# Type1ShadingContext.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.geom.AffineTransform;
    import java.awt.geom.NoninvertibleTransformException;
    import java.awt.image.ColorModel;
    import java.awt.image.Raster;
    import java.awt.image.WritableRaster;
    import java.io.IOException;
    import org.apache.commons.logging.Log;
    import org.apache.commons.logging.LogFactory;
    import org.apache.pdfbox.pdmodel.graphics.color.PDColorSpace;
    import org.apache.pdfbox.util.Matrix;

    /**
     * AWT PaintContext for function-based (Type 1) shading.
     *
     * @author Tilman Hausherr
     */
    class Type1ShadingContext extends ShadingContext
    {
        private static final Log LOG = LogFactory.getLog(Type1ShadingContext.class);

        private PDShadingType1 type1ShadingType;
        private AffineTransform rat;
        private final float[] domain;

        /**
         * 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
         */
        Type1ShadingContext(PDShadingType1 shading, ColorModel colorModel, AffineTransform xform,
                                   Matrix matrix) throws IOException
        {
            super(shading, colorModel, xform, matrix);
            this.type1ShadingType = shading;

            // (Optional) An array of four numbers [ xmin xmax ymin ymax ]
            // specifying the rectangular domain of coordinates over which the
            // color function(s) are defined. Default value: [ 0.0 1.0 0.0 1.0 ].
            if (shading.getDomain() != null)
            {
                domain = shading.getDomain().toFloatArray();
            }
            else
            {
                domain = new float[] { 0, 1, 0, 1 };
            }

            try
            {
                // get inverse transform to be independent of
                // shading matrix and current user / device space
                // when handling actual pixels in getRaster()
                rat = shading.getMatrix().createAffineTransform().createInverse();
                rat.concatenate(matrix.createAffineTransform().createInverse());
                rat.concatenate(xform.createInverse());
            }
            catch (NoninvertibleTransformException ex)
            {
                LOG.error(ex.getMessage() + ", matrix: " + matrix, ex);
                rat = new AffineTransform();
            }
        }

        @Override
        public void dispose()
        {
            super.dispose();
            type1ShadingType = null;
        }

        @Override
        public Raster getRaster(int x, int y, int w, int h)
        {
            WritableRaster raster = getColorModel().createCompatibleWritableRaster(w, h);
            int[] data = new int[w * h * 4];
            float[] values = new float[2];
            for (int j = 0; j < h; j++)
            {
                for (int i = 0; i < w; i++)
                {
                    int index = (j * w + i) * 4;
                    boolean useBackground = false;
                    values[0] = x + i;
                    values[1] = y + j;
                    rat.transform(values, 0, values, 0, 1);
                    if (values[0] < domain[0] || values[0] > domain[1] ||
                        values[1] < domain[2] || values[1] > domain[3])
                    {
                        if (getBackground() == null)
                        {
                            continue;
                        }
                        useBackground = true;
                    }

                    // evaluate function
                    float[] tmpValues; // "values" can't be reused due to different length
                    if (useBackground)
                    {
                        tmpValues = getBackground();
                    }
                    else
                    {
                        try
                        {
                            tmpValues = type1ShadingType.evalFunction(values);
                        }
                        catch (IOException e)
                        {
                            LOG.error("error while processing a function", e);
                            continue;
                        }
                    }

                    // convert color values from shading color space to RGB
                    PDColorSpace shadingColorSpace = getShadingColorSpace();
                    if (shadingColorSpace != null)
                    {
                        try
                        {
                            tmpValues = shadingColorSpace.toRGB(tmpValues);
                        }
                        catch (IOException e)
                        {
                            LOG.error("error processing color space", e);
                            continue;
                        }
                    }
                    data[index] = (int) (tmpValues[0] * 255);
                    data[index + 1] = (int) (tmpValues[1] * 255);
                    data[index + 2] = (int) (tmpValues[2] * 255);
                    data[index + 3] = 255;
                }
            }
            raster.setPixels(0, 0, w, h, data);
            return raster;
        }

        public float[] getDomain()
        {
            return domain;
        }
    }