FontVariation constructor
Creates a FontVariation object, which can be added to a TextStyle to change the variable attributes of a font.
axis
is the four-character tag that identifies the design axis.
OpenType lists the currently registered axis
tags.
value
is the value that the axis will be set to. The behavior
depends on how the font implements the axis.
Implementation
const FontVariation(
this.axis,
this.value,
) : assert(axis.length == 4, 'Axis tag must be exactly four characters long.'),
assert(value >= -32768.0 && value < 32768.0, 'Value must be representable as a signed 16.16 fixed-point number, i.e. it must be in this range: -32768.0 ≤ value < 32768.0');