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376 lines
13 KiB
C
376 lines
13 KiB
C
/*
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* The Python Imaging Library.
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* $Id$
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*
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* coder for ZIP (deflated) image data
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*
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* History:
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* 96-12-29 fl created
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* 96-12-30 fl adaptive filter selection, encoder tuning
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*
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* Copyright (c) Fredrik Lundh 1996.
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* Copyright (c) Secret Labs AB 1997.
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*
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* See the README file for information on usage and redistribution.
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*/
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#include "Imaging.h"
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#ifdef HAVE_LIBZ
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#include "Zip.h"
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int
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ImagingZipEncode(Imaging im, ImagingCodecState state, UINT8* buf, int bytes)
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{
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ZIPSTATE* context = (ZIPSTATE*) state->context;
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int err;
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int compress_level, compress_type;
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UINT8* ptr;
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int i, bpp, s, sum;
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ImagingSectionCookie cookie;
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if (!state->state) {
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/* Initialization */
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/* Valid modes are ZIP_PNG, ZIP_PNG_PALETTE, and ZIP_TIFF */
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/* overflow check for malloc */
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if (state->bytes > INT_MAX - 1) {
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state->errcode = IMAGING_CODEC_MEMORY;
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return -1;
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}
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/* Expand standard buffer to make room for the filter selector,
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and allocate filter buffers */
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free(state->buffer);
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/* malloc check ok, overflow checked above */
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state->buffer = (UINT8*) malloc(state->bytes+1);
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context->previous = (UINT8*) malloc(state->bytes+1);
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context->prior = (UINT8*) malloc(state->bytes+1);
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context->up = (UINT8*) malloc(state->bytes+1);
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context->average = (UINT8*) malloc(state->bytes+1);
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context->paeth = (UINT8*) malloc(state->bytes+1);
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if (!state->buffer || !context->previous || !context->prior ||
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!context->up || !context->average || !context->paeth) {
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free(context->paeth);
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free(context->average);
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free(context->up);
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free(context->prior);
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free(context->previous);
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state->errcode = IMAGING_CODEC_MEMORY;
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return -1;
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}
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/* Initalise filter buffers */
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state->buffer[0] = 0;
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context->prior[0] = 1;
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context->up[0] = 2;
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context->average[0] = 3;
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context->paeth[0] = 4;
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/* Initialise previous buffer to black */
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memset(context->previous, 0, state->bytes+1);
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/* Setup compression context */
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context->z_stream.zalloc = (alloc_func)0;
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context->z_stream.zfree = (free_func)0;
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context->z_stream.opaque = (voidpf)0;
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context->z_stream.next_in = 0;
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context->z_stream.avail_in = 0;
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compress_level = (context->optimize) ? Z_BEST_COMPRESSION
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: context->compress_level;
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if (context->compress_type == -1) {
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compress_type = (context->mode == ZIP_PNG) ? Z_FILTERED
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: Z_DEFAULT_STRATEGY;
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} else {
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compress_type = context->compress_type;
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}
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err = deflateInit2(&context->z_stream,
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/* compression level */
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compress_level,
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/* compression method */
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Z_DEFLATED,
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/* compression memory resources */
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15, 9,
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/* compression strategy (image data are filtered)*/
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compress_type);
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if (err < 0) {
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state->errcode = IMAGING_CODEC_CONFIG;
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return -1;
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}
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if (context->dictionary && context->dictionary_size > 0) {
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err = deflateSetDictionary(&context->z_stream, (unsigned char *)context->dictionary,
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context->dictionary_size);
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if (err < 0) {
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state->errcode = IMAGING_CODEC_CONFIG;
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return -1;
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}
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}
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/* Ready to decode */
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state->state = 1;
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}
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/* Setup the destination buffer */
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context->z_stream.next_out = buf;
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context->z_stream.avail_out = bytes;
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if (context->z_stream.next_in && context->z_stream.avail_in > 0) {
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/* We have some data from previous round, deflate it first */
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err = deflate(&context->z_stream, Z_NO_FLUSH);
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if (err < 0) {
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/* Something went wrong inside the compression library */
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if (err == Z_DATA_ERROR)
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state->errcode = IMAGING_CODEC_BROKEN;
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else if (err == Z_MEM_ERROR)
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state->errcode = IMAGING_CODEC_MEMORY;
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else
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state->errcode = IMAGING_CODEC_CONFIG;
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free(context->paeth);
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free(context->average);
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free(context->up);
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free(context->prior);
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free(context->previous);
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deflateEnd(&context->z_stream);
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return -1;
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}
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}
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ImagingSectionEnter(&cookie);
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for (;;) {
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switch (state->state) {
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case 1:
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/* Compress image data */
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while (context->z_stream.avail_out > 0) {
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if (state->y >= state->ysize) {
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/* End of image; now flush compressor buffers */
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state->state = 2;
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break;
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}
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/* Stuff image data into the compressor */
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state->shuffle(state->buffer+1,
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(UINT8*) im->image[state->y + state->yoff] +
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state->xoff * im->pixelsize,
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state->xsize);
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state->y++;
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context->output = state->buffer;
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if (context->mode == ZIP_PNG) {
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/* Filter the image data. For each line, select
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the filter that gives the least total distance
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from zero for the filtered data (taken from
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LIBPNG) */
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bpp = (state->bits + 7) / 8;
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/* 0. No filter */
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for (i = 1, sum = 0; i <= state->bytes; i++) {
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UINT8 v = state->buffer[i];
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sum += (v < 128) ? v : 256 - v;
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}
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/* 2. Up. We'll test this first to save time when
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an image line is identical to the one above. */
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if (sum > 0) {
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for (i = 1, s = 0; i <= state->bytes; i++) {
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UINT8 v = state->buffer[i] - context->previous[i];
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context->up[i] = v;
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s += (v < 128) ? v : 256 - v;
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}
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if (s < sum) {
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context->output = context->up;
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sum = s; /* 0 if line was duplicated */
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}
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}
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/* 1. Prior */
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if (sum > 0) {
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for (i = 1, s = 0; i <= bpp; i++) {
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UINT8 v = state->buffer[i];
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context->prior[i] = v;
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s += (v < 128) ? v : 256 - v;
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}
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for (; i <= state->bytes; i++) {
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UINT8 v = state->buffer[i] - state->buffer[i-bpp];
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context->prior[i] = v;
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s += (v < 128) ? v : 256 - v;
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}
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if (s < sum) {
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context->output = context->prior;
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sum = s; /* 0 if line is solid */
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}
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}
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/* 3. Average (not very common in real-life images,
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so its only used with the optimize option) */
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if (context->optimize && sum > 0) {
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for (i = 1, s = 0; i <= bpp; i++) {
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UINT8 v = state->buffer[i] - context->previous[i]/2;
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context->average[i] = v;
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s += (v < 128) ? v : 256 - v;
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}
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for (; i <= state->bytes; i++) {
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UINT8 v = state->buffer[i] -
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(state->buffer[i-bpp] + context->previous[i])/2;
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context->average[i] = v;
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s += (v < 128) ? v : 256 - v;
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}
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if (s < sum) {
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context->output = context->average;
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sum = s;
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}
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}
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/* 4. Paeth */
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if (sum > 0) {
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for (i = 1, s = 0; i <= bpp; i++) {
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UINT8 v = state->buffer[i] - context->previous[i];
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context->paeth[i] = v;
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s += (v < 128) ? v : 256 - v;
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}
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for (; i <= state->bytes; i++) {
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UINT8 v;
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int a, b, c;
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int pa, pb, pc;
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/* fetch pixels */
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a = state->buffer[i-bpp];
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b = context->previous[i];
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c = context->previous[i-bpp];
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/* distances to surrounding pixels */
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pa = abs(b - c);
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pb = abs(a - c);
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pc = abs(a + b - 2*c);
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/* pick predictor with the shortest distance */
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v = state->buffer[i] -
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((pa <= pb && pa <= pc) ? a :
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(pb <= pc) ? b : c);
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context->paeth[i] = v;
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s += (v < 128) ? v : 256 - v;
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}
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if (s < sum) {
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context->output = context->paeth;
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sum = s;
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}
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}
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}
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/* Compress this line */
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context->z_stream.next_in = context->output;
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context->z_stream.avail_in = state->bytes+1;
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err = deflate(&context->z_stream, Z_NO_FLUSH);
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if (err < 0) {
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/* Something went wrong inside the compression library */
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if (err == Z_DATA_ERROR)
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state->errcode = IMAGING_CODEC_BROKEN;
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else if (err == Z_MEM_ERROR)
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state->errcode = IMAGING_CODEC_MEMORY;
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else
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state->errcode = IMAGING_CODEC_CONFIG;
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free(context->paeth);
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free(context->average);
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free(context->up);
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free(context->prior);
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free(context->previous);
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deflateEnd(&context->z_stream);
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ImagingSectionLeave(&cookie);
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return -1;
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}
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/* Swap buffer pointers */
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ptr = state->buffer;
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state->buffer = context->previous;
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context->previous = ptr;
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}
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if (context->z_stream.avail_out == 0)
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break; /* Buffer full */
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case 2:
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/* End of image data; flush compressor buffers */
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while (context->z_stream.avail_out > 0) {
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err = deflate(&context->z_stream, Z_FINISH);
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if (err == Z_STREAM_END) {
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free(context->paeth);
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free(context->average);
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free(context->up);
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free(context->prior);
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free(context->previous);
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deflateEnd(&context->z_stream);
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state->errcode = IMAGING_CODEC_END;
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break;
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}
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if (context->z_stream.avail_out == 0)
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break; /* Buffer full */
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}
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}
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ImagingSectionLeave(&cookie);
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return bytes - context->z_stream.avail_out;
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}
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/* Should never ever arrive here... */
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state->errcode = IMAGING_CODEC_CONFIG;
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ImagingSectionLeave(&cookie);
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return -1;
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}
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/* -------------------------------------------------------------------- */
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/* Cleanup */
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/* -------------------------------------------------------------------- */
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int
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ImagingZipEncodeCleanup(ImagingCodecState state) {
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ZIPSTATE* context = (ZIPSTATE*) state->context;
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if (context->dictionary) {
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free (context->dictionary);
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context->dictionary = NULL;
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}
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return -1;
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}
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const char*
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ImagingZipVersion(void)
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{
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return ZLIB_VERSION;
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}
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#endif
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