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如何实现一个双向PK进度条

在Flutter应用中，进度条是一个非常常见的组件。而双向PK进度条则能够展示两个对立的数值，如对战中的双方得分对比等。本文将介绍如何实现一个具有双向PK效果的进度条，并支持竖直和斜角两种过渡效果。

1. 需求

我们需要一个自定义的双向PK进度条，要求如下：

• 能够显示两个对立的数值。
• 进度条两端有圆角。
• 中间过渡部分可以是竖直或者45度斜角。
• 支持自定义颜色和高度。

2. 效果

通过我们的实现，可以得到如下效果：

3. 实现思路

1. 定义组件：创建一个自定义的PKProgressBar组件，包含左右两侧的数值、颜色、高度和过渡类型。
2. 绘制左侧和右侧的圆角矩形：使用CustomPainter来绘制左右两部分的圆角矩形。
3. 处理中间过渡部分：根据过渡类型绘制竖直或者45度斜角的过渡效果。

4. 实现代码

下面是实现双向PK进度条的完整代码：

import 'package:flutter/material.dart';void main() => runApp(MyApp());class MyApp extends StatelessWidget {@overrideWidget build(BuildContext context) {return MaterialApp(home: Scaffold(appBar: AppBar(title: const Text('双向PK进度条')),body: const Center(child: Padding(padding: EdgeInsets.symmetric(horizontal: 16),child: Column(mainAxisAlignment: MainAxisAlignment.center,children: [PKProgressBar(leftValue: 75,rightValue: 150,leftColor: Colors.blue,rightColor: Colors.red,height: 20,transitionType: TransitionType.diagonal, // 设置过渡类型为斜角),SizedBox(height: 50),PKProgressBar(leftValue: 90,rightValue: 55,leftColor: Colors.brown,rightColor: Colors.green,height: 20,transitionType: TransitionType.vertical, // 设置过渡类型为竖直),],),)),),);}
}// 定义过渡类型枚举
enum TransitionType { vertical, diagonal }class PKProgressBar extends StatelessWidget {final double leftValue;final double rightValue;final Color leftColor;final Color rightColor;final double height;final TransitionType transitionType;const PKProgressBar({super.key,required this.leftValue,required this.rightValue,required this.leftColor,required this.rightColor,this.height = 20.0,this.transitionType = TransitionType.diagonal, // 默认过渡类型为斜角});@overrideWidget build(BuildContext context) {return CustomPaint(size: Size(double.infinity, height),painter: PKProgressPainter(leftValue: leftValue,rightValue: rightValue,leftColor: leftColor,rightColor: rightColor,transitionType: transitionType,),);}
}class PKProgressPainter extends CustomPainter {final double leftValue;final double rightValue;final Color leftColor;final Color rightColor;final TransitionType transitionType;PKProgressPainter({required this.leftValue,required this.rightValue,required this.leftColor,required this.rightColor,required this.transitionType,});@overridevoid paint(Canvas canvas, Size size) {final paint = Paint()..style = PaintingStyle.fill;final double totalValue = leftValue + rightValue;final double leftWidth = (leftValue / totalValue) * size.width;final double rightWidth = (rightValue / totalValue) * size.width;final double radius = size.height / 2;// 左侧带圆角的矩形final leftRRect = RRect.fromLTRBAndCorners(0,0,leftWidth,size.height,topLeft: Radius.circular(radius),bottomLeft: Radius.circular(radius),);// 右侧带圆角的矩形final rightRRect = RRect.fromLTRBAndCorners(leftWidth,0,size.width,size.height,topRight: Radius.circular(radius),bottomRight: Radius.circular(radius),);// 绘制左侧部分paint.color = leftColor;canvas.drawRRect(leftRRect, paint);// 绘制右侧部分paint.color = rightColor;canvas.drawRRect(rightRRect, paint);// 根据过渡类型绘制中间部分if (transitionType == TransitionType.vertical) {// 竖直过渡final middleRect = Rect.fromLTWH(leftWidth - radius,0,2 * radius,size.height,);paint.color = rightColor;canvas.drawRect(middleRect, paint);} else if (transitionType == TransitionType.diagonal) {// 斜角过渡，形成45度斜线final leftPath = Path()..moveTo(leftWidth - size.height / 2, 0)..lineTo(leftWidth + size.height / 2, size.height)..lineTo(leftWidth - size.height / 2, size.height)..close();paint.color = leftColor;canvas.drawPath(leftPath, paint);// 斜角过渡，形成45度斜线final rightPath = Path()..moveTo(leftWidth - size.height / 2, 0)..lineTo(leftWidth, 0)..lineTo(leftWidth, size.height)..close();paint.color = rightColor;canvas.drawPath(rightPath, paint);}}@overridebool shouldRepaint(covariant CustomPainter oldDelegate) {return false;}
}

在这个实现中，我们通过CustomPainter来自定义绘制PK进度条，并根据过渡类型绘制竖直或斜角的过渡效果。通过这些代码，你可以轻松实现一个具有双向PK效果的进度条，并根据需求调整样式和效果。