page.go
func (f Font) Width(code int) float64 {
	first := f.FirstChar()
	last := f.LastChar()
	if code < first || last < code {
		return 0
	}
	return f.V.Key("Widths").Index(code - first).Float64()
}
func (f Font) Width(code int) float64 {
	first := f.FirstChar()
	last := f.LastChar()
	if code < first || last < code {
		return 0
	}
	return f.V.Key("Widths").Index(code - first).Float64()
}
// Width returns the width of the given code point.