Extension points

phil/svg-chart

The package is at 0.x: its extension points are stable only from its 1.0 release. Until then, a minor version may change them, and its CHANGELOG says how.

To	Do
Read another configuration format	Build a `Chart` from `ChartType`, labels and `Dataset` values
Use the colours of a brand	Pass a palette to `SvgChartWriter`
Draw another kind of chart	Read the `Chart` and write the image yourself; `SvgChartWriter` is final

The classes under Internal are not extension points.