/*
 *    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 org.opengis.annotation.Extension;
import org.opengis.filter.expression.Expression;
import org.opengis.annotation.XmlElement;
import org.opengis.annotation.XmlParameter;


/**
 * Indicates how the interior of polygons will be filled.
 *
 *
 * @source $URL: http://svn.osgeo.org/geotools/trunk/modules/library/opengis/src/main/java/org/opengis/style/Fill.java $
 * @version <A HREF="http://www.opengeospatial.org/standards/symbol">Symbology Encoding Implementation Specification 1.1.0</A>
 * @author Open Geospatial Consortium
 * @author Johann Sorel (Geomatys)
 * @author Chris Dillard (SYS Technologies)
 * @since GeoAPI 2.2
 */
@XmlElement("Fill")
public interface Fill {

    /**
     * If this object is to be filled with tiled copies of an image, then returns
     * a non-null Graphic that indicates what image should be drawn.
     *
     * @return Graphic object or null if no graphic pattern to use.
     */
    @XmlElement("GraphicFill")
    GraphicFill getGraphicFill();

    //*************************************************************
    // SVG PARAMETERS
    //*************************************************************

    /**
     * Indicates the color to be used for solid-filling the interior of polygons.
     * The format of the color is {@code "#rrggbb"} where {@code rr}, {@code gg},
     * and {@code bb} are two digit hexadecimal integers specify the red, green,
     * and blue color intensities, repsectively.  If null, the default color is
     * 50% gray, {@code "#808080"}.
     *
     * @return Expression : if null the color used shall be a 50% gray {@code "#808080"}.
     */
    @XmlParameter("Fill")
    Expression getColor();

    /**
     * Indicates the opacity of the fill.  This value must be a floating point
     * number ranging from 0.0 to 1.0, where 0.0 means completely transparent
     * and 1.0 means completely opaque.  If null, the default value is 1.0,
     * completely opaque.
     *
     * @return Expression  : if null, value used shall be 1.0
     */
    @XmlParameter("Opacity")
    Expression getOpacity();

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