pub fn thumb(
viewport: Pixels,
max_offset: Pixels,
offset: Pixels,
min: Pixels,
) -> Option<Range<Pixels>>Expand description
Where the thumb sits in a track of viewport length, as a range from the
track’s start — or None when there is nothing to scroll.
None also covers a viewport of zero (the frame before layout has run) and
a thumb that would not fit, which is zed’s third guard: with a viewport
shorter than MIN_THUMB a bar would be all thumb and no travel.