# PatchMeshesShadingContext.java

    /*
     * Copyright 2014 The Apache Software Foundation.
     *
     * Licensed 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.HashMap;
    import java.util.List;
    import java.util.Map;

    import org.apache.pdfbox.util.Matrix;

    /**
     * This class is extended in Type6ShadingContext and Type7ShadingContext. This
     * was done as part of GSoC2014, Tilman Hausherr is the mentor.
     *
     * @author Shaola Ren
     */
    abstract class PatchMeshesShadingContext extends TriangleBasedShadingContext
    {
        /**
         * patch list
         */
        private List<Patch> patchList;

        /**
         * 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
         * @param deviceBounds device bounds
         * @param controlPoints number of control points, 12 for type 6 shading and 16 for type 7 shading
         * @throws IOException if something went wrong
         */
        protected PatchMeshesShadingContext(PDMeshBasedShadingType shading, ColorModel colorModel,
                AffineTransform xform, Matrix matrix, Rectangle deviceBounds,
                int controlPoints) throws IOException
        {
            super(shading, colorModel, xform, matrix);
            patchList = shading.collectPatches(xform, matrix, controlPoints);
            createPixelTable(deviceBounds);
        }

        @Override
        protected Map<Point, Integer> calcPixelTable(Rectangle deviceBounds)  throws IOException
        {
            Map<Point, Integer> map = new HashMap<>();
            for (Patch it : patchList)
            {
                super.calcPixelTable(it.listOfTriangles, map, deviceBounds);
            }
            return map;
        }

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

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