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/*
 *    GeoTools - The Open Source Java GIS Toolkit
 *    http://geotools.org
 *
 *    (C) 2002-2016, Open Source Geospatial Foundation (OSGeo)
 *
 *    This library is free software; you can redistribute it and/or
 *    modify it under the terms of the GNU Lesser General Public
 *    License as published by the Free Software Foundation;
 *    version 2.1 of the License.
 *
 *    This library is distributed in the hope that it will be useful,
 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *    Lesser General Public License for more details.
 */
package org.geotools.styling;

import org.opengis.filter.expression.Expression;

/**
 * A symbolizer describes how a polygon feature should appear on a map.
 *
 * The symbolizer describes not just the shape that should appear but also such graphical
 * properties as color and opacity.
 *
 * 
A symbolizer is obtained by specifying one of a small number of different types of symbolizer
 * and then supplying parameters to overide its default behaviour.
 *
 * 
The details of this object are taken from the OGC Styled-Layer Descriptor
 * Report (OGC 02-070) version 1.0.0.:
 *
 * 

 * <xsd:element name="PolygonSymbolizer" substitutionGroup="sld:Symbolizer">
 *    <xsd:annotation>
 *      <xsd:documentation>
 *        A "PolygonSymbolizer" specifies the rendering of a polygon or
 *        area geometry, including its interior fill and border stroke.
 *      </xsd:documentation>
 *    </xsd:annotation>
 *    <xsd:complexType>
 *      <xsd:complexContent>
 *       <xsd:extension base="sld:SymbolizerType">
 *         <xsd:sequence>
 *           <xsd:element ref="sld:Geometry" minOccurs="0"/>
 *           <xsd:element ref="sld:Fill" minOccurs="0"/>
 *           <xsd:element ref="sld:Stroke" minOccurs="0"/>
 *         </xsd:sequence>
 *       </xsd:extension>
 *     </xsd:complexContent>
 *   </xsd:complexType>
 * </xsd:element>
 * 
 *
 * Renderers can use this information when displaying styled features, though it must be
 * remembered that not all renderers will be able to fully represent strokes as set out by this
 * interface. For example, opacity may not be supported.
 *
 * 
Notes:
 *
 * 

 *   The graphical parameters and their values are derived from SVG/CSS2 standards with names
 *       and semantics which are as close as possible.
 * 
 *
 * @author James Macgill
 * @version $Id$
 */
public interface PolygonSymbolizer extends org.opengis.style.PolygonSymbolizer, Symbolizer {

    /** Pixels between each graphic of a polygon fill */
    public static String GRAPHIC_MARGIN_KEY = "graphic-margin";

    /**
     * Provides the graphical-symbolization parameter to use to fill the area of the geometry. Note
     * that the area should be filled first before the outline is rendered.
     *
     * @return The Fill style to use when rendering the area.
     */
    Fill getFill();

    /**
     * Provides the graphical-symbolization parameter to use to fill the area of the geometry. Note
     * that the area should be filled first before the outline is rendered.
     *
     * @param fill The Fill style to use when rendering the area.
     */
    void setFill(org.opengis.style.Fill fill);

    /**
     * Provides the graphical-symbolization parameter to use for the outline of the Polygon.
     *
     * @return The Stroke style to use when rendering lines.
     */
    Stroke getStroke();

    /**
     * Provides the graphical-symbolization parameter to use for the outline of the Polygon.
     *
     * @param stroke The Stroke style to use when rendering lines.
     */
    void setStroke(org.opengis.style.Stroke stroke);

    /**
     * PerpendicularOffset works as defined for LineSymbolizer, allowing to draw polygons smaller or
     * larger than their actual geometry.
     *
     * @param offset Offset from the edge polygon positive outside; negative to the inside with a
     *     default of 0.
     */
    public void setPerpendicularOffset(Expression offset);

    /**
     * Displacement from the original geometry in pixels.
     *
     * @return Displacement above and to the right of the indicated point; default x=0, y=0
     */
    public Displacement getDisplacement();

    /** Provide x / y offset in pixels used to crate shadows. */
    public void setDisplacement(org.opengis.style.Displacement displacement);
}