vue实现裁切图片同时实现放大、缩小、旋转功能 |
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vue实现裁切图片同时实现放大、缩小、旋转功能
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本篇文章主要介绍了vue实现裁切图片同时实现放大、缩小、旋转功能，分享给大家，具体如下： 实现效果： 裁切指定区域内的图片 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> + 转 - {{scale}} upload cancel 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} = this return parseFloat(clip.width.replace('px', '')) }, height () { const {clip} = this return parseFloat(clip.height.replace('px', '')) } }, mounted () { const {$options, $refs, width, height} = this // 初始化 canvas file nX nY Object.assign($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 < 1.9 && (this.scale = this.scale + 0.1) $options.img && draw($options.img, $options.nX + $options.xV, $options.nY + $options.yV, this.scale, deg) }, // 模拟file 点击事件 dispatchUpload (e) { this.clearState() const {file} = this.$options e.preventDefault() file.click() }, // 读取 input file 信息 readFileMsg () { const {file} = this.$options const {draw, createImage, $options: {nX, nY}, scale, deg} = this const wFile = file.files[0] const reader = new FileReader() reader.onload = (e) => { const img = createImage(e.target.result, (img) => { draw(img, nX, nY, scale, deg) }) file.value = http://www.cppcns.com/ruanjian/java/null } reader.readAsDataURL(wFile) }, // 生成 图像 createImage (src, cb) { const img = new Image() this.$el.append(img) img.className ='base64-hidden' img.onload = () => { cb(img) } img.src = http://www.cppcns.com/ruanjian/java/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 + $options.xV Object.assign($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; } }vue实现裁切图片同时实现放大、缩小、旋转功能 |
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