Forgive me if this is a simple fix but I am new to Flutter and I've had trouble finding a solution. I have one stateless widget, MySpriteGame which uses SpriteWidget. I have another widget called SpriteSquare, also stateless, which I am trying to add an event handler to. I'll add the code for both at the end (minus all of the imports to maximize space).
In want to pass down a function from MySpriteGame to SpriteSquare that basically adds _whitesquare, an instance of SpriteSquare to _background, another instance of SpriteSquare. The problem I am encountering is below.
The instance member 'handleEvent' can't be accessed in an initializer.
I know this is because I cannot add a function that adds _whitesquare to _background in the initialization of those variables. If MySpriteGame were stateful, I'd probably add the listener in an initState or something. I was wondering if there was a way to add these event listeners to the SpriteSquare nodes after initialization without having to make this widget stateful?
sprite_square.dart
class SpriteSquare extends NodeWithSize {
Color color;
Function handler;
SpriteSquare(size, this.color, this.handler) : super(size){
userInteractionEnabled = true;
}
@override handleEvent(SpriteBoxEvent event) {
handler(event);
return true;
}
@override
Future<void> paint(Canvas canvas) async {
applyTransformForPivot(canvas);
canvas.drawRect(
new Rect.fromLTWH(0.0, 0.0, size.width, size.height),
Paint()..color = color
);
}
}
sprite_game.dart
class MySpriteGame extends StatelessWidget {
final _background = SpriteSquare(const Size(400.0, 400.0), const Color(0xFF000000), (e)=>handleEvent(e));
final _whitesquare = SpriteSquare(const Size(200.0, 200.0), const Color(0xFFFFFFFF), (e)=>handleEvent(e));
MySpriteGame({Key? key}) : super(key: key);
handleEvent(SpriteBoxEvent event) {
_background.addChild(_whitesquare);
return true;
}
handleRemoveSelf(SpriteBoxEvent event){
print(event);
return true;
}
@override
Widget build(BuildContext context) {
return Center(
child: Container(
child:
SpriteWidget(
_background
)
),
);
}
}
EDIT
I feel like I might be onto something by adding the function after the Widget build... and before the return Center.... I can do _background.handleEvent() but I'm not sure how to add the logic from the handleEvent above into this handleEvent.
