vue.js 利用canvas绘制简易仪表盘进度条

html代码

因为动画效果比较消耗性能，所以进度条单独canvas绘制

<template>
  <div class="circle_box">
    <!-- 内容 -->
    <div class="circleText">
      <div class="score">{{ score }}</div>
      <div class="desc">您本次得分</div>
    </div>
    <!-- 进度条 -->
    <canvas class="circle canvasArcCir" style="z-index: 3;"></canvas>
    <!-- 大圆环 -->
    <canvas class="circle canvasCircle" style="z-index: 2;"></canvas>
  </div>
</template>

绘制灰色圆环

	drawLine() {
      //创建并返回绘图上下文context对象。
      //灰色圆环
      var el_circle = document.querySelector(".canvasCircle");
      el_circle.width = this.canvasWidth;
      el_circle.height = this.canvasWidth;
      var cxt_arc = el_circle.getContext("2d");
      //线条宽度
      cxt_arc.lineWidth = this.lineWidth;
      //线条颜色
      cxt_arc.strokeStyle = '#eaeaea';
      //线段两端为圆角
      cxt_arc.lineCap = 'round';
      cxt_arc.beginPath();
      //cxt_arc.arc(x,y,半径,开始端点,结束端点,顺时针)
      //arc绘制起点为时钟3点为起点，顺时针转0.8*Math.PI，对应的终点为2.8*Math.PI，需要两端对齐则终点为2.2*Math.PI
      cxt_arc.arc(this.canvasWidth / 2, this.canvasWidth / 2, this.canvasWidth / 2 - this.lineWidth * 3, 0.8 * Math.PI, 2.2 * Math.PI, false);
      cxt_arc.stroke();
      // 这里就是进度条的显示
      this.drawCirclePg();
    }

绘制进度条

	drawCirclePg() {
      //创建并返回绘图上下文context对象。
      var el_arcCir = document.querySelector(".canvasArcCir");
      el_arcCir.width = this.canvasWidth;
      el_arcCir.height = this.canvasWidth;
      var cxt_arc = el_arcCir.getContext("2d");
      var value = this.score / 100;    //得分占比
      var count = 0;
      var animation = () => {
        count += 0.01;
        // 清除上次绘画进度条
        cxt_arc.clearRect(0, 0, this.canvasWidth, this.canvasHeight);
        cxt_arc.lineWidth = this.lineWidth;

        // 颜色渐变-横向渐变
        var my_gradient = cxt_arc.createLinearGradient(0, 0, this.canvasWidth, 0);
        my_gradient.addColorStop(1, "#FF88CE");
        my_gradient.addColorStop(0, "orange");
        cxt_arc.strokeStyle = my_gradient;

        cxt_arc.lineCap = 'round';
        cxt_arc.beginPath();
        cxt_arc.arc(this.canvasWidth / 2, this.canvasWidth / 2, this.canvasWidth / 2 - this.lineWidth * 3, 0.8 * Math.PI, count * (1.4 * Math.PI) + 0.8 * Math.PI, false);
        cxt_arc.stroke();

        if (count >= value) {
          this.clearTime();
        }
      }
      this.varName = setInterval(animation, 30);
    } 

完整代码

<template>
  <div class="circle_box">
    <!-- 内容 -->
    <div class="circleText">
      <div class="score">{{ score }}</div>
      <div class="desc">您本次得分</div>
    </div>
    <!-- 进度条 -->
    <canvas class="circle canvasArcCir" style="z-index: 3;"></canvas>
    <!-- 大圆环 -->
    <canvas class="circle canvasCircle" style="z-index: 2;"></canvas>
  </div>
</template>

<script>

export default {
  data() {
    return {
      varName: null,
      score: 80,
      canvasWidth: 470,
      canvasHeight: 470,
      lineWidth: 16
    };
  },
  mounted() {
    this.drawLine();
  },
  beforeDestroy() {
    this.clearTime();
  },
  methods: {
    //清空定时器
    clearTime() {
      if (this.varName) {
        clearInterval(this.varName);
      }
    },
    drawLine() {
      //创建并返回绘图上下文context对象。
      //灰色圆环
      var el_circle = document.querySelector(".canvasCircle");
      el_circle.width = this.canvasWidth;
      el_circle.height = this.canvasWidth;
      var cxt_arc = el_circle.getContext("2d");
      //线条宽度
      cxt_arc.lineWidth = this.lineWidth;
      //线条颜色
      cxt_arc.strokeStyle = '#eaeaea';
      //线段两端为圆角
      cxt_arc.lineCap = 'round';
      cxt_arc.beginPath();
      //cxt_arc.arc(x,y,半径,开始端点,结束端点,顺时针)
      //arc绘制起点为时钟3点为起点，顺时针转0.8*Math.PI，对应的终点为2.8*Math.PI，需要两端对齐则终点为2.2*Math.PI
      cxt_arc.arc(this.canvasWidth / 2, this.canvasWidth / 2, this.canvasWidth / 2 - this.lineWidth * 3, 0.8 * Math.PI, 2.2 * Math.PI, false);
      cxt_arc.stroke();
      // 这里就是进度条的显示
      this.drawCirclePg();
    },
    drawCirclePg() {
      //创建并返回绘图上下文context对象。
      var el_arcCir = document.querySelector(".canvasArcCir");
      el_arcCir.width = this.canvasWidth;
      el_arcCir.height = this.canvasWidth;
      var cxt_arc = el_arcCir.getContext("2d");
      var value = this.score / 100;    //得分占比
      var count = 0;
      var animation = () => {
        count += 0.01;
        // 清除上次绘画进度条
        cxt_arc.clearRect(0, 0, this.canvasWidth, this.canvasHeight);
        cxt_arc.lineWidth = this.lineWidth;

        // 颜色渐变-横向渐变
        var my_gradient = cxt_arc.createLinearGradient(0, 0, this.canvasWidth, 0);
        my_gradient.addColorStop(1, "#FF88CE");
        my_gradient.addColorStop(0, "orange");
        cxt_arc.strokeStyle = my_gradient;

        cxt_arc.lineCap = 'round';
        cxt_arc.beginPath();
        cxt_arc.arc(this.canvasWidth / 2, this.canvasWidth / 2, this.canvasWidth / 2 - this.lineWidth * 3, 0.8 * Math.PI, count * (1.4 * Math.PI) + 0.8 * Math.PI, false);
        cxt_arc.stroke();

        if (count >= value) {
          this.clearTime();
        }
      }
      this.varName = setInterval(animation, 30);
    },
  }
};
</script>

<style scoped lang='scss'>
.circle_box {
  width: 470px;
  height: 470px;
  position: absolute;
  margin: auto;
  left: 0;
  top: 0;
  right: 0;
  bottom: 0;
  box-sizing: border-box;
}

.circle {
  position: absolute;
  left: 0;
  right: 0;
  margin: auto;
  width: 100%;
  height: 100%;
}

.circleText {
  text-align: center;
  position: absolute;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  margin: auto;
  width: 100%;
  height: 100%;
  left: 0;
  top: 0;
  right: 0;
  bottom: 0;

  .score {
    color: #FF7600;
    font-size: 80px;
  }

  .desc {
    font-size: 30px;
  }
}
</style>