Module scroll_fade 

Content that fades out where it runs off the edge of its region.

ScrollFade says the same thing the shadow along the top of a ScrollArea says — there is more content past this edge — and says it where a shadow cannot: over a translucent or frosted surface, where “the colour of what is behind the window” is not a colour anything can paint. Instead of covering the content with a gradient, the fade multiplies the opacity of every primitive by how close it is to an active edge, so a glyph half inside the band is half faded rather than the whole row dimming at once.

The edges are the caller’s statement about overflow, not this component’s guess: a region scrolled to its end fades at the start edge only, and one that fits fades at neither. Reading those from scroll_offset keeps the fade truthful, and turning both on unconditionally would tell the reader there is content past an edge where there is none.

A fade is information rather than decoration, so it is not suppressed under reduced motion; it does not animate, and nothing about it moves on its own.

Structs

FadeEdges

Which edges of a region its content fades towards.

ScrollFade

A region whose content fades towards the edges it is scrolled past.