MgPolygon Class Reference
[MgPolygon]
Inherits MgRegion.
Detailed Description
An MgPolygon is a region, defined by 1 exterior boundary and 0 or more interior boundaries.
- Remarks:
- Each interior boundary defines a hole in the polygon. The interior and exterior boundaries are defined with linear interpolation between points. Each consecutive pair of points defines a line segment. An object of this type is constructed by calling a non-static MgGeometryFactory::CreatePolygon() method and, once constructed, is immutable.
Example (PHP)
The following example code creates a square polygon, whose side is 3 units in length, and which contains a "hole" at its center. The "hole" is also a square, whose side is 1 unit in length.
The following example code creates a square polygon, whose side is 3 units in length, and which contains a "hole" at its center. The "hole" is also a square, whose side is 1 unit in length.
$geometryFactory = new MgGeometryFactory(); $coordinateCollection = new MgCoordinateCollection(); $interiorRingCollection = new MgLinearRingCollection(); $wktReaderWriter = new MgWktReaderWriter(); // note that the coordinates for the external boundary // are added to the coordinate collection in a // counterclockwise order // create first coordinate for external boundary $coordinate = $geometryFactory->CreateCoordinateXY(0,0); $index = $coordinateCollection->Add($coordinate); echo "Coordinate added to coordinate collection at index: $index\n"; // create second coordinate for external boundary $coordinate = $geometryFactory->CreateCoordinateXY(3,0); $index = $coordinateCollection->Add($coordinate); echo "Coordinate added to coordinate collection at index: $index\n"; // create third coordinate for external boundary $coordinate = $geometryFactory->CreateCoordinateXY(3,3); $index = $coordinateCollection->Add($coordinate); echo "Coordinate added to coordinate collection at index: $index\n"; // create fourth coordinate for external boundary $coordinate = $geometryFactory->CreateCoordinateXY(0,3); $index = $coordinateCollection->Add($coordinate); echo "Coordinate added to coordinate collection at index: $index\n"; // create fifth coordinate for external boundary that is the same as // the first to close the boundary $coordinate = $geometryFactory->CreateCoordinateXY(0,0); $index = $coordinateCollection->Add($coordinate); echo "Coordinate added to coordinate collection at index: $index\n"; // create LinearRing that defines the external boundary $exteriorRing = $geometryFactory->CreateLinearRing($coordinateCollection); // clear the collection before reusing for internal boundary $coordinateCollection->Clear(); // note that the coordinates for the internal boundary // are added to the coordinate collection in a // clockwise order // create first coordinate for internal boundary $coordinate = $geometryFactory->CreateCoordinateXY(1,1); $index = $coordinateCollection->Add($coordinate); echo "Coordinate added to coordinate collection at index: $index\n"; // create second coordinate for internal boundary $coordinate = $geometryFactory->CreateCoordinateXY(1,2); $index = $coordinateCollection->Add($coordinate); echo "Coordinate added to coordinate collection at index: $index\n"; // create third coordinate for internal boundary $coordinate = $geometryFactory->CreateCoordinateXY(2,2); $index = $coordinateCollection->Add($coordinate); echo "Coordinate added to coordinate collection at index: $index\n"; // create fourth coordinate for internal boundary $coordinate = $geometryFactory->CreateCoordinateXY(2,1); $index = $coordinateCollection->Add($coordinate); echo "Coordinate added to coordinate collection at index: $index\n"; // create fifth coordinate for internal boundary that is the same as // the first to close the boundary $coordinate = $geometryFactory->CreateCoordinateXY(1,1); $index = $coordinateCollection->Add($coordinate); echo "Coordinate added to coordinate collection at index: $index\n"; // create LinearRing that defines the internal boundary $interiorRing = $geometryFactory->CreateLinearRing($coordinateCollection); // add the interior ring to the interior ring collection $index = $interiorRingCollection->Add($interiorRing); // create the MgPolygon geometry $polygon = $geometryFactory->CreatePolygon($exteriorRing, $interiorRingCollection); // print out the Agf Text string for the geometry $polygonAgfText = $wktReaderWriter->Write($polygon); echo "AGF Text representation of line string: $polygonAgfText\n";
Example (C#)
The following example code creates a square polygon, whose side is 3 units in length, and which contains a "hole" at its center. The "hole" is also a square, whose side is 1 unit in length.
The following example code creates a square polygon, whose side is 3 units in length, and which contains a "hole" at its center. The "hole" is also a square, whose side is 1 unit in length.
using OSGeo.MapGuide; private MgWktReaderWriter wktReaderWriter; private MgGeometryFactory geometryFactory; // this polygon has one exterior ring and one interior ring private MgPolygon pner1141441411ir2223333222; // the following array is used for the exterior ring of a polygon // the points are in counter-clockwise order private double[,] da1141441411 = { { 1, 1 }, { 4, 1 }, { 4, 4 }, { 1, 4 }, { 1, 1 } }; // the following array is used for the interior ring of a polygon // the points are in clockwise order private double[,] da2223333222 = { { 2, 2 }, { 2, 3 }, { 3, 3 }, { 3, 2 }, { 2, 2 } }; // this array contains an array that will be used for an exterior ring // and one that will be used for an interior ring private double[][,] pnEr1141441411Ir2223333222Data; private String geometryAgfText; public MgLinearRing CreateALinearRingXY(double[,] ringData) { MgCoordinateCollection coords = new MgCoordinateCollection(); for (int i = 0; i < ringData.GetLength(0); i++) { coords.Add(geometryFactory.CreateCoordinateXY(ringData[i, 0], ringData[i, 1])); } return geometryFactory.CreateLinearRing(coords); } public MgPolygon CreateAPolygonXY(double[][,] ringsData) { MgLinearRing exteriorRing = CreateALinearRingXY(ringsData[0]); MgLinearRingCollection interiorRings = new MgLinearRingCollection(); for (int i = 1; i < ringsData.GetLength(0); i++) { interiorRings.Add(CreateALinearRingXY(ringsData[i])); } return geometryFactory.CreatePolygon(exteriorRing, interiorRings); } geometryFactory = new MgGeometryFactory(); pnEr1141441411Ir2223333222Data = new double[2][,]; pnEr1141441411Ir2223333222Data[0] = da1141441411; pnEr1141441411Ir2223333222Data[1] = da2223333222; // create a polygon using the geometry factory pner1141441411ir2223333222 = CreateAPolygonXY(pnEr1141441411Ir2223333222Data); // print out the Agf Text string for the geometry wktReaderWriter = new MgWktReaderWriter(); geometryAgfText = wktReaderWriter.Write(pner1141441411ir2223333222); // geometryAgfText now contains: // "POLYGON XY ((1 1, 4 1, 4 4, 1 4, 1 1), (2 2, 2 3, 3 3, 3 2, 2 2))"
Public Member Functions | |
| virtual MgGeometricEntity * | Copy () |
| virtual MgCoordinateIterator * | GetCoordinates () |
| Returns an iterator over the coordinates included in this geometric entity. | |
| virtual INT32 | GetDimension () |
| virtual MgLinearRing * | GetExteriorRing () |
| Gets the exterior ring of the polygon. | |
| virtual INT32 | GetGeometryType () |
| virtual MgLinearRing * | GetInteriorRing (INT32 index) |
| virtual INT32 | GetInteriorRingCount () |
| virtual bool | IsClosed () |
| virtual bool | IsEmpty () |
| virtual MgGeometricEntity * | Transform (MgTransform *transform) |
| Returns a transformed copy of this geometric entity. | |