Function anchored_rect 

pub fn anchored_rect(
    anchor: Rect,
    size: Size,
    preferred: Side,
    bounds: Rect,
) -> Rect

Place a size panel adjacent to anchor, preferring side, flipping to the opposite side when there isn’t room, and clamped to stay within bounds.

side decides which edge of anchor the panel opens from: Side::Below/Side::Above place the panel’s left edge at anchor’s left edge and stack it vertically off anchor’s bottom/top edge; Side::Right/Side::Left place the panel’s top edge at anchor’s top edge and lay it out horizontally off anchor‘s right/left edge. If the preferred side doesn’t have enough room within bounds (the panel’s far edge would fall outside bounds on that axis) but the opposite side does, the panel opens on the opposite side instead; if neither side has room, the preferred side is kept and clamped like the fitting case. Once a side is chosen, the panel is clamped along the perpendicular axis so it never runs past bounds’ edges: this is the three-line clamp a hand-rolled dropdown would otherwise repeat (x.min(bounds.right() - width).max(bounds.left())), applied to whichever axis side didn’t already pin.

size is clamped down to bounds’ own dimensions if larger, so the result is always fully within bounds, the same guarantee centered_rect makes for a centered box.

Pure layout math: no drawing, no Terminal. Callers still own sizing (deciding size from content, with a floor/ceiling) and overflow (scrolling when content is taller than the resulting rect); this only answers where the rect goes.

Never panics: every offset is computed with saturating arithmetic, so a degenerate anchor, size, or bounds (zero width/height, or anchor outside bounds) resolves to a clamped, zero-size-or-larger rect instead of under/overflowing.

Examples

use retroglyph_core::grid::{Rect, Size};
use retroglyph_ui::{Side, anchored_rect};

let bounds = Rect::new(0, 0, 40, 20);
let anchor = Rect::new(5, 5, 10, 1); // e.g. a menu label
let rect = anchored_rect(anchor, Size::new(12, 4), Side::Below, bounds);
assert_eq!(rect, Rect::new(5, 6, 12, 4));