iter method
Implementation
@override
void iter(String cls) {
if (opacityPattern.hasMatch(cls)) {
var value = opacityPattern.firstMatch(cls)?.group(1);
if (value == null) return;
if (value.startsWith('[') && value.endsWith(']')) {
value = value.substring(1, value.length - 1);
} else {
var v = (double.parse(value) / 100);
if (v > 1) v = 1;
if (v < 0) v = 0;
value = "$v";
}
_opacity = value;
}
}