.setBorderFlags(QwtInterval::ExcludeMaximu m);
samples[i] = QwtIntervalSample(histogram->GetFrequency(i), interval);
}

QwtIntervalSeriesData *data = new QwtIntervalSeriesData;
data->setSamples(samples);
eHisto->setData(data);

[ech01]

Hi everyone

The above obviously is fixed with the correct definitions of QwtInterval in the first line in the FOR statement loop

QwtInterval interval(double(min+i), double((i+min)+1.0), QwtInterval::ExcludeMaximum); // min yes, max no (e.g. -1024 (OK), -1023(no go))

Thank you,
S