Segmentize Class Reference

Inheritance diagram for Segmentize:

Collaboration diagram for Segmentize:

Public Member Functions
String	getURI ()
boolean	isSupported (KiWiDialect dialect)
	Return true if this function has available native support for the given dialect. More...
String	getNative (KiWiDialect dialect, String... args)
	Return a string representing how this GeoSPARQL function is translated into SQL ( Postgis Function ) in the given dialect. More...
ValueType	getReturnType ()
	Get the return type of the function. More...
ValueType	getArgumentType (int arg)
	Get the argument type of the function for the arg'th argument (starting to count at 0). More...
int	getMinArgs ()
	Return the minimum number of arguments this function requires. More...
int	getMaxArgs ()
	Return the maximum number of arguments this function can take. More...
List< LineString >	createSegments (Geometry track, double segmentLength) throws NoSuchAuthorityCodeException, FactoryException
Value	evaluate (ValueFactory valueFactory, Value... args) throws ValueExprEvaluationException

Protected Member Functions
Geometry	relation (Geometry geom, Double value)

Static Package Functions
	[static initializer]

Member Function Documentation

[static initializer]()

[static initializer] ( )

staticpackage

createSegments()

List<LineString> createSegments ( Geometry  track, double  segmentLength  ) throws NoSuchAuthorityCodeException, FactoryException

inherited

Referenced by Segmentize.relation().

                                                                                                                                           {

        //GeometryFactory geometryFactory = new GeometryFactory(new PrecisionModel(PrecisionModel.FLOATING));
        List<LineString> segments = new ArrayList<>();
        /*SRSInfo srsInfo = track.getSrsInfo();

        List<Coordinate> coordinates = new ArrayList<>(track.getCoordinates().length);
        Collections.addAll(coordinates, track.getCoordinates());

        double accumulatedLength = 0;
        List<Coordinate> lastSegment = new ArrayList<>();
 
        Iterator<Coordinate> itCoordinates = coordinates.iterator();

        for (int i = 0; itCoordinates.hasNext() && i < coordinates.size() - 1; i++) {
            Coordinate c1 = coordinates.get(i);
            Coordinate c2 = coordinates.get(i + 1);

            lastSegment.add(c1);

            double length;
            //Check for geographic or planar distance.
            //Does the rest of the calculation take into consideration geographic is non-linear in X/Y relationship?
            if (srsInfo.isGeographic()) {
                length = GreatCircleDistance.haversineFormula(c1, c2);
            } else {
                length = c1.distance(c2);
            }

            if (length + accumulatedLength >= segmentLength) {
                double offsetLength = segmentLength - accumulatedLength;
                double ratio = offsetLength / length;
                double dx = c2.x - c1.x;
                double dy = c2.y - c1.y;

                Coordinate segmentationPoint = new Coordinate(c1.x + (dx * ratio), c1.y + (dy * ratio));

                lastSegment.add(segmentationPoint); // Last point of the segment is the segmentation point
                segments.add(geometryFactory.createLineString(lastSegment.toArray(new Coordinate[lastSegment.size()])));

                lastSegment = new ArrayList<>(); // Resets the variable since a new segment will be built
                accumulatedLength = 0D;
                coordinates.add(i + 1, segmentationPoint);
            } else {
                accumulatedLength += length;
            }
        }

        lastSegment.add(coordinates.get(coordinates.size() - 1)); // Because the last one is never added in the loop above
        segments.add(geometryFactory.createLineString(lastSegment.toArray(new Coordinate[lastSegment.size()])));
                */
        return segments;
    }

evaluate()

Value evaluate ( ValueFactory  valueFactory, Value...  args  ) throws ValueExprEvaluationException

inherited

References LiteralRegistry.getLiteral(), and GeometricModifierDoubleFunction.relation().

                                                                                                            {
                if (args.length != 2) {
                        throw new ValueExprEvaluationException(getURI() + " requires exactly 2 arguments, got " + args.length);
                }

                LiteralType l=LiteralRegistry.getLiteral(((Literal)args[0]).getDatatype().toString());
                Double value=Double.valueOf(args[1].stringValue());
                if(l instanceof VectorLiteral) {
                        Geometry geom=((VectorLiteral)l).read(args[0].stringValue());
                        Geometry result = relation(geom,value);
                        return valueFactory.createLiteral(((VectorLiteral) l).unparse(result),((Literal)args[0]).getDatatype());
                }
                throw new ValueExprEvaluationException("Argument given is not a geometry literal");
        }

getArgumentType()

ValueType getArgumentType

(

int

arg

)

Get the argument type of the function for the arg'th argument (starting to count at 0).

This is needed for SQL type casting inside KiWi.

Parameters

arg

Returns

References ValueType.DOUBLE, and ValueType.GEOMETRY.

      {
        switch(arg) {
        case 0: return ValueType.GEOMETRY;
        case 1: return ValueType.DOUBLE;
        }
        return null;
    }

getMaxArgs()

int getMaxArgs

(

)

Return the maximum number of arguments this function can take.

Returns

                            {
        return 1;
    }

getMinArgs()

int getMinArgs

(

)

Return the minimum number of arguments this function requires.

Returns

                            {
        return 1;
    }

getNative()

String getNative	(	KiWiDialect	dialect,
		String...	args
	)

Return a string representing how this GeoSPARQL function is translated into SQL ( Postgis Function ) in the given dialect.

Parameters

dialect
args

Returns

References FN_POSTGIS.st_segmentize.

                                                                 {
        if (dialect instanceof PostgreSQLDialect) {
            if (args.length == 2) {
                String geom1 = args[0];
                Double segmentlength=Double.valueOf(args[1]);
                String SRID_default = "4326";
                /*
                 * The following condition is required to read WKT  inserted directly into args[0] and create a geometries with SRID
                 * POINT, MULTIPOINT, LINESTRING ... and MULTIPOLYGON conditions: 
                 *   example: geof:convexHull("POLYGON(( -7 43, -2 43, -2 38, -7 38, -7 43))"^^geo:wktLiteral)
                 * st_AsText condition: It is to use the geometry that is the result of another function geosparql.
                 *   example: geof:convexHull(geof:buffer(?geom, 50, units:meter))
                 */
                if (args[0].contains("POINT") || args[0].contains("MULTIPOINT") || args[0].contains("LINESTRING") || args[0].contains("MULTILINESTRING") || args[0].contains("POLYGON") || args[0].contains("MULTIPOLYGON") || args[0].contains("ST_AsText")) {
                    geom1 = String.format("ST_GeomFromText(%s,%s)", args[0], SRID_default);
                }
                return String.format("ST_Segmentize(%s,%s)", geom1,segmentlength);
            }
        }
        throw new UnsupportedOperationException(FN_POSTGIS.st_segmentize.toString()+" function not supported by dialect " + dialect);
    }

getReturnType()

ValueType getReturnType

(

)

Get the return type of the function.

This is needed for SQL type casting inside KiWi.

Returns

References ValueType.GEOMETRY.

                                     {
        return ValueType.GEOMETRY;
    }

getURI()

String getURI

(

)

References FN_POSTGIS.st_segmentize.

                           {
        return FN_POSTGIS.st_segmentize.stringValue();
    }

isSupported()

boolean isSupported

(

KiWiDialect

dialect

)

Return true if this function has available native support for the given dialect.

Parameters

dialect

Returns

                                                    {
        return dialect instanceof PostgreSQLDialect;
    }

relation()

Geometry relation ( Geometry  geom, Double  value  )

protectedinherited

References Segmentize.createSegments().

                                                                 {
        double segmentLength = value;

        List<LineString> linestrings;
        try {
                        linestrings = createSegments(geom, segmentLength);
                GeometryFactory fac=new GeometryFactory();
                return fac.createMultiLineString(linestrings.toArray(new LineString[0]));       
        } catch (FactoryException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                }
        return null;
 }