Function is_thumbnail_prerotated 

fn is_thumbnail_prerotated(
    thumb_w: i32,
    thumb_h: i32,
    sensor_w: u32,
    sensor_h: u32,
    flip: c_int,
) -> bool

Check whether a thumbnail has already been rotated to display orientation by the camera firmware. Compares the thumbnail’s aspect ratio to the raw sensor’s: if a 90-degree flip is needed (flip=5 or flip=6) but the thumbnail is already in the rotated aspect (portrait when sensor is landscape, or vice versa), the thumbnail is pre-rotated.