int main(int argc, char **argv)
{
QApplication a(argc, argv);
QwtPlot plot;
plot.setCanvasBackground(QColor(Qt::white));
plot.setTitle("Histogram");
QwtPlotGrid *grid = new QwtPlotGrid;
grid->enableXMin(true);
grid->enableYMin(true);
grid->setMajPen(QPen(Qt::black, 0, Qt::DotLine));
grid->setMinPen(QPen(Qt::gray, 0 , Qt::DotLine));
grid->attach(&plot);
HistogramItem *histogram = new HistogramItem();
histogram->setColor(Qt::darkCyan);
const int numValues = 20;
QwtArray<QwtDoubleInterval> intervals(numValues);
QwtArray<double> values(numValues);
double pos = 0.0;
for ( int i = 0; i < (int)intervals.size(); i++ )
{
const int width = 5 + rand() % 15;
const int value = rand() % 100;
intervals[i] = QwtDoubleInterval(pos, pos + double(width));
values[i] = value;
pos += width;
}
histogram->setData(QwtIntervalData(intervals, values));
histogram->attach(&plot);
plot.setAxisScale(QwtPlot::yLeft, 0.0, 100.0);
plot.setAxisScale(QwtPlot::xBottom, 0.0, pos);
plot.replot();
#if QT_VERSION < 0x040000
a.setMainWidget(&plot);
#endif
plot.resize(600,400);
plot.show();
return a.exec();
}
void QgsHistogramWidget::drawHistogram()
{
if ( !mVectorLayer || mSourceFieldExp.isEmpty() )
return;
QApplication::setOverrideCursor( Qt::WaitCursor );
if ( mValues.empty() )
{
bool ok;
mValues = mVectorLayer->getDoubleValues( mSourceFieldExp, ok );
if ( ! ok )
{
QApplication::restoreOverrideCursor();
return;
}
qSort( mValues.begin(), mValues.end() );
mHistogram.setValues( mValues );
mBinsSpinBox->blockSignals( true );
mBinsSpinBox->setValue( qMax( mHistogram.optimalNumberBins(), 30 ) );
mBinsSpinBox->blockSignals( false );
mStats.setStatistics( QgsStatisticalSummary::StDev );
mStats.calculate( mValues );
}
// clear plot
mpPlot->detachItems();
//ensure all children get removed
mpPlot->setAutoDelete( true );
// Set axis titles
mpPlot->setAxisTitle( QwtPlot::xBottom, QObject::tr( "Value" ) );
mpPlot->setAxisTitle( QwtPlot::yLeft, QObject::tr( "Count" ) );
mpPlot->setAxisAutoScale( QwtPlot::yLeft );
mpPlot->setAxisAutoScale( QwtPlot::xBottom );
// add a grid
QwtPlotGrid * grid = new QwtPlotGrid();
grid->enableX( false );
grid->setPen( mGridPen );
grid->attach( mpPlot );
// make colors list
mHistoColors.clear();
foreach ( QgsRendererRangeV2 range, mRanges )
{
mHistoColors << ( range.symbol() ? range.symbol()->color() : Qt::black );
}
//draw histogram
#if defined(QWT_VERSION) && QWT_VERSION>=0x060000
QwtPlotHistogram * plotHistogram = 0;
plotHistogram = createPlotHistogram( mRanges.count() > 0 ? mRanges.at( 0 ).label() : QString(),
mRanges.count() > 0 ? QBrush( mHistoColors.at( 0 ) ) : mBrush,
mRanges.count() > 0 ? Qt::NoPen : mPen );
#else
HistogramItem *plotHistogramItem = 0;
plotHistogramItem = createHistoItem( mRanges.count() > 0 ? mRanges.at( 0 ).label() : QString(),
mRanges.count() > 0 ? QBrush( mHistoColors.at( 0 ) ) : mBrush,
mRanges.count() > 0 ? Qt::NoPen : mPen );
#endif
#if defined(QWT_VERSION) && QWT_VERSION>=0x060000
QVector<QwtIntervalSample> dataHisto;
#else
// we safely assume that QT>=4.0 (min version is 4.7), therefore QwtArray is a QVector, so don't set size here
QwtArray<QwtDoubleInterval> intervalsHisto;
QwtArray<double> valuesHisto;
#endif
int bins = mBinsSpinBox->value();
QList<double> edges = mHistogram.binEdges( bins );
QList<int> counts = mHistogram.counts( bins );
int rangeIndex = 0;
int lastValue = 0;
for ( int bin = 0; bin < bins; ++bin )
{
int binValue = counts.at( bin );
//current bin crosses two graduated ranges, so we split between
//two histogram items
if ( rangeIndex < mRanges.count() - 1 && edges.at( bin ) > mRanges.at( rangeIndex ).upperValue() )
{
rangeIndex++;
#if defined(QWT_VERSION) && QWT_VERSION>=0x060000
plotHistogram->setSamples( dataHisto );
plotHistogram->attach( mpPlot );
plotHistogram = createPlotHistogram( mRanges.at( rangeIndex ).label(), mHistoColors.at( rangeIndex ) );
dataHisto.clear();
dataHisto << QwtIntervalSample( lastValue, mRanges.at( rangeIndex - 1 ).upperValue(), edges.at( bin ) );
#else
plotHistogramItem->setData( QwtIntervalData( intervalsHisto, valuesHisto ) );
plotHistogramItem->attach( mpPlot );
plotHistogramItem = createHistoItem( mRanges.at( rangeIndex ).label(), mHistoColors.at( rangeIndex ) );
intervalsHisto.clear();
valuesHisto.clear();
intervalsHisto.append( QwtDoubleInterval( mRanges.at( rangeIndex - 1 ).upperValue(), edges.at( bin ) ) );
valuesHisto.append( lastValue );
#endif
}
double upperEdge = mRanges.count() > 0 ? qMin( edges.at( bin + 1 ), mRanges.at( rangeIndex ).upperValue() )
: edges.at( bin + 1 );
#if defined(QWT_VERSION) && QWT_VERSION>=0x060000
dataHisto << QwtIntervalSample( binValue, edges.at( bin ), upperEdge );
#else
intervalsHisto.append( QwtDoubleInterval( edges.at( bin ), upperEdge ) );
valuesHisto.append( double( binValue ) );
#endif
lastValue = binValue;
}
#if defined(QWT_VERSION) && QWT_VERSION>=0x060000
plotHistogram->setSamples( dataHisto );
plotHistogram->attach( mpPlot );
#else
plotHistogramItem->setData( QwtIntervalData( intervalsHisto, valuesHisto ) );
plotHistogramItem->attach( mpPlot );
#endif
mRangeMarkers.clear();
foreach ( QgsRendererRangeV2 range, mRanges )
{
QwtPlotMarker* rangeMarker = new QwtPlotMarker();
rangeMarker->attach( mpPlot );
rangeMarker->setLineStyle( QwtPlotMarker::VLine );
rangeMarker->setXValue( range.upperValue() );
rangeMarker->setLabel( QString::number( range.upperValue() ) );
rangeMarker->setLabelOrientation( Qt::Vertical );
rangeMarker->setLabelAlignment( Qt::AlignLeft | Qt::AlignTop );
rangeMarker->show();
mRangeMarkers << rangeMarker;
}