getAdvanceWidth method
Advance width for glyphId scaled to fontSize in pixels.
Returns 0 if glyphId is out of range.
Implementation
double getAdvanceWidth(int glyphId, double fontSize) {
if (glyphId < 0 || glyphId >= _hmtx.length) return 0;
return _hmtx[glyphId].advanceWidth * fontSize / metrics.unitsPerEm;
}