android - 从库上传图像时无法获取方向

Question

从我的库中选择图像时，我无法获取方向。如果我转到图像详细信息，我可以看到图像方向设置为 90 度。然而，我的方向始终是0。

String[] orientationColumn =  { MediaStore.Images.ImageColumns.ORIENTATION };
Cursor cur = managedQuery(data.getData(), orientationColumn, null, null, null);
int orientation = -1;

if (cur != null && cur.moveToFirst()) {
     orientation = cur.getInt(cur.getColumnIndex(orientationColumn[0]));
}

使用退出接口(interface):

ExifInterface exif = new ExifInterface(data.getData().getPath());
int orientation = exif.getAttributeInt(ExifInterface.TAG_ORIENTATION);

两种方式都返回 0。我像这样启动“从库中选择” Activity :

protected void selectFromLibrary() {
    Intent intent = new Intent(Intent.ACTION_PICK);
    intent.setAction(Intent.ACTION_GET_CONTENT);
    intent.setData(MediaStore.Images.Media.EXTERNAL_CONTENT_URI);
    intent.setType("image/*");
    startActivityForResult(intent,
            REQUEST_SELECT_IMAGE_FILE);
}

这是在运行 4.4.2 的 LG G2 上

Answer 1

我遇到了几个解决方案(例如这里 Images taken with ACTION_IMAGE_CAPTURE always returns 1 for ExifInterface.TAG_ORIENTATION on some newer devices )，但没有一个适合我。

最终拯救我的是这段代码: http://androidxref.com/4.0.4/xref/packages/apps/Gallery2/src/com/android/gallery3d/data/Exif.java

所以，一开始我尝试使用默认的 exif 方法来获取方向。当它失败时，我就会释放野兽。 我的完整代码:

protected Matrix getRotationMatrix(String path, String mimeType, Context ctx, Uri imgUri)
{
    Matrix mtx = new Matrix();
    try {

        ExifInterface exif = new ExifInterface(path);

        if (mimeType.contains("jpeg") && exif != null) {
            int orientation = exif.getAttributeInt(ExifInterface.TAG_ORIENTATION, ExifInterface.ORIENTATION_NORMAL);
            if (orientation != ExifInterface.ORIENTATION_UNDEFINED) {
                switch (orientation) {
                    case ExifInterface.ORIENTATION_NORMAL:
                        break;
                    case ExifInterface.ORIENTATION_FLIP_HORIZONTAL:
                        mtx.setScale(-1, 1);
                        break;
                    case ExifInterface.ORIENTATION_ROTATE_180:
                        mtx.setRotate(180);
                        break;
                    case ExifInterface.ORIENTATION_FLIP_VERTICAL:
                        mtx.setRotate(180);
                        mtx.postScale(-1, 1);
                        break;
                    case ExifInterface.ORIENTATION_TRANSPOSE:
                        mtx.setRotate(90);
                        mtx.postScale(-1, 1);
                        break;
                    case ExifInterface.ORIENTATION_ROTATE_90:
                        mtx.setRotate(90);
                        break;
                    case ExifInterface.ORIENTATION_TRANSVERSE:
                        mtx.setRotate(-90);
                        mtx.postScale(-1, 1);
                        break;
                    case ExifInterface.ORIENTATION_ROTATE_270:
                        mtx.setRotate(-90);
                        break;
                }
            }
            else
            {
                if (ctx != null && imgUri != null)
                {
                    Cursor cursor = ctx.getContentResolver().query(imgUri,
                            new String[]{MediaStore.Images.ImageColumns.ORIENTATION},
                            null, null, null);

                    try {
                        if (cursor.moveToFirst()) {
                            orientation = cursor.getInt(0);
                            if (orientation != ExifInterface.ORIENTATION_UNDEFINED)
                                mtx.postRotate(cursor.getInt(0));
                            else {
                                // last try...
                                mtx.postRotate( Exif.getOrientation(ctx.getContentResolver().openInputStream(imgUri)));
                            }
                        }
                    } finally {
                        cursor.close();
                    }

                }
            }
        }
    }
    catch(Exception ex)
    {
        return mtx;
    }

    return mtx;
}

然后我在 Bitmap.createBitmap 方法中使用这个矩阵来以正确的方式旋转图像。