Function rectangle_union 

pub fn rectangle_union(a: &Rect, b: &Rect) -> Rect

Rectangle union (bounding box) calculation.

Computes the smallest rectangle that contains both input rectangles. This is used in region merging to create the combined dirty area.

Algorithm

1. Find minimum X and Y coordinates (top-left corner)
2. Find maximum X+width and Y+height coordinates (bottom-right corner)
3. Compute width and height from corners

Complexity

• Time: O(1) - arithmetic operations only
• Space: O(1) - no additional memory allocation

Overflow Handling

Uses saturating arithmetic to handle coordinate overflow gracefully. Large coordinates are clamped to u16::MAX rather than wrapping.

Examples

use hojicha_rendering::algorithms::rectangle_union;
use ratatui::layout::Rect;

let a = Rect::new(0, 0, 10, 10);
let b = Rect::new(5, 5, 10, 10);
let union = rectangle_union(&a, &b);

assert_eq!(union, Rect::new(0, 0, 15, 15));