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90 lines
4.1 KiB
Markdown
90 lines
4.1 KiB
Markdown
# Example (JKQTPlotter): Barchart With Custom Draw Functor {#JKQTPlotterBarchartsCustomDrawFunctor}
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This project (see [`barchart_customdrawfunctor`](https://github.com/jkriege2/JKQtPlotter/tree/master/examples/barchart_customdrawfunctor) shows how to draw customized barcharts, with a custom draw functor.
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The source code of the main application is (see [`barchart_customdrawfunctor.cpp`](https://github.com/jkriege2/JKQtPlotter/tree/master/examples/barchart_customdrawfunctor/barchart_customdrawfunctor.cpp):
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```.cpp
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// 1. create a plotter window and get a pointer to the internal datastore (for convenience)
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JKQTPDatastore* ds=plot.getDatastore();
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// 2. now we create two columns for key and value
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size_t columnK=ds->addLinearColumn(7, 0, 6, "k");
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size_t columnV=ds->addColumnCalculatedFromColumn(columnK, [](double x) { return jkqtp_sign(2.0*x-2.5)*qMax(2.0,fabs(2.0*x-2.5)); }, "v");
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// 3. load a stylesheet
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plot.loadCurrentPlotterStyle(QSettings(":/JKQTPlotter/styles/seaborn.ini", QSettings::IniFormat));
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// 4. create graph in the plot, which plots the dataset:
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JKQTPBarVerticalGraph* graph=new JKQTPBarVerticalGraph(&plot);
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graph->setKeyColumn(columnK);
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graph->setValueColumn(columnV);
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// this is the custom draw functor
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graph->setCustomDrawingFunctor(
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[](JKQTPEnhancedPainter& painter, const QRectF& bar_px, const QPointF& datapoint, Qt::Orientation orientation, JKQTPBarGraphBase* graph) {
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painter.save();
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painter.setPen(Qt::NoPen);
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QBrush b=painter.brush();
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QBrush bDeco=b;
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bDeco.setColor(b.color().lighter());
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// we draw the bar with a rounded end and add a lightly colored circle near the top
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if (orientation==Qt::Vertical) {
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// for vertical barcharts
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const double dx=bar_px.width()/2.0;
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const double r=dx*0.85;
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// depending in whether the bar elongates above or below the baseline,
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// we have to align the circle wrt the top or the bottom of the rectangle bar_px
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if (datapoint.y()>=graph->getBaseline()) {
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painter.drawComplexRoundedRect(bar_px, dx, dx, 0, 0, Qt::AbsoluteSize);
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painter.setBrush(bDeco);
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painter.drawEllipse(QPointF(bar_px.center().x(), bar_px.top()+dx), r,r);
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} else {
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painter.drawComplexRoundedRect(bar_px, 0, 0, dx, dx, Qt::AbsoluteSize);
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painter.setBrush(bDeco);
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painter.drawEllipse(QPointF(bar_px.center().x(), bar_px.bottom()-dx), r,r);
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}
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} else {
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// for horizontal barcharts
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const double dx=bar_px.height()/2.0;
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const double r=dx*0.85;
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if (datapoint.x()>=graph->getBaseline()) {
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painter.drawComplexRoundedRect(bar_px, 0, dx, 0, dx, Qt::AbsoluteSize);
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painter.setBrush(bDeco);
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painter.drawEllipse(QPointF(bar_px.right()-dx, bar_px.center().y()), r,r);
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} else {
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painter.drawComplexRoundedRect(bar_px, dx,0,dx,0, Qt::AbsoluteSize);
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painter.setBrush(bDeco);
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painter.drawEllipse(QPointF(bar_px.left()+dx, bar_px.center().y()), r,r);
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}
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}
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painter.restore();
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}
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);
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// enable usage of cutom draw functor
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graph->setUseCustomDrawFunctor(true);
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// set graph color
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graph->setColor(QColor("blue"));
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plot.addGraph(graph);
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// 5. autoscale the plot so the graph is contained
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plot.zoomToFit();
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// 6. show plotter and make it a decent size
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plot.setWindowTitle(title);
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plot.show();
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plot.resize(400,400);
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```
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The result looks like this:
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In order to draw horizontal error bars, you have to use `JKQTPBarHorizontalGraph` instead of `JKQTPBarVerticalGraph`. The functor given above also covers that case by checking the parameter `orientation`:
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