CanCirPro 使用canvas标签绘制 圆环进度条 有渐变和动画

CanCirPro 使用canvas标签绘制 圆环进度条 有渐变和动画

1. import React, { Component } from "react";
   import PropTypes from "prop-types";
   
   export default class CanCirPro extends Component {
   
      constructor(props) {
          super(props);
          this.state = {
              percent: 0,
          };
      }
   
      static defaultProps = {
          radius: 45,
          percent: 47.7,
          borderWidth: 6,
          startcolor: '#ffd460',
          centercolor: '#fcc241',
          endColor: '#f79d00',
          textStyle: { fontSize: 11, color: "#fa9a22", textAlign: 'center' },
          openAnimation: true
      }
      static propTypes = {
          radius: PropTypes.number,
          percent: PropTypes.number,
          borderWidth: PropTypes.number,
          startcolor: PropTypes.string,
          centercolor: PropTypes.string,
          endColor: PropTypes.string,
          textStyle: PropTypes.object,
          openAnimation: PropTypes.bool,
      }
      render() {
          return (
   "cancirproOut" style={{
              width: (this.props.radius + this.props.borderWidth) * 2,
              height: (this.props.radius + this.props.borderWidth) * 2,
          }} >
              "cancirproIn" ref={cancirpro => {
                  this.onDraw(cancirpro);//ref时开始绘制
              }}
                  width={(this.props.radius + this.props.borderWidth) * 2} height={(this.props.radius + this.props.borderWidth) * 2}
              />
   
              
   "cancirproContent" style={{
                  width: (this.props.radius + this.props.borderWidth) * 2,
                  height: (this.props.radius + this.props.borderWidth) * 2,
                  marginTop: - (this.props.radius + this.props.borderWidth) * 2 - this.props.borderWidth/2
              }} >
                  {this.props.children ? this.props.children :
                      
   this.props.textStyle}>{this.props.openAnimation ? this.state.percent : this.props.percent}%
   }
              
   
          
   );
      }
      componentWillReceiveProps(newprops) {
          this.setState({ percent: 0 });
          this.time = setTimeout(() => {
              this.componentDidMount();
          }, 1);
      }
      componentDidMount() {
          if (this.props.openAnimation) {
              this.startAnimation();
          }
      }
   
      startAnimation() {
          if (this.state.percent < this.props.percent - 2) {
              this.time = setTimeout(() => {
                  this.setState({ percent: this.state.percent + 2 });
                  this.startAnimation();
              }, 11);
          } else {
              this.setState({ percent: this.props.percent });
          }
      }
   
      onDraw(cancirpro) {
          if (cancirpro) {//如果cancirpro存在
   
              let canvas = cancirpro;
              let ctx = canvas.getContext("2d");
              ctx.clearRect(0, 0, (this.props.radius + this.props.borderWidth) * 2, (this.props.radius + this.props.borderWidth) * 2);//清空绘画区域
   
              if (this.props.percent !== 0) {
                  let percent = this.props.openAnimation ? this.state.percent : this.props.percent;
                  let width = (this.props.radius + this.props.borderWidth) * 2;
                  if (window.devicePixelRatio) {
                      canvas.style.width = width + "px";
                      canvas.style.height = width + "px";
                      canvas.height = width * window.devicePixelRatio;
                      canvas.width = width * window.devicePixelRatio;
                      ctx.scale(window.devicePixelRatio, window.devicePixelRatio);
                  }//使用ctx.scale，解决锯齿严重问题
   
                  ctx.beginPath();
                  let grd1 = ctx.createLinearGradient(0, 0, 0, this.props.radius * 2);
                  grd1.addColorStop(0, this.props.startcolor);
                  grd1.addColorStop(1, this.props.centercolor);//线性渐变定义
                  ctx.lineCap = 'round';//连接处圆头
                  ctx.strokeStyle = grd1;//设置strokeStyle为渐变色
                  ctx.lineWidth = this.props.borderWidth;//圆环宽度
   
                  if (percent < 50) {//小于50,绘制前半部分的部分半圆
                      ctx.arc(this.props.radius + this.props.borderWidth, this.props.radius + this.props.borderWidth, this.props.radius, Math.PI * (1.4), Math.PI * (1.4 + percent / 50), false);
                  } else {//大于50,绘制前半部分的完整半圆
                      ctx.arc(this.props.radius + this.props.borderWidth, this.props.radius + this.props.borderWidth, this.props.radius, Math.PI * (1.4), Math.PI * (1.4 + 1), false);
                  }
                  ctx.stroke();
   
   
                  if (percent > 50) {//大于50,才绘制后半部分需要的半圆
                      ctx.beginPath();
                      let grd2 = ctx.createLinearGradient(0, this.props.radius * 2, 0, 0);
                      grd2.addColorStop(0, this.props.centercolor);
                      grd2.addColorStop(1, this.props.endColor);
                      ctx.lineCap = 'round';
                      ctx.strokeStyle = grd2;
                      ctx.lineWidth = this.props.borderWidth;
                      ctx.arc(this.props.radius + this.props.borderWidth, this.props.radius + this.props.borderWidth, this.props.radius, Math.PI * (2.4), Math.PI * (2.4 + ((percent - 50) / 50)), false);
                      ctx.stroke();
                  }
              }
          }
      }
   
   }
   

2. .cancirproOut {
      overflow: hidden;
    }
   .cancirproContent {
      display: flex;
      display: -webkit-flex;
      justify-content: center;
      -webkit-justify-content: center;
      align-items: center;
      -webkit-align-items: center;
    }

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github

​ https://github.com/1cao2mu/react-circle-progress 如果只是参考思路，也请给个star 谢谢