(H5)canvas实现裁剪图片和马赛克功能,以及又拍云上传图片
1.核心功能
此组件功能包含:
图片裁剪(裁剪框拖动,裁剪框改变大小);
图片马赛克(绘制马赛克,清除马赛克);
图片预览、图片还原(返回原图、返回处理图);
图片上传(获取签名、上传图片)。
2.核心逻辑
2.1图片裁剪
获取裁剪框(矩形)相对于画布的位置(左上)和裁剪框的height、width。获取(getImageData)canvas相应位置的图片对象(ImageData)。清空canvas画布。在canvas画布的相应位置绘制(putImageData)获取的图片对象(ImageData)。生成预览图。
2.2图片马赛克
马赛克的绘制,就是在以鼠标划过路径(画笔宽度)为中心的区域,重新绘制成其他的颜色。一般结果是,会取周围的相近的颜色。
取色方法:
1)比如现有一鼠标划过的点的坐标(x,y),定义一个矩形左上角坐标取(x,y),宽30px,高30px。我们把矩形宽高都除以5(分成5份,可以自定义为n份),所以现在是25个6px的小格子。每个小格子宽高都是6px。
2)然后,我们随机获取一个小格子,获取(getImageData)这个小格子的图片对象(ImageData);再随机获取此图片对象上某个像素点(宽1px,高1px)的颜色color(rgba:ImageData.data[0],ImageData.data[1],ImageData.data[2],ImageData.data[3]);最后我们把第一个6x6px的小格子的每个像素点的颜色都设置为color。
3)其他24个小格子的颜色,遍历2步骤即可。
2.3清除马赛克
我们需要理解一个问题,不管是绘制马赛克,还是清除马赛克,其本质都是在绘制图片。我们在某个位置绘制了马赛克,清除的时候,就是把原图在当前位置的图片对象再画出来。就达到了清除的效果。所以,我们需要备份一个canvas,和原图一模一样,清除的时候,需要获取备份画布上对应位置的图像,绘制到马赛克的位置。
2.4图片预览
图片预览就是获取裁剪框的区域,获取区域内的图片对象。再绘制到画布上。
2.5图片还原至原图
清空画布,再次绘制原图
2.6还原至已操作图片
预览是保存画布图片对象(ImageData),清空画布,绘制保存的图片对象至画布
2.7图片上传
获取(toDataURL)canvas图片路径,将获取到的base64图片转化为File对象。进行上传。
3.完整代码如下:
<template> <div class="canvas-clip" :loading="loading"> <div v-show="isDrop" class="canvas-mainBox" ref="canvas-mainBox" id="canvas-mainBox" @mousedown.stop="startMove($event)" > <div class="canvas-minBox left-up" @mousedown.stop="startResize($event,0)"></div> <div class="canvas-minBox up" @mousedown.stop="startResize($event,1)"></div> <div class="canvas-minBox right-up" @mousedown.stop="startResize($event,2)"></div> <div class="canvas-minBox right" @mousedown.stop="startResize($event,3)"></div> <div class="canvas-minBox right-down" @mousedown.stop="startResize($event,4)"></div> <div class="canvas-minBox down" @mousedown.stop="startResize($event,5)"></div> <div class="canvas-minBox left-down" @mousedown.stop="startResize($event,6)"></div> <div class="canvas-minBox left" @mousedown.stop="startResize($event,7)"></div> </div> <!-- 画布 --> <canvas class="canvas-area" ref="canvas" id="canvas" :width="canvasWidth" :height="canvasHeight" @mousedown.stop="startMove($event)" :class="{hoverPaint:isMa,hoverClear:isMaClear}" ></canvas> <!-- 备份画布 --> <canvas class="canvas-copy" ref="canvasCopy" :width="canvasWidth" :height="canvasHeight"></canvas> <div class="canvas-btns"> <button v-if="backBtn" @click="clipBack">返回</button> <button :class="{active:btnIndex==0}" @click="sourceImg">原图</button> <button :class="{active:btnIndex==1}" @click="paintRectReady" :disabled="isDisabled">马赛克</button> <button :class="{active:btnIndex==2}" @click="paintRectClearReady" :disabled="isDisabled">橡皮擦</button> <button :class="{active:btnIndex==3}" @click="clipReady" :disabled="isDisabled">裁剪</button> <button :class="{active:btnIndex==4}" @click="clipPosition">预览</button> <button @click="getSignature">上传</button> <button class="close" @click="canvasClose()">x</button> <!-- <div class="paint-size" v-if="isMaClear || isMa"> <span>画笔大小</span> <input :defaultValue="maSize" v-model="maSize" max="100" min="1" type="range"> <span class="size-num">{{maSize}}</span> </div> --> </div> </div> </template> <script> import axios from "axios"; import md5 from "js-md5"; import req from "../../axios/config"; export default { props: ["imgUrl"], data() { return { resizeFX: "", movePrev: "", canvasWidth: 800, // 画布宽 canvasHeight: 600, // 画布高 loading: false, isDrop: false, // 裁剪 isMa: false, // 马赛克 maSize: 30, // 马赛克大小 isMaClear: false, // 清除马赛克 backBtn: false, // 返回按钮 isDisabled: false,//禁用按钮 btnIndex: 0,//当前按钮 mouseX:\'\',// 鼠标位置 mouseY:\'\', clipEle: "", // 裁剪框元素 canvasDataSession: "", // 预览前的画布信息 canvas: "", // 画布 ctx: "", // 画布上下文 canvasCopy: "", // copy画布 ctxCopy: "", // copy画布上下文 uploadOption: { // 图片上传参数 path: "", policy: "", signature: "", username: "" } }; }, mounted() { this.clipEle = this.$refs["canvas-mainBox"]; this.canvas = this.$refs["canvas"]; this.ctx = this.canvas.getContext("2d"); this.canvasCopy = this.$refs["canvasCopy"]; this.ctxCopy = this.canvasCopy.getContext("2d"); this.draw(); }, methods: { // 创建图片 draw() { var img = new Image(); img.setAttribute(\'crossOrigin\', \'anonymous\'); img.onload = () => { this.ctx.drawImage(img, 0, 0, 800, 600); this.ctxCopy.drawImage(img, 0, 0, 800, 600); }; img.src = this.imgUrl + \'?time=\' + new Date().valueOf(); }, //预览 计算裁剪框的位置(左上坐标) clipPosition() { this.isDisabled = true; this.backBtn = true; this.isMa = false; this.isMaClear = false; this.btnIndex = 4; //画布位置 var canvasPx = this.canvas.offsetLeft, canvasPy = this.canvas.offsetTop; if (this.isDrop) { // 裁剪框位置 var clipPx = this.clipEle.offsetLeft, clipPy = this.clipEle.offsetTop, x = clipPx - canvasPx, y = clipPy - canvasPy, w = this.clipEle.offsetWidth, h = this.clipEle.offsetHeight, // 预览图居中 positionX = 400 - this.clipEle.offsetWidth / 2, positionY = 300 - this.clipEle.offsetHeight / 2; } else { // 没有裁剪框,保存完整图片 var x = 0, y = 0, w = this.canvas.offsetWidth, h = this.canvas.offsetHeight, // 预览图居中 positionX = 0, positionY = 0; } var imageData = this.ctx.getImageData(x, y, w, h); this.canvasDataSession = this.ctx.getImageData( 0, 0, this.canvasWidth, this.canvasHeight ); this.ctx.clearRect(0, 0, this.canvasWidth, this.canvasHeight); this.ctx.putImageData(imageData, positionX, positionY); this.clipEle.style.display = "none"; this.canvasCopy.style.display = "none"; }, // 返回预览前状态 clipBack() { this.btnIndex = -1; this.backBtn = false; this.isDisabled = false; this.isDrop = false; this.ctx.putImageData(this.canvasDataSession, 0, 0); this.canvasCopy.style.display = "block"; }, // 原图 sourceImg() { this.isDisabled = false; this.btnIndex = 0; this.backBtn = false; this.isMa = false; this.isDrop = false; this.isMaClear = false; var img = new Image(); this.ctx.clearRect(0, 0, this.canvasWidth, this.canvasHeight); img.setAttribute(\'crossOrigin\', \'anonymous\'); img.onload = () => { this.ctx.drawImage(img, 0, 0, this.canvasWidth, this.canvasHeight); }; img.src = this.imgUrl + \'?time=\' + new Date().valueOf(); this.canvasCopy.style.display = "block"; }, // 获取签名 getSignature() { // canvas图片base64 转 File 对象 var dataURL = this.canvas.toDataURL("image/jpg"), arr = dataURL.split(","), mime = arr[0].match(/:(.*?);/)[1], bstr = atob(arr[1]), n = bstr.length, u8arr = new Uint8Array(n); while (n--) { u8arr[n] = bstr.charCodeAt(n); } var obj = new Blob([u8arr], { type: mime }), time = new Date().toGMTString(), formData = new FormData(); formData.append("file", obj); // 获取文件后缀 var suffix = formData.get("file").type.split("/")[1]; req .get("/carsource-api/upyun/sign", { suffix: suffix }) .then(response => { if (response.data.code === 0) { this.uploadOption.path = response.data.data.path; formData.append("policy", response.data.data.policy); formData.append("authorization", response.data.data.signature); this.updateImg(formData); } }) .catch(function(error) {}); }, // 上传 updateImg(formData) { axios({ url: "http://v0.api.upyun.com/tmp-img", method: "POST", data: formData }).then(response => { if (response.data.code == 200) { this.$message.success("图片修改成功"); this.canvasClose("upload", response.data.url.slice(4)); } }); }, // 裁剪框缩放 移动 startResize(e, n) { this.resizeFX = n; $(document).mousemove(this.resizeDiv); document.addEventListener("mouseup", this.stopResize); }, stopResize(e) { $(document).off("mousemove", this.resizeDiv); document.removeEventListener("mouseup", this.stopResize); }, startMove(e) { this.movePrev = [e.pageX, e.pageY]; $(document).mousemove(this.moveDiv); document.addEventListener("mouseup", this.stopMove); }, stopMove(e) { $(document).off("mousemove", this.moveDiv); document.removeEventListener("mouseup", this.stopMove); }, moveDiv(e) { // 马赛克 if (this.isMa) { this.paintRect(e); } // 清除马赛克 if (this.isMaClear) { this.paintRectClear(e); } // 裁剪 if (this.isDrop) { var targetDiv = $("#canvas-mainBox"), offsetArr = targetDiv.offset(); var chaX = e.pageX - this.movePrev[0], chaY = e.pageY - this.movePrev[1], ox = parseFloat(targetDiv.css("left")), oy = parseFloat(targetDiv.css("top")); targetDiv.css({ left: ox + chaX + "px", top: oy + chaY + "px" }); this.movePrev = [e.pageX, e.pageY]; } }, resizeDiv(e) { e.preventDefault(); e.stopPropagation(); // 获取需要改变尺寸元素到页面的距离 var targetDiv = $("#canvas-mainBox"), offsetArr = targetDiv.offset(); var eleSWidth = targetDiv.width(), eleSHeight = targetDiv.height(), ox = parseFloat(targetDiv.css("left")), oy = parseFloat(targetDiv.css("top")); // 获取鼠标位置,和元素初始offset进行对比, var chaX = e.pageX - offsetArr.left, chaY = e.pageY - offsetArr.top; switch (this.resizeFX) { case 0: //如果移动距离接近宽度或高度,则不进行改变 if (chaX >= eleSWidth - 10 || chaY >= eleSHeight - 10) { return; } // 获得位置差(m-e),先设置宽度和高度,再设置位置 // 原始宽高+((m-e)*-1),原始位置+(m-e) targetDiv.css({ width: eleSWidth + chaX * -1 + "px", height: eleSHeight + chaY * -1 + "px", left: ox + chaX + "px", top: oy + chaY + "px" }); break; case 1: //如果移动距离接近宽度或高度,则不进行改变 if (chaY >= eleSHeight - 10) { return; } // 获得位置差(m-e),先设置宽度和高度,再设置位置 // 原始宽高+((m-e)*-1),原始位置+(m-e) targetDiv.css({ height: eleSHeight + chaY * -1 + "px", top: oy + chaY + "px" }); break; case 2: //如果移动距离接近宽度或高度,则不进行改变 if (chaX <= 10 || chaY >= eleSHeight - 10) { return; } // 获得位置差(m-e),先设置宽度和高度,设置位置 // 原始高+((m-e)*-1),原始宽+((m-e)),原始位置+(m-e) targetDiv.css({ width: chaX + "px", height: eleSHeight + chaY * -1 + "px", top: oy + chaY + "px" }); break; case 3: //如果移动距离接近宽度或高度,则不进行改变 if (chaX <= 10) { return; } // 获得位置差(m-e),先设置宽度和高度,再设置位置 // 原始宽高+((m-e)*-1),原始位置+(m-e) targetDiv.css({ width: chaX + "px" }); break; case 4: //如果移动距离接近宽度或高度,则不进行改变 if (chaX <= 10 || chaY <= 10) { return; } // 获得位置差(m-e),先设置宽度和高度,再设置位置 // 原始宽高+((m-e)*-1),原始位置+(m-e) targetDiv.css({ width: chaX + "px", height: chaY + "px" }); break; case 5: //如果移动距离接近宽度或高度,则不进行改变 if (chaY <= 10) { return; } // 获得位置差(m-e),先设置宽度和高度,再设置位置 // 原始宽高+((m-e)*-1),原始位置+(m-e) targetDiv.css({ height: chaY + "px" }); break; case 6: //如果移动距离接近宽度或高度,则不进行改变 if (chaX >= eleSWidth - 10 || chaY <= 10) { return; } // 获得位置差(m-e),先设置宽度和高度,再设置位置 // 原始宽高+((m-e)*-1),原始位置+(m-e) targetDiv.css({ width: eleSWidth + chaX * -1 + "px", height: chaY + "px", left: ox + chaX + "px" }); break; case 7: //如果移动距离接近宽度或高度,则不进行改变 if (chaX >= eleSWidth - 10) { return; } // 获得位置差(m-e),先设置宽度和高度,再设置位置 // 原始宽高+((m-e)*-1),原始位置+(m-e) targetDiv.css({ width: eleSWidth + chaX * -1 + "px", left: ox + chaX + "px" }); break; default: break; } }, // 裁剪 clipReady() { this.btnIndex = 3; this.isMa = false; this.isDrop = true; this.isMaClear = false; }, // 马赛克 paintRectReady() { this.btnIndex = 1; this.isMa = true; this.isDrop = false; this.isMaClear = false; }, // 橡皮擦 paintRectClearReady() { this.btnIndex = 2; this.isMa = false; this.isDrop = false; this.isMaClear = true; }, // 绘制马赛克 paintRect(e) { var offT = this.canvas.offsetTop, // 距离上边距离 offL = this.canvas.offsetLeft, // 距离左边距离 x = e.clientX, y = e.clientY; if(this.mouseX - x > this.maSize/2 || x - this.mouseX > this.maSize/2 || this.mouseY - y > this.maSize/2 || y - this.mouseY > this.maSize/2){ var oImg = this.ctx.getImageData(x - offL ,y - offT,this.maSize,this.maSize); var w = oImg.width; var h = oImg.height; //马赛克的程度,数字越大越模糊 var num = 6; //等分画布 var stepW = w/num; var stepH = h/num; //这里是循环画布的像素点 for(var i=0;i<stepH;i++){ for(var j=0;j<stepW;j++){ //获取一个小方格的随机颜色,这是小方格的随机位置获取的 var color = this.getXY(oImg,j*num+Math.floor(Math.random()*num),i*num+Math.floor(Math.random()*num)); //这里是循环小方格的像素点, for(var k=0;k<num;k++){ for(var l=0;l<num;l++){ //设置小方格的颜色 this.setXY(oImg,j*num+l,i*num+k,color); } } } } this.ctx.putImageData(oImg,x - offL ,y - offT); this.mouseX = e.clientX this.mouseY = e.clientY } }, getXY(obj,x,y){ var w = obj.width; var h = obj.height; var d = obj.data; var color = []; color[0] = d[4*(y*w+x)]; color[1] = d[4*(y*w+x)+1]; color[2] = d[4*(y*w+x)+2]; color[3] = d[4*(y*w+x)+3]; return color; }, setXY(obj,x,y,color){ var w = obj.width; var h = obj.height; var d = obj.data; d[4*(y*w+x)] = color[0]; d[4*(y*w+x)+1] = color[1]; d[4*(y*w+x)+2] = color[2]; d[4*(y*w+x)+3] = color[3]; }, // 清除马赛克 paintRectClear(e) { var offT = this.canvasCopy.offsetTop, // 距离上边距离 offL = this.canvasCopy.offsetLeft, // 距离左边距离 x = e.clientX, y = e.clientY, // 获取原图此位置图像数据 imageData = this.ctxCopy.getImageData( x - offL, y - offT, this.maSize, this.maSize ); this.ctx.putImageData(imageData, x - offL, y - offT); }, // 关闭画布 canvasClose(type, url) { this.$emit("isShowImgChange", type, url); } } }; </script> <style scoped> .canvas-clip { position: fixed; top: 0; bottom: 0; left: 0; right: 0; z-index: 9010; background: #000; } .canvas-mainBox { position: absolute; width: 400px; height: 300px; left: 50%; top: 50%; margin-left: -200px; margin-top: -150px; border: 1px solid #FFF; cursor: move; z-index: 9009; } .canvas-minBox { position: absolute; width: 8px; height: 8px; background: #FFF; } .left-up { top: -4px; left: -4px; cursor: nw-resize; } .up { top: -4px; left: 50%; margin-left: -4px; cursor: n-resize; } .right-up { top: -4px; right: -4px; cursor: ne-resize; } .right { top: 50%; margin-top: -4px; right: -4px; cursor: e-resize; } .right-down { bottom: -4px; right: -4px; cursor: se-resize; } .down { bottom: -4px; left: 50%; margin-left: -4px; cursor: s-resize; } .left-down { bottom: -4px; left: -4px; cursor: sw-resize; } .left { top: 50%; margin-top: -4px; left: -4px; cursor: w-resize; } .canvas-btns { position: fixed; right: 50px; top: 30px; z-index: 9003; } .canvas-btns button { display: inline-blovk; background: green; cursor: pointer; border: none; width: 60px; height: 30px; line-height: 30px; color: #fff; font-size: 15px; } .canvas-btns button.active { background: rgb(32, 230, 32); } .canvas-btns button.close { background: rgb(230, 72, 32); } .canvas-copy { position: absolute; top: 50%; left: 50%; margin-top: -300px; margin-left: -400px; z-index: 9007; } .canvas-mosatic { position: absolute; top: 50%; left: 50%; margin-top: -300px; margin-left: -400px; z-index: 9009; } .canvas-area { position: absolute; top: 50%; left: 50%; margin-top: -300px; margin-left: -400px; z-index: 9008; } .paint-size{ margin-top: 20px; font-size: 13px; color: #FFF; height: 30px; line-height: 30px; text-align: right; } .paint-size input{ vertical-align: middle; background: green; } .paint-size .size-num{ display: inline-block; width: 15px; } .hoverClear{ cursor: url(\'./paint.png\'),auto; } .hoverPaint{ cursor: url(\'./paint.png\'),auto; } </style>
4.效果图如下:
5.组件是基于vue实现的,代码实现仓促,如有帮助或参考,请自行调试。欢迎留下意见和建议。