/*
 *    GeoTools - The Open Source Java GIS Toolkit
 *    http://geotools.org
 * 
 *    (C) 2002-2008, 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 Halo fills an extended area outside the glyphs of a rendered textlabel to
 * make it easier to read over a background.
 *
 * <p>
 * The details of this object are taken from the <a
 * href="https://portal.opengeospatial.org/files/?artifact_id=1188"> OGC
 * Styled-Layer Descriptor Report (OGC 02-070) version 1.0.0.</a>:
 * <pre><code>
 * <xsd:element name="Halo">
 *   <xsd:annotation>
 *     <xsd:documentation>
 *      A "Halo" fills an extended area outside the glyphs of a rendered
 *       text label to make the label easier to read over a background.
 *     </xsd:documentation>
 *   </xsd:annotation>
 *   <xsd:complexType>
 *     <xsd:sequence>
 *       <xsd:element ref="sld:Radius" minOccurs="0"/>
 *       <xsd:element ref="sld:Fill" minOccurs="0"/>
 *     </xsd:sequence>
 *   </xsd:complexType>
 * </xsd:element>
 * </code></pre>
 * </p>
 *
 * <p>
 * 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.
 * </p>
 *
 * <p>
 * Notes:
 *
 * <ul>
 * <li>
 * The graphical parameters and their values are derived from SVG/CSS2
 * standards with names and semantics which are as close as possible.
 * </li>
 * </ul>
 * </p>
 * $Id$
 *
 * @author Ian Turton, CCG
 *
 * @source $URL$
 */
public interface Halo extends org.opengis.style.Halo{

    /**
     * Expression that represents the the distance the halo extends from the
     * text
     * @param radius
     */
    void setRadius(Expression radius);

    /**
     * The fill (color) of the halo
     *
     * @return fill (color) of the halo
     */
    Fill getFill();

    /**
     * The fill (color) of the halo
     *
     * @param fill
     */
    void setFill(org.opengis.style.Fill fill);

    void accept(org.geotools.styling.StyleVisitor visitor);
}