itextpdf-master/itext/src/main/java/com/itextpdf/text/pdf/PdfLayerMembership.java
/*
 *
 * This file is part of the iText (R) project.
    Copyright (c) 1998-2022 iText Group NV
 * Authors: Bruno Lowagie, Paulo Soares, et al.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License version 3
 * as published by the Free Software Foundation with the addition of the
 * following permission added to Section 15 as permitted in Section 7(a):
 * FOR ANY PART OF THE COVERED WORK IN WHICH THE COPYRIGHT IS OWNED BY
 * ITEXT GROUP. ITEXT GROUP DISCLAIMS THE WARRANTY OF NON INFRINGEMENT
 * OF THIRD PARTY RIGHTS
 *
 * This program 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 Affero General Public License for more details.
 * You should have received a copy of the GNU Affero General Public License
 * along with this program; if not, see http://www.gnu.org/licenses or write to
 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 * Boston, MA, 02110-1301 USA, or download the license from the following URL:
 * http://itextpdf.com/terms-of-use/
 *
 * The interactive user interfaces in modified source and object code versions
 * of this program must display Appropriate Legal Notices, as required under
 * Section 5 of the GNU Affero General Public License.
 *
 * In accordance with Section 7(b) of the GNU Affero General Public License,
 * a covered work must retain the producer line in every PDF that is created
 * or manipulated using iText.
 *
 * You can be released from the requirements of the license by purchasing
 * a commercial license. Buying such a license is mandatory as soon as you
 * develop commercial activities involving the iText software without
 * disclosing the source code of your own applications.
 * These activities include: offering paid services to customers as an ASP,
 * serving PDFs on the fly in a web application, shipping iText with a closed
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 */
package com.itextpdf.text.pdf;

import java.util.Collection;
import java.util.HashSet;

/**
 * Content typically belongs to a single optional content group,
 * and is visible when the group is <B>ON</B> and invisible when it is <B>OFF</B>. To express more
 * complex visibility policies, content should not declare itself to belong to an optional
 * content group directly, but rather to an optional content membership dictionary
 * represented by this class.
 *
 * @author Paulo Soares
 */
public class PdfLayerMembership extends PdfDictionary implements PdfOCG {

    /**
     * Visible only if all of the entries are <B>ON</B>.
     */
    public static final PdfName ALLON = new PdfName("AllOn");
    /**
     * Visible if any of the entries are <B>ON</B>.
     */
    public static final PdfName ANYON = new PdfName("AnyOn");
    /**
     * Visible if any of the entries are <B>OFF</B>.
     */
    public static final PdfName ANYOFF = new PdfName("AnyOff");
    /**
     * Visible only if all of the entries are <B>OFF</B>.
     */
    public static final PdfName ALLOFF = new PdfName("AllOff");

    PdfIndirectReference ref;
    PdfArray members = new PdfArray();
    HashSet<PdfLayer> layers = new HashSet<PdfLayer>();

    /**
     * Creates a new, empty, membership layer.
     * @param writer the writer
     */
    public PdfLayerMembership(PdfWriter writer) {
        super(PdfName.OCMD);
        put(PdfName.OCGS, members);
        ref = writer.getPdfIndirectReference();
    }

    /**
     * Gets the <CODE>PdfIndirectReference</CODE> that represents this membership layer.
     * @return the <CODE>PdfIndirectReference</CODE> that represents this layer
     */
    public PdfIndirectReference getRef() {
        return ref;
    }

    /**
     * Adds a new member to the layer.
     * @param layer the new member to the layer
     */
    public void addMember(PdfLayer layer) {
        if (!layers.contains(layer)) {
            members.add(layer.getRef());
            layers.add(layer);
        }
    }

    /**
     * Gets the member layers.
     * @return the member layers
     */
    public Collection<PdfLayer> getLayers() {
        return layers;
    }

    /**
     * Sets the visibility policy for content belonging to this
     * membership dictionary. Possible values are ALLON, ANYON, ANYOFF and ALLOFF.
     * The default value is ANYON.
     * @param type the visibility policy
     */
    public void setVisibilityPolicy(PdfName type) {
        put(PdfName.P, type);
    }

    /**
     * Sets the visibility expression for content belonging to this
     * membership dictionary.
     * @param ve A (nested) array of which the first value is /And, /Or, or /Not
     * followed by a series of indirect references to OCGs or other visibility
     * expressions.
     * @since 5.0.2
     */
    public void setVisibilityExpression(PdfVisibilityExpression ve) {
        put(PdfName.VE, ve);
    }

    /**
     * Gets the dictionary representing the membership layer. It just returns <CODE>this</CODE>.
     * @return the dictionary representing the layer
     */
    public PdfObject getPdfObject() {
        return this;
    }
}
