The optical size for drawing the icon.
Requires the underlying icon font to support the
axis, otherwise has no effect. Variable font filenames often indicate
the supported axes. Must be greater than 0.
For an icon to look the same at different sizes, the stroke weight (thickness) must change as the icon size scales. Optical size offers a way to automatically adjust the stroke weight as icon size changes.
- fill, for controlling fill.
- weight, for controlling stroke weight.
- grade, for controlling stroke weight in a more granular way.
final double? opticalSize;