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