Function ctx_read_pixels 

pub fn ctx_read_pixels(
    ctx: u32,
    x: i32,
    y: i32,
    width: u32,
    height: u32,
    _format: u32,
    _type_: u32,
    dest_ptr: u32,
    dest_len: u32,
) -> u32

Read pixels from the currently bound framebuffer’s color attachment. Writes RGBA u8 data to dest_ptr in WASM linear memory. Returns errno.