PolygonBuilder class

Forms {@link Polygon}s out of a graph of {@link DirectedEdge}s. The edges to use are marked as being in the result Area.

@version 1.7

Constructors

PolygonBuilder(GeometryFactory geometryFactory)

Properties

geometryFactory ↔ GeometryFactory

getter/setter pair

hashCode → int

The hash code for this object.

no setter, inherited

runtimeType → Type

A representation of the runtime type of the object.

no setter, inherited

shellList ↔ List

getter/setter pair

Methods

add(List dirEdges, List nodes) → void

Add a set of edges and nodes, which form a graph. The graph is assumed to contain one or more polygons, possibly with holes.

addGraph(PlanarGraph graph) → void

Add a complete graph. The graph is assumed to contain one or more polygons, possibly with holes.

buildMaximalEdgeRings(List dirEdges) → List

for all DirectedEdges in result, form them into MaximalEdgeRings

buildMinimalEdgeRings(List maxEdgeRings, List shellList, List freeHoleList) → List

computePolygons(List shellList) → List<Polygon>

findShell(List minEdgeRings) → EdgeRing?

This method takes a list of MinimalEdgeRings derived from a MaximalEdgeRing, and tests whether they form a Polygon. This is the case if there is a single shell in the list. In this case the shell is returned. The other possibility is that they are a series of connected holes, in which case no shell is returned.

getPolygons() → List<Polygon>

noSuchMethod(Invocation invocation) → dynamic

Invoked when a nonexistent method or property is accessed.

inherited

placeFreeHoles(List shellList, List freeHoleList) → void

This method determines finds a containing shell for all holes which have not yet been assigned to a shell. These "free" holes should all be properly contained in their parent shells, so it is safe to use the findEdgeRingContaining method. (This is the case because any holes which are NOT properly contained (i.e. are connected to their parent shell) would have formed part of a MaximalEdgeRing and been handled in a previous step).

placePolygonHoles(EdgeRing shell, List minEdgeRings) → void

This method assigns the holes for a Polygon (formed from a list of MinimalEdgeRings) to its shell. Determining the holes for a MinimalEdgeRing polygon serves two purposes:

sortShellsAndHoles(List edgeRings, List shellList, List freeHoleList) → void

For all rings in the input list, determine whether the ring is a shell or a hole and add it to the appropriate list. Due to the way the DirectedEdges were linked, a ring is a shell if it is oriented CW, a hole otherwise.

toString() → String

A string representation of this object.

inherited

Operators

operator ==(Object other) → bool

The equality operator.

inherited

Static Methods

findEdgeRingContaining(EdgeRing testEr, List shellList) → EdgeRing

Find the innermost enclosing shell EdgeRing containing the argument EdgeRing, if any. The innermost enclosing ring is the smallest enclosing ring. The algorithm used depends on the fact that:
ring A contains ring B iff envelope(ring A) contains envelope(ring B)
This routine is only safe to use if the chosen point of the hole is known to be properly contained in a shell (which is guaranteed to be the case if the hole does not touch its shell)