js照片拍摄方向

// 需要先引入exif-js库
EXIF.getData(img, function() {
    var orientation = EXIF.getTag(this, "Orientation");
    console.log("Orientation: " + orientation);
});

function rotateImage(img, orientation, callback) {
    var canvas = document.createElement('canvas');
    var ctx = canvas.getContext('2d');

    // 设置canvas尺寸
    canvas.width = img.width;
    canvas.height = img.height;

    // 根据方向旋转
    switch (orientation) {
        case 3:
            ctx.rotate(Math.PI);
            ctx.drawImage(img, -img.width, -img.height, img.width, img.height);
            break;
        case 6:
            canvas.width = img.height;
            canvas.height = img.width;
            ctx.rotate(Math.PI / 2);
            ctx.drawImage(img, 0, -img.height, img.width, img.height);
            break;
        case 8:
            canvas.width = img.height;
            canvas.height = img.width;
            ctx.rotate(-Math.PI / 2);
            ctx.drawImage(img, -img.width, 0, img.width, img.height);
            break;
        default:
            ctx.drawImage(img, 0, 0, img.width, img.height);
    }

    // 将canvas转为DataURL
    callback(canvas.toDataURL('image/png'));
}