org.opengis.cite.geomatics.gml

Class GmlUtils

java.lang.Object

org.opengis.cite.geomatics.gml.GmlUtils

public class GmlUtils
extends Object

Provides utility methods for processing representations of GML elements.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	GmlUtils.GmlNamespaceContext A NamespaceContext that only recognizes the conventional "gml" namespace prefix.
static class	GmlUtils.NodeNamespaceContext A NamespaceContext that provides the in-scope namespace bindings for a given DOM Node.

Field Summary

Fields

Modifier and Type	Field and Description
static String	GML_NS
static String	SRS_NAME
(package private) static int	TOTAL_ARC_POINTS Total number of arc points to be computed (including end points).

Constructor Summary

Constructors

Constructor and Description
GmlUtils()

Method Summary

Methods

Modifier and Type	Method and Description
static Geometry	computeConvexHull(org.geotoolkit.gml.xml.AbstractGeometry gmlGeom) Calculates the planar convex hull of the given GML geometry element.
static void	extractCoordinatesFromPosList(List<Double> tupleList, int crsDim, List<Coordinate> coords) Extracts (2D) coordinates from a sequence of coordinate tuples and adds them to a list.
static String	findCRSReference(Element geom) Returns the value of the srsName attribute for the given geometry element.
static boolean	hasChildElement(Element elem, String namespace, String localName) Checks if a DOM Element has a child element with the given qualified name.
static void	inferPointsOnArc(org.geotoolkit.gml.xml.AbstractCurveSegment segment, CoordinateReferenceSystem crs, List<Coordinate> coordList) Computes the positions of at least three points on a curve segment representing an arc: the two end points and one or more intermediate points.
static double	lengthInMeters(org.geotoolkit.gml.xml.v321.LengthType length) Converts the given length measurement to meters.
static int	minCurveSegmentLength(String segmentTypeName) Indicates the minimum number of direct positions required to specify a GML curve segment.
static void	setSrsNameOnCollectionMembers(Node... geometryNodes) Sets the srsName attribute on all members of a GML geometry collection if it is specified for the collection.
static org.geotoolkit.gml.xml.AbstractGeometry	unmarshalGMLGeometry(URI uriRef) Deserializes an XML resource into a GML geometry representation.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

SRS_NAME

public static final String SRS_NAME

See Also:

Constant Field Values

GML_NS

public static final String GML_NS

See Also:

Constant Field Values

TOTAL_ARC_POINTS

static final int TOTAL_ARC_POINTS

Total number of arc points to be computed (including end points).

See Also:

Constant Field Values

Constructor Detail

GmlUtils

public GmlUtils()

Method Detail

inferPointsOnArc

public static void inferPointsOnArc(org.geotoolkit.gml.xml.AbstractCurveSegment segment,
                    CoordinateReferenceSystem crs,
                    List<Coordinate> coordList)

Computes the positions of at least three points on a curve segment representing an arc: the two end points and one or more intermediate points. The total number of points on the arc is specified by TOTAL_ARC_POINTS; the approximation improves as the number of points increases. The calculated positions are added to the given list as JTS Coordinate objects.

Parameters:

segment - A curve segment representing an arc (gml:ArcByCenterPoint or an allowable substitution).

crs - The CRS used by the curve to which this segment belongs.

coordList - The collection to which the coordinates will be added.

computeConvexHull

public static Geometry computeConvexHull(org.geotoolkit.gml.xml.AbstractGeometry gmlGeom)

Calculates the planar convex hull of the given GML geometry element. The convex hull is the smallest convex geometry that contains the input geometry.

Parameters:

gmlGeom - A GML geometry element.

Returns:

A JTS Geometry object. This will be a Polygon if the hull contains 3 or more points; fewer points will produce a LineString or a Point.

setSrsNameOnCollectionMembers

public static void setSrsNameOnCollectionMembers(Node... geometryNodes)

Sets the srsName attribute on all members of a GML geometry collection if it is specified for the collection. If a geometry member already has a srsName attribute it is left as is.

Parameters:

geometryNodes - A sequence of GML geometry elements.

See Also:

"ISO 19136, cl. 10.1.3.2: SRSReferenceGroup"

lengthInMeters

public static double lengthInMeters(org.geotoolkit.gml.xml.v321.LengthType length)

Converts the given length measurement to meters. The unit of measurement is identified by its symbol or by URI reference (containing the symbol in the fragment part). Common units of length are shown in the following table. Standard SI prefix symbols may also be used to specify decimal multiples and submultiples of the unit of length (e.g. km).

Units of length

Unit	Symbol(s)	Length /m
meter	m	1
mile	mi	1609.34
nautical mile	M, NM, [nmi_i]	1852

Parameters:

length - A length measurement.

Returns:

The length in meters.

See Also:

SI brochure (8th edition), The Unified Code for Units of Measure

extractCoordinatesFromPosList

public static void extractCoordinatesFromPosList(List<Double> tupleList,
                                 int crsDim,
                                 List<Coordinate> coords)

Extracts (2D) coordinates from a sequence of coordinate tuples and adds them to a list.

Parameters:

tupleList - A sequence of coordinate tuples within the same coordinate reference system (CRS).

crsDim - The dimension of the CRS.

coords - The list to which the coordinates will be added.

minCurveSegmentLength

public static int minCurveSegmentLength(String segmentTypeName)

Indicates the minimum number of direct positions required to specify a GML curve segment. The value depends on the type of curve segment, but falls in the range 1-3.

Parameters:

segmentTypeName - The local name of element representing a the curve segment.

Returns:

An integer value > 0.

findCRSReference

public static String findCRSReference(Element geom)

Returns the value of the srsName attribute for the given geometry element. If a geometry element does not explicitly carry the srsName attribute, then it shall be inherited from either:

1. the nearest ancestor geometry (aggregate) that has the srsName attribute, or
2. the gml:boundedBy/gml:Envelope element in the containing feature instance.

As a side effect, an implicit CRS reference will be added to the element using the inherited srsName value.

Parameters:

geom - An Element representing a GML geometry object.

Returns:

A String denoting a CRS reference (an absolute URI value), or an empty string if no reference was found.

See Also:

"ISO 19136, cl. 9.10, 10.1.3.2"

hasChildElement

public static boolean hasChildElement(Element elem,
                      String namespace,
                      String localName)

Checks if a DOM Element has a child element with the given qualified name.

Parameters:

elem - A DOM Element.

namespace - A namespace name (absolute URI).

localName - A String representing the local name of an element.

Returns:

true if one or more matching child elements are present; false otherwise.

unmarshalGMLGeometry

public static org.geotoolkit.gml.xml.AbstractGeometry unmarshalGMLGeometry(URI uriRef)
                                                                    throws Exception

Deserializes an XML resource into a GML geometry representation.

Parameters:

uriRef - An absolute URI that specifies the location of the resource.

Returns:

A GML geometry object.

Throws:

Exception - If any unexpected errors occur while unmarshalling.