Flutter 颤振-我正在寻找一种方法来创建一个均匀放置图标的圆

导入“包：flift/foundation.dart”；
进口“包装：颤振/材料.省道”；
导入'dart:math'作为数学；
常数double _radisperderegree=Math.pi/180；
最终双倍_startAngle=-90.0*_弧度等级；
typedef双项目角度计算器（int索引）；
类主页扩展了StatefulWidget{
@凌驾
状态createState（）{
返回新的_HomePageState（）；
}
}
类_HomePageState使用TickerProviderStateMixin扩展状态{
最终清单项目=[
新容器(
装饰：新盒子装饰（形状：BoxShape.circle，
),
孩子：新材料按钮(
按下：（）{}，
子：新建Image.asset(
“images/recycling.png”，
宽度：60.0，
身高：60.0，
适合：BoxFit.cover，
),
),
),
新扁平按钮(
按下：（）{}，
子：新建Image.asset(
“images/gas station.png”，
宽度：60.0，
身高：60.0，
适合：BoxFit.cover，
),
),
新扁平按钮(
按下：（）{}，
子：新建Image.asset(
“images/lightbulb.png”，
宽度：60.0，
身高：60.0，
适合：BoxFit.cover，
),
),
新扁平按钮(
按下：（）{}，
子：新建Image.asset(
“images/cflamp.png”，
宽度：60.0，
身高：60.0，
适合：BoxFit.cover，
),
),
新扁平按钮(
按下：（）{}，
子：新建Image.asset(
“images/plug.png”，
宽度：60.0，
身高：60.0，
适合：BoxFit.cover，
),
)
];
@凌驾
小部件构建（构建上下文）{
归还新脚手架(
正文：_buildBody（），
);
}
小部件_buildBody（）{
返回容器(
装饰：新盒子装饰(
颜色：颜色。青色），
宽度：MediaQuery.of（context）.size.width，
孩子：填充(
填充：常数边集全部（25.0），
子：新列(
mainAxisAlignment:mainAxisAlignment.start，
儿童：[
新填料(
填充：仅限常量边集（顶部：20.0，左侧：20.0，右侧：20.0），
子容器：新容器(
装饰：新盒子装饰(
渐变：新的线性渐变（颜色：[
新颜色（0xFFA19D9A），
颜色，白色，
新颜色（0xFFA19D9A），
]),
边界半径：
新边界半径。全部（新半径。圆形（25.0）），
子容器：新容器(
边距：所有常数边集（5.0），
装饰：新盒子装饰(
颜色：Colors.teal，
边界半径：
新边界半径。全部（新半径。圆形（22.0）），
孩子：新的填充物(
填充：常数边集全部（5.0），
儿童：新文本(
“通过选择任何图标获取建议”，
样式：新文本样式(
字体大小：22.0，
颜色：颜色，白色，
fontFamily：“鱼子酱梦”，
fontWeight:fontWeight.w600），
textAlign:textAlign.center，
),
),
),
),
),
_buildStackView（），
],
),
),
);
}
小部件_buildStackView（）{
最终列表饮料=[]；
double width=MediaQuery.of（context）.size.width；
double height=MediaQuery.of（context）.size.height；
双外表面=数学最小值（宽度*3/4，高度*3/4）；
双内半径=外半径*3/4；
对于（int i=0；iimport 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
import 'dart:math' as Math;

const double _radiansPerDegree = Math.pi / 180;
final double _startAngle = -90.0 * _radiansPerDegree;

typedef double ItemAngleCalculator(int index);

class HomePage extends StatefulWidget {
  @override
  State createState() {
    return new _HomePageState();
  }
}

class _HomePageState extends State<HomePage> with TickerProviderStateMixin {

  final List<Widget> items = [
    new Container(
      decoration: new BoxDecoration(shape: BoxShape.circle,
      ),
      child: new MaterialButton(
        onPressed: () {},
        child: new Image.asset(
          'images/recycling.png',
          width: 60.0,
          height: 60.0,
          fit: BoxFit.cover,
        ),
      ),
    ),
    new FlatButton(
      onPressed: () {},
      child: new Image.asset(
        'images/gas-station.png',
        width: 60.0,
        height: 60.0,
        fit: BoxFit.cover,
      ),
    ),
    new FlatButton(
      onPressed: () {},
      child: new Image.asset(
        'images/light-bulb.png',
        width: 60.0,
        height: 60.0,
        fit: BoxFit.cover,
      ),
    ),
    new FlatButton(
      onPressed: () {},
      child: new Image.asset(
        'images/cflamp.png',
        width: 60.0,
        height: 60.0,
        fit: BoxFit.cover,
      ),
    ),
    new FlatButton(
      onPressed: () {},
      child: new Image.asset(
        'images/plug.png',
        width: 60.0,
        height: 60.0,
        fit: BoxFit.cover,
      ),
    )
  ];

  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      body: _buildBody(),
    );
  }

  Widget _buildBody() {
    return Container(
      decoration: new BoxDecoration(
          color: Colors.teal),
      width: MediaQuery.of(context).size.width,
      child: Padding(
        padding: const EdgeInsets.all(25.0),
        child: new Column(
          mainAxisAlignment: MainAxisAlignment.start,
          children: <Widget>[
            new Padding(
              padding: const EdgeInsets.only(top: 20.0,left: 20.0,right: 20.0),
              child: new Container(
                decoration: new BoxDecoration(
                    gradient: new LinearGradient(colors: [
                      new Color(0xFFA19D9A),
                      Colors.white,
                      new Color(0xFFA19D9A),
                    ]),
                    borderRadius:
                    new BorderRadius.all(new Radius.circular(25.0))),
                child: new Container(
                  margin: const EdgeInsets.all(5.0),
                  decoration: new BoxDecoration(
                      color: Colors.teal,
                      borderRadius:
                      new BorderRadius.all(new Radius.circular(22.0))),
                  child: new Padding(
                    padding: const EdgeInsets.all(5.0),
                    child: new Text(
                      "Get recommendations by selecting any icon",
                      style: new TextStyle(
                          fontSize: 22.0,
                          color: Colors.white,
                          fontFamily: 'CaviarDreams',
                          fontWeight: FontWeight.w600),
                      textAlign: TextAlign.center,
                    ),
                  ),
                ),
              ),
            ),
            _buildStackView(),
          ],
        ),
      ),
    );
  }

  Widget _buildStackView() {
    final List<Widget> beverages = <Widget>[];
    double width = MediaQuery.of(context).size.width;
    double height = MediaQuery.of(context).size.height;
    double outerRadius = Math.min(width * 3 / 4, height * 3 / 4);
    double innerWhiteRadius = outerRadius * 3 / 4;

    for (int i = 0; i < items.length; i++) {
      beverages.add(_buildIcons(i));
    }

    return Flexible(
      child: Container(
        padding: EdgeInsets.all(10.0),
        child: new Stack(
          alignment: AlignmentDirectional.center,
          children: <Widget>[
            _drawCircle(outerRadius, Color.fromRGBO(255, 255, 255, 0.3)),
            _drawCircle(outerRadius - 25, Color.fromRGBO(255, 255, 255, 0.2)),
            new CustomMultiChildLayout(
              delegate: new _CircularLayoutDelegate(
                itemCount: items.length,
                radius: outerRadius / 2,
              ),
              children: beverages,
            ),
            GestureDetector(
                onTap: () {
                  Navigator.of(context).pushNamed("/ask/capture");
                },
                child: Image.asset(
                  "images/earth-globe.png",
                  width: innerWhiteRadius,
                  height: innerWhiteRadius,
                  fit: BoxFit.cover,
                )
            ),
          ],
        ),
      ),
    );
  }

  // Draw a circle with given radius and color.
  Widget _drawCircle(double radius, Color color) {
    return new Container(
      decoration: new BoxDecoration(shape: BoxShape.circle, color: color),
      width: radius,
      height: radius,
    );
  }



  Widget _buildIcons(int index) {
    final Widget item = items[index];

    return new LayoutId(
      id: 'BUTTON$index',
      child: item,
    );
  }
}

double _calculateItemAngle(int index) {
  double _itemSpacing = 360.0 / 5.0;
  return _startAngle + index * _itemSpacing * _radiansPerDegree;
}

class _CircularLayoutDelegate extends MultiChildLayoutDelegate {
  static const String actionButton = 'BUTTON';

  final int itemCount;
  final double radius;

  _CircularLayoutDelegate({
    @required this.itemCount,
    @required this.radius,
  });

  Offset center;

  @override
  void performLayout(Size size) {
    center = new Offset(size.width / 2, size.height / 2);
    for (int i = 0; i < itemCount; i++) {
      final String actionButtonId = '$actionButton$i';

      if (hasChild(actionButtonId)) {
        final Size buttonSize =
        layoutChild(actionButtonId, new BoxConstraints.loose(size));

        final double itemAngle = _calculateItemAngle(i);

        positionChild(
          actionButtonId,
          new Offset(
            (center.dx - buttonSize.width / 2) + (radius) * Math.cos(itemAngle),
            (center.dy - buttonSize.height / 2) +
                (radius) * Math.sin(itemAngle),
          ),
        );
      }
    }
  }

  @override
  bool shouldRelayout(_CircularLayoutDelegate oldDelegate) =>
      itemCount != oldDelegate.itemCount ||
          radius != oldDelegate.radius ;
}

import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
import 'dart:math' as Math;

const double _radiansPerDegree = Math.pi / 180;
final double _startAngle = -90.0 * _radiansPerDegree;

typedef double ItemAngleCalculator(int index);

class HomePage extends StatefulWidget {
  @override
  State createState() {
    return new _HomePageState();
  }
}

class _HomePageState extends State<HomePage> with TickerProviderStateMixin {
  final List<Widget> items = [
    new Container(
      decoration: new BoxDecoration(
        shape: BoxShape.circle,
        color: Colors.white,
      ),
      padding: EdgeInsets.all(10),
      child: new MaterialButton(
        onPressed: () {},
        child: new Image.asset(
          'assets/images/ball1.png',
          width: 60.0,
          height: 60.0,
          fit: BoxFit.cover,
        ),
      ),
    ),
    Container(
      decoration: new BoxDecoration(
        shape: BoxShape.circle,
        color: Colors.white,
      ),
      padding: EdgeInsets.all(10),
      child: new FlatButton(
        onPressed: () {},
        child: new Image.asset(
          'assets/images/ball1.png',
          width: 60.0,
          height: 60.0,
          fit: BoxFit.cover,
        ),
      ),
    ),
    Container(
      decoration: new BoxDecoration(
        shape: BoxShape.circle,
        color: Colors.white,
      ),
      padding: EdgeInsets.all(10),
      child: new FlatButton(
        onPressed: () {},
        child: new Image.asset(
          'assets/images/ball1.png',
          width: 60.0,
          height: 60.0,
          fit: BoxFit.cover,
        ),
      ),
    ),
    Container(
      decoration: new BoxDecoration(
        shape: BoxShape.circle,
        color: Colors.white,
      ),
      padding: EdgeInsets.all(10),
      child: new FlatButton(
        onPressed: () {},
        child: new Image.asset(
          'assets/images/ball1.png',
          width: 60.0,
          height: 60.0,
          fit: BoxFit.cover,
        ),
      ),
    ),
    Container(
      decoration: new BoxDecoration(
        shape: BoxShape.circle,
        color: Colors.white,
      ),
      padding: EdgeInsets.all(10),
      child: new FlatButton(
        onPressed: () {},
        child: new Image.asset(
          'assets/images/ball1.png',
          width: 60.0,
          height: 60.0,
          fit: BoxFit.cover,
        ),
      ),
    )
  ];

  @override
  Widget build(BuildContext context) {
    return _buildBody();
  }

  Widget _buildBody() {
    return Container(
      decoration: new BoxDecoration(color: Colors.white),
      width: MediaQuery.of(context).size.width,
      child: Padding(
        padding: const EdgeInsets.all(25.0),
        child: new Column(
          mainAxisAlignment: MainAxisAlignment.start,
          children: <Widget>[
            new Padding(
              padding:
                  const EdgeInsets.only(top: 20.0, left: 20.0, right: 20.0),
              child: new Container(
                decoration: new BoxDecoration(
                    gradient: new LinearGradient(colors: [
                      new Color(0xFFA19D9A),
                      Colors.white,
                      new Color(0xFFA19D9A),
                    ]),
                    borderRadius:
                        new BorderRadius.all(new Radius.circular(25.0))),
                child: new Container(
                  margin: const EdgeInsets.all(5.0),
                  decoration: new BoxDecoration(
                      color: Colors.teal,
                      borderRadius:
                          new BorderRadius.all(new Radius.circular(22.0))),
                  child: new Padding(
                    padding: const EdgeInsets.all(5.0),
                    child: new Text(
                      "Get recommendations by selecting any icon",
                      style: new TextStyle(
                          fontSize: 22.0,
                          color: Colors.white,
                          fontFamily: 'CaviarDreams',
                          fontWeight: FontWeight.w600),
                      textAlign: TextAlign.center,
                    ),
                  ),
                ),
              ),
            ),
            _buildStackView(),
          ],
        ),
      ),
    );
  }

  Widget _buildStackView() {
    final List<Widget> beverages = <Widget>[];
    double width = MediaQuery.of(context).size.width;
    double height = MediaQuery.of(context).size.height;
    double outerRadius = Math.min(width * 3 / 4, height * 3 / 4);
    double innerWhiteRadius = outerRadius * 3 / 4;

    for (int i = 0; i < items.length; i++) {
      beverages.add(_buildIcons(i));
    }

    return Flexible(
      child: Container(
        padding: EdgeInsets.all(10.0),
        child: new Stack(
          alignment: AlignmentDirectional.center,
          children: <Widget>[
            _drawCircle(outerRadius + 5, Colors.teal[100]),
            _drawCircle(outerRadius, Colors.white),
            _drawCircle(outerRadius / 2, Colors.teal[100]),
            _drawCircle((outerRadius - 40) / 2, Colors.teal),
            new CustomMultiChildLayout(
              delegate: new _CircularLayoutDelegate(
                itemCount: items.length,
                radius: outerRadius / 2,
              ),
              children: beverages,
            ),
            GestureDetector(
                onTap: () {
                  Navigator.of(context).pushNamed("/ask/capture");
                },
                child: Icon(
                  Icons.check,
                  size: 100,
                  color: Colors.white,
                )),
          ],
        ),
      ),
    );
  }

  // Draw a circle with given radius and color.
  Widget _drawCircle(double outerRadius, Color color) {
    return new Container(
      decoration: new BoxDecoration(shape: BoxShape.circle, color: color),
      width: outerRadius,
      height: outerRadius,
    );
  }

  Widget _buildIcons(int index) {
    final Widget item = items[index];

    return new LayoutId(
      id: 'BUTTON$index',
      child: item,
    );
  }
}

double _calculateItemAngle(int index) {
  double _itemSpacing = 360.0 / 5.0;
  return _startAngle + index * _itemSpacing * _radiansPerDegree;
}

class _CircularLayoutDelegate extends MultiChildLayoutDelegate {
  static const String actionButton = 'BUTTON';

  final int itemCount;
  final double radius;

  _CircularLayoutDelegate({
    @required this.itemCount,
    @required this.radius,
  });

  Offset center;

  @override
  void performLayout(Size size) {
    center = new Offset(size.width / 2, size.height / 2);
    for (int i = 0; i < itemCount; i++) {
      final String actionButtonId = '$actionButton$i';

      if (hasChild(actionButtonId)) {
        final Size buttonSize =
            layoutChild(actionButtonId, new BoxConstraints.loose(size));

        final double itemAngle = _calculateItemAngle(i);

        positionChild(
          actionButtonId,
          new Offset(
            (center.dx - buttonSize.width / 2) + (radius) * Math.cos(itemAngle),
            (center.dy - buttonSize.height / 2) +
                (radius) * Math.sin(itemAngle),
          ),
        );
      }
    }
  }

  @override
  bool shouldRelayout(_CircularLayoutDelegate oldDelegate) =>
      itemCount != oldDelegate.itemCount || radius != oldDelegate.radius;
}