Function cursor_to_png 

fn cursor_to_png(
    img: &GetCursorImageReply,
    cap: i32,
) -> (&'static str, Vec<u8>, i32, i32)

XFixes ARGB image -> callback payload: cropped to the visible bounding box (hotspot re-based to it), downscaled so the longest edge fits cap, un-premultiplied, and PNG-encoded. Scaling runs in premultiplied space — per-channel filtering is only linear there, and fully transparent texels cannot bleed dark fringes into edges — and straight alpha is produced last, since that is what PNG carries. A fully transparent image is an intentional pointer hide.