Function msg_surface_subscribe_scaled 

pub fn msg_surface_subscribe_scaled(
    surface_id: u16,
    codec_support: u8,
    quality: u8,
    width: u16,
    height: u16,
) -> Vec<u8> 

Scaled surface subscribe: ask the server to encode this surface at exactly width × height for this client, bypassing surface-size mediation. Intended for side-panel thumbnails and any viewer that wants a fixed-size stream independent of the compositor’s native surface size and of other clients’ view sizes.

width / height in pixels. Passing 0, 0 is equivalent to msg_surface_subscribe_ext (mediated subscription).