JS解決IOS中照片預(yù)覽時旋轉(zhuǎn)90度出現(xiàn)的BUG

//獲取圖片方向
function getPhotoOrientation(img) {
 var orient;
 EXIF.getData(img, function () {
 orient = EXIF.getTag(this, 'Orientation');
 });
 return orient;
}

//圖片壓縮
function compress(img, width, height, ratio) {
 var canvas, ctx, img64, orient;
　　　 
 //獲取圖片方向
 orient = getPhotoOrientation(img);

 canvas = document.createElement('canvas');
 canvas.width = width;
 canvas.height = height;

 ctx = canvas.getContext("2d");

 //如果圖片方向等于6 ，則旋轉(zhuǎn)矯正，反之則不做處理
 if (orient == 6) {
 ctx.save();
 ctx.translate(width / 2, height / 2);
 ctx.rotate(90 * Math.PI / 180);
 ctx.drawImage(img, 0 - height / 2, 0 - width / 2, height, width);
 ctx.restore();
 } else {
 ctx.drawImage(img, 0, 0, width, height);
 }

 img64 = canvas.toDataURL("image/jpeg", ratio);
 return img64;
}