# Type4ShadingContext.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.shading;

    import java.awt.Rectangle;
    import java.awt.geom.AffineTransform;
    import java.awt.image.ColorModel;
    import java.io.IOException;

    import org.apache.commons.logging.Log;
    import org.apache.commons.logging.LogFactory;
    import org.apache.pdfbox.util.Matrix;

    /**
     * AWT PaintContext for Gouraud Triangle Mesh (Type 4) shading.
     *
     * @author Tilman Hausherr
     * @author Shaola Ren
     */
    class Type4ShadingContext extends GouraudShadingContext
    {
        private static final Log LOG = LogFactory.getLog(Type4ShadingContext.class);
        private final int bitsPerFlag;

        /**
         * Constructor creates an instance to be used for fill operations.
         *
         * @param shading the shading type to be used
         * @param cm the color model to be used
         * @param xform transformation for user to device space
         * @param matrix the pattern matrix concatenated with that of the parent content stream
         */
        Type4ShadingContext(PDShadingType4 shading, ColorModel cm, AffineTransform xform,
                                   Matrix matrix, Rectangle deviceBounds) throws IOException
        {
            super(shading, cm, xform, matrix);
            LOG.debug("Type4ShadingContext");

            bitsPerFlag = shading.getBitsPerFlag();
            //TODO handle cases where bitperflag isn't 8
            LOG.debug("bitsPerFlag: " + bitsPerFlag);
            setTriangleList(shading.collectTriangles(xform, matrix));
            createPixelTable(deviceBounds);
        }
    }