如何在颤动中拥有这样的圆形？答案

【问题标题】：How to have a circle shape like this in flutter?如何在颤动中拥有这样的圆形？
【发布时间】：2019-06-17 07:43:13
【问题描述】：

我试图在我的颤振项目中使用这样的圆形。我尝试在容器中使用边界半径。但它并没有像我预期的那样工作。

那么，我怎样才能有这样一个给定图片的形状？

我尝试过使用这样的容器。

    Container(
            height: 72,
            width: 211,
            decoration: BoxDecoration(
              color: Colors.blue,
              borderRadius: BorderRadius.only(
                topRight: Radius.circular(50),
                topLeft: Radius.circular(30))
            ),
          )

【问题讨论】：

你有没有尝试过实现这个目标？
是的，我在容器中尝试了边界半径。但它并没有像我预期的那样工作
也发布您的代码？
你能分享更详细的图像，以便用户可以轻松识别你想要的视图形状吗？
它已更新。请检查@farhana

标签： user-interface flutter dart geometry shapes

【解决方案1】：

您几乎可以使用 CustomPaint 绘制任何东西，看看：

https://api.flutter.dev/flutter/rendering/CustomPainter-class.html

在下面的代码中，我画了类似那个圆圈的东西：

import "package:flutter/material.dart";

void main() {
  runApp(MaterialApp(title: "", home: Home()));
}

class Home extends StatefulWidget {
  @override
  _HomeState createState() => _HomeState();
}

class _HomeState extends State<Home> {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(),
        body: Container(
            width: double.infinity,
            height: double.infinity,
            child: CustomPaint(
              painter: CirclePainter(),
            )),
      ),
    );
  }
}

class CirclePainter extends CustomPainter {
  final Paint lightBluePaint = Paint()..color = Color(0xFFbde5fa);
  final Paint bluePaint = Paint()..color = Color(0xFF5abef2);
  final TextPainter textPainter = TextPainter(
    textDirection: TextDirection.ltr,
  );

  final TextStyle textStyle = TextStyle(
      color: Colors.white.withAlpha(240),
      fontSize: 18,
      letterSpacing: 1.2,
      fontWeight: FontWeight.w900);

  @override
  void paint(Canvas canvas, Size size) {
    var rect = Rect.fromLTRB(
        -100, size.height - 120, size.width * 0.7, size.height + 250);

    final Path circle = Path()..addOval(rect);
    final Path smallCircle = Path()..addOval(rect.inflate(50));

    canvas.drawPath(smallCircle, lightBluePaint);
    canvas.drawPath(circle, bluePaint);

    drawText(canvas, size, 'Write now');
  }

  void drawText(Canvas canvas, Size size, String text) {
    textPainter.text = TextSpan(style: textStyle, text: text);
    textPainter.layout();
    textPainter.paint(canvas, Offset(50, size.height - 60));
  }

  @override
  bool shouldRepaint(CustomPainter oldDelegate) {
    return true;
  }
}

【讨论】：

【解决方案2】：

要实现图像预览，您需要使用 Stack 类和 Positioned 元素。我做了一个小部件，如图所示。角落里的圆圈可以用带有边界半径的容器制作。

  Container(
    width: MediaQuery.of(context).size.width,
    height: 250,
    margin: EdgeInsets.all(20),
    decoration: BoxDecoration(
      color: Colors.white,
      boxShadow: <BoxShadow>[
        BoxShadow(
          color: Color(0x40000000),
          blurRadius: 5.0,
          spreadRadius: 0.0,
          offset: Offset(0.0, 2.0),
        ),
      ],
    ),
    child: Stack(
      children: <Widget>[
        Container(
          padding: EdgeInsets.all(15.0),
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.start,
            children: <Widget>[
              Text(
                'Step 3',
                style: TextStyle(
                  color: Colors.blue,
                ),
              ),
              SizedBox(height: 5),
              Text(
                'It is a long established fact that a reader will be '
                  'distracted by the readable content of a page when '
                  'looking at its layout.',
                style: TextStyle(
                  color: Colors.black54,
                ),
              )
            ],
          ),
        ),
        Positioned(
          top: 150,
          right: MediaQuery.of(context).size.width - 200,
          child: Container(
            width: 200,
            height: 200,
            decoration: BoxDecoration(
              color: Color(0xFFB5E1F9),
              borderRadius: BorderRadius.all(
                Radius.circular(200),
              ),
            ),
            child: Center(
              child: Container(
                width: 150,
                height: 150,
                decoration: BoxDecoration(
                  color: Color(0xFF4FB6F0),
                  borderRadius: BorderRadius.all(
                    Radius.circular(150),
                  ),
                ),
              ),
            ),
          ),
        ),
        Positioned(
          bottom: 30,
          left: 30,
          child: Text(
            'Write now',
            style: TextStyle(
              color: Colors.white,
            ),
          ),
        ),
      ],
    ),
  );

【讨论】：