王明 / Recruitment

  <template>

  	<view

  		class="u-count-num"
  		:style="{

  			fontSize: fontSize + 'rpx',

  			fontWeight: bold ? 'bold' : 'normal',
  			color: color
  		}"

  	>
  		{{ displayValue }}
  	</view>

  </template>
  
  <script>

  /**
   * 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} start-val 开始值
   * @property {String Number} end-val 结束值
   * @property {String Number} duration 滚动过程所需的时间，单位ms（默认2000）
   * @property {Boolean} autoplay 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} use-easing 滚动结束时，是否缓动结尾，见官网说明（默认true）
   * @property {String} separator 千位分隔符，见官网说明
   * @property {String} color 字体颜色（默认#303133）
   * @property {String Number} font-size 字体大小，单位rpx（默认50）
   * @property {Boolean} bold 字体是否加粗（默认false）

   * @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',

  	props: {
  		// 开始的数值，默认从0增长到某一个数
  		startVal: {
  			type: [Number, String],
  			default: 0
  		},
  		// 要滚动的目标数值，必须
  		endVal: {
  			type: [Number, String],
  			default: 0,
  			required: true
  		},
  		// 滚动到目标数值的动画持续时间，单位为毫秒（ms）
  		duration: {
  			type: [Number, String],
  			default: 2000
  		},
  		// 设置数值后是否自动开始滚动
  		autoplay: {
  			type: Boolean,
  			default: true
  		},
  		// 要显示的小数位数
  		decimals: {
  			type: [Number, String],
  			default: 0
  		},
  		// 是否在即将到达目标数值的时候，使用缓慢滚动的效果
  		useEasing: {
  			type: Boolean,
  			default: true
  		},
  		// 十进制分割
  		decimal: {
  			type: [Number, String],
  			default: '.'
  		},
  		// 字体颜色
  		color: {
  			type: String,
  			default: '#303133'
  		},
  		// 字体大小
  		fontSize: {
  			type: [Number, String],
  			default: 50
  		},
  		// 是否加粗字体
  		bold: {
  			type: Boolean,
  			default: false
  		},
  		// 千位分隔符，类似金额的分割(￥23,321.05中的",")
  		separator: {
  			type: String,
  			default: ''
  		}
  	},

  	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
  		};
  	},

  	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() {

  			this.startTime = null;

  			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);

  			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/style.components.scss";

  
  .u-count-num {
  	/* #ifndef APP-NVUE */

  	display: inline-flex;		

  	/* #endif */
  	text-align: center;
  }
  </style>