buildWithChild method
A build method that receives an extra child parameter.
This method may be called with a child different from the parameter
passed to the constructor of SingleChildStatelessWidget.
It may also be called again with a different child, without this widget
being recreated.
Implementation
@override
Widget buildWithChild(BuildContext context, Widget? child) {
return duration == null
? Opacity(
opacity: opacity,
alwaysIncludeSemantics: alwaysIncludeSemantics,
child: child,
)
: AnimatedOpacity(
opacity: opacity,
alwaysIncludeSemantics: alwaysIncludeSemantics,
duration: duration!,
curve: curve,
onEnd: onEnd,
child: child,
);
}