Flutter Dart layouts, Stack, Positioned how to stretch matrix of Material Buttons over whole screen

Issue

How can I have matrix of material buttons stretch across whole screen, if I just use height they will stretch to little or out of the screen based on screen size?

I can do that easily just in matrix with height: double.infinity, and CrossAxisAlignment.stretch,.

Though when I add Stack and Positioned widgets to the mix, then screen goes white if I use height: double.infinity,. and I get error: BoxConstraints forces an infinite height.
The relevant error-causing widget was:
MaterialButton file:///Users/janiveble/AndroidStudioProjects/midi_app/lib/main.dart:113:14

Though when I search for this error, I can’t figure out how is it related to my issue.

Also how can I position text on white keys to the botom of key instead of center?

Also I would like to get width of white keys, as I would like to use it to control position and width of black keys based on it.

  Expanded buildWhiteKey({Color color, int soundNumber}) {
    return Expanded(
      child: MaterialButton(
        //height: double.infinity,
        height: 100,
        color: color,
        textColor: Colors.red,
        padding: EdgeInsets.all(1.0),
        onPressed: () {
          //playSound(soundNumber);
          FlutterMidi.playMidiNote(midi: soundNumber);
          setState(() {
            userAnswer = soundNumber;
          });
        },
        child: Text('$soundNumber'),
      ),
    );
  }

  Expanded buildBlackKey({Color color, int soundNumber}) {
    return Expanded(
      child: MaterialButton(
        //height: double.infinity,
        height: 100,
        color: color,
        textColor: Colors.red,
        padding: EdgeInsets.all(1.0),
        onPressed: () {
          //playSound(soundNumber);
          FlutterMidi.playMidiNote(midi: soundNumber);
          setState(() {
            userAnswer = soundNumber;
          });
        },
        child: Text(
          '$soundNumber',
        ),
      ),
    );
  }

@override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        backgroundColor: Colors.white30,
        body: SafeArea(
          child: Column(
            mainAxisAlignment: MainAxisAlignment.spaceEvenly,
            crossAxisAlignment: CrossAxisAlignment.stretch,
            children: [
              Row(
                children: <Widget>[
                  quizKey(color: Colors.green),
                  checkAnswer(color: Colors.red),
                ],
              ),
              Stack(children: <Widget>[
                Row(mainAxisSize: MainAxisSize.min, children: <Widget>[
                  buildWhiteKey(color: Colors.white, soundNumber: 96),
                  buildWhiteKey(color: Colors.white, soundNumber: 98),
                  buildWhiteKey(color: Colors.white, soundNumber: 100),
                  buildWhiteKey(color: Colors.white, soundNumber: 101),
                  buildWhiteKey(color: Colors.white, soundNumber: 103),
                  buildWhiteKey(color: Colors.white, soundNumber: 105),
                  buildWhiteKey(color: Colors.white, soundNumber: 107),
                ]),
                Positioned(
                    left: 0.0,
                    right: 0.0,
                    bottom: 50.0,
                    top: 0.0,
                    child: Row(
                        mainAxisAlignment: MainAxisAlignment.spaceBetween,
                        mainAxisSize: MainAxisSize.min,
                        children: <Widget>[
                          Container(width: keyWidth),
                          buildBlackKey(color: Colors.black, soundNumber: 97),
                          Container(width: keyWidth1),
                          buildBlackKey(color: Colors.black, soundNumber: 99),
                          Container(width: keyWidth2),
                          buildBlackKey(color: Colors.black, soundNumber: 102),
                          Container(width: keyWidth1),
                          buildBlackKey(color: Colors.black, soundNumber: 104),
                          Container(width: keyWidth1),
                          buildBlackKey(color: Colors.black, soundNumber: 106),
                          Container(width: keyWidth),
                        ])),
              ]),
              Stack(children: <Widget>[
                Row(mainAxisSize: MainAxisSize.min, children: <Widget>[
                  buildWhiteKey(color: Colors.white, soundNumber: 84),
                  buildWhiteKey(color: Colors.white, soundNumber: 86),
                  buildWhiteKey(color: Colors.white, soundNumber: 88),
                  buildWhiteKey(color: Colors.white, soundNumber: 89),
                  buildWhiteKey(color: Colors.white, soundNumber: 91),
                  buildWhiteKey(color: Colors.white, soundNumber: 93),
                  buildWhiteKey(color: Colors.white, soundNumber: 95),
                ]),
                Positioned(
                    left: 0.0,
                    right: 0.0,
                    bottom: 50.0,
                    top: 0.0,
                    child: Row(
                        mainAxisAlignment: MainAxisAlignment.spaceBetween,
                        mainAxisSize: MainAxisSize.min,
                        children: <Widget>[
                          Container(width: keyWidth),
                          buildBlackKey(color: Colors.black, soundNumber: 85),
                          Container(width: keyWidth1),
                          buildBlackKey(color: Colors.black, soundNumber: 87),
                          Container(width: keyWidth2),
                          buildBlackKey(color: Colors.black, soundNumber: 90),
                          Container(width: keyWidth1),
                          buildBlackKey(color: Colors.black, soundNumber: 92),
                          Container(width: keyWidth1),
                          buildBlackKey(color: Colors.black, soundNumber: 94),
                          Container(width: keyWidth),
                        ])),
              ]),
              Stack(children: <Widget>[
                Row(mainAxisSize: MainAxisSize.min, children: <Widget>[
                  buildWhiteKey(color: Colors.white, soundNumber: 72),
                  buildWhiteKey(color: Colors.white, soundNumber: 74),
                  buildWhiteKey(color: Colors.white, soundNumber: 76),
                  buildWhiteKey(color: Colors.white, soundNumber: 77),
                  buildWhiteKey(color: Colors.white, soundNumber: 79),
                  buildWhiteKey(color: Colors.white, soundNumber: 81),
                  buildWhiteKey(color: Colors.white, soundNumber: 83),
                ]),
                Positioned(
                    left: 0.0,
                    right: 0.0,
                    bottom: 50.0,
                    top: 0.0,
                    child: Row(
                        mainAxisAlignment: MainAxisAlignment.spaceBetween,
                        mainAxisSize: MainAxisSize.min,
                        children: <Widget>[
                          Container(width: keyWidth),
                          buildBlackKey(color: Colors.black, soundNumber: 73),
                          Container(width: keyWidth1),
                          buildBlackKey(color: Colors.black, soundNumber: 75),
                          Container(width: keyWidth2),
                          buildBlackKey(color: Colors.black, soundNumber: 78),
                          Container(width: keyWidth1),
                          buildBlackKey(color: Colors.black, soundNumber: 80),
                          Container(width: keyWidth1),
                          buildBlackKey(color: Colors.black, soundNumber: 82),
                          Container(width: keyWidth),
                        ])),
              ]),
              Stack(children: <Widget>[
                Row(mainAxisSize: MainAxisSize.min, children: <Widget>[
                  buildWhiteKey(color: Colors.white, soundNumber: 60),
                  buildWhiteKey(color: Colors.white, soundNumber: 62),
                  buildWhiteKey(color: Colors.white, soundNumber: 64),
                  buildWhiteKey(color: Colors.white, soundNumber: 65),
                  buildWhiteKey(color: Colors.white, soundNumber: 67),
                  buildWhiteKey(color: Colors.white, soundNumber: 69),
                  buildWhiteKey(color: Colors.white, soundNumber: 71),
                ]),
                Positioned(
                    left: 0.0,
                    right: 0.0,
                    bottom: 50.0,
                    top: 0.0,
                    child: Row(
                        mainAxisAlignment: MainAxisAlignment.spaceBetween,
                        mainAxisSize: MainAxisSize.min,
                        children: <Widget>[
                          Container(width: keyWidth),
                          buildBlackKey(color: Colors.black, soundNumber: 61),
                          Container(width: keyWidth1),
                          buildBlackKey(color: Colors.black, soundNumber: 63),
                          Container(width: keyWidth2),
                          buildBlackKey(color: Colors.black, soundNumber: 66),
                          Container(width: keyWidth1),
                          buildBlackKey(color: Colors.black, soundNumber: 68),
                          Container(width: keyWidth1),
                          buildBlackKey(color: Colors.black, soundNumber: 70),
                          Container(width: keyWidth),
                        ])),
              ]),
              Stack(children: <Widget>[
                Row(mainAxisSize: MainAxisSize.min, children: <Widget>[
                  buildWhiteKey(color: Colors.white, soundNumber: 48),
                  buildWhiteKey(color: Colors.white, soundNumber: 50),
                  buildWhiteKey(color: Colors.white, soundNumber: 52),
                  buildWhiteKey(color: Colors.white, soundNumber: 53),
                  buildWhiteKey(color: Colors.white, soundNumber: 55),
                  buildWhiteKey(color: Colors.white, soundNumber: 57),
                  buildWhiteKey(color: Colors.white, soundNumber: 59),
                ]),
                Positioned(
                    left: 0.0,
                    right: 0.0,
                    bottom: 50.0,
                    top: 0.0,
                    child: Row(
                        mainAxisAlignment: MainAxisAlignment.spaceBetween,
                        mainAxisSize: MainAxisSize.min,
                        children: <Widget>[
                          Container(width: keyWidth),
                          buildBlackKey(color: Colors.black, soundNumber: 49),
                          Container(width: keyWidth1),
                          buildBlackKey(color: Colors.black, soundNumber: 51),
                          Container(width: keyWidth2),
                          buildBlackKey(color: Colors.black, soundNumber: 54),
                          Container(width: keyWidth1),
                          buildBlackKey(color: Colors.black, soundNumber: 56),
                          Container(width: keyWidth1),
                          buildBlackKey(color: Colors.black, soundNumber: 58),
                          Container(width: keyWidth),
                        ])),
              ]),
              Stack(children: <Widget>[
                Row(mainAxisSize: MainAxisSize.min, children: <Widget>[
                  buildWhiteKey(color: Colors.white, soundNumber: 36),
                  buildWhiteKey(color: Colors.white, soundNumber: 38),
                  buildWhiteKey(color: Colors.white, soundNumber: 40),
                  buildWhiteKey(color: Colors.white, soundNumber: 41),
                  buildWhiteKey(color: Colors.white, soundNumber: 43),
                  buildWhiteKey(color: Colors.white, soundNumber: 45),
                  buildWhiteKey(color: Colors.white, soundNumber: 47),
                ]),
                Positioned(
                    left: 0.0,
                    right: 0.0,
                    bottom: 50.0,
                    top: 0.0,
                    child: Row(
                        mainAxisAlignment: MainAxisAlignment.spaceBetween,
                        mainAxisSize: MainAxisSize.min,
                        children: <Widget>[
                          Container(width: keyWidth),
                          buildBlackKey(color: Colors.black, soundNumber: 37),
                          Container(width: keyWidth1),
                          buildBlackKey(color: Colors.black, soundNumber: 39),
                          Container(width: keyWidth2),
                          buildBlackKey(color: Colors.black, soundNumber: 42),
                          Container(width: keyWidth1),
                          buildBlackKey(color: Colors.black, soundNumber: 44),
                          Container(width: keyWidth1),
                          buildBlackKey(color: Colors.black, soundNumber: 46),
                          Container(width: keyWidth),
                        ])),
              ]),
              Stack(children: <Widget>[
                Row(mainAxisSize: MainAxisSize.min, children: <Widget>[
                  buildWhiteKey(color: Colors.white, soundNumber: 24),
                  buildWhiteKey(color: Colors.white, soundNumber: 26),
                  buildWhiteKey(color: Colors.white, soundNumber: 28),
                  buildWhiteKey(color: Colors.white, soundNumber: 29),
                  buildWhiteKey(color: Colors.white, soundNumber: 31),
                  buildWhiteKey(color: Colors.white, soundNumber: 33),
                  buildWhiteKey(color: Colors.white, soundNumber: 35),
                ]),
                Positioned(
                    left: 0.0,
                    right: 0.0,
                    bottom: 50.0,
                    top: 0.0,
                    child: Row(
                        mainAxisAlignment: MainAxisAlignment.spaceBetween,
                        mainAxisSize: MainAxisSize.min,
                        children: <Widget>[
                          Container(width: keyWidth),
                          buildBlackKey(color: Colors.black, soundNumber: 25),
                          Container(width: keyWidth1),
                          buildBlackKey(color: Colors.black, soundNumber: 27),
                          Container(width: keyWidth2),
                          buildBlackKey(color: Colors.black, soundNumber: 30),
                          Container(width: keyWidth1),
                          buildBlackKey(color: Colors.black, soundNumber: 32),
                          Container(width: keyWidth1),
                          buildBlackKey(color: Colors.black, soundNumber: 34),
                          Container(width: keyWidth),
                        ])),
              ]),
            ],
          ),
        ),
      ),
    );
  }

Solution

Ive solved the issues

for proper button arrangements I’ve had to wrap Stack and Positioned widgets in one Expanded widget in proper place

 @override
  Widget build(BuildContext context) {
    return SafeArea(
      child: Column(
        mainAxisSize: MainAxisSize.max,
        crossAxisAlignment: CrossAxisAlignment.stretch,
        children: [
          Row(
            children: <Widget>[
              quizKey(color: Colors.green),
              checkAnswer(color: Colors.red),
            ],
          ),
          Expanded(
            child: Stack(children: <Widget>[
              Row(children: <Widget>[
                buildWhiteKey(color: Colors.white, soundNumber: 96),
                buildWhiteKey(color: Colors.white, soundNumber: 98),
                buildWhiteKey(color: Colors.white, soundNumber: 100),
                buildWhiteKey(color: Colors.white, soundNumber: 101),
                buildWhiteKey(color: Colors.white, soundNumber: 103),
                buildWhiteKey(color: Colors.white, soundNumber: 105),
                buildWhiteKey(color: Colors.white, soundNumber: 107),
              ]),
              Positioned(
                  left: 0.0,
                  right: 0.0,
                  bottom: kbottomHeight,
                  top: 0.0,
                  child: Row(children: <Widget>[
                    Container(width: kkeyWidth),
                    buildBlackKey(color: Colors.black, soundNumber: 97),
                    Container(width: kkeyWidth * 0.5),
                    buildBlackKey(color: Colors.black, soundNumber: 99),
                    Container(width: kkeyWidth * 2),
                    buildBlackKey(color: Colors.black, soundNumber: 102),
                    Container(width: kkeyWidth * 0.5),
                    buildBlackKey(color: Colors.black, soundNumber: 104),
                    Container(width: kkeyWidth * 0.5),
                    buildBlackKey(color: Colors.black, soundNumber: 106),
                    Container(width: kkeyWidth),
                  ])),
            ]),
          ),
         
          ],
        ),
      );
  }

For proper aligment of text in Button widget I’ve used InkWell button widget and then it works fine.

  Expanded buildWhiteKey({Color color, int soundNumber}) {
    return Expanded(
      child: Padding(
        padding: const EdgeInsets.all(1.0),
        child: InkWell(
          onTap: () {
            //playSound(soundNumber);
          },
          child: Container(
            //height: double.infinity,
            color: color,
            padding: EdgeInsets.all(1.0),
            child: Align(
              alignment: Alignment.bottomCenter,
              child: Text(
                '$soundNumber',
                textAlign: TextAlign.left,
              ),
            ),
          ),
        ),
      ),
    );
  }

For how to get width of white keys, I’m not really sure how that works yet, but have work around, where I found how to control it with one constant and divide it or multiply based on position of black key.

Thank Ammar for your time and effort, even though your code didn’t really work out for me (guess you couldn’t really test it out as you didn’t have machine at hand), though your advices helped me as well in my work.

Answered By – Jan

Answer Checked By – Jay B. (FlutterFixes Admin)

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