/* ======================================================================== */ /* GIF Encoder routines. */ /* */ /* These are intended to support single-frame and multi-frame GIFs. */ /* Single frame support is for screen shots, multi-frame support is for */ /* converting movies to animated GIFs. */ /* */ /* This GIF encoder doesn't trust that the decoder honors the aspect */ /* ratio stored in the GIF. We just set it to 0. */ /* */ /* None of this code's thread-safe/reentrant. BFD. */ /* ======================================================================== */ #include "config.h" #include "gif/gif_enc.h" #include "gif/lzw_enc.h" LOCAL uint_8 *gif_enc_buf = NULL; LOCAL int gif_enc_buf_sz = 0; LOCAL uint_8 *gif_img_tr = NULL; LOCAL uint_8 *gif_img_a = NULL; LOCAL uint_8 *gif_img_b = NULL; LOCAL uint_8 *gif_img_d = NULL, *gif_pal_d = NULL; LOCAL uint_8 *gif_img_e = NULL, *gif_pal_e = NULL; LOCAL uint_8 *gif_img_f = NULL, *gif_pal_f = NULL; LOCAL int gif_img_sz = 0; LOCAL int gen_mpi(uint_8 *src, uint_8 *xtra, uint_8 *dst, int cnt, uint_8 *pal); int gif_best_stats[6]; /* ======================================================================== */ /* GIF_START -- Starts a single or multi-frame GIF. */ /* ======================================================================== */ int gif_start ( gif_t *gif, FILE *f, /* file to attach to GIF. */ int x_dim, /* source image X dimension */ int y_dim, /* source image Y dimension */ uint_8 pal[][3], /* palette to use for GIF. */ int n_cols, /* number of colors in GIF. */ int multi /* 0: Single image, 1: Multiple image */ ) { int i, gt_size; uint_8 *enc_ptr; size_t wrote; /* -------------------------------------------------------------------- */ /* Set up our GIF structure to hold incoming images. */ /* -------------------------------------------------------------------- */ memset(gif, 0, sizeof(gif_t)); gif->f = f; gif->x_dim = x_dim; gif->y_dim = y_dim; if (multi) { gif->vid = CALLOC(uint_8, x_dim * y_dim); gif->pal = CALLOC(uint_8, n_cols * 3); } else { gif->vid = gif->pal = NULL; } if (!gif_enc_buf || gif_enc_buf_sz < x_dim * y_dim * 2) { if (gif_enc_buf) free(gif_enc_buf); gif_enc_buf_sz = x_dim * y_dim * 2; gif_enc_buf = CALLOC(uint_8, gif_enc_buf_sz); } if (!gif_enc_buf || (multi && (!gif->pal || !gif->vid))) { fprintf(stderr, "gif_start: out of memory\n"); return -1; } if (multi && n_cols < 256) { gif->n_cols = n_cols + 1; gif->trans = n_cols; } else { gif->n_cols = n_cols; gif->trans = -1; } if (multi) memset(gif->vid, 0xFF & gif->trans, x_dim * y_dim); /* -------------------------------------------------------------------- */ /* Save a copy of the palette if this is a multiframe GIF. */ /* -------------------------------------------------------------------- */ if (multi) memcpy(gif->pal, pal, n_cols * 3); /* -------------------------------------------------------------------- */ /* Output a GIF header. */ /* -------------------------------------------------------------------- */ gt_size = 0; for (i = 0; i < 8; i++) if ((2 << i) >= gif->n_cols) { gt_size = i; break; } memcpy(gif_enc_buf, multi ? "GIF89a" : "GIF87a", 6); enc_ptr = gif_enc_buf + 6; *enc_ptr++ = (x_dim >> 0) & 0xFF; /* X dimension LSB */ *enc_ptr++ = (x_dim >> 8) & 0xFF; /* X dimension MSB */ *enc_ptr++ = (y_dim >> 0) & 0xFF; /* Y dimension LSB */ *enc_ptr++ = (y_dim >> 8) & 0xFF; /* Y dimension MSB */ *enc_ptr++ = 0x80 /* Global Color Table present */ | 0x70 /* 8 significant bits in palette entries */ | gt_size; /* Color Depth (sets GCT size) */ *enc_ptr++ = 0; /* Background color index. */ *enc_ptr++ = 0; /* Aspect ratio. We hardcode to 0. */ for (i = 0; i < gif->n_cols; i++) { *enc_ptr++ = pal[i][0]; *enc_ptr++ = pal[i][1]; *enc_ptr++ = pal[i][2]; } for (i = gif->n_cols; i < (2 << gt_size); i++) { *enc_ptr++ = 0xFF; *enc_ptr++ = 0x80; *enc_ptr++ = 0x80; } /* -------------------------------------------------------------------- */ /* If this is a multi-frame GIF, write out the extension block which */ /* instructs the web browser to loop the animation. */ /* */ /* byte 1 : 33 (hex 0x21) GIF Extension code */ /* byte 2 : 255 (hex 0xFF) Application Extension Label */ /* byte 3 : 11 (hex (0x0B) Length of Application Block */ /* (eleven bytes of data to follow) */ /* bytes 4 to 11 : "NETSCAPE" */ /* bytes 12 to 14 : "2.0" */ /* byte 15 : 3 (hex 0x03) Length of Data Sub-Block */ /* (three bytes of data to follow) */ /* byte 16 : 1 (hex 0x01) */ /* bytes 17 to 18 : 0 to 65535, little-endian unsigned integer */ /* This indicate the number of iterations the */ /* loop should be executed. 0 == infinite */ /* bytes 19 : 0 (hex 0x00) a Data Sub-block Terminator. */ /* */ /* Text above comes from http://the-labs.com/GIFMerge/ w/ minor edits. */ /* -------------------------------------------------------------------- */ if (multi) { *enc_ptr++ = 0x21; *enc_ptr++ = 0xFF; *enc_ptr++ = 0x0B; memcpy(enc_ptr, "NETSCAPE2.0", 11); enc_ptr += 11; *enc_ptr++ = 3; *enc_ptr++ = 1; *enc_ptr++ = 0; /* "forever" */ *enc_ptr++ = 0; /* "forever" */ *enc_ptr++ = 0; } /* -------------------------------------------------------------------- */ /* Write out the GIF header, and that's it. The caller will need */ /* to call gif_wr_frame_X() to write out the image(s). */ /* -------------------------------------------------------------------- */ wrote = fwrite(gif_enc_buf, 1, enc_ptr - gif_enc_buf, gif->f); if (wrote < (unsigned)(enc_ptr - gif_enc_buf)) return -1; return wrote; } /* ======================================================================== */ /* GIF_FINISH -- Finishes off a GIF, terminating it and freeing memory. */ /* ======================================================================== */ int gif_finish(gif_t *gif) { /* -------------------------------------------------------------------- */ /* Write an image terminator. */ /* -------------------------------------------------------------------- */ fputc(0x3B, gif->f); fflush(gif->f); /* -------------------------------------------------------------------- */ /* Free any allocated memory in the gif structure. */ /* -------------------------------------------------------------------- */ if (gif->vid) { free(gif->vid); gif->vid = NULL; } if (gif->pal) { free(gif->pal); gif->pal = NULL; } return 1; /* wrote 1 byte. */ } /* ======================================================================== */ /* GIF_WR_FRAME_S -- Writes single-frame image to GIF. */ /* ======================================================================== */ int gif_wr_frame_s ( gif_t *gif, uint_8 *vid ) { uint_8 *enc_ptr = gif_enc_buf; int lzw_len; size_t wrote; assert(enc_ptr); /* -------------------------------------------------------------------- */ /* Output local header. */ /* -------------------------------------------------------------------- */ *enc_ptr++ = 0x2C; /* Local header signature. */ *enc_ptr++ = 0; /* X position of image = 0 LSB */ *enc_ptr++ = 0; /* X position of image = 0 MSB */ *enc_ptr++ = 0; /* Y position of image = 0 LSB */ *enc_ptr++ = 0; /* Y position of image = 0 MSB */ *enc_ptr++ = (gif->x_dim >> 0) & 0xFF; /* Width = X dimension LSB */ *enc_ptr++ = (gif->x_dim >> 8) & 0xFF; /* Width = X dimension MSB */ *enc_ptr++ = (gif->y_dim >> 0) & 0xFF; /* Height = Y dimension LSB */ *enc_ptr++ = (gif->y_dim >> 8) & 0xFF; /* Height = Y dimension MSB */ *enc_ptr++ = 0; /* No local colors */ /* -------------------------------------------------------------------- */ /* Now compress the image. */ /* -------------------------------------------------------------------- */ lzw_len = lzw_encode(vid, enc_ptr, gif->x_dim*gif->y_dim, gif_enc_buf_sz - (enc_ptr - gif_enc_buf)); if (lzw_len < 0) return -1; enc_ptr += lzw_len; assert(enc_ptr < gif_enc_buf + gif_enc_buf_sz); /* -------------------------------------------------------------------- */ /* Write the compressed image out. */ /* -------------------------------------------------------------------- */ wrote = fwrite(gif_enc_buf, 1, enc_ptr - gif_enc_buf, gif->f); if (wrote < (unsigned)(enc_ptr - gif_enc_buf)) return -1; return wrote; } /* ======================================================================== */ /* GIF_WRITE -- Wrapper around gif_start/gif_wr_frame_s. */ /* ======================================================================== */ int gif_write ( FILE *f, uint_8 *vid, int x_dim, int y_dim, uint_8 pal[][3], int n_cols ) { gif_t gif; int wrote = 0, ret; /* -------------------------------------------------------------------- */ /* Start the GIF. */ /* -------------------------------------------------------------------- */ ret = gif_start(&gif, f, x_dim, y_dim, pal, n_cols, 0); wrote += ret; if (ret < 0) return -1; /* -------------------------------------------------------------------- */ /* Send the image. */ /* -------------------------------------------------------------------- */ ret = gif_wr_frame_s(&gif, vid); wrote += ret; if (ret < 0) return -1; /* -------------------------------------------------------------------- */ /* Terminate it. */ /* -------------------------------------------------------------------- */ ret = gif_finish(&gif); wrote += ret; if (ret < 0) return -1; return wrote; } /* ======================================================================== */ /* GIF_WR_FRAME_M -- Writes next frame to a multi-frame GIF. */ /* Attempts to optimize image. */ /* ======================================================================== */ int gif_wr_frame_m ( gif_t *gif, uint_8 *vid, int delay, int mode ) { int trans = gif->trans >= 0; uint_8 *enc_ptr = gif_enc_buf; uint_8 *vid_ptr, *prv_ptr, *trn_ptr; uint_8 *best_img1, *best_img2, *best_lct; int x, y, xx, yy, min_x, min_y, max_x, max_y, width, height; int n_col_d, n_col_e = 0, n_col_f = 0, lct_sz_d, lct_sz_e, lct_sz_f; int enc_sz_a, enc_sz_b, enc_sz_c, enc_sz_d, enc_sz_e, enc_sz_f; int best_sz, best_lct_sz, trans_idx, do_trans = 0; int lzw_len; int cnt, num_trans = 0; char best = '*'; size_t wrote; assert(enc_ptr); /* -------------------------------------------------------------------- */ /* Allocate our image optimization scratch buffers, if necessary. */ /* -------------------------------------------------------------------- */ if (gif_img_sz < gif->x_dim * gif->y_dim) { if (gif_img_tr) free(gif_img_tr); gif_img_sz = gif->x_dim * gif->y_dim; gif_img_tr = CALLOC(uint_8, 7 * gif->x_dim * gif->y_dim + 3*256); if (!gif_img_tr) { fprintf(stderr, "gif_wr_frame_m: out of memory\n"); return -1; } gif_img_a = gif_img_tr + gif_img_sz * 2; gif_img_b = gif_img_a + gif_img_sz; gif_img_d = gif_img_b + gif_img_sz; gif_img_e = gif_img_d + gif_img_sz; gif_img_f = gif_img_e + gif_img_sz; gif_pal_d = gif_img_f + gif_img_sz; gif_pal_e = gif_pal_d + 256; gif_pal_f = gif_pal_e + 256; } /* -------------------------------------------------------------------- */ /* Optimize image: */ /* */ /* 1. Generate "transparency" image with trans pixels wherever this */ /* image is the same as the previous one. */ /* */ /* 2. Compute tighter bounding box on image--that is, smallest box */ /* that contains all the non-trans pixels. */ /* */ /* 3. Crop the incoming image based on the tighter bounding box. */ /* */ /* 4. Generate "minimal palette" images that renumber all the */ /* pixels into the smallest possible numbering space. */ /* */ /* 5. Compress the image multiple ways, and take the best: */ /* */ /* a. Cropped image, orig palette, no trans pixels */ /* b. Cropped image, orig palette, trans pixels */ /* c. Cropped image, orig palette, "wildcard" trans/no-trans */ /* d. Cropped image, new palette, no trans pixels */ /* e. Cropped image, new palette, trans pixels */ /* f. Cropped image, new palette, "wildcard" trans/no-trans */ /* */ /* When comparing new palette to orig palette, include cost */ /* of sending local palette. If the global palette has too */ /* many colors, we may not be able to try b or c. If the local */ /* palette has too many colors, we may not be able to try e or */ /* f. */ /* */ /* -------------------------------------------------------------------- */ /* -------------------------------------------------------------------- */ /* 1. Generate "transparency" image... */ /* 2. Compute tighter bounding box on image... */ /* -------------------------------------------------------------------- */ min_x = gif->x_dim; min_y = gif->y_dim; max_x = 0; max_y = 0; vid_ptr = vid; prv_ptr = gif->vid; trn_ptr = gif_img_tr; for (y = 0; y < gif->y_dim; y++) for (x = 0; x < gif->x_dim; x++) { uint_8 curr = *vid_ptr++; uint_8 prev = *prv_ptr++; uint_8 tran = gif->trans; if (curr != prev) { tran = curr; if (x < min_x) min_x = x; if (y < min_y) min_y = y; if (x > max_x) max_x = x; if (y > max_y) max_y = y; } *trn_ptr++ = tran; } /* -------------------------------------------------------------------- */ /* Stop now if current image matches previous image. */ /* -------------------------------------------------------------------- */ if (min_x > max_x || min_y > max_y) return 0; if (mode != 0) { min_x = 0; min_y = 0; max_x = gif->x_dim - 1; max_y = gif->y_dim - 1; } width = max_x - min_x + 1; height = max_y - min_y + 1; cnt = width*height; /* -------------------------------------------------------------------- */ /* 3. Crop the incoming image based on the tighter bounding box. */ /* -------------------------------------------------------------------- */ for (y = min_y, yy = 0; y <= max_y; y++, yy++) for (x = min_x, xx = 0; x <= max_x; x++, xx++) { /* a. Cropped image, orig palette, no trans pixels */ /* b. Cropped image, orig palette, trans pixels */ gif_img_a[xx + yy*width] = vid [x + y*gif->x_dim]; gif_img_b[xx + yy*width] = gif_img_tr[x + y*gif->x_dim]; if (gif_img_tr[x + y*gif->x_dim] == gif->trans) num_trans++; } if (num_trans == 0) trans = 0; if (mode != 0) trans = 0; #if 0 { FILE *ff; ff = fopen("debug", "wb"); if (ff) { fwrite(gif_img_a, 1, cnt, ff); fclose(ff); } } #endif /* -------------------------------------------------------------------- */ /* 4. Generate "minimal palette" images... */ /* d. Cropped image, new palette, no trans pixels */ /* e. Cropped image, new palette, trans pixels */ /* f. Cropped image, new palette, "wildcard" trans/no-trans */ /* -------------------------------------------------------------------- */ n_col_d = gen_mpi(gif_img_a, NULL, gif_img_d, cnt, gif_pal_d); if(trans) n_col_e = gen_mpi(gif_img_b, NULL, gif_img_e, cnt, gif_pal_e); if(trans) n_col_f = gen_mpi(gif_img_b,gif_img_a,gif_img_f, cnt, gif_pal_f); for (lct_sz_d = 1; (2 << lct_sz_d) < n_col_d; lct_sz_d++); for (lct_sz_e = 1; (2 << lct_sz_e) < n_col_e; lct_sz_e++); for (lct_sz_f = 1; (2 << lct_sz_f) < n_col_f; lct_sz_f++); if (trans) { int i; for (i = 0; i < n_col_d; i++) assert(gif_pal_d[i] == gif_pal_f[i]); /*printf("n_col_d=%d, n_col_f=%d gif_pal_f[n_col_f-1]=%d gif->trans=%d\n", n_col_d, n_col_f, gif_pal_f[n_col_f-1], gif->trans);*/ assert(n_col_d < n_col_f); assert(gif_pal_f[n_col_f - 1] == gif->trans); } /* -------------------------------------------------------------------- */ /* 5. Compress the image multiple ways, and take the best... */ /* */ /* We reuse gif_img_tr as a compression buffer here, since we don't */ /* need that image any longer, but we do need a temp buffer for LZW. */ /* -------------------------------------------------------------------- */ enc_sz_a = lzw_encode(gif_img_a, gif_img_tr, cnt, gif_img_sz*2); enc_sz_b = -1; enc_sz_c = -1; enc_sz_d = lzw_encode(gif_img_d, gif_img_tr, cnt, gif_img_sz*2); enc_sz_e = -1; enc_sz_f = -1; if (trans) { enc_sz_b = lzw_encode(gif_img_b, gif_img_tr, cnt, gif_img_sz*2); enc_sz_e = lzw_encode(gif_img_e, gif_img_tr, cnt, gif_img_sz*2); #if 1 enc_sz_c = lzw_encode2(gif_img_b, gif_img_a, gif_img_tr, cnt, gif_img_sz); enc_sz_f = lzw_encode2(gif_img_f, gif_img_d, gif_img_tr, cnt, gif_img_sz); #endif } if (enc_sz_d > 0) enc_sz_d += 3 << (lct_sz_d + 1); if (enc_sz_e > 0) enc_sz_e += 3 << (lct_sz_e + 1); if (enc_sz_f > 0) enc_sz_f += 3 << (lct_sz_f + 1); if (enc_sz_a < 0) enc_sz_a = INT_MAX; if (enc_sz_b < 0) enc_sz_b = INT_MAX; if (enc_sz_c < 0) enc_sz_c = INT_MAX; if (enc_sz_d < 0) enc_sz_d = INT_MAX; if (enc_sz_e < 0) enc_sz_e = INT_MAX; if (enc_sz_f < 0) enc_sz_f = INT_MAX; /* Initially assume A's the best. */ best_img1 = gif_img_a; best_img2 = NULL; best_lct = NULL; best_lct_sz = 0; best_sz = enc_sz_a; trans_idx = 0; do_trans = 0; best = 'a'; #if 1 if (enc_sz_b < best_sz) { best_img1 = gif_img_b; best_img2 = NULL; best_lct = NULL; best_lct_sz = 0; best_sz = enc_sz_b; trans_idx = gif->trans; do_trans = 1; best = 'b'; } if (enc_sz_d < best_sz) { best_img1 = gif_img_d; best_img2 = NULL; best_lct = gif_pal_d; best_lct_sz = lct_sz_d; best_sz = enc_sz_d; trans_idx = 0; do_trans = 0; best = 'd'; } if (enc_sz_e < best_sz) { best_img1 = gif_img_e; best_img2 = NULL; best_lct = gif_pal_e; best_lct_sz = lct_sz_e; best_sz = enc_sz_e; trans_idx = n_col_e - 1; do_trans = 1; best = 'e'; } if (enc_sz_c < best_sz) { best_img1 = gif_img_b; best_img2 = gif_img_a; best_lct = NULL; best_lct_sz = 0; best_sz = enc_sz_c; trans_idx = gif->trans; do_trans = 1; best = 'c'; } if (enc_sz_f < best_sz) { best_img1 = gif_img_f; best_img2 = gif_img_d; best_lct = gif_pal_f; best_lct_sz = lct_sz_f; best_sz = enc_sz_f; trans_idx = n_col_f - 1; do_trans = 1; best = 'f'; } if (best_sz < 0 || best_sz == INT_MAX) { fprintf(stderr, "gif_wr_frame_m: Image overflowed compression " "buffer.\n"); return -1; } #endif gif_best_stat[best - 'a']++; /* -------------------------------------------------------------------- */ /* Output a Graphic Control Ext. */ /* -------------------------------------------------------------------- */ *enc_ptr++ = 0x21; /* Extension signature */ *enc_ptr++ = 0xF9; /* Graphic control extension */ *enc_ptr++ = 0x04; /* Length of block: Fixed at 4. */ *enc_ptr++ = 0x04 | do_trans; /* Disposal 01, No input, Trans */ *enc_ptr++ = (delay >> 0) & 0xFF; /* delay in 100ths of a second LSB */ *enc_ptr++ = (delay >> 8) & 0xFF; /* delay in 100ths of a second MSB */ *enc_ptr++ = trans_idx; /* Transparency index, if any. */ *enc_ptr++ = 0x00; /* GCE block terminator. */ /* -------------------------------------------------------------------- */ /* Output an Image Descriptor. */ /* -------------------------------------------------------------------- */ *enc_ptr++ = 0x2C; /* Image Separator */ *enc_ptr++ = (min_x >> 0) & 0xFF; /* Left edge, LSB */ *enc_ptr++ = (min_x >> 8) & 0xFF; /* Left edge, MSB */ *enc_ptr++ = (min_y >> 0) & 0xFF; /* Top edge, LSB */ *enc_ptr++ = (min_y >> 8) & 0xFF; /* Top edge, MSB */ *enc_ptr++ = (width >> 0) & 0xFF; /* Image width, LSB */ *enc_ptr++ = (width >> 8) & 0xFF; /* Image width, MSB */ *enc_ptr++ = (height >> 0) & 0xFF; /* Image height, LSB */ *enc_ptr++ = (height >> 8) & 0xFF; /* Image height, MSB */ *enc_ptr++ = best_lct_sz == 0 ? 0 /* no local color table? */ : best_lct_sz | 0x80; /* or yes local color table? */ /*printf("[%3d,%3d] [%3d,%3d] [%3d,%3d] delay=%-3d trans=%-3d%c lct=%d\n", min_x, min_y, width, height, min_x + width, min_y + height, delay, trans_idx, do_trans ? '*' : ' ', best_lct_sz);*/ /* -------------------------------------------------------------------- */ /* If we're sending a local color table, put it here. */ /* -------------------------------------------------------------------- */ if (best_lct_sz) { int i; for (i = 0; i < (2 << best_lct_sz); i++) { if (best_lct[i] < gif->n_cols) { *enc_ptr++ = gif->pal[3*best_lct[i] + 0]; *enc_ptr++ = gif->pal[3*best_lct[i] + 1]; *enc_ptr++ = gif->pal[3*best_lct[i] + 2]; } else { *enc_ptr++ = 0; *enc_ptr++ = 0; *enc_ptr++ = 0; } } } /* -------------------------------------------------------------------- */ /* Now, re-encode the winning image. */ /* -------------------------------------------------------------------- */ if (best_img2) { lzw_len = lzw_encode2(best_img1, best_img2, enc_ptr, cnt, gif_enc_buf_sz - (enc_ptr - gif_enc_buf) - 1); } else { lzw_len = lzw_encode(best_img1, enc_ptr, cnt, gif_enc_buf_sz - (enc_ptr - gif_enc_buf) - 1); } if (lzw_len < 0) { fprintf(stderr, "gif_wr_frame_m: Final encode failed?\n"); return -1; } enc_ptr += lzw_len; assert(enc_ptr < gif_enc_buf + gif_enc_buf_sz); /* -------------------------------------------------------------------- */ /* Write the compressed image out. */ /* -------------------------------------------------------------------- */ wrote = fwrite(gif_enc_buf, 1, enc_ptr - gif_enc_buf, gif->f); if (wrote < (unsigned)(enc_ptr - gif_enc_buf)) { fprintf(stderr, "gif_wr_frame_m: Short write? %ld vs %ld\n", (long)wrote, (long)(enc_ptr - gif_enc_buf)); return -1; } /* -------------------------------------------------------------------- */ /* Make the current image the new previous image. */ /* -------------------------------------------------------------------- */ memcpy(gif->vid, vid, gif->x_dim * gif->y_dim); return wrote; } /* ======================================================================== */ /* GEN_MPI -- Generate Minimal Palette Image, and its palette. */ /* ======================================================================== */ LOCAL int gen_mpi ( uint_8 *src, uint_8 *xtra, uint_8 *dst, int cnt, uint_8 *pal_map ) { int hist1[256]; int hist2[256]; int rev_map[256]; int i, r = 0; memset(hist1, 0, sizeof(hist1)); memset(hist2, 0, sizeof(hist2)); memset(rev_map, 0, sizeof(rev_map)); /* -------------------------------------------------------------------- */ /* Find what colors are in the source image. */ /* -------------------------------------------------------------------- */ for (i = 0; i < cnt; i++) hist1[src[i]]++; /* -------------------------------------------------------------------- */ /* If we have a secondary image, look for its palette also. It gets */ /* first dibs on palette allocation, because our goal is to just */ /* *extend* the extra image's palette to accomodate our source image. */ /* -------------------------------------------------------------------- */ if (xtra) { for (i = 0; i < cnt; i++) hist2[xtra[i]]++; for (i = 0; i < 256; i++) if (hist2[i]) { rev_map[i] = r; pal_map[r] = i; r++; } } /* -------------------------------------------------------------------- */ /* Build up our palette map from the source image. */ /* -------------------------------------------------------------------- */ for (i = 0; i < 256; i++) if (hist1[i] && !hist2[i]) { rev_map[i] = r; pal_map[r] = i; r++; } /* -------------------------------------------------------------------- */ /* Remap the source image to the smaller palette. */ /* -------------------------------------------------------------------- */ for (i = 0; i < cnt; i++) dst[i] = rev_map[src[i]]; return r; } /* ======================================================================== */ /* This program is free software; you can redistribute it and/or modify */ /* it under the terms of the GNU General Public License as published by */ /* the Free Software Foundation; either version 2 of the License, or */ /* (at your option) any later version. */ /* */ /* This program is distributed in the hope that it will be useful, */ /* but WITHOUT ANY WARRANTY; without even the implied warranty of */ /* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU */ /* General Public License for more details. */ /* */ /* You should have received a copy of the GNU General Public License */ /* along with this program; if not, write to the Free Software */ /* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */ /* ======================================================================== */ /* Copyright (c) 2005, Joseph Zbiciak */ /* ======================================================================== */