Build CGPaths during parallel projection, not on every draw call - #43
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The two GeoMapView subclasses (AppKit + UIKit) used to reconstruct `CGMutablePath` from raw `Point` arrays on every `setNeedsDisplay`, including trivial redraws — `mapBackground` toggles, tile arrivals triggering a re-render, drag-frame invalidations, mapOutline flips. The path-building loop is now done once inside a new `projectInParallelCG` alongside the projection math, producing pre-built `CGPath` objects stored in CG-specific projected types (`CGProjectedLine`, `CGProjectedPolygon`, `CGProjectedContent`). The `draw([CGProjectedContent])` path then just calls `context.addPath(path)` — no allocation, no per-vertex iteration per frame. Polygon interior holes switch from a `CGContext` clip-state approach to even-odd fill on a compound path, which also fixes a latent clip-leak when polygons with interiors were followed by polygons without. Parallel projection chunk size is 5 (vs. the original 25 in `projectInParallel`) so finer-grained work distributes more evenly across cores. `projectInParallel` / `draw([ProjectedContent])` stay untouched for SVG output. Ported from claude/investigate-map-performance-rb4u7 (commit 5c59a00) onto today's layout — handles the tiledBaseMap case added since, and the UIKit CTM counter-flip for raster underlays. Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
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Summary
GeoMapViewused to rebuildCGMutablePathfrom rawPointarrays on everysetNeedsDisplayeven for redraws that don't touch the geometry (e.g.,mapBackground/mapOutlinetoggles, re-render on tile arrival, invalidation on drag). Now the path-building loop runs once alongside the projection math on the background task, anddraw(_:)iscontext.addPath(path).Also folds the polygon-interior "clip out holes" step into an even-odd fill on a compound path, which has the same visual result but no
CGContextclip state that could leak into the next polygon.Test plan
swift test— 53 tests pass.CGMutablePath.addLinegone fromdraw(_:)samples.