pco/app/uview-ui/components/u-count-to/u-count-to.vue

<template>
  <text
      class="u-count-num"
      :style="{
			fontSize: $u.addUnit(fontSize),
			fontWeight: bold ? 'bold' : 'normal',
			color: color
		}"
  >{{ displayValue }}
  </text>
</template>

<script>
import props from './props.js';

/**
 * countTo 数字滚动
 * @description 该组件一般用于需要滚动数字到某一个值的场景，目标要求是一个递增的值。
 * @tutorial https://www.uviewui.com/components/countTo.html
 * @property {String | Number}  startVal  开始的数值，默认从0增长到某一个数（默认 0 ）
 * @property {String | Number}  endVal    要滚动的目标数值，必须 （默认 0 ）
 * @property {String | Number}  duration  滚动到目标数值的动画持续时间，单位为毫秒（ms） （默认 2000 ）
 * @property {Boolean}      autoplay  设置数值后是否自动开始滚动 （默认 true ）
 * @property {String | Number}  decimals  要显示的小数位数，见官网说明（默认 0 ）
 * @property {Boolean}      useEasing  滚动结束时，是否缓动结尾，见官网说明（默认 true ）
 * @property {String}      decimal    十进制分割 （ 默认 "." ）
 * @property {String}      color    字体颜色（ 默认 '#606266' )
 * @property {String | Number}  fontSize  字体大小，单位px（ 默认 22 ）
 * @property {Boolean}      bold    字体是否加粗（默认 false ）
 * @property {String}      separator  千位分隔符，见官网说明
 * @event {Function} end 数值滚动到目标值时触发
 * @example <u-count-to ref="uCountTo" :end-val="endVal" :autoplay="autoplay"></u-count-to>
 */
export default {
  name: 'u-count-to',
  data() {
    return {
      localStartVal: this.startVal,
      displayValue: this.formatNumber(this.startVal),
      printVal: null,
      paused: false, // 是否暂停
      localDuration: Number(this.duration),
      startTime: null, // 开始的时间
      timestamp: null, // 时间戳
      remaining: null, // 停留的时间
      rAF: null,
      lastTime: 0 // 上一次的时间
    };
  },
  mixins: [uni.$u.mpMixin, uni.$u.mixin, props],
  computed: {
    countDown() {
      return this.startVal > this.endVal;
    }
  },
  watch: {
    startVal() {
      this.autoplay && this.start();
    },
    endVal() {
      this.autoplay && this.start();
    }
  },
  mounted() {
    this.autoplay && this.start();
  },
  methods: {
    easingFn(t, b, c, d) {
      return (c * (-Math.pow(2, (-10 * t) / d) + 1) * 1024) / 1023 + b;
    },
    requestAnimationFrame(callback) {
      const currTime = new Date().getTime();
      // 为了使setTimteout的尽可能的接近每秒60帧的效果
      const timeToCall = Math.max(0, 16 - (currTime - this.lastTime));
      const id = setTimeout(() => {
        callback(currTime + timeToCall);
      }, timeToCall);
      this.lastTime = currTime + timeToCall;
      return id;
    },
    cancelAnimationFrame(id) {
      clearTimeout(id);
    },
    // 开始滚动数字
    start() {
      this.localStartVal = this.startVal;
      this.startTime = null;
      this.localDuration = this.duration;
      this.paused = false;
      this.rAF = this.requestAnimationFrame(this.count);
    },
    // 暂定状态，重新再开始滚动；或者滚动状态下，暂停
    reStart() {
      if (this.paused) {
        this.resume();
        this.paused = false;
      } else {
        this.stop();
        this.paused = true;
      }
    },
    // 暂停
    stop() {
      this.cancelAnimationFrame(this.rAF);
    },
    // 重新开始(暂停的情况下)
    resume() {
      if (!this.remaining) return
      this.startTime = 0;
      this.localDuration = this.remaining;
      this.localStartVal = this.printVal;
      this.requestAnimationFrame(this.count);
    },
    // 重置
    reset() {
      this.startTime = null;
      this.cancelAnimationFrame(this.rAF);
      this.displayValue = this.formatNumber(this.startVal);
    },
    count(timestamp) {
      if (!this.startTime) this.startTime = timestamp;
      this.timestamp = timestamp;
      const progress = timestamp - this.startTime;
      this.remaining = this.localDuration - progress;
      if (this.useEasing) {
        if (this.countDown) {
          this.printVal = this.localStartVal - this.easingFn(progress, 0, this.localStartVal - this.endVal, this.localDuration);
        } else {
          this.printVal = this.easingFn(progress, this.localStartVal, this.endVal - this.localStartVal, this.localDuration);
        }
      } else {
        if (this.countDown) {
          this.printVal = this.localStartVal - (this.localStartVal - this.endVal) * (progress / this.localDuration);
        } else {
          this.printVal = this.localStartVal + (this.endVal - this.localStartVal) * (progress / this.localDuration);
        }
      }
      if (this.countDown) {
        this.printVal = this.printVal < this.endVal ? this.endVal : this.printVal;
      } else {
        this.printVal = this.printVal > this.endVal ? this.endVal : this.printVal;
      }
      this.displayValue = this.formatNumber(this.printVal) || 0;
      if (progress < this.localDuration) {
        this.rAF = this.requestAnimationFrame(this.count);
      } else {
        this.$emit('end');
      }
    },
    // 判断是否数字
    isNumber(val) {
      return !isNaN(parseFloat(val));
    },
    formatNumber(num) {
      // 将num转为Number类型，因为其值可能为字符串数值，调用toFixed会报错
      num = Number(num);
      num = num.toFixed(Number(this.decimals));
      num += '';
      const x = num.split('.');
      let x1 = x[0];
      const x2 = x.length > 1 ? this.decimal + x[1] : '';
      const rgx = /(\d+)(\d{3})/;
      if (this.separator && !this.isNumber(this.separator)) {
        while (rgx.test(x1)) {
          x1 = x1.replace(rgx, '$1' + this.separator + '$2');
        }
      }
      return x1 + x2;
    },
    destroyed() {
      this.cancelAnimationFrame(this.rAF);
    }
  }
};
</script>

<style lang="scss" scoped>
@import "../../libs/css/components.scss";

.u-count-num {
  /* #ifndef APP-NVUE */
  display: inline-flex;
  /* #endif */
  text-align: center;
}
</style>