layout method
Implementation
@override
void layout(FConstraints constraints) {
final measured = backend.render.measureTextEx(
app.defaultFont, 'Ag', fontSize, fontSpacing,
);
final naturalWidth = constraints.minWidth == constraints.maxWidth
? constraints.maxWidth // parent forced an exact width, respect it
: 160.0; // otherwise fall back to a sensible default
final naturalHeight = constraints.minHeight == constraints.maxHeight
? constraints.maxHeight // parent forced an exact height, respect it
: measured.y; // otherwise size to the font metrics
// NOTE: keep this here because _paddingY is not used at all for now
// : measured.y + _paddingY * 2
size = constraints.constrain(.vec2(naturalWidth, naturalHeight));
}