转:https://www.cnblogs.com/lovelgx/articles/8656615.html
---恢复内容开始---
问题:html5+canvas进行移动端手机照片上传时,发现ios手机上传竖拍照片会逆时针旋转90度,横拍照片无此问题;Android手机没这个问题。
解决方法:利用exif.js解决ios手机上传竖拍照片旋转90度问题
因此解决这个问题的思路是:获取到照片拍摄的方向角,对非横拍的ios照片进行角度旋转修正。
利用exif.js读取照片的拍摄信息,详见 http://code.ciaoca.com/javascript/exif-js/
这里主要用到Orientation属性。
Orientation属性说明如下:
exif.js 参考 http://code.ciaoca.com/javascript/exif-js/
主要代码参考如下:
<input type="file" id="files" > <img src="blank.gif" id="preview"> <script src="exif.js"></script> <script> var ipt = document.getElementById(‘files‘), img = document.getElementById(‘preview‘), Orientation = null; ipt.onchange = function () { var file = ipt.files[0], reader = new FileReader(), image = new Image(); if(file){ EXIF.getData(file, function() { Orientation = EXIF.getTag(this, ‘Orientation‘); }); reader.onload = function (ev) { image.src = ev.target.result; image.onload = function () { var imgWidth = this.width, imgHeight = this.height; // 控制上传图片的宽高 if(imgWidth > imgHeight && imgWidth > 750){ imgWidth = 750; imgHeight = Math.ceil(750 * this.height / this.width); }else if(imgWidth < imgHeight && imgHeight > 1334){ imgWidth = Math.ceil(1334 * this.width / this.height); imgHeight = 1334; } var canvas = document.createElement("canvas"), ctx = canvas.getContext(‘2d‘); canvas.width = imgWidth; canvas.height = imgHeight; if(Orientation && Orientation != 1){ switch(Orientation){ case 6: // 旋转90度 canvas.width = imgHeight; canvas.height = imgWidth; ctx.rotate(Math.PI / 2); // (0,-imgHeight) 从旋转原理图那里获得的起始点 ctx.drawImage(this, 0, -imgHeight, imgWidth, imgHeight); break; case 3: // 旋转180度 ctx.rotate(Math.PI); ctx.drawImage(this, -imgWidth, -imgHeight, imgWidth, imgHeight); break; case 8: // 旋转-90度 canvas.width = imgHeight; canvas.height = imgWidth; ctx.rotate(3 * Math.PI / 2); ctx.drawImage(this, -imgWidth, 0, imgWidth, imgHeight); break; } }else{ ctx.drawImage(this, 0, 0, imgWidth, imgHeight); } img.src = canvas.toDataURL("image/jpeg", 0.8); } } reader.readAsDataURL(file); } } </script>
---恢复内容结束---
通过上述参考代码,实践一个比较适用的代码
主要参考文章 http://www.cnblogs.com/xjnotxj/p/5576073.html
代码如下 :
<li style="height:100px;line-height:100px"><span class="">图片</span> <canvas id="myCanvas" style="display: none"></canvas> <img src="" id="ago" style="display: none"> <div class="check_img"><img src="" id="check_img" ></div> <div class="imgupdata"> <!--<input type="file" id="fileId" name="fileId" hidefocus="true">--> <input type="file" id="uploadImage" onchange="selectFileImage(this);" /> </div></li>
function selectFileImage(fileObj) { var file = fileObj.files[‘0‘]; var agoimg=document.getElementById("ago"); //图片方向角 added by lzk var Orientation = null; if (file) { var rFilter = /^(image\/jpeg|image\/png)$/i; // 检查图片格式 if (!rFilter.test(file.type)) { wfy.alert("请选择jpeg、png格式的图片"); return; } // var URL = URL || webkitURL; //获取照片方向角属性,用户旋转控制 EXIF.getData(file, function() { EXIF.getAllTags(this); Orientation = EXIF.getTag(this, ‘Orientation‘); }); var oReader = new FileReader(); oReader.onload = function(e) { var image = new Image(); image.src = e.target.result; agoimg.src = e.target.result; agoimg.onload = function() { var expectWidth = this.naturalWidth; var expectHeight = this.naturalHeight; var calc = expectWidth / expectHeight; //比例参数 实现等比缩放 var canvas = document.getElementById(‘myCanvas‘); var ctx = canvas.getContext("2d"); canvas.width = 1200;//此处可以随便设置 压缩后的宽度 canvas.height = (canvas.width)*calc; console.log(‘canvas数据‘+canvas.width) var base64 = null; //修复ios Orientation ==6 只考虑一种情况 为做全面优化 if (Orientation == 6) { //alert(‘需要顺时针(向左)90度旋转‘); ctx.save(); //保存状态 ctx.translate(canvas.width/2, canvas.height/2); //设置画布上的(0,0)位置,也就是旋转的中心点 ctx.rotate(90 * Math.PI / 180); //把画布旋转90度 // 执行Canvas的drawImage语句 ctx.drawImage(image, -(canvas.width/2), -(canvas.height/2), canvas.width, canvas.height); //把图片绘制在画布translate之前的中心点,这是关键点 ctx.restore(); //恢复状态 }else { ctx.drawImage(image, 0, 0, canvas.width, canvas.height); } base64 = canvas.toDataURL("image/jpeg", 0.92); $("#check_img").attr("src", base64); }; }; oReader.readAsDataURL(file); } //$(‘#uploadImage‘).imgloadsize(); }
原文地址:https://www.cnblogs.com/whatstone/p/11183646.html
时间: 2024-10-09 22:14:50