org.opengis.style.Symbolizer Maven / Gradle / Ivy

/*
 *    GeoTools - The Open Source Java GIS Toolkit
 *    http://geotools.org
 *
 *    (C) 2011, Open Source Geospatial Foundation (OSGeo)
 *    (C) 2008, Open Geospatial Consortium Inc.
 *
 *    All Rights Reserved. http://www.opengis.org/legal/
 */
package org.opengis.style;

import static org.opengis.annotation.Specification.*;

import javax.measure.Unit;
import javax.measure.quantity.Length;
import org.opengis.annotation.Extension;
import org.opengis.annotation.UML;
import org.opengis.annotation.XmlElement;

/**
 * Abstract superclass of the symbolizers defined by the Symbology Encoding specification.
 *
 * Please note you are not free to create your own subtype o Symbolizer - we are limited to
 * LineSymbolizer, PointSymbolizer, PolygonSymbolizer, RasterSymbolizer and TextSymbolizer.
 *
 * 
using a static geometry you can use static geometry if needed, see {@link
 * #getGeometryAttribute} Particular cases if the geometry is not the defined type of the
 * symbolizer
 *
 * 
Geometry types other than inherently linear types can also be used. If a point geometry is
 * used, it should be interpreted as a line of "epsilon" (arbitrarily small) length with a
 * horizontal orientation centered on the point, and should be rendered with two end caps. If a
 * polygon is used (or other "area" type), then its closed outline is used as the line string (with
 * no end caps). If a raster geometry is used, its coverage-area outline is used for the line,
 * rendered with no end caps.
 *
 * @version Symbology Encoding
 *     Implementation Specification 1.1.0
 * @author Open Geospatial Consortium
 * @author Johann Sorel (Geomatys)
 * @author Chris Dillard (SYS Technologies)
 * @since GeoAPI 2.2
 */
@UML(identifier = "PF_PortrayalSpecification", specification = ISO_19117)
public interface Symbolizer {

    /**
     * Returns a measure unit. This parameter is inherited from GML. Renderers shall use the unit to
     * correctly render symbols.
     *
     * 
Recommended uom definitions are :
     *
     * 

     *
     * 

     *   {@code metre}
     *   
{@code foot}
     *   
{@code pixel}
     * 

     *
     * 
     *
     * @return can be null. If the unit is null than we shall use a the pixel unit
     */
    @XmlElement("uom")
    Unit getUnitOfMeasure();

    /**
     * Returns the name of the geometry feature attribute to use for drawing. May return null (or
     * Expression.NIL) if this symbol is to use the default geometry attribute, whatever it may be.
     * Using null in this fashion is similar to a PropertyName using the XPath expression ".".
     *
     * The content of the element gives the property name in XPath syntax. In principle, a fixed
     * geometry could be defined using GML or operators could be defined for computing the geometry
     * from references or literals. However, using a feature property directly is by far the most
     * commonly useful method.
     *
     * @return Geometry attribute name, or null to indicate default geometry
     */
    @XmlElement("Geometry")
    String getGeometryPropertyName();

    /**
     * Exrepssion used to define a geometry for drawing. May return null if the default geometry
     * attribute should be used. This expression is often a PropertyName.
     *
     * @return Expression used to define a geometry for drawing, or Expression.NIL if the default
     *     geometry should be used.
     */
    /* Expression getGeometry(); */

    /**
     * Returns a name for this symbolizer. This can be any string that uniquely identifies this
     * style within a given canvas. It is not meant to be human-friendly. (The "title" property is
     * meant to be human friendly.)
     *
     * @return a name for this style.
     */
    @XmlElement("Name")
    String getName();

    /**
     * Returns the description of this symbolizer.
     *
     * @return Description with usual informations used for user interfaces.
     */
    @XmlElement("Description")
    Description getDescription();

    /**
     * Calls the visit method of a StyleVisitor
     *
     * @param visitor the style visitor
     * @return value produced
     */
    @Extension
    Object accept(StyleVisitor visitor, Object extraData);
}