JKQtPlotter/examples/barchart_functorfill/README.md

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# Example (JKQTPlotter): Barchart With Functor Fill-Mode {#JKQTPlotterBarchartsFunctorFilling}
This project (see [`barchart_functorfill`](https://github.com/jkriege2/JKQtPlotter/tree/master/examples/barchart_functorfill) shows how to draw barcharts, where the bars are filled differently, as defined by a custom functor.
The source code of the main application is (see [`barchart_functorfill.cpp`](https://github.com/jkriege2/JKQtPlotter/tree/master/examples/barchart_functorfill/barchart_functorfill.cpp):
```.cpp
// 1. create a plotter window and get a pointer to the internal datastore (for convenience)
JKQTPDatastore* ds=plot.getDatastore();
// 2. now we create two columns for key and value
size_t columnK=ds->addLinearColumn(11, 0, 10, "k");
size_t columnV=ds->addColumnCalculatedFromColumn(columnK, [](double x) { return 5.0+x; }, "v");
// 3. create graph in the plot, which plots the dataset:
JKQTPBarVerticalGraph* graph=new JKQTPBarVerticalGraph(&plot);
graph->setKeyColumn(columnK);
graph->setValueColumn(columnV);
// set FunctorFilling fill Mode
graph->setFillMode(JKQTPBarGraphBase::FillMode::FunctorFilling);
// define filling functor
graph->setFillBrushFunctor(
[](double key, double value) {
return QBrush(QColor::fromHsvF(key/12.0, 1.0, 1.0));
}
);
plot.addGraph(graph);
// 4 autoscale the plot so the graph is contained
plot.zoomToFit();
// 5. show plotter and make it a decent size
plot.setWindowTitle(title);
plot.show();
plot.resize(400,400);
```
The result looks like this:
![barchart_functorfill](https://raw.githubusercontent.com/jkriege2/JKQtPlotter/master/screenshots/barchart_functorfill.png)
In order to draw horizontal error bars, you have to use `JKQTPBarHorizontalGraph` instead of `JKQTPBarVerticalGraph`:
![barchart_functorfill_hor](https://raw.githubusercontent.com/jkriege2/JKQtPlotter/master/screenshots/barchart_functorfill_hor.png)