layout method
Implementation
@override
void layout(FConstraints constraints) {
final child = this.child!;
child._doLayout(.new(
minWidth: (constraints.minWidth - left - right).clamp(0, double.infinity),
maxWidth: constraints.maxWidth - left - right,
minHeight: (constraints.minHeight - top - bottom).clamp(0, double.infinity),
maxHeight: constraints.maxHeight - top - bottom,
));
child.localOffset = .vec2(left, top);
size = .vec2(
child.size.x + left + right,
child.size.y + top + bottom,
);
}