libjpegturbo/turbojpeg/TJTransformer.java

/*
 * Copyright (C)2011 D. R. Commander.  All Rights Reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * - Redistributions of source code must retain the above copyright notice,
 *   this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright notice,
 *   this list of conditions and the following disclaimer in the documentation
 *   and/or other materials provided with the distribution.
 * - Neither the name of the libjpeg-turbo Project nor the names of its
 *   contributors may be used to endorse or promote products derived from this
 *   software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS",
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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 */

package org.libjpegturbo.turbojpeg;

/**
 * TurboJPEG lossless transformer
 */
public class TJTransformer extends TJDecompressor {

  /**
   * Create a TurboJPEG lossless transformer instance.
   */
  public TJTransformer() throws Exception {
    init();
  }

  /**
   * Create a TurboJPEG lossless transformer instance and associate the JPEG
   * image stored in <code>jpegImage</code> with the newly-created instance.
   *
   * @param jpegImage JPEG image buffer (size of JPEG image is assumed to be
   * the length of the buffer)
   */
  public TJTransformer(byte[] jpegImage) throws Exception {
    init();
    setJPEGBuffer(jpegImage, jpegImage.length);
  }

  /**
   * Create a TurboJPEG lossless transformer instance and associate the JPEG
   * image of length <code>imageSize</code> bytes stored in
   * <code>jpegImage</code> with the newly-created instance.
   *
   * @param jpegImage JPEG image buffer
   *
   * @param imageSize size of JPEG image (in bytes)
   */
  public TJTransformer(byte[] jpegImage, int imageSize) throws Exception {
    init();
    setJPEGBuffer(jpegImage, imageSize);
  }

  /**
   * Losslessly transform the JPEG image associated with this transformer
   * instance into one or more JPEG images stored in the given destination
   * buffers.  Lossless transforms work by moving the raw coefficients from one
   * JPEG image structure to another without altering the values of the
   * coefficients.  While this is typically faster than decompressing the
   * image, transforming it, and re-compressing it, lossless transforms are not
   * free.  Each lossless transform requires reading and Huffman decoding all
   * of the coefficients in the source image, regardless of the size of the
   * destination image.  Thus, this function provides a means of generating
   * multiple transformed images from the same source or of applying multiple
   * transformations simultaneously, in order to eliminate the need to read the
   * source coefficients multiple times.
   *
   * @param dstBufs an array of n image buffers.  <code>dstbufs[i]</code> will
   * receive a JPEG image that has been transformed using the parameters in
   * <code>transforms[i]</code>.  Use {@link TJ#bufSizeYUV} to determine the
   * maximum size for each buffer based on the cropped width and height.
   *
   * @param transforms an array of n {@link TJTransform} instances, each of
   * which specifies the transform parameters and/or cropping region for the
   * corresponding transformed output image
   *
   * @param flags the bitwise OR of one or more of the flags described in
   * {@link TJ}
   */
  public void transform(byte[][] dstBufs, TJTransform[] transforms,
    int flags) throws Exception {
    if(jpegBuf == null) throw new Exception("JPEG buffer not initialized");
    transformedSizes = transform(jpegBuf, jpegBufSize, dstBufs, transforms,
      flags);
  }

  /**
   * Losslessly transform the JPEG image associated with this transformer
   * instance and return an array of {@link TJDecompressor} instances, each of
   * which has a transformed JPEG image associated with it.
   *
   * @param transforms an array of n {@link TJTransform} instances, each of
   * which specifies the transform parameters and/or cropping region for the
   * corresponding transformed output image
   *
   * @return an array of {@link TJDecompressor} instances, each of
   * which has a transformed JPEG image associated with it
   *
   * @param flags the bitwise OR of one or more of the flags described in
   * {@link TJ}
   */
  public TJDecompressor[] transform(TJTransform[] transforms, int flags)
    throws Exception {
    byte[][] dstBufs = new byte[transforms.length][];
    if(jpegWidth < 1 || jpegHeight < 1)
      throw new Exception("JPEG buffer not initialized");
    for(int i = 0; i < transforms.length; i++) {
      int w = jpegWidth, h = jpegHeight;
      if((transforms[i].options & TJTransform.OPT_CROP) != 0) {
        if(transforms[i].width != 0) w = transforms[i].width;
        if(transforms[i].height != 0) h = transforms[i].height;
      }
      dstBufs[i] = new byte[TJ.bufSize(w, h)];
    }
    TJDecompressor[] tjd = new TJDecompressor[transforms.length];
    transform(dstBufs, transforms, flags);
    for(int i = 0; i < transforms.length; i++)
      tjd[i] = new TJDecompressor(dstBufs[i], transformedSizes[i]);
    return tjd;
  }

  /**
   * Returns an array containing the sizes of the transformed JPEG images from
   * the most recent call to {@link #transform transform()}.
   *
   * @return an array containing the sizes of the transformed JPEG images from
   * the most recent call to {@link #transform transform()}
   */
  public int[] getTransformedSizes() throws Exception {
    if(transformedSizes == null)
      throw new Exception("No image has been transformed yet");
    return transformedSizes;
  }

  private native void init() throws Exception;

  private native int[] transform(byte[] srcBuf, int srcSize, byte[][] dstBufs,
    TJTransform[] transforms, int flags) throws Exception;

  static {
    System.loadLibrary("turbojpeg");
  }

  private int[] transformedSizes = null;
};