width not set after Transform.scale

Question

Unable to change the width after "Transform.scale"?

In the following sample code, the red Container, do not change width after setting fitWidth(width of container) when pressing the floatingbutton.

Only if it is les than MediaQuery.of(context).size.width.

import 'package:flutter/material.dart';
import 'package:flutter/rendering.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  static const String _title = 'Flutter Code Sample';

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: _title,
      home: MyStatefulWidget(),
    );
  }
}

class MyStatefulWidget extends StatefulWidget {
  MyStatefulWidget({Key key}) : super(key: key);

  @override
  _MyStatefulWidgetState createState() => _MyStatefulWidgetState();
}

// State

class _MyStatefulWidgetState extends State<MyStatefulWidget> {
  Matrix4 matrix = Matrix4.identity();
  double fitWidth;

  @override
  void initState() {
    fitWidth = 0;
    super.initState();
  }

  double getSizeWidth(BuildContext context) {
    if (fitWidth != 0) {
      return fitWidth;
    } else {
      return MediaQuery.of(context).size.width;
    }
  }

  Widget build(BuildContext context) {
    var sizWidth = getSizeWidth(context);
    print(sizWidth);
    return Scaffold(
        appBar: AppBar(
          title: const Text('Sample Code'),
        ),
        body: Transform.scale(
          scale: 0.5,
          child: Container(
            color: Colors.red,
            width: sizWidth,
            height: 400,
          ),
        ),
        floatingActionButton: FloatingActionButton(
          onPressed: () {
            setState(() {
              fitWidth = 800;
            });
            // Add your onPressed code here!
          },
          backgroundColor: Colors.green,
        ));
  }
}

may I ask why'd you create a function just to get the width of the device? you could just do var sizWidth = MediaQuery.of(context).size.width; in your build — Z. Cajurao
– Z. Cajurao, Commented Dec 27, 2019 at 3:24

Jaydeep chatrola · Accepted Answer · 2019-12-27 05:40:46Z

2

its works for me

Widget build(BuildContext context) {
        print(sizWidth);
        return Scaffold(
            appBar: AppBar(
              title: const Text('Sample Code'),
            ),
            body: Transform.scale(
              scale: 0.5,
              child: Container(
                color: Colors.red,
                width: fitWidth != 0?fitWidth:MediaQuery.of(context).size.width,
                height: 400,
              ),
            ),
            floatingActionButton: FloatingActionButton(
              onPressed: () {
                setState(() {
                  fitWidth = 800;
                });
                // Add your onPressed code here!
              },
              backgroundColor: Colors.green,
            ));
      }

cheers...

answered Dec 27, 2019 at 5:40

Jaydeep chatrola

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Comments

Nardeepsinh Vaghela · Accepted Answer · 2019-12-27 04:42:36Z

1

try this,

class MyStatefulWidget extends StatefulWidget {
  MyStatefulWidget({Key key}) : super(key: key);

  @override
  _MyStatefulWidgetState createState() => _MyStatefulWidgetState();
}


class _MyStatefulWidgetState extends State<MyStatefulWidget> {
  Matrix4 matrix = Matrix4.identity();
  double widthScale = 0.0;

  @override
  void initState() {
    super.initState();
  }

  double getSizeWidth(BuildContext context) {
    if (widthScale != 0.0) {
      return widthScale;
    } else {
      return 1.0;
    }
  }

  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(
          title: const Text('Sample Code'),
        ),
        body: Transform(
          alignment: Alignment.center,
          transform: new Matrix4.identity()..scale(getSizeWidth(context), 0.5),
          child: Container(
            color: Colors.red,
            width: MediaQuery.of(context).size.width,
            height: 400,
          ),
        ),
        floatingActionButton: FloatingActionButton(
          onPressed: () {
            setState(() {
              widthScale = 0.5;
            });
            // Add your onPressed code here!
          },
          backgroundColor: Colors.green,
        ));
  }
}

answered Dec 27, 2019 at 4:42

Nardeepsinh Vaghela

9786 silver badges7 bronze badges

1 Comment

Chris G. Over a year ago

Nice suggestion, but I need the width to be bigger after scaling - not scaling the width - if possible.

Crazy Lazy Cat · Accepted Answer · 2019-12-27 05:34:36Z

1

Give alignment(Align)

Transform.scale(
  scale: 0.5,
  child: Center(  // or Align
    child: Container(
      color: Colors.red,
      width: sizWidth,
      height: 400,
    ),
  ),
)

answered Dec 27, 2019 at 5:34

Crazy Lazy Cat

15.3k5 gold badges36 silver badges55 bronze badges

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