A legend item marker.
The marker's color.
This option supports the following colors:
The marker's opacity.
This option accepts a value from 0 to 1: 0 makes the marker transparent; 1 makes it opaque.
The diameter of the legend item's marker in pixels.
If the legend is grouped by size, this option's value is different for each legend item. Otherwise, the value equals the markerSize.
The marker's state.