Delegate PatternClipMemoizer
Memoizes the (palette-independent) result of the pattern priority-clip (Clip(IReadOnlyList<PatternGroup>, IReadOnlyList<Polygon>)) so a VectorSceneBuilder re-build that does not change the clip inputs — most importantly a Day/Dusk/Night palette switch — reuses the previously computed clip geometry instead of repeating the expensive NetTopologySuite overlay.
public delegate IReadOnlyList<PatternPriorityClipper.ClippedPattern> PatternClipMemoizer(Func<IReadOnlyList<PatternPriorityClipper.ClippedPattern>> compute)Parameters
computeFunc<IReadOnlyList<PatternPriorityClipper.ClippedPattern>>Runs the clip on a cache miss. The delegate invokes it only when it has no cached result to return; on a hit it returns the cached geometry and
computeis not called.
Returns
- IReadOnlyList<PatternPriorityClipper.ClippedPattern>
The clipped pattern geometry, cached or freshly computed.
Remarks
The clipped boundary geometry is fully determined by the fixed dataset
geometry plus the mariner/ECDIS display state and is independent of the
palette (which only recolours the pattern tiles applied after
clipping), so a single cached result is valid across palette switches. The
Mapsui renderer wires this to its IPatternClipCache (bound to the
current portrayal cache key) for the default TiledScene ("B") arm — bringing
it to parity with the Mapsui feature ("A") arm. The headless Skia path leaves
it unset, since a headless render performs the clip exactly once.