# GouraudShadingContext.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.Point;
    import java.awt.Rectangle;
    import java.awt.geom.AffineTransform;
    import java.awt.image.ColorModel;
    import java.io.IOException;
    import java.util.ArrayList;
    import java.util.HashMap;
    import java.util.List;
    import java.util.Map;

    import org.apache.pdfbox.util.Matrix;

    /**
     * Shades Gouraud triangles for Type4ShadingContext and Type5ShadingContext.
     *
     * @author Tilman Hausherr
     * @author Shaola Ren
     */
    abstract class GouraudShadingContext extends TriangleBasedShadingContext
    {
        /**
         * triangle list.
         */
        private List<ShadedTriangle> triangleList = new ArrayList<>();

        /**
         * Constructor creates an instance to be used for fill operations.
         *
         * @param shading the shading type to be used
         * @param colorModel 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
         * @throws IOException if something went wrong
         */
        protected GouraudShadingContext(PDShading shading, ColorModel colorModel, AffineTransform xform,
                                        Matrix matrix) throws IOException
        {
            super(shading, colorModel, xform, matrix);
        }

        final void setTriangleList(List<ShadedTriangle> triangleList)
        {
            this.triangleList = triangleList;
        }

        @Override
        protected Map<Point, Integer> calcPixelTable(Rectangle deviceBounds) throws IOException
        {
            Map<Point, Integer> map = new HashMap<>();
            super.calcPixelTable(triangleList, map, deviceBounds);
            return map;
        }

        @Override
        public void dispose()
        {
            triangleList = null;
            super.dispose();
        }

        @Override
        protected boolean isDataEmpty()
        {
            return triangleList.isEmpty();
        }
    }