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Rushabh Doshi
Rushabh Doshi

Reputation: 21

How to get the object of button [flutter]

I have created a RaisedButton.Now I want to know can I pass key to it and access its object in a function or is there any other way to access the Raisebutton other then storing it in a variable.

Upvotes: 1

Views: 3495

Answers (2)

Dhrumil Shah - dhuma1981
Dhrumil Shah - dhuma1981

Reputation: 15789

Flutter is different than traditional Android Development. Here Everything is Widget and Widget has its own state.

According to Flutter documentation,

If you want to disable a button you just have to pass null to onPressed of the RaisedButton. And if you want to enable it pass a function, you can pass an empty function also like (){} this.

Check the below Example to understand it.

void main() {
  runApp(new ButtonDemoNew());
}

class ButtonDemoNew extends StatefulWidget {
  @override
  State<StatefulWidget> createState() {
    return new _ButtonStateDemo();
  }
}

class _ButtonStateDemo extends State<ButtonDemoNew> {
  bool enabled = false;

  @override
  Widget build(BuildContext context) {
    // TODO: implement build
    return new MaterialApp(
      title: "Button Demo",
      home: new Scaffold(
        appBar: new AppBar(
          title: new Text("Button Demo"),
        ),
        body: new Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            new RaisedButton(
              onPressed: enabled ? () {} : null,
              child: new Text("Demo Button"),
            ),
            new RaisedButton(
              onPressed: () {
                setState(() {
                  enabled = enabled ? false : true;
                });
              },
              child: new Text("Enable / Disable"),
            )
          ],
        ),
      ),
    );
  }
}

Upvotes: 1

rmtmckenzie
rmtmckenzie

Reputation: 40433

Clarification on what is actually wanting to be performed would be very useful.

However, I think I can guess what the issue is - confusion about how flutter's statefulness works.

The general way that things like RaisedButton work in Flutter is that you hold the state in a StatefulWidget somewhere above it, which does the building of the RaisedButton. If you want to change the raisedButton, you set a variable on the StatefulWidget within a setState(() => ?? = ??); and use it in the StatefulWidget's build function to decide which parameters to build the RaisedButton with.

Here's a short example that raises the button each time you press it.

class Raising extends StatefulWidget {
  final String text;

  Raising({@required this.text});

  @override
  State<StatefulWidget> createState() => RaisingState();
}

class RaisingState extends State<Raising> {
  double elevation = 0.0;

  @override
  Widget build(BuildContext context) => new RaisedButton(
        child: new Text(widget.text),
        elevation: elevation,
        onPressed: () => setState(() => elevation += 1),
      );
}

Upvotes: 0

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