org.apache.commons.imaging.formats.png.ScanExpediterInterlaced Maven / Gradle / Ivy

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Apache Commons Imaging (previously Sanselan) is a pure-Java image library.
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/*
 * 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.commons.imaging.formats.png;

import java.awt.image.BufferedImage;
import java.io.IOException;
import java.io.InputStream;

import org.apache.commons.imaging.ImageReadException;
import org.apache.commons.imaging.formats.png.chunks.PngChunkPlte;
import org.apache.commons.imaging.formats.png.transparencyfilters.TransparencyFilter;

class ScanExpediterInterlaced extends ScanExpediter {
    private static final int[] STARTING_ROW = { 0, 0, 4, 0, 2, 0, 1 };
    private static final int[] STARTING_COL = { 0, 4, 0, 2, 0, 1, 0 };
    private static final int[] ROW_INCREMENT = { 8, 8, 8, 4, 4, 2, 2 };
    private static final int[] COL_INCREMENT = { 8, 8, 4, 4, 2, 2, 1 };
//    private static final int Block_Height[] = { 8, 8, 4, 4, 2, 2, 1 };
//    private static final int Block_Width[] = { 8, 4, 4, 2, 2, 1, 1 };

    ScanExpediterInterlaced(final int width, final int height, final InputStream is,
            final BufferedImage bi,
            final PngColorType pngColorType, final int bitDepth, final int bitsPerPixel,
            final PngChunkPlte fPNGChunkPLTE,
            final GammaCorrection gammaCorrection,
            final TransparencyFilter transparencyFilter) {
        super(width, height, is, bi, pngColorType, bitDepth, bitsPerPixel,
                fPNGChunkPLTE, gammaCorrection, transparencyFilter);
    }

    private void visit(final int x, final int y, final BufferedImage bi, final BitParser fBitParser,
            final int pixelIndexInScanline)
            throws ImageReadException, IOException {
        final int rgb = getRGB(fBitParser, pixelIndexInScanline);
        bi.setRGB(x, y, rgb);
    }

    @Override
    public void drive() throws ImageReadException, IOException {

        int pass = 1;
        while (pass <= 7) {
            byte[] prev = null;

            int y = STARTING_ROW[pass - 1];
            // int y_stride = ROW_INCREMENT[pass - 1];
            //final boolean rows_in_pass = (y < height);
            while (y < height) {
                int x = STARTING_COL[pass - 1];
                int pixelIndexInScanline = 0;

                if (x < width) {
                    // only get data if there are pixels in this scanline/pass
                    final int columnsInRow = 1 + ((width - STARTING_COL[pass - 1] - 1) / COL_INCREMENT[pass - 1]);
                    final int bitsPerScanLine = bitsPerPixel * columnsInRow;
                    final int pixelBytesPerScanLine = getBitsToBytesRoundingUp(bitsPerScanLine);

                    final byte[] unfiltered = getNextScanline(is, pixelBytesPerScanLine, prev, bytesPerPixel);

                    prev = unfiltered;

                    final BitParser fBitParser = new BitParser(unfiltered, bitsPerPixel, bitDepth);

                    while (x < width) {
                        visit(x, y, bi, fBitParser, pixelIndexInScanline);

                        x = x + COL_INCREMENT[pass - 1];
                        pixelIndexInScanline++;
                    }
                }
                y = y + ROW_INCREMENT[pass - 1];
            }
            pass = pass + 1;
        }
    }
}