web前端|js教程
旋转,缩小,放大
web前端-js教程
本文主要和大家介绍了vue实现裁切图片同时实现放大、缩小、旋转功能，小编觉得挺不错的，现在分享给大家，也给大家做个参考，希望能帮助到大家。
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实现效果：
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裁切指定区域内的图片
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旋转图片
放大图片
输出bolb 格式数据 提供给 formData 对象
效果图
大概原理：
利用h5 FileReader 对象， 获取 “上传到浏览器的文件” ，文件形式 为base64形式， 把 base64 赋给canvas的上下文。
然后给canvas 元素上加入对（mousedown）监听事件。 当用户鼠标左键在canvas按下时：
挂载对 window 对象mousemove事件 —> 获取 鼠标移动x,y距离.从而操作 canvas里的图像的位置移动。
挂载对 window 对象mouseup 事件， 清除 mousemove事件的绑定。（同时该事件触发后会被删除）
剩下的 放大、缩小 、 旋转 是对 canvas 对象的操作/坐标体系的操作。具体api详见mdn canvas 文档
代码
dom.js
export const on = ({el, type, fn}) => {if (typeof window) { if (window.addEventListener) { el.addEventListener(type, fn, false)} else { el.attachEvent(`on${type}`, fn)}} } export const off = ({el, type, fn}) => { if (typeof window) {if (window.addEventListener) { el.removeEventListener(type, fn)} else { el.detachEvent(`on${type}`, fn)} } } export const once = ({el, type, fn}) => { const hyFn = (event) => {try { fn(event)} finally { off({el, type, fn: hyFn})} } on({el, type, fn: hyFn}) } // 最后一个 export const fbTwice = ({fn, time = 300}) => { let [cTime, k] = [null, null] // 获取当前时间 const getTime = () => new Date().getTime() // 混合函数 const hyFn = () => {const ags = argmentsreturn () => { clearTimeout(k) k = cTime = null fn(...ags)} } return () => {if (cTime == null) { k = setTimeout(hyFn(...arguments), time) cTime = getTime()} else { if ( getTime() - cTime {return item !== className }) el.className = classList.join( ) } export const delay = ({fn, time}) => { let oT = null let k = null return () => {// 当前时间let cT = new Date().getTime()const fixFn = () => { k = oT = null fn()}if (k === null) { oT = cT k = setTimeout(fixFn, time) return}if (cT - oT {fn()this.off({type, fn: fixFn}) } this.on({type, fn: fixFn}) } Event.prototype.trigger = function (type){ if (this.typeList.hasOwnProperty(type)) {this.typeList[type].forEach(fn => { fn()}) } }
组件模板
+转-{{scale}}
uploadcancel
生成文件
import {on, off, once} from ../../utils/dom export default { ctx: null,file: null,x: 0, // 点击canvas x 鼠标地址 y: 0,// 点击canvas y 鼠标地址 xV: 0, // 鼠标移动 x距离 yV: 0, // 鼠标移动 y距离 nX: 0, // 原始坐标点 图像 x nY: 0,// 原始坐标点 图像 y img: null, props: { src: {type: String, default: null},clip: {type: Object, default () { return {width: 200px, height: 200px} }} }, data () {return { isShow: false,base64: null,scale: 1.5, //放大比例deg: 0 //旋转角度 } }, computed: {width () { const {clip} = thisreturn parseFloat(clip.width.replace(px, \)) }, height () {const {clip} = thisreturn parseFloat(clip.height.replace(px, \)) } }, mounted () { const {$options, $refs, width, height} = this // 初始化 canvas file nX nYObject.assign($options, { ctx: $refs.ctx.getContext(2d), file: $refs.file, nX: -width / 2, nY: -height / 2}) }, methods: { // 旋转操作rotate () { const {$options, draw} = this this.deg = (this.deg + Math.PI /2)% (Math.PI * 2) draw($options.img, $options.nX + $options.xV, $options.nY + $options.yV, this.scale, this.deg)},// 处理放大 handleScale (flag) { const {$options, draw, deg} = this flag && this.scale > 0.1 && (this.scale = this.scale - 0.1) !flag && this.scale {const img = createImage(e.target.result, (img) => { draw(img, nX, nY, scale, deg)})file.value = null } reader.readAsDataURL(wFile)},// 生成 图像createImage (src, cb) { const img = new Image() this.$el.append(img) img.className = ase64-hidden img.onload = () => { cb(img) } img.src = src this.$options.img = img},// 操作画布画图draw (img, x = 0, y = 0, scale = 0.5,deg = Math.PI ) { const {ctx} = this.$options let {width, height} = this // 图片尺寸 let imgW = img.offsetWidth let imgH = img.offsetHeight ctx.save() ctx.clearRect( 0, 0, width, height) ctx.translate( width / 2, height / 2, img) ctx.rotate(deg) ctx.drawImage(img, x, y, imgW * scale, imgH * scale) ctx.restore()},// ... 事件绑定handleClip (e) { const {handleMove, $options, deg} = this if (!$options.img) { return } Object.assign(this.$options, {x: e.screenX, y: e.screenY }) on({el: window,type: mousemove,fn: handleMove }) once({el: window,type: mouseup,fn: (e) =>{ console.log(down) switch (deg) { case 0: {Object.assign($options, { nX: $options.nX + $options.xV, nY: $options.nY + $options.yV, xV: 0, yV: 0})break; } case Math.PI / 2: {Object.assign($options, { nX: $options.nY + $options.yV, nY: $options.nX - $options.xV, xV: 0, yV: 0})break; } case Math.PI: {Object.assign($options, { nX: $options.nX - $options.xV, nY: $options.nY - $options.yV, xV: 0, yV: 0})break; } default: {// $options.nY - $options.yV, $options.nX + $options.xVObject.assign($options, { nX: $options.nY - $options.yV, nY: $options.nX + $options.xV, xV: 0, yV: 0}) } }off({ el: window, type: mousemove, fn: handleMove})} })},// ... 处理鼠标移动handleMove (e){ e.preventDefault() e.stopPropagation() const {$options, draw, scale, deg} = this Object.assign($options, {xV: e.screenX - $options.x,yV: e.screenY - $options.y }) switch (deg) {case 0: { draw($options.img, $options.nX + $options.xV, $options.nY + $options.yV, scale, deg) break;}case Math.PI / 2: { draw($options.img, $options.nY + $options.yV, $options.nX - $options.xV, scale, deg) break;}case Math.PI: { draw($options.img, $options.nX - $options.xV, $options.nY - $options.yV, scale, deg) break;}default: { draw($options.img, $options.nY - $options.yV, $options.nX + $options.xV, scale, deg) break;} }},// 清除状态clearState () {const {$options, width, height} = this if ($options.img) { this.$el.removeChild($options.img) Object.assign($options, {x: 0,y: 0,xV: 0,yV: 0,nX: -width / 2,nY: -height / 2,img: null, })}},// 输出文件outFile () {const {$refs: {ctx}} = this console.log(ctx.toDataURL()) ctx.toBlob((blob) => {console.log(blob)})} } } @component-namespace jc { @component clip-image{position: relative;width: 100%;canvas { position: relative; width: 100%; height: 100%; cursor: pointer; box-shadow: 0 0 3px #333;}input { display: none;}.base64-hidden { position: absolute; top: 0; left: 0; display: block; width: 100%; height: auto; z-index: -999; opacity: 0;}.clip-scale-btn { position: relative;@utils-clearfix; margin-bottom: 5px; text-align: center; a {float: left;width: 20px;height: 20px;border-radius: 50%;color: #fff;background: #49a9ee;text-align: center;cursor: pointer; } &>.poor, &>.right-rotate { float: right; }&>span{position: absolute;z-index: -9;top: 0;left: 0; display: block; position: relative; width: 100%; text-align: center; height: 20px; line-height: 20px;}}.upload-warp {@utils-clearfix;.upload-btn,.upload-cancel {float: left;display:inline-block;width: 60px;height: 25px;line-height: 25px;color: #fff;border-radius: 5px;background: #49a9ee;box-shadow: 0 0 0 #333;text-align: center;top: 0;left: 0;right: 0;bottom: 0;margin: auto;cursor: pointer;margin-top: 5px; }.upload-cancel{ background: gray; float: right;}}.to-send-file { margin-top: 5px; display: block; width: 50px; height: 25px; line-height: 25px; color: #fff; border-radius: 5px; background: #49a9ee; cursor: pointer;} }
