private PolygonScanner(
ScanEdgeCollection edgeCollection,
int maxIntersectionCount,
int minY,
int maxY,
int subsampling,
IntersectionRule intersectionRule,
MemoryAllocator allocator)
{
this.minY = minY;
this.maxY = maxY;
this.SubpixelDistance = 1f / subsampling;
this.SubpixelArea = this.SubpixelDistance / subsampling;
this.intersectionRule = intersectionRule;
this.edgeCollection = edgeCollection;
this.edges = edgeCollection.Edges;
int edgeCount = this.edges.Length;
int dataBufferSize = (edgeCount * 3) + maxIntersectionCount;
// In case of IntersectionRule.Nonzero, we need more space for intersectionTypes:
if (intersectionRule == IntersectionRule.Nonzero)
{
dataBufferSize += maxIntersectionCount;
}
this.dataBuffer = allocator.Allocate <int>(dataBufferSize);
Span <int> dataBufferInt32Span = this.dataBuffer.Memory.Span;
Span <float> dataBufferFloatSpan = MemoryMarshal.Cast <int, float>(dataBufferInt32Span);
this.sorted0 = dataBufferInt32Span.Slice(0, edgeCount);
this.sorted1 = dataBufferInt32Span.Slice(edgeCount, edgeCount);
this.activeEdges = new ActiveEdgeList(dataBufferInt32Span.Slice(edgeCount * 2, edgeCount));
this.intersections = dataBufferFloatSpan.Slice(edgeCount * 3, maxIntersectionCount);
if (intersectionRule == IntersectionRule.Nonzero)
{
Span <int> remainder =
dataBufferInt32Span.Slice((edgeCount * 3) + maxIntersectionCount, maxIntersectionCount);
this.intersectionTypes = MemoryMarshal.Cast <int, NonZeroIntersectionType>(remainder);
}
else
{
this.intersectionTypes = default;
}
this.idx0 = 0;
this.idx1 = 0;
this.PixelLineY = minY - 1;
this.SubPixelY = default;
this.yPlusOne = default;
}
public static PolygonScanner Create(
IPath polygon,
int minY,
int maxY,
int subsampling,
IntersectionRule intersectionRule,
MemoryAllocator allocator)
{
var multipolygon = TessellatedMultipolygon.Create(polygon, allocator);
var edges = ScanEdgeCollection.Create(multipolygon, allocator, subsampling);
var scanner = new PolygonScanner(edges, multipolygon.TotalVertexCount * 2, minY, maxY, subsampling, intersectionRule, allocator);
scanner.Init();
return(scanner);
}
