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/*!
\example donutbreakdown
\title Donut chart breakdown example
\ingroup qtcharts_examples
\brief This example shows how to use create a donut breakdown chart using QPieSeries API.
\image examples_donutbreakdown.png
Let's start by defining some data for the chart.
\snippet donutbreakdown/main.cpp 1
Then we create a chart where we add the data. Note that this is our own chart derived from QChart.
\snippet donutbreakdown/main.cpp 2
Our own chart works in such a way that we create a main series in the constructor we create a main series,
which aggregates the data provided by the breakdown series. This is the piechart in the center.
\snippet donutbreakdown/donutbreakdownchart.cpp 1
When a breakdown series is added the data is used to create a slice in the main series and the
breakdown series itself is used to create a segment of a donut positioned so that it is aligned
with the corresponding slice in the main series.
\snippet donutbreakdown/donutbreakdownchart.cpp 2
Here's how the start and end angles for the donut segments are calculated.
\snippet donutbreakdown/donutbreakdownchart.cpp 3
The legend markers are customized to show the breakdown percentage. The markers for the main level slices are hidden.
\snippet donutbreakdown/donutbreakdownchart.cpp 4
Instead the main level slices show the percentage on the label.
\snippet donutbreakdown/mainslice.cpp 1
\snippet donutbreakdown/mainslice.cpp 2
Now that we have our chart defined, we can finally create a QChartView and show the chart.
\snippet donutbreakdown/main.cpp 3
*/
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