flutter - 如何在颤动的盒子周围创建虚线边框？

Question

我正在使用颤振在我的应用程序中构建一个盒子布局列表。我想要盒子周围的虚线边框。我已经使用card小部件来创建盒子。但是，我怎样才能在盒子周围得到虚线边框？

Answer 1

编辑

我已将此作为包添加到pub中。

现在，你需要做的就是

DottedBorder(
  color: Colors.black,
  gap: 3,
  strokeWidth: 1,
  child: FlutterLogo(size: 148),
)

工作解决方案[过时]

就像tomerpacific在这个答案中所说的那样，Flutter 目前没有虚线边框的默认实现。

我昨天工作了一段时间，并且能够使用CustomPainter. 希望这可以帮助某人。

像这样添加DashedRect到您的容器中

class _MyHomePageState extends State<MyHomePage> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Center(
        child: Container(
          height: 400,
          width: 300,
          color: Colors.black12,
          child: DashedRect(color: Colors.red, strokeWidth: 2.0, gap: 3.0,),
        ),
      ),
    );
  }
}

虚线矩形.dart

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

class DashedRect extends StatelessWidget {
  final Color color;
  final double strokeWidth;
  final double gap;

  DashedRect(
      {this.color = Colors.black, this.strokeWidth = 1.0, this.gap = 5.0});

  @override
  Widget build(BuildContext context) {
    return Container(
      child: Padding(
        padding: EdgeInsets.all(strokeWidth / 2),
        child: CustomPaint(
          painter:
              DashRectPainter(color: color, strokeWidth: strokeWidth, gap: gap),
        ),
      ),
    );
  }
}

class DashRectPainter extends CustomPainter {
  double strokeWidth;
  Color color;
  double gap;

  DashRectPainter(
      {this.strokeWidth = 5.0, this.color = Colors.red, this.gap = 5.0});

  @override
  void paint(Canvas canvas, Size size) {
    Paint dashedPaint = Paint()
      ..color = color
      ..strokeWidth = strokeWidth
      ..style = PaintingStyle.stroke;

    double x = size.width;
    double y = size.height;

    Path _topPath = getDashedPath(
      a: math.Point(0, 0),
      b: math.Point(x, 0),
      gap: gap,
    );

    Path _rightPath = getDashedPath(
      a: math.Point(x, 0),
      b: math.Point(x, y),
      gap: gap,
    );

    Path _bottomPath = getDashedPath(
      a: math.Point(0, y),
      b: math.Point(x, y),
      gap: gap,
    );

    Path _leftPath = getDashedPath(
      a: math.Point(0, 0),
      b: math.Point(0.001, y),
      gap: gap,
    );

    canvas.drawPath(_topPath, dashedPaint);
    canvas.drawPath(_rightPath, dashedPaint);
    canvas.drawPath(_bottomPath, dashedPaint);
    canvas.drawPath(_leftPath, dashedPaint);
  }

  Path getDashedPath({
    @required math.Point<double> a,
    @required math.Point<double> b,
    @required gap,
  }) {
    Size size = Size(b.x - a.x, b.y - a.y);
    Path path = Path();
    path.moveTo(a.x, a.y);
    bool shouldDraw = true;
    math.Point currentPoint = math.Point(a.x, a.y);

    num radians = math.atan(size.height / size.width);

    num dx = math.cos(radians) * gap < 0
        ? math.cos(radians) * gap * -1
        : math.cos(radians) * gap;

    num dy = math.sin(radians) * gap < 0
        ? math.sin(radians) * gap * -1
        : math.sin(radians) * gap;

    while (currentPoint.x <= b.x && currentPoint.y <= b.y) {
      shouldDraw
          ? path.lineTo(currentPoint.x, currentPoint.y)
          : path.moveTo(currentPoint.x, currentPoint.y);
      shouldDraw = !shouldDraw;
      currentPoint = math.Point(
        currentPoint.x + dx,
        currentPoint.y + dy,
      );
    }
    return path;
  }

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

我不希望这适用于所有用例，并且有很大的定制和改进空间。如果您发现任何错误，请发表评论。

Answer 2

这是一个fdottedline颤振包，可轻松在小部件周围添加虚线边框。这使用最简单的方法来创建虚线视图，并为开发人员提供创建虚线的能力。它还支持为 [Widget] 创建虚线边框。支持控制虚线边框的粗细、间距和角。

1. 要使用此包，请在文件中添加fdottedline作为依赖项。pubspec.yaml

2. 用法：虚线形状演示

   FDottedLine(
     color: Colors.lightBlue[600],
     height: 100.0,
     width: 50,
     strokeWidth: 2.0,
     dottedLength: 10.0,
     space: 2.0,
   )
   

Answer 3

您可以使用dotted_border Flutter 包

return DottedBorder(
   borderType: BorderType.RRect,
   radius: Radius.circular(20),
   dashPattern: [10, 10],
   color: Colors.grey,
   strokeWidth: 2,
   child: Card(
       color: Colors.amber,
       shape: RoundedRectangleBorder(
          borderRadius: BorderRadius.circular(10),
       ),
       child: Center(child: Text("hi")),
   )

Answer 4

最近 Flutter 发布了一个用于在小部件周围绘制虚线边框的插件

https://pub.dev/packages/dotted_border

使用此插件，您可以绘制虚线或虚线边框

//1. Install the plugin by add dependencies in pubspace.yaml
dotted_border: ^1.0.6

添加以下代码以显示边框

DottedBorder(
color: Colors.black,
strokeWidth: 1,
child: FlutterLogo(size: 148),
)

Answer 5

目前，Flutter 不支持虚线边框，因为只有两种样式：

Solid or None

要为您的小部件添加边框，您需要执行以下操作：

• 将 BoxDecoration 属性添加到您的小部件

• BoxDecoration 的部分属性是border

   decoration: BoxDecoration(
    border: Border.all(
       width: 1,
       style: BorderStyle.solid/none
     ),
   );
  

我还发现了这个 SO question，它演示了如何添加圆形虚线边框。

Answer 6

如果您想应用一些动画或删除\添加边框功能 onTap（如照明边框）事件或类似事件，BorderStyle.none 会很有用。