Function cover 

pub fn cover(picture: &ImageData, edge: u32) -> String

A cover already decoded (crate::peniko::ImageData from an image store or a media reading) as the small data: picture a card draws, or another process is handed: a edge square cut from its centre, JPEG-encoded so it costs a few kilobytes rather than a cover’s own tens. Empty for a picture that is not straight 8-bit RGBA or that does not encode.

The picture keeps inside PICTURE_BUDGET even for a cover busy enough to fill the square with detail: it is cut smaller, and its quality lowered, until it does, because it rides beside the song a live activity publishes and that message is bounded.