1、引用exif.js
<script src="https://cdn.bootcss.com/exif-js/2.3.0/exif.min.js"></script>
//图片方向角 added by lzk var Orientation = null; EXIF.getData(file, function() { EXIF.getAllTags(this); Orientation = EXIF.getTag(this, 'Orientation'); console.log(Orientation); }); //对图片旋转处理 added by lzk function rotateImg(img, direction, canvas) { // 最小与最大旋转方向,图片旋转4次后回到原方向 var min_step = 0; var max_step = 3; // var img = document.getElementById(pid); if (img == null) return; // img的高度和宽度不能在img元素隐藏后获取,否则会出错 var height = img.height; var width = img.width; // var step = img.getAttribute('step'); var step = 2; if (step == null) { step = min_step; } if (direction == 'right') { step++; //旋转到原位置,即超过最大值 step > max_step && (step = min_step); } else { step--; step < min_step && (step = max_step); } //旋转角度以弧度值为参数 var degree = step * 90 * Math.PI / 180; var ctx = canvas.getContext('2d'); switch (step) { case 0: canvas.width = width; canvas.height = height; ctx.drawImage(img, 0, 0); break; case 1: canvas.width = height; canvas.height = width; ctx.rotate(degree); ctx.drawImage(img, 0, -height); break; case 2: canvas.width = width; canvas.height = height; ctx.rotate(degree); ctx.drawImage(img, -width, -height); break; case 3: canvas.width = height; canvas.height = width; ctx.rotate(degree); ctx.drawImage(img, -width, 0); break; }
} const canvas = document.createElement('canvas'); const ctx = canvas.getContext('2d'); if (Orientation != undefined && Orientation != "" && Orientation != 1) { // 旋转处理 switch (Orientation) { case 6: //需要顺时针(向左)90度旋转 rotateImg(this, 'left', canvas); break; case 8: //需要逆时针(向右)90度旋转 rotateImg(this, 'right', canvas); break; case 3: //需要180度旋转 rotateImg(this, 'right', canvas); //转两次 rotateImg(this, 'right', canvas); break; } } else { canvas.width = img.width; canvas.height = img.height; ctx.drawImage(img, 0, 0, canvas.width, canvas.height); }