It's time to see how we can use the Canvas and CustomPaint widget to create a widget that has its own painting. In this example, we are going to create chart widgets—a pie and radial chart, to be more specific. Pie charts are a useful kind of circular statistical graphic, which is divided into slices to illustrate numerical proportions.

We are going to start with the pie chart widget, where we retrieve slice values and draw them proportionally in a circle. This is what it is going to look like:

Now, let's define the new PieChart widget with the help of the Canvas and CustomPaint classes.