# PDTransparencyGroupAttributes.java

    /*
     * Licensed to the Apache Software Foundation (ASF) under one or more
     * contributor license agreements.  See the NOTICE file distributed with
     * this work for additional information regarding copyright ownership.
     * The ASF licenses this file to You under the Apache License, Version 2.0
     * (the "License"); you may not use this file except in compliance with
     * the License.  You may obtain a copy of the License at
     *
     *      http://www.apache.org/licenses/LICENSE-2.0
     *
     * Unless required by applicable law or agreed to in writing, software
     * distributed under the License is distributed on an "AS IS" BASIS,
     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     * See the License for the specific language governing permissions and
     * limitations under the License.
     */
    package org.apache.pdfbox.pdmodel.graphics.form;

    import java.io.IOException;

    import org.apache.pdfbox.cos.COSDictionary;
    import org.apache.pdfbox.cos.COSName;
    import org.apache.pdfbox.pdmodel.PDResources;
    import org.apache.pdfbox.pdmodel.common.COSObjectable;
    import org.apache.pdfbox.pdmodel.graphics.color.PDColorSpace;

    /**
     * Transparency group attributes.
     *
     * @author Kühn &amp; Weyh Software GmbH
     */
    public final class PDTransparencyGroupAttributes implements COSObjectable
    {
        private final COSDictionary dictionary;
        private PDColorSpace colorSpace;

        /**
         * Creates a group object with /Transparency subtype entry.
         */
        public PDTransparencyGroupAttributes()
        {
            dictionary = new COSDictionary();
            dictionary.setItem(COSName.S, COSName.TRANSPARENCY);
        }

        /**
         * Creates a group object from a given dictionary
         * @param dic {@link COSDictionary} object
         */
        public PDTransparencyGroupAttributes(COSDictionary dic)
        {
            dictionary = dic;
        }

        @Override
        public COSDictionary getCOSObject()
        {
            return dictionary;
        }

        /**
         * Returns the group color space or null if it isn't defined.
         *
         * @return the group color space.
         * @throws IOException
         */
        public PDColorSpace getColorSpace() throws IOException
        {
            return getColorSpace(null);
        }

        /**
         * Returns the group color space or null if it isn't defined.
         *
         * @param resources useful for its cache. Can be null.
         * @return the group color space.
         * @throws IOException
         */
        public PDColorSpace getColorSpace(PDResources resources) throws IOException
        {
            if (colorSpace == null && getCOSObject().containsKey(COSName.CS))
            {
                colorSpace = PDColorSpace.create(getCOSObject().getDictionaryObject(COSName.CS), resources);
            }
            return colorSpace;
        }

        /**
         * Returns true if this group is isolated. Isolated groups begin with the fully transparent
         * image, non-isolated begin with the current backdrop.
         */
        public boolean isIsolated()
        {
            return getCOSObject().getBoolean(COSName.I, false);
        }

        /**
         * Returns true if this group is a knockout. A knockout group blends with original backdrop,
         * a non-knockout group blends with the current backdrop.
         */
        public boolean isKnockout()
        {
            return getCOSObject().getBoolean(COSName.K, false);
        }
    }