| name | constraint-layout |
| description | Use when implementing or testing TaTUÍ's layout engine: Constraint, Rect splitting, the solver, spacing/margins, or the layout cache. Covers constraint semantics, integer rounding, and cache keying. Triggers: layout, constraint, split, rect, flex, percentage, ratio, fill, solver. |
Constraint-based layout
Constraint kinds (ADR-0004)
Length(n), Percentage(p), Ratio(num, den), Min(n), Max(n), Fill(weight).
Semantics
- A layout splits a
Rect along a Direction (Horizontal/Vertical) into segments.
- Fixed intents (
Length, Percentage, Ratio) are honored first; Min/Max clamp; Fill
distributes leftover space proportional to weight.
- All arithmetic is on integer cells. Distribute rounding remainder deterministically
(left-to-right / top-to-bottom) so totals equal the parent extent — no lost or overlapping cells.
Solver strategy
- v1: greedy solver behind the final
Constraint API.
- Later: linear (kasuari-style) solver, swappable without changing callers.
Caching
- Solving repeats every frame; cache solved results in a thread-local LRU keyed by
(area, direction, constraints, spacing, margin).
Testing
Table-driven truth-tables: (area, direction, constraints) -> expected rects. Cover Min/Max/Ratio/
Fill interactions and rounding edges.
