constrain method
限定尺寸 >>>
Implementation
ConstrainedBox constrain(
{double? minWidth,
double? maxWidth,
double? minHeight,
double? maxHeight}) {
return ConstrainedBox(
child: this,
constraints: BoxConstraints(
minWidth: minWidth ?? 0,
minHeight: minHeight ?? 0,
maxWidth: maxWidth ?? double.infinity,
maxHeight: maxHeight ?? double.infinity),
);
}