phosphor-geometry

‍Pure-function geometry helpers: zone clamping, overlap resolution, per-window minimum-size enforcement, overlay-coordinate projection, and the canonical rect-to-JSON encoder.

Responsibility

Pure-function corrections shared by the snap engine and the autotile engine: clamp to screen, eliminate overlaps, grow zones to respect window minimum sizes, project geometry into an overlay window's local coordinate system.

Input rects in, output rects out — no Qt objects, no signals, no allocation beyond the result vector. Headless geometry tests link the lib without GUI infrastructure.

Key types

Type	Purpose
PhosphorGeometry::availableAreaToOverlayCoordinates	Project an "available-area" rect into an overlay window's coords
PhosphorGeometry::snapToRect	QRectF → QRect with consistent rounding
PhosphorGeometry::enforceMinSizes	Grow zones to fit per-window minimum sizes by stealing surplus from neighbours, then resolve overlap
PhosphorGeometry::clampZonesToScreen	Position-only clamp; shifts zones so each window's effective rect stays on screen, sizes preserved
PhosphorGeometry::removeRectOverlaps	Resolve residual overlap between zones (used after min-size growth)
PhosphorGeometry::rectToJson	Canonical rect-string format for D-Bus + JSON roundtrip
PhosphorGeometry::JsonKeys	Key constants for the rect-JSON encoder

Design notes

• Position-only vs growth. clampZonesToScreen only shifts; it never resizes. enforceMinSizes is the one path allowed to grow or shrink. They run in that order: first grow to fit minimums, then position-clamp anything still off-screen. For overlap-tolerant algorithms (Deck, Stair, Cascade, Monocle, Paper, Spread, horizontal-deck) enforceMinSizes is skipped — neighbour stealing would destroy intentional overlap — and the position clamp is the only safe correction.
• Vector-tolerant. enforceMinSizes and clampZonesToScreen both accept a minSizes vector that may be shorter than zones (or empty for enforceMinSizes). Missing entries are treated as no-minimum; extras are ignored.
• Pure functions. No Qt objects, no signals, no allocation other than the result vector. Engines call these directly inside their layout-emit hot path.

Dependencies

• QtCore

See also

• `phosphor-snap-engine` and `phosphor-tile-engine` — both run zone output through these helpers before publishing.