vue后台实现点击图片放大

需求：
点击小图可以放大，放大后，通过手势等比例放大缩小、左右切换图、旋转、关闭。由于element-ui版本较低不支持使用图片放大的image组件。

代码
父组件：

<template>
	<div>
		
		<el-image-viewer v-if="showImg" :on-close="closeViewer"
                     :src="currItem"
                     :url-list="baseInfo.pictureUrlList"/>
		
		
		<div class="baseBoxPic">
          <div v-for="(item, index) in baseInfo.pictureUrlList" :key="index" class="picBox">
            <img :src="item" class="litPic" @click="bigImg(item)"/>
          div>
         div>
	div>
template>

<script>
import ElImageViewer from 'base/image/image-viewer'
export default {
	data() {
		return {
			baseInfo: {
				pictureUrlList: []
			},
			showImg: false,
     		currItem: ''
		}
	},
	components: {
   		'ElImageViewer': ElImageViewer
 	},
 	methods: {
  		// 放大
  		bigImg(e) {
    		this.currItem = e
    		this.showImg = true
  		},
  		// 关闭
  		closeViewer() {
    		this.showImg = false
  		},
  	}
}
script>
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子组件
base/image/image-viewer.vue

<template>
  <transition name="viewer-fade">
    <div class="el-image-viewer__wrapper" :style="{ 'z-index': zIndex }">
      <div class="el-image-viewer__mask">div>
      
      <span class="el-image-viewer__btn el-image-viewer__close" @click="hide">
        <i class="el-icon-circle-close">i>
      span>
      
      <template v-if="!isSingle">
        <span class="el-image-viewer__btn el-image-viewer__prev" :class="{ 'is-disabled': !infinite && isFirst }" @click="prev">
          <i class="el-icon-arrow-left" />
        span>
        <span class="el-image-viewer__btn el-image-viewer__next" :class="{ 'is-disabled': !infinite && isLast }" @click="next">
          <i class="el-icon-arrow-right" />
        span>
      template>
      
      <div class="el-image-viewer__btn el-image-viewer__actions">
        <div class="el-image-viewer__actions__inner">
          <i class="el-icon-zoom-out" style="margin-right: 10px;" @click="handleActions('zoomOut')">i>
          <i class="el-icon-zoom-in" style="margin-right: 10px;" @click="handleActions('zoomIn')">i>
          <i class="el-icon-refresh" @click="handleActions('clocelise')">i>
          <i class="el-image-viewer__actions__divider">i>
          <i :class="mode.icon" @click="toggleMode">i>
          <i class="el-image-viewer__actions__divider">i>
          <i class="el-icon-refresh-left" @click="handleActions('anticlocelise')">i>
          <i class="el-icon-refresh-right" @click="handleActions('clocelise')">i>
        div>
      div>
      
      <div class="el-image-viewer__canvas">
        <div v-for="(url, i) in urlList" v-if="i === index">
          <div v-if="isPdf">
            <a target="_blank" :href="currentImg" style="color: #fff; position: absolute;left: 50%; top: 50%">点击新页面查看a>
          div>
          <img v-else ref="img" class="el-image-viewer__img" :key="url" :src="currentImg" :style="imgStyle" @load="handleImgLoad" @error="handleImgError" @mousedown="handleMouseDown">
        div>
      div>
    div>
  transition>
template>

<script>
import { on, off } from './dom';
import { rafThrottle, isFirefox } from './util';
import pdf from 'vue-pdf'

const Mode = {
  CONTAIN: {
    name: 'contain',
    icon: 'el-icon-full-screen'
  },
  ORIGINAL: {
    name: 'original',
    icon: 'el-icon-c-scale-to-original'
  }
};
const mousewheelEventName = isFirefox() ? 'DOMMouseScroll' : 'mousewheel';
export default {
  name: 'elImageViewer',
  props: {
    urlList: {
      type: Array,
      default: () => []
    },
    zIndex: {
      type: Number,
      default: 2300
    },
    onSwitch: {
      type: Function,
      default: () => { }
    },
    onClose: {
      type: Function,
      default: () => { }
    }
  },
  data () {
    return {
      index: 0,
      isShow: false,
      infinite: true,
      loading: false,
      mode: Mode.CONTAIN,
      transform: {
        scale: 1,
        deg: 0,
        offsetX: 0,
        offsetY: 0,
        enableTransition: false
      }
    };
  },
  components: {
    pdf
  },
  computed: {
    isSingle () {
      return this.urlList.length <= 1;
    },
    isFirst () {
      return this.index === 0;
    },
    isLast () {
      return this.index === this.urlList.length - 1;
    },
    isPdf() {
      return this.urlList[this.index] && this.urlList[this.index].toString().indexOf('.pdf') !== -1;
    },
    currentImg () {
      return this.urlList[this.index]
    },
    isPdf() {
      return this.urlList[this.index] &&  this.urlList[this.index].toString().indexOf('.pdf')!== -1;
    },
    imgStyle () {
      const { scale, deg, offsetX, offsetY, enableTransition } = this.transform;
      const style = {
        transform: `scale(${scale}) rotate(${deg}deg)`,
        transition: enableTransition ? 'transform .3s' : '',
        'margin-left': `${offsetX}px`,
        'margin-top': `${offsetY}px`
      };
      if (this.mode === Mode.CONTAIN) {
        style.maxWidth = style.maxHeight = '100%';
      }
      return style;
    }
  },
  watch: {
    index: {
      handler: function (val) {
        this.reset();
        this.onSwitch(val);
      }
    },
    currentImg (val) {
      this.$nextTick(_ => {
        const $img = this.$refs.img[0];
        if (!$img.complete) {
          this.loading = true;
        }
      });
    }
  },
  methods: {
    hide () {
      this.deviceSupportUninstall();
      this.onClose();
    },
    deviceSupportInstall () {
      this._keyDownHandler = rafThrottle(e => {
        const keyCode = e.keyCode;
        switch (keyCode) {
          // ESC
          case 27:
            this.hide();
            break;
          // SPACE
          case 32:
            this.toggleMode();
            break;
          // LEFT_ARROW
          case 37:
            this.prev();
            break;
          // UP_ARROW
          case 38:
            this.handleActions('zoomIn');
            break;
          // RIGHT_ARROW
          case 39:
            this.next();
            break;
          // DOWN_ARROW
          case 40:
            this.handleActions('zoomOut');
            break;
        }
      });
      this._mouseWheelHandler = rafThrottle(e => {
        const delta = e.wheelDelta ? e.wheelDelta : -e.detail;
        if (delta > 0) {
          this.handleActions('zoomIn', {
            zoomRate: 0.015,
            enableTransition: false
          });
        } else {
          this.handleActions('zoomOut', {
            zoomRate: 0.015,
            enableTransition: false
          });
        }
      });
      on(document, 'keydown', this._keyDownHandler);
      on(document, mousewheelEventName, this._mouseWheelHandler);
    },
    deviceSupportUninstall () {
      off(document, 'keydown', this._keyDownHandler);
      off(document, mousewheelEventName, this._mouseWheelHandler);
      this._keyDownHandler = null;
      this._mouseWheelHandler = null;
    },
    handleImgLoad (e) {
      this.loading = false;
    },
    handleImgError (e) {
      this.loading = false;
      e.target.alt = '加载失败';
    },
    handleMouseDown (e) {
      if (this.loading || e.button !== 0) return;
      const { offsetX, offsetY } = this.transform;
      const startX = e.pageX;
      const startY = e.pageY;
      this._dragHandler = rafThrottle(ev => {
        this.transform.offsetX = offsetX + ev.pageX - startX;
        this.transform.offsetY = offsetY + ev.pageY - startY;
      });
      on(document, 'mousemove', this._dragHandler);
      on(document, 'mouseup', ev => {
        off(document, 'mousemove', this._dragHandler);
      });
      e.preventDefault();
    },
    reset () {
      this.transform = {
        scale: 1,
        deg: 0,
        offsetX: 0,
        offsetY: 0,
        enableTransition: false
      };
    },
    toggleMode () {
      if (this.loading) return;
      const modeNames = Object.keys(Mode);
      const modeValues = Object.values(Mode);
      const index = modeValues.indexOf(this.mode);
      const nextIndex = (index + 1) % modeNames.length;
      this.mode = Mode[modeNames[nextIndex]];
      this.reset();
    },
    prev () {
      if (this.isFirst && !this.infinite) return;
      const len = this.urlList.length;
      this.index = (this.index - 1 + len) % len;
    },
    next () {
      if (this.isLast && !this.infinite) return;
      const len = this.urlList.length;
      this.index = (this.index + 1) % len;
    },
    handleActions (action, options = {}) {
      if (this.loading) return;
      const { zoomRate, rotateDeg, enableTransition } = {
        zoomRate: 0.2,
        rotateDeg: 90,
        enableTransition: true,
        ...options
      };
      const { transform } = this;
      switch (action) {
        case 'zoomOut':
          if (transform.scale > 0.2) {
            transform.scale = parseFloat((transform.scale - zoomRate).toFixed(3));
          }
          break;
        case 'zoomIn':
          transform.scale = parseFloat((transform.scale + zoomRate).toFixed(3));
          break;
        case 'clocelise':
          transform.deg += rotateDeg;
          break;
        case 'anticlocelise':
          transform.deg -= rotateDeg;
          break;
      }
      transform.enableTransition = enableTransition;
    }
  },
  mounted () {
    this.deviceSupportInstall();
  }
};
script>
<style  scoped>
.el-image__error,
.el-image__inner,
.el-image__placeholder {
  width: 100%;
  height: 100%;
}

.el-image {
  position: relative;
  display: inline-block;
  overflow: hidden;
}

.el-image__inner {
  vertical-align: top;
}

.el-image__inner--center {
  position: relative;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  display: block;
}

.el-image__error,
.el-image__placeholder {
  background: #f5f7fa;
}

.el-image__error {
  display: flex;
  justify-content: center;
  align-items: center;
  font-size: 14px;
  color: #c0c4cc;
  vertical-align: middle;
}

.el-image__preview {
  cursor: pointer;
}

.el-image-viewer__wrapper {
  position: fixed;
  top: 0;
  right: 0;
  bottom: 0;
  left: 0;
}

.el-image-viewer__btn {
  position: absolute;
  z-index: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 50%;
  opacity: 0.8;
  cursor: pointer;
  box-sizing: border-box;
  user-select: none;
}

.el-image-viewer__close {
  top: 40px;
  right: 40px;
  width: 40px;
  height: 40px;
  font-size: 40px;
}

.el-image-viewer__canvas {
  width: 100%;
  height: 100%;
  display: flex;
  justify-content: center;
  align-items: center;
}

.el-image-viewer__actions {
  left: 50%;
  bottom: 30px;
  transform: translateX(-50%);
  width: 100px;
  height: 44px;
  padding: 0 23px;
  background-color: #606266;
  border-color: #fff;
  border-radius: 22px;
}

.el-image-viewer__actions__inner {
  width: 100%;
  height: 100%;
  text-align: justify;
  cursor: default;
  font-size: 23px;
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: space-around;
}

.el-image-viewer__prev {
  left: 40px;
}

.el-image-viewer__next,
.el-image-viewer__prev {
  top: 50%;
  transform: translateY(-50%);
  width: 44px;
  height: 44px;
  font-size: 24px;
  color: #fff;
  background-color: #606266;
  border-color: #fff;
}

.el-image-viewer__next {
  right: 40px;
  text-indent: 2px;
}

.el-image-viewer__mask {
  position: absolute;
  width: 100%;
  height: 100%;
  top: 0;
  left: 0;
  opacity: 0.5;
  background: #000;
}

.viewer-fade-enter-active {
  animation: viewer-fade-in 0.3s;
}

.viewer-fade-leave-active {
  animation: viewer-fade-out 0.3s;
}

@keyframes viewer-fade-in {
  0% {
    transform: translate3d(0, -20px, 0);
    opacity: 0;
  }

  to {
    transform: translateZ(0);
    opacity: 1;
  }
}

@keyframes viewer-fade-out {
  0% {
    transform: translateZ(0);
    opacity: 1;
  }

  to {
    transform: translate3d(0, -20px, 0);
    opacity: 0;
  }
}
style>
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dom.js

/* istanbul ignore next */

import Vue from 'vue';

const isServer = Vue.prototype.$isServer;
const SPECIAL_CHARS_REGEXP = /([:\-_]+(.))/g;
const MOZ_HACK_REGEXP = /^moz([A-Z])/;
const ieVersion = isServer ? 0 : Number(document.documentMode);

/* istanbul ignore next */
export const on = (function () {
  if (!isServer && document.addEventListener) {
    return function (element, event, handler) {
      if (element && event && handler) {
        element.addEventListener(event, handler, false);
      }
    };
  } else {
    return function (element, event, handler) {
      if (element && event && handler) {
        element.attachEvent('on' + event, handler);
      }
    };
  }
})();

/* istanbul ignore next */
export const off = (function () {
  if (!isServer && document.removeEventListener) {
    return function (element, event, handler) {
      if (element && event) {
        element.removeEventListener(event, handler, false);
      }
    };
  } else {
    return function (element, event, handler) {
      if (element && event) {
        element.detachEvent('on' + event, handler);
      }
    };
  }
})();

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/util.js

import Vue from 'vue';
import {
  isString,
  isObject
} from './types';

const hasOwnProperty = Object.prototype.hasOwnProperty;

export const isFirefox = function () {
  return !Vue.prototype.$isServer && !!window.navigator.userAgent.match(/firefox/i);
};

export const autoprefixer = function (style) {
  if (typeof style !== 'object') return style;
  const rules = ['transform', 'transition', 'animation'];
  const prefixes = ['ms-', 'webkit-'];
  rules.forEach(rule => {
    const value = style[rule];
    if (rule && value) {
      prefixes.forEach(prefix => {
        style[prefix + rule] = value;
      });
    }
  });
  return style;
};

export function rafThrottle(fn) {
  let locked = false;
  return function (...args) {
    if (locked) return;
    locked = true;
    window.requestAnimationFrame(_ => {
      fn.apply(this, args);
      locked = false;
    });
  };
}

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/types.js

export function isString(obj) {
  return Object.prototype.toString.call(obj) === '[object String]';
}
export function isObject(obj) {
  return Object.prototype.toString.call(obj) === '[object Object]';
}

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