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29 package org.libjpegturbo.turbojpeg;
32 * TurboJPEG lossless transformer
34 public class TJTransformer extends TJDecompressor {
37 * Create a TurboJPEG lossless transformer instance.
39 public TJTransformer() throws Exception {
44 * Create a TurboJPEG lossless transformer instance and associate the JPEG
45 * image stored in <code>jpegImage</code> with the newly created instance.
47 * @param jpegImage JPEG image buffer (size of the JPEG image is assumed to
48 * be the length of the array.) This buffer is not modified.
50 public TJTransformer(byte[] jpegImage) throws Exception {
52 setSourceImage(jpegImage, jpegImage.length);
56 * Create a TurboJPEG lossless transformer instance and associate the JPEG
57 * image of length <code>imageSize</code> bytes stored in
58 * <code>jpegImage</code> with the newly created instance.
60 * @param jpegImage JPEG image buffer. This buffer is not modified.
62 * @param imageSize size of the JPEG image (in bytes)
64 public TJTransformer(byte[] jpegImage, int imageSize) throws Exception {
66 setSourceImage(jpegImage, imageSize);
70 * Losslessly transform the JPEG image associated with this transformer
71 * instance into one or more JPEG images stored in the given destination
72 * buffers. Lossless transforms work by moving the raw coefficients from one
73 * JPEG image structure to another without altering the values of the
74 * coefficients. While this is typically faster than decompressing the
75 * image, transforming it, and re-compressing it, lossless transforms are not
76 * free. Each lossless transform requires reading and performing Huffman
77 * decoding on all of the coefficients in the source image, regardless of the
78 * size of the destination image. Thus, this method provides a means of
79 * generating multiple transformed images from the same source or of applying
80 * multiple transformations simultaneously, in order to eliminate the need to
81 * read the source coefficients multiple times.
83 * @param dstBufs an array of image buffers. <code>dstbufs[i]</code> will
84 * receive a JPEG image that has been transformed using the parameters in
85 * <code>transforms[i]</code>. Use {@link TJ#bufSize} to determine the
86 * maximum size for each buffer based on the transformed or cropped width and
87 * height and the level of subsampling used in the source image.
89 * @param transforms an array of {@link TJTransform} instances, each of
90 * which specifies the transform parameters and/or cropping region for the
91 * corresponding transformed output image
93 * @param flags the bitwise OR of one or more of
94 * {@link TJ#FLAG_BOTTOMUP TJ.FLAG_*}
96 public void transform(byte[][] dstBufs, TJTransform[] transforms,
97 int flags) throws Exception {
99 throw new Exception("JPEG buffer not initialized");
100 transformedSizes = transform(jpegBuf, jpegBufSize, dstBufs, transforms,
105 * Losslessly transform the JPEG image associated with this transformer
106 * instance and return an array of {@link TJDecompressor} instances, each of
107 * which has a transformed JPEG image associated with it.
109 * @param transforms an array of {@link TJTransform} instances, each of
110 * which specifies the transform parameters and/or cropping region for the
111 * corresponding transformed output image
113 * @return an array of {@link TJDecompressor} instances, each of
114 * which has a transformed JPEG image associated with it.
116 * @param flags the bitwise OR of one or more of
117 * {@link TJ#FLAG_BOTTOMUP TJ.FLAG_*}
119 public TJDecompressor[] transform(TJTransform[] transforms, int flags)
121 byte[][] dstBufs = new byte[transforms.length][];
122 if (jpegWidth < 1 || jpegHeight < 1)
123 throw new Exception("JPEG buffer not initialized");
124 for (int i = 0; i < transforms.length; i++) {
125 int w = jpegWidth, h = jpegHeight;
126 if ((transforms[i].options & TJTransform.OPT_CROP) != 0) {
127 if (transforms[i].width != 0) w = transforms[i].width;
128 if (transforms[i].height != 0) h = transforms[i].height;
130 dstBufs[i] = new byte[TJ.bufSize(w, h, jpegSubsamp)];
132 TJDecompressor[] tjd = new TJDecompressor[transforms.length];
133 transform(dstBufs, transforms, flags);
134 for (int i = 0; i < transforms.length; i++)
135 tjd[i] = new TJDecompressor(dstBufs[i], transformedSizes[i]);
140 * Returns an array containing the sizes of the transformed JPEG images
141 * generated by the most recent transform operation.
143 * @return an array containing the sizes of the transformed JPEG images
144 * generated by the most recent transform operation.
146 public int[] getTransformedSizes() throws Exception {
147 if (transformedSizes == null)
148 throw new Exception("No image has been transformed yet");
149 return transformedSizes;
152 private native void init() throws Exception;
154 private native int[] transform(byte[] srcBuf, int srcSize, byte[][] dstBufs,
155 TJTransform[] transforms, int flags) throws Exception;
161 private int[] transformedSizes = null;