1 2/* pngrtran.c - transforms the data in a row for PNG readers 3 * 4 * Last changed in libpng 1.6.22 [May 26, 2016] 5 * Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson 6 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger) 7 * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.) 8 * 9 * This code is released under the libpng license. 10 * For conditions of distribution and use, see the disclaimer 11 * and license in png.h 12 * 13 * This file contains functions optionally called by an application 14 * in order to tell libpng how to handle data when reading a PNG. 15 * Transformations that are used in both reading and writing are 16 * in pngtrans.c. 17 */ 18 19#include "pngpriv.h" 20 21#ifdef PNG_READ_SUPPORTED 22 23/* Set the action on getting a CRC error for an ancillary or critical chunk. */ 24void PNGAPI 25png_set_crc_action(png_structrp png_ptr, int crit_action, int ancil_action) 26{ 27 png_debug(1, "in png_set_crc_action"); 28 29 if (png_ptr == NULL) 30 return; 31 32 /* Tell libpng how we react to CRC errors in critical chunks */ 33 switch (crit_action) 34 { 35 case PNG_CRC_NO_CHANGE: /* Leave setting as is */ 36 break; 37 38 case PNG_CRC_WARN_USE: /* Warn/use data */ 39 png_ptr->flags &= ~PNG_FLAG_CRC_CRITICAL_MASK; 40 png_ptr->flags |= PNG_FLAG_CRC_CRITICAL_USE; 41 break; 42 43 case PNG_CRC_QUIET_USE: /* Quiet/use data */ 44 png_ptr->flags &= ~PNG_FLAG_CRC_CRITICAL_MASK; 45 png_ptr->flags |= PNG_FLAG_CRC_CRITICAL_USE | 46 PNG_FLAG_CRC_CRITICAL_IGNORE; 47 break; 48 49 case PNG_CRC_WARN_DISCARD: /* Not a valid action for critical data */ 50 png_warning(png_ptr, 51 "Can't discard critical data on CRC error"); 52 case PNG_CRC_ERROR_QUIT: /* Error/quit */ 53 54 case PNG_CRC_DEFAULT: 55 default: 56 png_ptr->flags &= ~PNG_FLAG_CRC_CRITICAL_MASK; 57 break; 58 } 59 60 /* Tell libpng how we react to CRC errors in ancillary chunks */ 61 switch (ancil_action) 62 { 63 case PNG_CRC_NO_CHANGE: /* Leave setting as is */ 64 break; 65 66 case PNG_CRC_WARN_USE: /* Warn/use data */ 67 png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK; 68 png_ptr->flags |= PNG_FLAG_CRC_ANCILLARY_USE; 69 break; 70 71 case PNG_CRC_QUIET_USE: /* Quiet/use data */ 72 png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK; 73 png_ptr->flags |= PNG_FLAG_CRC_ANCILLARY_USE | 74 PNG_FLAG_CRC_ANCILLARY_NOWARN; 75 break; 76 77 case PNG_CRC_ERROR_QUIT: /* Error/quit */ 78 png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK; 79 png_ptr->flags |= PNG_FLAG_CRC_ANCILLARY_NOWARN; 80 break; 81 82 case PNG_CRC_WARN_DISCARD: /* Warn/discard data */ 83 84 case PNG_CRC_DEFAULT: 85 default: 86 png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK; 87 break; 88 } 89} 90 91#ifdef PNG_READ_TRANSFORMS_SUPPORTED 92/* Is it OK to set a transformation now? Only if png_start_read_image or 93 * png_read_update_info have not been called. It is not necessary for the IHDR 94 * to have been read in all cases; the need_IHDR parameter allows for this 95 * check too. 96 */ 97static int 98png_rtran_ok(png_structrp png_ptr, int need_IHDR) 99{ 100 if (png_ptr != NULL) 101 { 102 if ((png_ptr->flags & PNG_FLAG_ROW_INIT) != 0) 103 png_app_error(png_ptr, 104 "invalid after png_start_read_image or png_read_update_info"); 105 106 else if (need_IHDR && (png_ptr->mode & PNG_HAVE_IHDR) == 0) 107 png_app_error(png_ptr, "invalid before the PNG header has been read"); 108 109 else 110 { 111 /* Turn on failure to initialize correctly for all transforms. */ 112 png_ptr->flags |= PNG_FLAG_DETECT_UNINITIALIZED; 113 114 return 1; /* Ok */ 115 } 116 } 117 118 return 0; /* no png_error possible! */ 119} 120#endif 121 122#ifdef PNG_READ_BACKGROUND_SUPPORTED 123/* Handle alpha and tRNS via a background color */ 124void PNGFAPI 125png_set_background_fixed(png_structrp png_ptr, 126 png_const_color_16p background_color, int background_gamma_code, 127 int need_expand, png_fixed_point background_gamma) 128{ 129 png_debug(1, "in png_set_background_fixed"); 130 131 if (png_rtran_ok(png_ptr, 0) == 0 || background_color == NULL) 132 return; 133 134 if (background_gamma_code == PNG_BACKGROUND_GAMMA_UNKNOWN) 135 { 136 png_warning(png_ptr, "Application must supply a known background gamma"); 137 return; 138 } 139 140 png_ptr->transformations |= PNG_COMPOSE | PNG_STRIP_ALPHA; 141 png_ptr->transformations &= ~PNG_ENCODE_ALPHA; 142 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA; 143 144 png_ptr->background = *background_color; 145 png_ptr->background_gamma = background_gamma; 146 png_ptr->background_gamma_type = (png_byte)(background_gamma_code); 147 if (need_expand != 0) 148 png_ptr->transformations |= PNG_BACKGROUND_EXPAND; 149 else 150 png_ptr->transformations &= ~PNG_BACKGROUND_EXPAND; 151} 152 153# ifdef PNG_FLOATING_POINT_SUPPORTED 154void PNGAPI 155png_set_background(png_structrp png_ptr, 156 png_const_color_16p background_color, int background_gamma_code, 157 int need_expand, double background_gamma) 158{ 159 png_set_background_fixed(png_ptr, background_color, background_gamma_code, 160 need_expand, png_fixed(png_ptr, background_gamma, "png_set_background")); 161} 162# endif /* FLOATING_POINT */ 163#endif /* READ_BACKGROUND */ 164 165/* Scale 16-bit depth files to 8-bit depth. If both of these are set then the 166 * one that pngrtran does first (scale) happens. This is necessary to allow the 167 * TRANSFORM and API behavior to be somewhat consistent, and it's simpler. 168 */ 169#ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED 170void PNGAPI 171png_set_scale_16(png_structrp png_ptr) 172{ 173 png_debug(1, "in png_set_scale_16"); 174 175 if (png_rtran_ok(png_ptr, 0) == 0) 176 return; 177 178 png_ptr->transformations |= PNG_SCALE_16_TO_8; 179} 180#endif 181 182#ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED 183/* Chop 16-bit depth files to 8-bit depth */ 184void PNGAPI 185png_set_strip_16(png_structrp png_ptr) 186{ 187 png_debug(1, "in png_set_strip_16"); 188 189 if (png_rtran_ok(png_ptr, 0) == 0) 190 return; 191 192 png_ptr->transformations |= PNG_16_TO_8; 193} 194#endif 195 196#ifdef PNG_READ_STRIP_ALPHA_SUPPORTED 197void PNGAPI 198png_set_strip_alpha(png_structrp png_ptr) 199{ 200 png_debug(1, "in png_set_strip_alpha"); 201 202 if (png_rtran_ok(png_ptr, 0) == 0) 203 return; 204 205 png_ptr->transformations |= PNG_STRIP_ALPHA; 206} 207#endif 208 209#if defined(PNG_READ_ALPHA_MODE_SUPPORTED) || defined(PNG_READ_GAMMA_SUPPORTED) 210static png_fixed_point 211translate_gamma_flags(png_structrp png_ptr, png_fixed_point output_gamma, 212 int is_screen) 213{ 214 /* Check for flag values. The main reason for having the old Mac value as a 215 * flag is that it is pretty near impossible to work out what the correct 216 * value is from Apple documentation - a working Mac system is needed to 217 * discover the value! 218 */ 219 if (output_gamma == PNG_DEFAULT_sRGB || 220 output_gamma == PNG_FP_1 / PNG_DEFAULT_sRGB) 221 { 222 /* If there is no sRGB support this just sets the gamma to the standard 223 * sRGB value. (This is a side effect of using this function!) 224 */ 225# ifdef PNG_READ_sRGB_SUPPORTED 226 png_ptr->flags |= PNG_FLAG_ASSUME_sRGB; 227# else 228 PNG_UNUSED(png_ptr) 229# endif 230 if (is_screen != 0) 231 output_gamma = PNG_GAMMA_sRGB; 232 else 233 output_gamma = PNG_GAMMA_sRGB_INVERSE; 234 } 235 236 else if (output_gamma == PNG_GAMMA_MAC_18 || 237 output_gamma == PNG_FP_1 / PNG_GAMMA_MAC_18) 238 { 239 if (is_screen != 0) 240 output_gamma = PNG_GAMMA_MAC_OLD; 241 else 242 output_gamma = PNG_GAMMA_MAC_INVERSE; 243 } 244 245 return output_gamma; 246} 247 248# ifdef PNG_FLOATING_POINT_SUPPORTED 249static png_fixed_point 250convert_gamma_value(png_structrp png_ptr, double output_gamma) 251{ 252 /* The following silently ignores cases where fixed point (times 100,000) 253 * gamma values are passed to the floating point API. This is safe and it 254 * means the fixed point constants work just fine with the floating point 255 * API. The alternative would just lead to undetected errors and spurious 256 * bug reports. Negative values fail inside the _fixed API unless they 257 * correspond to the flag values. 258 */ 259 if (output_gamma > 0 && output_gamma < 128) 260 output_gamma *= PNG_FP_1; 261 262 /* This preserves -1 and -2 exactly: */ 263 output_gamma = floor(output_gamma + .5); 264 265 if (output_gamma > PNG_FP_MAX || output_gamma < PNG_FP_MIN) 266 png_fixed_error(png_ptr, "gamma value"); 267 268 return (png_fixed_point)output_gamma; 269} 270# endif 271#endif /* READ_ALPHA_MODE || READ_GAMMA */ 272 273#ifdef PNG_READ_ALPHA_MODE_SUPPORTED 274void PNGFAPI 275png_set_alpha_mode_fixed(png_structrp png_ptr, int mode, 276 png_fixed_point output_gamma) 277{ 278 int compose = 0; 279 png_fixed_point file_gamma; 280 281 png_debug(1, "in png_set_alpha_mode"); 282 283 if (png_rtran_ok(png_ptr, 0) == 0) 284 return; 285 286 output_gamma = translate_gamma_flags(png_ptr, output_gamma, 1/*screen*/); 287 288 /* Validate the value to ensure it is in a reasonable range. The value 289 * is expected to be 1 or greater, but this range test allows for some 290 * viewing correction values. The intent is to weed out users of this API 291 * who use the inverse of the gamma value accidentally! Since some of these 292 * values are reasonable this may have to be changed: 293 * 294 * 1.6.x: changed from 0.07..3 to 0.01..100 (to accomodate the optimal 16-bit 295 * gamma of 36, and its reciprocal.) 296 */ 297 if (output_gamma < 1000 || output_gamma > 10000000) 298 png_error(png_ptr, "output gamma out of expected range"); 299 300 /* The default file gamma is the inverse of the output gamma; the output 301 * gamma may be changed below so get the file value first: 302 */ 303 file_gamma = png_reciprocal(output_gamma); 304 305 /* There are really 8 possibilities here, composed of any combination 306 * of: 307 * 308 * premultiply the color channels 309 * do not encode non-opaque pixels 310 * encode the alpha as well as the color channels 311 * 312 * The differences disappear if the input/output ('screen') gamma is 1.0, 313 * because then the encoding is a no-op and there is only the choice of 314 * premultiplying the color channels or not. 315 * 316 * png_set_alpha_mode and png_set_background interact because both use 317 * png_compose to do the work. Calling both is only useful when 318 * png_set_alpha_mode is used to set the default mode - PNG_ALPHA_PNG - along 319 * with a default gamma value. Otherwise PNG_COMPOSE must not be set. 320 */ 321 switch (mode) 322 { 323 case PNG_ALPHA_PNG: /* default: png standard */ 324 /* No compose, but it may be set by png_set_background! */ 325 png_ptr->transformations &= ~PNG_ENCODE_ALPHA; 326 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA; 327 break; 328 329 case PNG_ALPHA_ASSOCIATED: /* color channels premultiplied */ 330 compose = 1; 331 png_ptr->transformations &= ~PNG_ENCODE_ALPHA; 332 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA; 333 /* The output is linear: */ 334 output_gamma = PNG_FP_1; 335 break; 336 337 case PNG_ALPHA_OPTIMIZED: /* associated, non-opaque pixels linear */ 338 compose = 1; 339 png_ptr->transformations &= ~PNG_ENCODE_ALPHA; 340 png_ptr->flags |= PNG_FLAG_OPTIMIZE_ALPHA; 341 /* output_gamma records the encoding of opaque pixels! */ 342 break; 343 344 case PNG_ALPHA_BROKEN: /* associated, non-linear, alpha encoded */ 345 compose = 1; 346 png_ptr->transformations |= PNG_ENCODE_ALPHA; 347 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA; 348 break; 349 350 default: 351 png_error(png_ptr, "invalid alpha mode"); 352 } 353 354 /* Only set the default gamma if the file gamma has not been set (this has 355 * the side effect that the gamma in a second call to png_set_alpha_mode will 356 * be ignored.) 357 */ 358 if (png_ptr->colorspace.gamma == 0) 359 { 360 png_ptr->colorspace.gamma = file_gamma; 361 png_ptr->colorspace.flags |= PNG_COLORSPACE_HAVE_GAMMA; 362 } 363 364 /* But always set the output gamma: */ 365 png_ptr->screen_gamma = output_gamma; 366 367 /* Finally, if pre-multiplying, set the background fields to achieve the 368 * desired result. 369 */ 370 if (compose != 0) 371 { 372 /* And obtain alpha pre-multiplication by composing on black: */ 373 memset(&png_ptr->background, 0, (sizeof png_ptr->background)); 374 png_ptr->background_gamma = png_ptr->colorspace.gamma; /* just in case */ 375 png_ptr->background_gamma_type = PNG_BACKGROUND_GAMMA_FILE; 376 png_ptr->transformations &= ~PNG_BACKGROUND_EXPAND; 377 378 if ((png_ptr->transformations & PNG_COMPOSE) != 0) 379 png_error(png_ptr, 380 "conflicting calls to set alpha mode and background"); 381 382 png_ptr->transformations |= PNG_COMPOSE; 383 } 384} 385 386# ifdef PNG_FLOATING_POINT_SUPPORTED 387void PNGAPI 388png_set_alpha_mode(png_structrp png_ptr, int mode, double output_gamma) 389{ 390 png_set_alpha_mode_fixed(png_ptr, mode, convert_gamma_value(png_ptr, 391 output_gamma)); 392} 393# endif 394#endif 395 396#ifdef PNG_READ_QUANTIZE_SUPPORTED 397/* Dither file to 8-bit. Supply a palette, the current number 398 * of elements in the palette, the maximum number of elements 399 * allowed, and a histogram if possible. If the current number 400 * of colors is greater than the maximum number, the palette will be 401 * modified to fit in the maximum number. "full_quantize" indicates 402 * whether we need a quantizing cube set up for RGB images, or if we 403 * simply are reducing the number of colors in a paletted image. 404 */ 405 406typedef struct png_dsort_struct 407{ 408 struct png_dsort_struct * next; 409 png_byte left; 410 png_byte right; 411} png_dsort; 412typedef png_dsort * png_dsortp; 413typedef png_dsort * * png_dsortpp; 414 415void PNGAPI 416png_set_quantize(png_structrp png_ptr, png_colorp palette, 417 int num_palette, int maximum_colors, png_const_uint_16p histogram, 418 int full_quantize) 419{ 420 png_debug(1, "in png_set_quantize"); 421 422 if (png_rtran_ok(png_ptr, 0) == 0) 423 return; 424 425 png_ptr->transformations |= PNG_QUANTIZE; 426 427 if (full_quantize == 0) 428 { 429 int i; 430 431 png_ptr->quantize_index = (png_bytep)png_malloc(png_ptr, 432 (png_uint_32)(num_palette * (sizeof (png_byte)))); 433 for (i = 0; i < num_palette; i++) 434 png_ptr->quantize_index[i] = (png_byte)i; 435 } 436 437 if (num_palette > maximum_colors) 438 { 439 if (histogram != NULL) 440 { 441 /* This is easy enough, just throw out the least used colors. 442 * Perhaps not the best solution, but good enough. 443 */ 444 445 int i; 446 447 /* Initialize an array to sort colors */ 448 png_ptr->quantize_sort = (png_bytep)png_malloc(png_ptr, 449 (png_uint_32)(num_palette * (sizeof (png_byte)))); 450 451 /* Initialize the quantize_sort array */ 452 for (i = 0; i < num_palette; i++) 453 png_ptr->quantize_sort[i] = (png_byte)i; 454 455 /* Find the least used palette entries by starting a 456 * bubble sort, and running it until we have sorted 457 * out enough colors. Note that we don't care about 458 * sorting all the colors, just finding which are 459 * least used. 460 */ 461 462 for (i = num_palette - 1; i >= maximum_colors; i--) 463 { 464 int done; /* To stop early if the list is pre-sorted */ 465 int j; 466 467 done = 1; 468 for (j = 0; j < i; j++) 469 { 470 if (histogram[png_ptr->quantize_sort[j]] 471 < histogram[png_ptr->quantize_sort[j + 1]]) 472 { 473 png_byte t; 474 475 t = png_ptr->quantize_sort[j]; 476 png_ptr->quantize_sort[j] = png_ptr->quantize_sort[j + 1]; 477 png_ptr->quantize_sort[j + 1] = t; 478 done = 0; 479 } 480 } 481 482 if (done != 0) 483 break; 484 } 485 486 /* Swap the palette around, and set up a table, if necessary */ 487 if (full_quantize != 0) 488 { 489 int j = num_palette; 490 491 /* Put all the useful colors within the max, but don't 492 * move the others. 493 */ 494 for (i = 0; i < maximum_colors; i++) 495 { 496 if ((int)png_ptr->quantize_sort[i] >= maximum_colors) 497 { 498 do 499 j--; 500 while ((int)png_ptr->quantize_sort[j] >= maximum_colors); 501 502 palette[i] = palette[j]; 503 } 504 } 505 } 506 else 507 { 508 int j = num_palette; 509 510 /* Move all the used colors inside the max limit, and 511 * develop a translation table. 512 */ 513 for (i = 0; i < maximum_colors; i++) 514 { 515 /* Only move the colors we need to */ 516 if ((int)png_ptr->quantize_sort[i] >= maximum_colors) 517 { 518 png_color tmp_color; 519 520 do 521 j--; 522 while ((int)png_ptr->quantize_sort[j] >= maximum_colors); 523 524 tmp_color = palette[j]; 525 palette[j] = palette[i]; 526 palette[i] = tmp_color; 527 /* Indicate where the color went */ 528 png_ptr->quantize_index[j] = (png_byte)i; 529 png_ptr->quantize_index[i] = (png_byte)j; 530 } 531 } 532 533 /* Find closest color for those colors we are not using */ 534 for (i = 0; i < num_palette; i++) 535 { 536 if ((int)png_ptr->quantize_index[i] >= maximum_colors) 537 { 538 int min_d, k, min_k, d_index; 539 540 /* Find the closest color to one we threw out */ 541 d_index = png_ptr->quantize_index[i]; 542 min_d = PNG_COLOR_DIST(palette[d_index], palette[0]); 543 for (k = 1, min_k = 0; k < maximum_colors; k++) 544 { 545 int d; 546 547 d = PNG_COLOR_DIST(palette[d_index], palette[k]); 548 549 if (d < min_d) 550 { 551 min_d = d; 552 min_k = k; 553 } 554 } 555 /* Point to closest color */ 556 png_ptr->quantize_index[i] = (png_byte)min_k; 557 } 558 } 559 } 560 png_free(png_ptr, png_ptr->quantize_sort); 561 png_ptr->quantize_sort = NULL; 562 } 563 else 564 { 565 /* This is much harder to do simply (and quickly). Perhaps 566 * we need to go through a median cut routine, but those 567 * don't always behave themselves with only a few colors 568 * as input. So we will just find the closest two colors, 569 * and throw out one of them (chosen somewhat randomly). 570 * [We don't understand this at all, so if someone wants to 571 * work on improving it, be our guest - AED, GRP] 572 */ 573 int i; 574 int max_d; 575 int num_new_palette; 576 png_dsortp t; 577 png_dsortpp hash; 578 579 t = NULL; 580 581 /* Initialize palette index arrays */ 582 png_ptr->index_to_palette = (png_bytep)png_malloc(png_ptr, 583 (png_uint_32)(num_palette * (sizeof (png_byte)))); 584 png_ptr->palette_to_index = (png_bytep)png_malloc(png_ptr, 585 (png_uint_32)(num_palette * (sizeof (png_byte)))); 586 587 /* Initialize the sort array */ 588 for (i = 0; i < num_palette; i++) 589 { 590 png_ptr->index_to_palette[i] = (png_byte)i; 591 png_ptr->palette_to_index[i] = (png_byte)i; 592 } 593 594 hash = (png_dsortpp)png_calloc(png_ptr, (png_uint_32)(769 * 595 (sizeof (png_dsortp)))); 596 597 num_new_palette = num_palette; 598 599 /* Initial wild guess at how far apart the farthest pixel 600 * pair we will be eliminating will be. Larger 601 * numbers mean more areas will be allocated, Smaller 602 * numbers run the risk of not saving enough data, and 603 * having to do this all over again. 604 * 605 * I have not done extensive checking on this number. 606 */ 607 max_d = 96; 608 609 while (num_new_palette > maximum_colors) 610 { 611 for (i = 0; i < num_new_palette - 1; i++) 612 { 613 int j; 614 615 for (j = i + 1; j < num_new_palette; j++) 616 { 617 int d; 618 619 d = PNG_COLOR_DIST(palette[i], palette[j]); 620 621 if (d <= max_d) 622 { 623 624 t = (png_dsortp)png_malloc_warn(png_ptr, 625 (png_uint_32)(sizeof (png_dsort))); 626 627 if (t == NULL) 628 break; 629 630 t->next = hash[d]; 631 t->left = (png_byte)i; 632 t->right = (png_byte)j; 633 hash[d] = t; 634 } 635 } 636 if (t == NULL) 637 break; 638 } 639 640 if (t != NULL) 641 for (i = 0; i <= max_d; i++) 642 { 643 if (hash[i] != NULL) 644 { 645 png_dsortp p; 646 647 for (p = hash[i]; p; p = p->next) 648 { 649 if ((int)png_ptr->index_to_palette[p->left] 650 < num_new_palette && 651 (int)png_ptr->index_to_palette[p->right] 652 < num_new_palette) 653 { 654 int j, next_j; 655 656 if (num_new_palette & 0x01) 657 { 658 j = p->left; 659 next_j = p->right; 660 } 661 else 662 { 663 j = p->right; 664 next_j = p->left; 665 } 666 667 num_new_palette--; 668 palette[png_ptr->index_to_palette[j]] 669 = palette[num_new_palette]; 670 if (full_quantize == 0) 671 { 672 int k; 673 674 for (k = 0; k < num_palette; k++) 675 { 676 if (png_ptr->quantize_index[k] == 677 png_ptr->index_to_palette[j]) 678 png_ptr->quantize_index[k] = 679 png_ptr->index_to_palette[next_j]; 680 681 if ((int)png_ptr->quantize_index[k] == 682 num_new_palette) 683 png_ptr->quantize_index[k] = 684 png_ptr->index_to_palette[j]; 685 } 686 } 687 688 png_ptr->index_to_palette[png_ptr->palette_to_index 689 [num_new_palette]] = png_ptr->index_to_palette[j]; 690 691 png_ptr->palette_to_index[png_ptr->index_to_palette[j]] 692 = png_ptr->palette_to_index[num_new_palette]; 693 694 png_ptr->index_to_palette[j] = 695 (png_byte)num_new_palette; 696 697 png_ptr->palette_to_index[num_new_palette] = 698 (png_byte)j; 699 } 700 if (num_new_palette <= maximum_colors) 701 break; 702 } 703 if (num_new_palette <= maximum_colors) 704 break; 705 } 706 } 707 708 for (i = 0; i < 769; i++) 709 { 710 if (hash[i] != NULL) 711 { 712 png_dsortp p = hash[i]; 713 while (p) 714 { 715 t = p->next; 716 png_free(png_ptr, p); 717 p = t; 718 } 719 } 720 hash[i] = 0; 721 } 722 max_d += 96; 723 } 724 png_free(png_ptr, hash); 725 png_free(png_ptr, png_ptr->palette_to_index); 726 png_free(png_ptr, png_ptr->index_to_palette); 727 png_ptr->palette_to_index = NULL; 728 png_ptr->index_to_palette = NULL; 729 } 730 num_palette = maximum_colors; 731 } 732 if (png_ptr->palette == NULL) 733 { 734 png_ptr->palette = palette; 735 } 736 png_ptr->num_palette = (png_uint_16)num_palette; 737 738 if (full_quantize != 0) 739 { 740 int i; 741 png_bytep distance; 742 int total_bits = PNG_QUANTIZE_RED_BITS + PNG_QUANTIZE_GREEN_BITS + 743 PNG_QUANTIZE_BLUE_BITS; 744 int num_red = (1 << PNG_QUANTIZE_RED_BITS); 745 int num_green = (1 << PNG_QUANTIZE_GREEN_BITS); 746 int num_blue = (1 << PNG_QUANTIZE_BLUE_BITS); 747 png_size_t num_entries = ((png_size_t)1 << total_bits); 748 749 png_ptr->palette_lookup = (png_bytep)png_calloc(png_ptr, 750 (png_uint_32)(num_entries * (sizeof (png_byte)))); 751 752 distance = (png_bytep)png_malloc(png_ptr, (png_uint_32)(num_entries * 753 (sizeof (png_byte)))); 754 755 memset(distance, 0xff, num_entries * (sizeof (png_byte))); 756 757 for (i = 0; i < num_palette; i++) 758 { 759 int ir, ig, ib; 760 int r = (palette[i].red >> (8 - PNG_QUANTIZE_RED_BITS)); 761 int g = (palette[i].green >> (8 - PNG_QUANTIZE_GREEN_BITS)); 762 int b = (palette[i].blue >> (8 - PNG_QUANTIZE_BLUE_BITS)); 763 764 for (ir = 0; ir < num_red; ir++) 765 { 766 /* int dr = abs(ir - r); */ 767 int dr = ((ir > r) ? ir - r : r - ir); 768 int index_r = (ir << (PNG_QUANTIZE_BLUE_BITS + 769 PNG_QUANTIZE_GREEN_BITS)); 770 771 for (ig = 0; ig < num_green; ig++) 772 { 773 /* int dg = abs(ig - g); */ 774 int dg = ((ig > g) ? ig - g : g - ig); 775 int dt = dr + dg; 776 int dm = ((dr > dg) ? dr : dg); 777 int index_g = index_r | (ig << PNG_QUANTIZE_BLUE_BITS); 778 779 for (ib = 0; ib < num_blue; ib++) 780 { 781 int d_index = index_g | ib; 782 /* int db = abs(ib - b); */ 783 int db = ((ib > b) ? ib - b : b - ib); 784 int dmax = ((dm > db) ? dm : db); 785 int d = dmax + dt + db; 786 787 if (d < (int)distance[d_index]) 788 { 789 distance[d_index] = (png_byte)d; 790 png_ptr->palette_lookup[d_index] = (png_byte)i; 791 } 792 } 793 } 794 } 795 } 796 797 png_free(png_ptr, distance); 798 } 799} 800#endif /* READ_QUANTIZE */ 801 802#ifdef PNG_READ_GAMMA_SUPPORTED 803void PNGFAPI 804png_set_gamma_fixed(png_structrp png_ptr, png_fixed_point scrn_gamma, 805 png_fixed_point file_gamma) 806{ 807 png_debug(1, "in png_set_gamma_fixed"); 808 809 if (png_rtran_ok(png_ptr, 0) == 0) 810 return; 811 812 /* New in libpng-1.5.4 - reserve particular negative values as flags. */ 813 scrn_gamma = translate_gamma_flags(png_ptr, scrn_gamma, 1/*screen*/); 814 file_gamma = translate_gamma_flags(png_ptr, file_gamma, 0/*file*/); 815 816 /* Checking the gamma values for being >0 was added in 1.5.4 along with the 817 * premultiplied alpha support; this actually hides an undocumented feature 818 * of the previous implementation which allowed gamma processing to be 819 * disabled in background handling. There is no evidence (so far) that this 820 * was being used; however, png_set_background itself accepted and must still 821 * accept '0' for the gamma value it takes, because it isn't always used. 822 * 823 * Since this is an API change (albeit a very minor one that removes an 824 * undocumented API feature) the following checks were only enabled in 825 * libpng-1.6.0. 826 */ 827 if (file_gamma <= 0) 828 png_error(png_ptr, "invalid file gamma in png_set_gamma"); 829 830 if (scrn_gamma <= 0) 831 png_error(png_ptr, "invalid screen gamma in png_set_gamma"); 832 833 /* Set the gamma values unconditionally - this overrides the value in the PNG 834 * file if a gAMA chunk was present. png_set_alpha_mode provides a 835 * different, easier, way to default the file gamma. 836 */ 837 png_ptr->colorspace.gamma = file_gamma; 838 png_ptr->colorspace.flags |= PNG_COLORSPACE_HAVE_GAMMA; 839 png_ptr->screen_gamma = scrn_gamma; 840} 841 842# ifdef PNG_FLOATING_POINT_SUPPORTED 843void PNGAPI 844png_set_gamma(png_structrp png_ptr, double scrn_gamma, double file_gamma) 845{ 846 png_set_gamma_fixed(png_ptr, convert_gamma_value(png_ptr, scrn_gamma), 847 convert_gamma_value(png_ptr, file_gamma)); 848} 849# endif /* FLOATING_POINT */ 850#endif /* READ_GAMMA */ 851 852#ifdef PNG_READ_EXPAND_SUPPORTED 853/* Expand paletted images to RGB, expand grayscale images of 854 * less than 8-bit depth to 8-bit depth, and expand tRNS chunks 855 * to alpha channels. 856 */ 857void PNGAPI 858png_set_expand(png_structrp png_ptr) 859{ 860 png_debug(1, "in png_set_expand"); 861 862 if (png_rtran_ok(png_ptr, 0) == 0) 863 return; 864 865 png_ptr->transformations |= (PNG_EXPAND | PNG_EXPAND_tRNS); 866} 867 868/* GRR 19990627: the following three functions currently are identical 869 * to png_set_expand(). However, it is entirely reasonable that someone 870 * might wish to expand an indexed image to RGB but *not* expand a single, 871 * fully transparent palette entry to a full alpha channel--perhaps instead 872 * convert tRNS to the grayscale/RGB format (16-bit RGB value), or replace 873 * the transparent color with a particular RGB value, or drop tRNS entirely. 874 * IOW, a future version of the library may make the transformations flag 875 * a bit more fine-grained, with separate bits for each of these three 876 * functions. 877 * 878 * More to the point, these functions make it obvious what libpng will be 879 * doing, whereas "expand" can (and does) mean any number of things. 880 * 881 * GRP 20060307: In libpng-1.2.9, png_set_gray_1_2_4_to_8() was modified 882 * to expand only the sample depth but not to expand the tRNS to alpha 883 * and its name was changed to png_set_expand_gray_1_2_4_to_8(). 884 */ 885 886/* Expand paletted images to RGB. */ 887void PNGAPI 888png_set_palette_to_rgb(png_structrp png_ptr) 889{ 890 png_debug(1, "in png_set_palette_to_rgb"); 891 892 if (png_rtran_ok(png_ptr, 0) == 0) 893 return; 894 895 png_ptr->transformations |= (PNG_EXPAND | PNG_EXPAND_tRNS); 896} 897 898/* Expand grayscale images of less than 8-bit depth to 8 bits. */ 899void PNGAPI 900png_set_expand_gray_1_2_4_to_8(png_structrp png_ptr) 901{ 902 png_debug(1, "in png_set_expand_gray_1_2_4_to_8"); 903 904 if (png_rtran_ok(png_ptr, 0) == 0) 905 return; 906 907 png_ptr->transformations |= PNG_EXPAND; 908} 909 910/* Expand tRNS chunks to alpha channels. */ 911void PNGAPI 912png_set_tRNS_to_alpha(png_structrp png_ptr) 913{ 914 png_debug(1, "in png_set_tRNS_to_alpha"); 915 916 if (png_rtran_ok(png_ptr, 0) == 0) 917 return; 918 919 png_ptr->transformations |= (PNG_EXPAND | PNG_EXPAND_tRNS); 920} 921#endif /* READ_EXPAND */ 922 923#ifdef PNG_READ_EXPAND_16_SUPPORTED 924/* Expand to 16-bit channels, expand the tRNS chunk too (because otherwise 925 * it may not work correctly.) 926 */ 927void PNGAPI 928png_set_expand_16(png_structrp png_ptr) 929{ 930 png_debug(1, "in png_set_expand_16"); 931 932 if (png_rtran_ok(png_ptr, 0) == 0) 933 return; 934 935 png_ptr->transformations |= (PNG_EXPAND_16 | PNG_EXPAND | PNG_EXPAND_tRNS); 936} 937#endif 938 939#ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED 940void PNGAPI 941png_set_gray_to_rgb(png_structrp png_ptr) 942{ 943 png_debug(1, "in png_set_gray_to_rgb"); 944 945 if (png_rtran_ok(png_ptr, 0) == 0) 946 return; 947 948 /* Because rgb must be 8 bits or more: */ 949 png_set_expand_gray_1_2_4_to_8(png_ptr); 950 png_ptr->transformations |= PNG_GRAY_TO_RGB; 951} 952#endif 953 954#ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED 955void PNGFAPI 956png_set_rgb_to_gray_fixed(png_structrp png_ptr, int error_action, 957 png_fixed_point red, png_fixed_point green) 958{ 959 png_debug(1, "in png_set_rgb_to_gray"); 960 961 /* Need the IHDR here because of the check on color_type below. */ 962 /* TODO: fix this */ 963 if (png_rtran_ok(png_ptr, 1) == 0) 964 return; 965 966 switch (error_action) 967 { 968 case PNG_ERROR_ACTION_NONE: 969 png_ptr->transformations |= PNG_RGB_TO_GRAY; 970 break; 971 972 case PNG_ERROR_ACTION_WARN: 973 png_ptr->transformations |= PNG_RGB_TO_GRAY_WARN; 974 break; 975 976 case PNG_ERROR_ACTION_ERROR: 977 png_ptr->transformations |= PNG_RGB_TO_GRAY_ERR; 978 break; 979 980 default: 981 png_error(png_ptr, "invalid error action to rgb_to_gray"); 982 } 983 984 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) 985#ifdef PNG_READ_EXPAND_SUPPORTED 986 png_ptr->transformations |= PNG_EXPAND; 987#else 988 { 989 /* Make this an error in 1.6 because otherwise the application may assume 990 * that it just worked and get a memory overwrite. 991 */ 992 png_error(png_ptr, 993 "Cannot do RGB_TO_GRAY without EXPAND_SUPPORTED"); 994 995 /* png_ptr->transformations &= ~PNG_RGB_TO_GRAY; */ 996 } 997#endif 998 { 999 if (red >= 0 && green >= 0 && red + green <= PNG_FP_1) 1000 { 1001 png_uint_16 red_int, green_int; 1002 1003 /* NOTE: this calculation does not round, but this behavior is retained 1004 * for consistency; the inaccuracy is very small. The code here always 1005 * overwrites the coefficients, regardless of whether they have been 1006 * defaulted or set already. 1007 */ 1008 red_int = (png_uint_16)(((png_uint_32)red*32768)/100000); 1009 green_int = (png_uint_16)(((png_uint_32)green*32768)/100000); 1010 1011 png_ptr->rgb_to_gray_red_coeff = red_int; 1012 png_ptr->rgb_to_gray_green_coeff = green_int; 1013 png_ptr->rgb_to_gray_coefficients_set = 1; 1014 } 1015 1016 else 1017 { 1018 if (red >= 0 && green >= 0) 1019 png_app_warning(png_ptr, 1020 "ignoring out of range rgb_to_gray coefficients"); 1021 1022 /* Use the defaults, from the cHRM chunk if set, else the historical 1023 * values which are close to the sRGB/HDTV/ITU-Rec 709 values. See 1024 * png_do_rgb_to_gray for more discussion of the values. In this case 1025 * the coefficients are not marked as 'set' and are not overwritten if 1026 * something has already provided a default. 1027 */ 1028 if (png_ptr->rgb_to_gray_red_coeff == 0 && 1029 png_ptr->rgb_to_gray_green_coeff == 0) 1030 { 1031 png_ptr->rgb_to_gray_red_coeff = 6968; 1032 png_ptr->rgb_to_gray_green_coeff = 23434; 1033 /* png_ptr->rgb_to_gray_blue_coeff = 2366; */ 1034 } 1035 } 1036 } 1037} 1038 1039#ifdef PNG_FLOATING_POINT_SUPPORTED 1040/* Convert a RGB image to a grayscale of the same width. This allows us, 1041 * for example, to convert a 24 bpp RGB image into an 8 bpp grayscale image. 1042 */ 1043 1044void PNGAPI 1045png_set_rgb_to_gray(png_structrp png_ptr, int error_action, double red, 1046 double green) 1047{ 1048 png_set_rgb_to_gray_fixed(png_ptr, error_action, 1049 png_fixed(png_ptr, red, "rgb to gray red coefficient"), 1050 png_fixed(png_ptr, green, "rgb to gray green coefficient")); 1051} 1052#endif /* FLOATING POINT */ 1053 1054#endif /* RGB_TO_GRAY */ 1055 1056#if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) || \ 1057 defined(PNG_WRITE_USER_TRANSFORM_SUPPORTED) 1058void PNGAPI 1059png_set_read_user_transform_fn(png_structrp png_ptr, png_user_transform_ptr 1060 read_user_transform_fn) 1061{ 1062 png_debug(1, "in png_set_read_user_transform_fn"); 1063 1064#ifdef PNG_READ_USER_TRANSFORM_SUPPORTED 1065 png_ptr->transformations |= PNG_USER_TRANSFORM; 1066 png_ptr->read_user_transform_fn = read_user_transform_fn; 1067#endif 1068} 1069#endif 1070 1071#ifdef PNG_READ_TRANSFORMS_SUPPORTED 1072#ifdef PNG_READ_GAMMA_SUPPORTED 1073/* In the case of gamma transformations only do transformations on images where 1074 * the [file] gamma and screen_gamma are not close reciprocals, otherwise it 1075 * slows things down slightly, and also needlessly introduces small errors. 1076 */ 1077static int /* PRIVATE */ 1078png_gamma_threshold(png_fixed_point screen_gamma, png_fixed_point file_gamma) 1079{ 1080 /* PNG_GAMMA_THRESHOLD is the threshold for performing gamma 1081 * correction as a difference of the overall transform from 1.0 1082 * 1083 * We want to compare the threshold with s*f - 1, if we get 1084 * overflow here it is because of wacky gamma values so we 1085 * turn on processing anyway. 1086 */ 1087 png_fixed_point gtest; 1088 return !png_muldiv(>est, screen_gamma, file_gamma, PNG_FP_1) || 1089 png_gamma_significant(gtest); 1090} 1091#endif 1092 1093/* Initialize everything needed for the read. This includes modifying 1094 * the palette. 1095 */ 1096 1097/* For the moment 'png_init_palette_transformations' and 1098 * 'png_init_rgb_transformations' only do some flag canceling optimizations. 1099 * The intent is that these two routines should have palette or rgb operations 1100 * extracted from 'png_init_read_transformations'. 1101 */ 1102static void /* PRIVATE */ 1103png_init_palette_transformations(png_structrp png_ptr) 1104{ 1105 /* Called to handle the (input) palette case. In png_do_read_transformations 1106 * the first step is to expand the palette if requested, so this code must 1107 * take care to only make changes that are invariant with respect to the 1108 * palette expansion, or only do them if there is no expansion. 1109 * 1110 * STRIP_ALPHA has already been handled in the caller (by setting num_trans 1111 * to 0.) 1112 */ 1113 int input_has_alpha = 0; 1114 int input_has_transparency = 0; 1115 1116 if (png_ptr->num_trans > 0) 1117 { 1118 int i; 1119 1120 /* Ignore if all the entries are opaque (unlikely!) */ 1121 for (i=0; i<png_ptr->num_trans; ++i) 1122 { 1123 if (png_ptr->trans_alpha[i] == 255) 1124 continue; 1125 else if (png_ptr->trans_alpha[i] == 0) 1126 input_has_transparency = 1; 1127 else 1128 { 1129 input_has_transparency = 1; 1130 input_has_alpha = 1; 1131 break; 1132 } 1133 } 1134 } 1135 1136 /* If no alpha we can optimize. */ 1137 if (input_has_alpha == 0) 1138 { 1139 /* Any alpha means background and associative alpha processing is 1140 * required, however if the alpha is 0 or 1 throughout OPTIMIZE_ALPHA 1141 * and ENCODE_ALPHA are irrelevant. 1142 */ 1143 png_ptr->transformations &= ~PNG_ENCODE_ALPHA; 1144 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA; 1145 1146 if (input_has_transparency == 0) 1147 png_ptr->transformations &= ~(PNG_COMPOSE | PNG_BACKGROUND_EXPAND); 1148 } 1149 1150#if defined(PNG_READ_EXPAND_SUPPORTED) && defined(PNG_READ_BACKGROUND_SUPPORTED) 1151 /* png_set_background handling - deals with the complexity of whether the 1152 * background color is in the file format or the screen format in the case 1153 * where an 'expand' will happen. 1154 */ 1155 1156 /* The following code cannot be entered in the alpha pre-multiplication case 1157 * because PNG_BACKGROUND_EXPAND is cancelled below. 1158 */ 1159 if ((png_ptr->transformations & PNG_BACKGROUND_EXPAND) != 0 && 1160 (png_ptr->transformations & PNG_EXPAND) != 0) 1161 { 1162 { 1163 png_ptr->background.red = 1164 png_ptr->palette[png_ptr->background.index].red; 1165 png_ptr->background.green = 1166 png_ptr->palette[png_ptr->background.index].green; 1167 png_ptr->background.blue = 1168 png_ptr->palette[png_ptr->background.index].blue; 1169 1170#ifdef PNG_READ_INVERT_ALPHA_SUPPORTED 1171 if ((png_ptr->transformations & PNG_INVERT_ALPHA) != 0) 1172 { 1173 if ((png_ptr->transformations & PNG_EXPAND_tRNS) == 0) 1174 { 1175 /* Invert the alpha channel (in tRNS) unless the pixels are 1176 * going to be expanded, in which case leave it for later 1177 */ 1178 int i, istop = png_ptr->num_trans; 1179 1180 for (i=0; i<istop; i++) 1181 png_ptr->trans_alpha[i] = (png_byte)(255 - 1182 png_ptr->trans_alpha[i]); 1183 } 1184 } 1185#endif /* READ_INVERT_ALPHA */ 1186 } 1187 } /* background expand and (therefore) no alpha association. */ 1188#endif /* READ_EXPAND && READ_BACKGROUND */ 1189} 1190 1191static void /* PRIVATE */ 1192png_init_rgb_transformations(png_structrp png_ptr) 1193{ 1194 /* Added to libpng-1.5.4: check the color type to determine whether there 1195 * is any alpha or transparency in the image and simply cancel the 1196 * background and alpha mode stuff if there isn't. 1197 */ 1198 int input_has_alpha = (png_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0; 1199 int input_has_transparency = png_ptr->num_trans > 0; 1200 1201 /* If no alpha we can optimize. */ 1202 if (input_has_alpha == 0) 1203 { 1204 /* Any alpha means background and associative alpha processing is 1205 * required, however if the alpha is 0 or 1 throughout OPTIMIZE_ALPHA 1206 * and ENCODE_ALPHA are irrelevant. 1207 */ 1208# ifdef PNG_READ_ALPHA_MODE_SUPPORTED 1209 png_ptr->transformations &= ~PNG_ENCODE_ALPHA; 1210 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA; 1211# endif 1212 1213 if (input_has_transparency == 0) 1214 png_ptr->transformations &= ~(PNG_COMPOSE | PNG_BACKGROUND_EXPAND); 1215 } 1216 1217#if defined(PNG_READ_EXPAND_SUPPORTED) && defined(PNG_READ_BACKGROUND_SUPPORTED) 1218 /* png_set_background handling - deals with the complexity of whether the 1219 * background color is in the file format or the screen format in the case 1220 * where an 'expand' will happen. 1221 */ 1222 1223 /* The following code cannot be entered in the alpha pre-multiplication case 1224 * because PNG_BACKGROUND_EXPAND is cancelled below. 1225 */ 1226 if ((png_ptr->transformations & PNG_BACKGROUND_EXPAND) != 0 && 1227 (png_ptr->transformations & PNG_EXPAND) != 0 && 1228 (png_ptr->color_type & PNG_COLOR_MASK_COLOR) == 0) 1229 /* i.e., GRAY or GRAY_ALPHA */ 1230 { 1231 { 1232 /* Expand background and tRNS chunks */ 1233 int gray = png_ptr->background.gray; 1234 int trans_gray = png_ptr->trans_color.gray; 1235 1236 switch (png_ptr->bit_depth) 1237 { 1238 case 1: 1239 gray *= 0xff; 1240 trans_gray *= 0xff; 1241 break; 1242 1243 case 2: 1244 gray *= 0x55; 1245 trans_gray *= 0x55; 1246 break; 1247 1248 case 4: 1249 gray *= 0x11; 1250 trans_gray *= 0x11; 1251 break; 1252 1253 default: 1254 1255 case 8: 1256 /* FALL THROUGH (Already 8 bits) */ 1257 1258 case 16: 1259 /* Already a full 16 bits */ 1260 break; 1261 } 1262 1263 png_ptr->background.red = png_ptr->background.green = 1264 png_ptr->background.blue = (png_uint_16)gray; 1265 1266 if ((png_ptr->transformations & PNG_EXPAND_tRNS) == 0) 1267 { 1268 png_ptr->trans_color.red = png_ptr->trans_color.green = 1269 png_ptr->trans_color.blue = (png_uint_16)trans_gray; 1270 } 1271 } 1272 } /* background expand and (therefore) no alpha association. */ 1273#endif /* READ_EXPAND && READ_BACKGROUND */ 1274} 1275 1276void /* PRIVATE */ 1277png_init_read_transformations(png_structrp png_ptr) 1278{ 1279 png_debug(1, "in png_init_read_transformations"); 1280 1281 /* This internal function is called from png_read_start_row in pngrutil.c 1282 * and it is called before the 'rowbytes' calculation is done, so the code 1283 * in here can change or update the transformations flags. 1284 * 1285 * First do updates that do not depend on the details of the PNG image data 1286 * being processed. 1287 */ 1288 1289#ifdef PNG_READ_GAMMA_SUPPORTED 1290 /* Prior to 1.5.4 these tests were performed from png_set_gamma, 1.5.4 adds 1291 * png_set_alpha_mode and this is another source for a default file gamma so 1292 * the test needs to be performed later - here. In addition prior to 1.5.4 1293 * the tests were repeated for the PALETTE color type here - this is no 1294 * longer necessary (and doesn't seem to have been necessary before.) 1295 */ 1296 { 1297 /* The following temporary indicates if overall gamma correction is 1298 * required. 1299 */ 1300 int gamma_correction = 0; 1301 1302 if (png_ptr->colorspace.gamma != 0) /* has been set */ 1303 { 1304 if (png_ptr->screen_gamma != 0) /* screen set too */ 1305 gamma_correction = png_gamma_threshold(png_ptr->colorspace.gamma, 1306 png_ptr->screen_gamma); 1307 1308 else 1309 /* Assume the output matches the input; a long time default behavior 1310 * of libpng, although the standard has nothing to say about this. 1311 */ 1312 png_ptr->screen_gamma = png_reciprocal(png_ptr->colorspace.gamma); 1313 } 1314 1315 else if (png_ptr->screen_gamma != 0) 1316 /* The converse - assume the file matches the screen, note that this 1317 * perhaps undesireable default can (from 1.5.4) be changed by calling 1318 * png_set_alpha_mode (even if the alpha handling mode isn't required 1319 * or isn't changed from the default.) 1320 */ 1321 png_ptr->colorspace.gamma = png_reciprocal(png_ptr->screen_gamma); 1322 1323 else /* neither are set */ 1324 /* Just in case the following prevents any processing - file and screen 1325 * are both assumed to be linear and there is no way to introduce a 1326 * third gamma value other than png_set_background with 'UNIQUE', and, 1327 * prior to 1.5.4 1328 */ 1329 png_ptr->screen_gamma = png_ptr->colorspace.gamma = PNG_FP_1; 1330 1331 /* We have a gamma value now. */ 1332 png_ptr->colorspace.flags |= PNG_COLORSPACE_HAVE_GAMMA; 1333 1334 /* Now turn the gamma transformation on or off as appropriate. Notice 1335 * that PNG_GAMMA just refers to the file->screen correction. Alpha 1336 * composition may independently cause gamma correction because it needs 1337 * linear data (e.g. if the file has a gAMA chunk but the screen gamma 1338 * hasn't been specified.) In any case this flag may get turned off in 1339 * the code immediately below if the transform can be handled outside the 1340 * row loop. 1341 */ 1342 if (gamma_correction != 0) 1343 png_ptr->transformations |= PNG_GAMMA; 1344 1345 else 1346 png_ptr->transformations &= ~PNG_GAMMA; 1347 } 1348#endif 1349 1350 /* Certain transformations have the effect of preventing other 1351 * transformations that happen afterward in png_do_read_transformations; 1352 * resolve the interdependencies here. From the code of 1353 * png_do_read_transformations the order is: 1354 * 1355 * 1) PNG_EXPAND (including PNG_EXPAND_tRNS) 1356 * 2) PNG_STRIP_ALPHA (if no compose) 1357 * 3) PNG_RGB_TO_GRAY 1358 * 4) PNG_GRAY_TO_RGB iff !PNG_BACKGROUND_IS_GRAY 1359 * 5) PNG_COMPOSE 1360 * 6) PNG_GAMMA 1361 * 7) PNG_STRIP_ALPHA (if compose) 1362 * 8) PNG_ENCODE_ALPHA 1363 * 9) PNG_SCALE_16_TO_8 1364 * 10) PNG_16_TO_8 1365 * 11) PNG_QUANTIZE (converts to palette) 1366 * 12) PNG_EXPAND_16 1367 * 13) PNG_GRAY_TO_RGB iff PNG_BACKGROUND_IS_GRAY 1368 * 14) PNG_INVERT_MONO 1369 * 15) PNG_INVERT_ALPHA 1370 * 16) PNG_SHIFT 1371 * 17) PNG_PACK 1372 * 18) PNG_BGR 1373 * 19) PNG_PACKSWAP 1374 * 20) PNG_FILLER (includes PNG_ADD_ALPHA) 1375 * 21) PNG_SWAP_ALPHA 1376 * 22) PNG_SWAP_BYTES 1377 * 23) PNG_USER_TRANSFORM [must be last] 1378 */ 1379#ifdef PNG_READ_STRIP_ALPHA_SUPPORTED 1380 if ((png_ptr->transformations & PNG_STRIP_ALPHA) != 0 && 1381 (png_ptr->transformations & PNG_COMPOSE) == 0) 1382 { 1383 /* Stripping the alpha channel happens immediately after the 'expand' 1384 * transformations, before all other transformation, so it cancels out 1385 * the alpha handling. It has the side effect negating the effect of 1386 * PNG_EXPAND_tRNS too: 1387 */ 1388 png_ptr->transformations &= ~(PNG_BACKGROUND_EXPAND | PNG_ENCODE_ALPHA | 1389 PNG_EXPAND_tRNS); 1390 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA; 1391 1392 /* Kill the tRNS chunk itself too. Prior to 1.5.4 this did not happen 1393 * so transparency information would remain just so long as it wasn't 1394 * expanded. This produces unexpected API changes if the set of things 1395 * that do PNG_EXPAND_tRNS changes (perfectly possible given the 1396 * documentation - which says ask for what you want, accept what you 1397 * get.) This makes the behavior consistent from 1.5.4: 1398 */ 1399 png_ptr->num_trans = 0; 1400 } 1401#endif /* STRIP_ALPHA supported, no COMPOSE */ 1402 1403#ifdef PNG_READ_ALPHA_MODE_SUPPORTED 1404 /* If the screen gamma is about 1.0 then the OPTIMIZE_ALPHA and ENCODE_ALPHA 1405 * settings will have no effect. 1406 */ 1407 if (png_gamma_significant(png_ptr->screen_gamma) == 0) 1408 { 1409 png_ptr->transformations &= ~PNG_ENCODE_ALPHA; 1410 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA; 1411 } 1412#endif 1413 1414#ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED 1415 /* Make sure the coefficients for the rgb to gray conversion are set 1416 * appropriately. 1417 */ 1418 if ((png_ptr->transformations & PNG_RGB_TO_GRAY) != 0) 1419 png_colorspace_set_rgb_coefficients(png_ptr); 1420#endif 1421 1422#ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED 1423#if defined(PNG_READ_EXPAND_SUPPORTED) && defined(PNG_READ_BACKGROUND_SUPPORTED) 1424 /* Detect gray background and attempt to enable optimization for 1425 * gray --> RGB case. 1426 * 1427 * Note: if PNG_BACKGROUND_EXPAND is set and color_type is either RGB or 1428 * RGB_ALPHA (in which case need_expand is superfluous anyway), the 1429 * background color might actually be gray yet not be flagged as such. 1430 * This is not a problem for the current code, which uses 1431 * PNG_BACKGROUND_IS_GRAY only to decide when to do the 1432 * png_do_gray_to_rgb() transformation. 1433 * 1434 * TODO: this code needs to be revised to avoid the complexity and 1435 * interdependencies. The color type of the background should be recorded in 1436 * png_set_background, along with the bit depth, then the code has a record 1437 * of exactly what color space the background is currently in. 1438 */ 1439 if ((png_ptr->transformations & PNG_BACKGROUND_EXPAND) != 0) 1440 { 1441 /* PNG_BACKGROUND_EXPAND: the background is in the file color space, so if 1442 * the file was grayscale the background value is gray. 1443 */ 1444 if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) == 0) 1445 png_ptr->mode |= PNG_BACKGROUND_IS_GRAY; 1446 } 1447 1448 else if ((png_ptr->transformations & PNG_COMPOSE) != 0) 1449 { 1450 /* PNG_COMPOSE: png_set_background was called with need_expand false, 1451 * so the color is in the color space of the output or png_set_alpha_mode 1452 * was called and the color is black. Ignore RGB_TO_GRAY because that 1453 * happens before GRAY_TO_RGB. 1454 */ 1455 if ((png_ptr->transformations & PNG_GRAY_TO_RGB) != 0) 1456 { 1457 if (png_ptr->background.red == png_ptr->background.green && 1458 png_ptr->background.red == png_ptr->background.blue) 1459 { 1460 png_ptr->mode |= PNG_BACKGROUND_IS_GRAY; 1461 png_ptr->background.gray = png_ptr->background.red; 1462 } 1463 } 1464 } 1465#endif /* READ_EXPAND && READ_BACKGROUND */ 1466#endif /* READ_GRAY_TO_RGB */ 1467 1468 /* For indexed PNG data (PNG_COLOR_TYPE_PALETTE) many of the transformations 1469 * can be performed directly on the palette, and some (such as rgb to gray) 1470 * can be optimized inside the palette. This is particularly true of the 1471 * composite (background and alpha) stuff, which can be pretty much all done 1472 * in the palette even if the result is expanded to RGB or gray afterward. 1473 * 1474 * NOTE: this is Not Yet Implemented, the code behaves as in 1.5.1 and 1475 * earlier and the palette stuff is actually handled on the first row. This 1476 * leads to the reported bug that the palette returned by png_get_PLTE is not 1477 * updated. 1478 */ 1479 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) 1480 png_init_palette_transformations(png_ptr); 1481 1482 else 1483 png_init_rgb_transformations(png_ptr); 1484 1485#if defined(PNG_READ_BACKGROUND_SUPPORTED) && \ 1486 defined(PNG_READ_EXPAND_16_SUPPORTED) 1487 if ((png_ptr->transformations & PNG_EXPAND_16) != 0 && 1488 (png_ptr->transformations & PNG_COMPOSE) != 0 && 1489 (png_ptr->transformations & PNG_BACKGROUND_EXPAND) == 0 && 1490 png_ptr->bit_depth != 16) 1491 { 1492 /* TODO: fix this. Because the expand_16 operation is after the compose 1493 * handling the background color must be 8, not 16, bits deep, but the 1494 * application will supply a 16-bit value so reduce it here. 1495 * 1496 * The PNG_BACKGROUND_EXPAND code above does not expand to 16 bits at 1497 * present, so that case is ok (until do_expand_16 is moved.) 1498 * 1499 * NOTE: this discards the low 16 bits of the user supplied background 1500 * color, but until expand_16 works properly there is no choice! 1501 */ 1502# define CHOP(x) (x)=((png_uint_16)PNG_DIV257(x)) 1503 CHOP(png_ptr->background.red); 1504 CHOP(png_ptr->background.green); 1505 CHOP(png_ptr->background.blue); 1506 CHOP(png_ptr->background.gray); 1507# undef CHOP 1508 } 1509#endif /* READ_BACKGROUND && READ_EXPAND_16 */ 1510 1511#if defined(PNG_READ_BACKGROUND_SUPPORTED) && \ 1512 (defined(PNG_READ_SCALE_16_TO_8_SUPPORTED) || \ 1513 defined(PNG_READ_STRIP_16_TO_8_SUPPORTED)) 1514 if ((png_ptr->transformations & (PNG_16_TO_8|PNG_SCALE_16_TO_8)) != 0 && 1515 (png_ptr->transformations & PNG_COMPOSE) != 0 && 1516 (png_ptr->transformations & PNG_BACKGROUND_EXPAND) == 0 && 1517 png_ptr->bit_depth == 16) 1518 { 1519 /* On the other hand, if a 16-bit file is to be reduced to 8-bits per 1520 * component this will also happen after PNG_COMPOSE and so the background 1521 * color must be pre-expanded here. 1522 * 1523 * TODO: fix this too. 1524 */ 1525 png_ptr->background.red = (png_uint_16)(png_ptr->background.red * 257); 1526 png_ptr->background.green = 1527 (png_uint_16)(png_ptr->background.green * 257); 1528 png_ptr->background.blue = (png_uint_16)(png_ptr->background.blue * 257); 1529 png_ptr->background.gray = (png_uint_16)(png_ptr->background.gray * 257); 1530 } 1531#endif 1532 1533 /* NOTE: below 'PNG_READ_ALPHA_MODE_SUPPORTED' is presumed to also enable the 1534 * background support (see the comments in scripts/pnglibconf.dfa), this 1535 * allows pre-multiplication of the alpha channel to be implemented as 1536 * compositing on black. This is probably sub-optimal and has been done in 1537 * 1.5.4 betas simply to enable external critique and testing (i.e. to 1538 * implement the new API quickly, without lots of internal changes.) 1539 */ 1540 1541#ifdef PNG_READ_GAMMA_SUPPORTED 1542# ifdef PNG_READ_BACKGROUND_SUPPORTED 1543 /* Includes ALPHA_MODE */ 1544 png_ptr->background_1 = png_ptr->background; 1545# endif 1546 1547 /* This needs to change - in the palette image case a whole set of tables are 1548 * built when it would be quicker to just calculate the correct value for 1549 * each palette entry directly. Also, the test is too tricky - why check 1550 * PNG_RGB_TO_GRAY if PNG_GAMMA is not set? The answer seems to be that 1551 * PNG_GAMMA is cancelled even if the gamma is known? The test excludes the 1552 * PNG_COMPOSE case, so apparently if there is no *overall* gamma correction 1553 * the gamma tables will not be built even if composition is required on a 1554 * gamma encoded value. 1555 * 1556 * In 1.5.4 this is addressed below by an additional check on the individual 1557 * file gamma - if it is not 1.0 both RGB_TO_GRAY and COMPOSE need the 1558 * tables. 1559 */ 1560 if ((png_ptr->transformations & PNG_GAMMA) != 0 || 1561 ((png_ptr->transformations & PNG_RGB_TO_GRAY) != 0 && 1562 (png_gamma_significant(png_ptr->colorspace.gamma) != 0 || 1563 png_gamma_significant(png_ptr->screen_gamma) != 0)) || 1564 ((png_ptr->transformations & PNG_COMPOSE) != 0 && 1565 (png_gamma_significant(png_ptr->colorspace.gamma) != 0 || 1566 png_gamma_significant(png_ptr->screen_gamma) != 0 1567# ifdef PNG_READ_BACKGROUND_SUPPORTED 1568 || (png_ptr->background_gamma_type == PNG_BACKGROUND_GAMMA_UNIQUE && 1569 png_gamma_significant(png_ptr->background_gamma) != 0) 1570# endif 1571 )) || ((png_ptr->transformations & PNG_ENCODE_ALPHA) != 0 && 1572 png_gamma_significant(png_ptr->screen_gamma) != 0)) 1573 { 1574 png_build_gamma_table(png_ptr, png_ptr->bit_depth); 1575 1576#ifdef PNG_READ_BACKGROUND_SUPPORTED 1577 if ((png_ptr->transformations & PNG_COMPOSE) != 0) 1578 { 1579 /* Issue a warning about this combination: because RGB_TO_GRAY is 1580 * optimized to do the gamma transform if present yet do_background has 1581 * to do the same thing if both options are set a 1582 * double-gamma-correction happens. This is true in all versions of 1583 * libpng to date. 1584 */ 1585 if ((png_ptr->transformations & PNG_RGB_TO_GRAY) != 0) 1586 png_warning(png_ptr, 1587 "libpng does not support gamma+background+rgb_to_gray"); 1588 1589 if ((png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) != 0) 1590 { 1591 /* We don't get to here unless there is a tRNS chunk with non-opaque 1592 * entries - see the checking code at the start of this function. 1593 */ 1594 png_color back, back_1; 1595 png_colorp palette = png_ptr->palette; 1596 int num_palette = png_ptr->num_palette; 1597 int i; 1598 if (png_ptr->background_gamma_type == PNG_BACKGROUND_GAMMA_FILE) 1599 { 1600 1601 back.red = png_ptr->gamma_table[png_ptr->background.red]; 1602 back.green = png_ptr->gamma_table[png_ptr->background.green]; 1603 back.blue = png_ptr->gamma_table[png_ptr->background.blue]; 1604 1605 back_1.red = png_ptr->gamma_to_1[png_ptr->background.red]; 1606 back_1.green = png_ptr->gamma_to_1[png_ptr->background.green]; 1607 back_1.blue = png_ptr->gamma_to_1[png_ptr->background.blue]; 1608 } 1609 else 1610 { 1611 png_fixed_point g, gs; 1612 1613 switch (png_ptr->background_gamma_type) 1614 { 1615 case PNG_BACKGROUND_GAMMA_SCREEN: 1616 g = (png_ptr->screen_gamma); 1617 gs = PNG_FP_1; 1618 break; 1619 1620 case PNG_BACKGROUND_GAMMA_FILE: 1621 g = png_reciprocal(png_ptr->colorspace.gamma); 1622 gs = png_reciprocal2(png_ptr->colorspace.gamma, 1623 png_ptr->screen_gamma); 1624 break; 1625 1626 case PNG_BACKGROUND_GAMMA_UNIQUE: 1627 g = png_reciprocal(png_ptr->background_gamma); 1628 gs = png_reciprocal2(png_ptr->background_gamma, 1629 png_ptr->screen_gamma); 1630 break; 1631 default: 1632 g = PNG_FP_1; /* back_1 */ 1633 gs = PNG_FP_1; /* back */ 1634 break; 1635 } 1636 1637 if (png_gamma_significant(gs) != 0) 1638 { 1639 back.red = png_gamma_8bit_correct(png_ptr->background.red, 1640 gs); 1641 back.green = png_gamma_8bit_correct(png_ptr->background.green, 1642 gs); 1643 back.blue = png_gamma_8bit_correct(png_ptr->background.blue, 1644 gs); 1645 } 1646 1647 else 1648 { 1649 back.red = (png_byte)png_ptr->background.red; 1650 back.green = (png_byte)png_ptr->background.green; 1651 back.blue = (png_byte)png_ptr->background.blue; 1652 } 1653 1654 if (png_gamma_significant(g) != 0) 1655 { 1656 back_1.red = png_gamma_8bit_correct(png_ptr->background.red, 1657 g); 1658 back_1.green = png_gamma_8bit_correct( 1659 png_ptr->background.green, g); 1660 back_1.blue = png_gamma_8bit_correct(png_ptr->background.blue, 1661 g); 1662 } 1663 1664 else 1665 { 1666 back_1.red = (png_byte)png_ptr->background.red; 1667 back_1.green = (png_byte)png_ptr->background.green; 1668 back_1.blue = (png_byte)png_ptr->background.blue; 1669 } 1670 } 1671 1672 for (i = 0; i < num_palette; i++) 1673 { 1674 if (i < (int)png_ptr->num_trans && 1675 png_ptr->trans_alpha[i] != 0xff) 1676 { 1677 if (png_ptr->trans_alpha[i] == 0) 1678 { 1679 palette[i] = back; 1680 } 1681 else /* if (png_ptr->trans_alpha[i] != 0xff) */ 1682 { 1683 png_byte v, w; 1684 1685 v = png_ptr->gamma_to_1[palette[i].red]; 1686 png_composite(w, v, png_ptr->trans_alpha[i], back_1.red); 1687 palette[i].red = png_ptr->gamma_from_1[w]; 1688 1689 v = png_ptr->gamma_to_1[palette[i].green]; 1690 png_composite(w, v, png_ptr->trans_alpha[i], back_1.green); 1691 palette[i].green = png_ptr->gamma_from_1[w]; 1692 1693 v = png_ptr->gamma_to_1[palette[i].blue]; 1694 png_composite(w, v, png_ptr->trans_alpha[i], back_1.blue); 1695 palette[i].blue = png_ptr->gamma_from_1[w]; 1696 } 1697 } 1698 else 1699 { 1700 palette[i].red = png_ptr->gamma_table[palette[i].red]; 1701 palette[i].green = png_ptr->gamma_table[palette[i].green]; 1702 palette[i].blue = png_ptr->gamma_table[palette[i].blue]; 1703 } 1704 } 1705 1706 /* Prevent the transformations being done again. 1707 * 1708 * NOTE: this is highly dubious; it removes the transformations in 1709 * place. This seems inconsistent with the general treatment of the 1710 * transformations elsewhere. 1711 */ 1712 png_ptr->transformations &= ~(PNG_COMPOSE | PNG_GAMMA); 1713 } /* color_type == PNG_COLOR_TYPE_PALETTE */ 1714 1715 /* if (png_ptr->background_gamma_type!=PNG_BACKGROUND_GAMMA_UNKNOWN) */ 1716 else /* color_type != PNG_COLOR_TYPE_PALETTE */ 1717 { 1718 int gs_sig, g_sig; 1719 png_fixed_point g = PNG_FP_1; /* Correction to linear */ 1720 png_fixed_point gs = PNG_FP_1; /* Correction to screen */ 1721 1722 switch (png_ptr->background_gamma_type) 1723 { 1724 case PNG_BACKGROUND_GAMMA_SCREEN: 1725 g = png_ptr->screen_gamma; 1726 /* gs = PNG_FP_1; */ 1727 break; 1728 1729 case PNG_BACKGROUND_GAMMA_FILE: 1730 g = png_reciprocal(png_ptr->colorspace.gamma); 1731 gs = png_reciprocal2(png_ptr->colorspace.gamma, 1732 png_ptr->screen_gamma); 1733 break; 1734 1735 case PNG_BACKGROUND_GAMMA_UNIQUE: 1736 g = png_reciprocal(png_ptr->background_gamma); 1737 gs = png_reciprocal2(png_ptr->background_gamma, 1738 png_ptr->screen_gamma); 1739 break; 1740 1741 default: 1742 png_error(png_ptr, "invalid background gamma type"); 1743 } 1744 1745 g_sig = png_gamma_significant(g); 1746 gs_sig = png_gamma_significant(gs); 1747 1748 if (g_sig != 0) 1749 png_ptr->background_1.gray = png_gamma_correct(png_ptr, 1750 png_ptr->background.gray, g); 1751 1752 if (gs_sig != 0) 1753 png_ptr->background.gray = png_gamma_correct(png_ptr, 1754 png_ptr->background.gray, gs); 1755 1756 if ((png_ptr->background.red != png_ptr->background.green) || 1757 (png_ptr->background.red != png_ptr->background.blue) || 1758 (png_ptr->background.red != png_ptr->background.gray)) 1759 { 1760 /* RGB or RGBA with color background */ 1761 if (g_sig != 0) 1762 { 1763 png_ptr->background_1.red = png_gamma_correct(png_ptr, 1764 png_ptr->background.red, g); 1765 1766 png_ptr->background_1.green = png_gamma_correct(png_ptr, 1767 png_ptr->background.green, g); 1768 1769 png_ptr->background_1.blue = png_gamma_correct(png_ptr, 1770 png_ptr->background.blue, g); 1771 } 1772 1773 if (gs_sig != 0) 1774 { 1775 png_ptr->background.red = png_gamma_correct(png_ptr, 1776 png_ptr->background.red, gs); 1777 1778 png_ptr->background.green = png_gamma_correct(png_ptr, 1779 png_ptr->background.green, gs); 1780 1781 png_ptr->background.blue = png_gamma_correct(png_ptr, 1782 png_ptr->background.blue, gs); 1783 } 1784 } 1785 1786 else 1787 { 1788 /* GRAY, GRAY ALPHA, RGB, or RGBA with gray background */ 1789 png_ptr->background_1.red = png_ptr->background_1.green 1790 = png_ptr->background_1.blue = png_ptr->background_1.gray; 1791 1792 png_ptr->background.red = png_ptr->background.green 1793 = png_ptr->background.blue = png_ptr->background.gray; 1794 } 1795 1796 /* The background is now in screen gamma: */ 1797 png_ptr->background_gamma_type = PNG_BACKGROUND_GAMMA_SCREEN; 1798 } /* color_type != PNG_COLOR_TYPE_PALETTE */ 1799 }/* png_ptr->transformations & PNG_BACKGROUND */ 1800 1801 else 1802 /* Transformation does not include PNG_BACKGROUND */ 1803#endif /* READ_BACKGROUND */ 1804 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE 1805#ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED 1806 /* RGB_TO_GRAY needs to have non-gamma-corrected values! */ 1807 && ((png_ptr->transformations & PNG_EXPAND) == 0 || 1808 (png_ptr->transformations & PNG_RGB_TO_GRAY) == 0) 1809#endif 1810 ) 1811 { 1812 png_colorp palette = png_ptr->palette; 1813 int num_palette = png_ptr->num_palette; 1814 int i; 1815 1816 /* NOTE: there are other transformations that should probably be in 1817 * here too. 1818 */ 1819 for (i = 0; i < num_palette; i++) 1820 { 1821 palette[i].red = png_ptr->gamma_table[palette[i].red]; 1822 palette[i].green = png_ptr->gamma_table[palette[i].green]; 1823 palette[i].blue = png_ptr->gamma_table[palette[i].blue]; 1824 } 1825 1826 /* Done the gamma correction. */ 1827 png_ptr->transformations &= ~PNG_GAMMA; 1828 } /* color_type == PALETTE && !PNG_BACKGROUND transformation */ 1829 } 1830#ifdef PNG_READ_BACKGROUND_SUPPORTED 1831 else 1832#endif 1833#endif /* READ_GAMMA */ 1834 1835#ifdef PNG_READ_BACKGROUND_SUPPORTED 1836 /* No GAMMA transformation (see the hanging else 4 lines above) */ 1837 if ((png_ptr->transformations & PNG_COMPOSE) != 0 && 1838 (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)) 1839 { 1840 int i; 1841 int istop = (int)png_ptr->num_trans; 1842 png_color back; 1843 png_colorp palette = png_ptr->palette; 1844 1845 back.red = (png_byte)png_ptr->background.red; 1846 back.green = (png_byte)png_ptr->background.green; 1847 back.blue = (png_byte)png_ptr->background.blue; 1848 1849 for (i = 0; i < istop; i++) 1850 { 1851 if (png_ptr->trans_alpha[i] == 0) 1852 { 1853 palette[i] = back; 1854 } 1855 1856 else if (png_ptr->trans_alpha[i] != 0xff) 1857 { 1858 /* The png_composite() macro is defined in png.h */ 1859 png_composite(palette[i].red, palette[i].red, 1860 png_ptr->trans_alpha[i], back.red); 1861 1862 png_composite(palette[i].green, palette[i].green, 1863 png_ptr->trans_alpha[i], back.green); 1864 1865 png_composite(palette[i].blue, palette[i].blue, 1866 png_ptr->trans_alpha[i], back.blue); 1867 } 1868 } 1869 1870 png_ptr->transformations &= ~PNG_COMPOSE; 1871 } 1872#endif /* READ_BACKGROUND */ 1873 1874#ifdef PNG_READ_SHIFT_SUPPORTED 1875 if ((png_ptr->transformations & PNG_SHIFT) != 0 && 1876 (png_ptr->transformations & PNG_EXPAND) == 0 && 1877 (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)) 1878 { 1879 int i; 1880 int istop = png_ptr->num_palette; 1881 int shift = 8 - png_ptr->sig_bit.red; 1882 1883 png_ptr->transformations &= ~PNG_SHIFT; 1884 1885 /* significant bits can be in the range 1 to 7 for a meaninful result, if 1886 * the number of significant bits is 0 then no shift is done (this is an 1887 * error condition which is silently ignored.) 1888 */ 1889 if (shift > 0 && shift < 8) 1890 for (i=0; i<istop; ++i) 1891 { 1892 int component = png_ptr->palette[i].red; 1893 1894 component >>= shift; 1895 png_ptr->palette[i].red = (png_byte)component; 1896 } 1897 1898 shift = 8 - png_ptr->sig_bit.green; 1899 if (shift > 0 && shift < 8) 1900 for (i=0; i<istop; ++i) 1901 { 1902 int component = png_ptr->palette[i].green; 1903 1904 component >>= shift; 1905 png_ptr->palette[i].green = (png_byte)component; 1906 } 1907 1908 shift = 8 - png_ptr->sig_bit.blue; 1909 if (shift > 0 && shift < 8) 1910 for (i=0; i<istop; ++i) 1911 { 1912 int component = png_ptr->palette[i].blue; 1913 1914 component >>= shift; 1915 png_ptr->palette[i].blue = (png_byte)component; 1916 } 1917 } 1918#endif /* READ_SHIFT */ 1919} 1920 1921/* Modify the info structure to reflect the transformations. The 1922 * info should be updated so a PNG file could be written with it, 1923 * assuming the transformations result in valid PNG data. 1924 */ 1925void /* PRIVATE */ 1926png_read_transform_info(png_structrp png_ptr, png_inforp info_ptr) 1927{ 1928 png_debug(1, "in png_read_transform_info"); 1929 1930#ifdef PNG_READ_EXPAND_SUPPORTED 1931 if ((png_ptr->transformations & PNG_EXPAND) != 0) 1932 { 1933 if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE) 1934 { 1935 /* This check must match what actually happens in 1936 * png_do_expand_palette; if it ever checks the tRNS chunk to see if 1937 * it is all opaque we must do the same (at present it does not.) 1938 */ 1939 if (png_ptr->num_trans > 0) 1940 info_ptr->color_type = PNG_COLOR_TYPE_RGB_ALPHA; 1941 1942 else 1943 info_ptr->color_type = PNG_COLOR_TYPE_RGB; 1944 1945 info_ptr->bit_depth = 8; 1946 info_ptr->num_trans = 0; 1947 1948 if (png_ptr->palette == NULL) 1949 png_error (png_ptr, "Palette is NULL in indexed image"); 1950 } 1951 else 1952 { 1953 if (png_ptr->num_trans != 0) 1954 { 1955 if ((png_ptr->transformations & PNG_EXPAND_tRNS) != 0) 1956 info_ptr->color_type |= PNG_COLOR_MASK_ALPHA; 1957 } 1958 if (info_ptr->bit_depth < 8) 1959 info_ptr->bit_depth = 8; 1960 1961 info_ptr->num_trans = 0; 1962 } 1963 } 1964#endif 1965 1966#if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\ 1967 defined(PNG_READ_ALPHA_MODE_SUPPORTED) 1968 /* The following is almost certainly wrong unless the background value is in 1969 * the screen space! 1970 */ 1971 if ((png_ptr->transformations & PNG_COMPOSE) != 0) 1972 info_ptr->background = png_ptr->background; 1973#endif 1974 1975#ifdef PNG_READ_GAMMA_SUPPORTED 1976 /* The following used to be conditional on PNG_GAMMA (prior to 1.5.4), 1977 * however it seems that the code in png_init_read_transformations, which has 1978 * been called before this from png_read_update_info->png_read_start_row 1979 * sometimes does the gamma transform and cancels the flag. 1980 * 1981 * TODO: this looks wrong; the info_ptr should end up with a gamma equal to 1982 * the screen_gamma value. The following probably results in weirdness if 1983 * the info_ptr is used by the app after the rows have been read. 1984 */ 1985 info_ptr->colorspace.gamma = png_ptr->colorspace.gamma; 1986#endif 1987 1988 if (info_ptr->bit_depth == 16) 1989 { 1990# ifdef PNG_READ_16BIT_SUPPORTED 1991# ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED 1992 if ((png_ptr->transformations & PNG_SCALE_16_TO_8) != 0) 1993 info_ptr->bit_depth = 8; 1994# endif 1995 1996# ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED 1997 if ((png_ptr->transformations & PNG_16_TO_8) != 0) 1998 info_ptr->bit_depth = 8; 1999# endif 2000 2001# else 2002 /* No 16-bit support: force chopping 16-bit input down to 8, in this case 2003 * the app program can chose if both APIs are available by setting the 2004 * correct scaling to use. 2005 */ 2006# ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED 2007 /* For compatibility with previous versions use the strip method by 2008 * default. This code works because if PNG_SCALE_16_TO_8 is already 2009 * set the code below will do that in preference to the chop. 2010 */ 2011 png_ptr->transformations |= PNG_16_TO_8; 2012 info_ptr->bit_depth = 8; 2013# else 2014 2015# ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED 2016 png_ptr->transformations |= PNG_SCALE_16_TO_8; 2017 info_ptr->bit_depth = 8; 2018# else 2019 2020 CONFIGURATION ERROR: you must enable at least one 16 to 8 method 2021# endif 2022# endif 2023#endif /* !READ_16BIT */ 2024 } 2025 2026#ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED 2027 if ((png_ptr->transformations & PNG_GRAY_TO_RGB) != 0) 2028 info_ptr->color_type = (png_byte)(info_ptr->color_type | 2029 PNG_COLOR_MASK_COLOR); 2030#endif 2031 2032#ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED 2033 if ((png_ptr->transformations & PNG_RGB_TO_GRAY) != 0) 2034 info_ptr->color_type = (png_byte)(info_ptr->color_type & 2035 ~PNG_COLOR_MASK_COLOR); 2036#endif 2037 2038#ifdef PNG_READ_QUANTIZE_SUPPORTED 2039 if ((png_ptr->transformations & PNG_QUANTIZE) != 0) 2040 { 2041 if (((info_ptr->color_type == PNG_COLOR_TYPE_RGB) || 2042 (info_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA)) && 2043 png_ptr->palette_lookup != 0 && info_ptr->bit_depth == 8) 2044 { 2045 info_ptr->color_type = PNG_COLOR_TYPE_PALETTE; 2046 } 2047 } 2048#endif 2049 2050#ifdef PNG_READ_EXPAND_16_SUPPORTED 2051 if ((png_ptr->transformations & PNG_EXPAND_16) != 0 && 2052 info_ptr->bit_depth == 8 && 2053 info_ptr->color_type != PNG_COLOR_TYPE_PALETTE) 2054 { 2055 info_ptr->bit_depth = 16; 2056 } 2057#endif 2058 2059#ifdef PNG_READ_PACK_SUPPORTED 2060 if ((png_ptr->transformations & PNG_PACK) != 0 && 2061 (info_ptr->bit_depth < 8)) 2062 info_ptr->bit_depth = 8; 2063#endif 2064 2065 if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE) 2066 info_ptr->channels = 1; 2067 2068 else if ((info_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0) 2069 info_ptr->channels = 3; 2070 2071 else 2072 info_ptr->channels = 1; 2073 2074#ifdef PNG_READ_STRIP_ALPHA_SUPPORTED 2075 if ((png_ptr->transformations & PNG_STRIP_ALPHA) != 0) 2076 { 2077 info_ptr->color_type = (png_byte)(info_ptr->color_type & 2078 ~PNG_COLOR_MASK_ALPHA); 2079 info_ptr->num_trans = 0; 2080 } 2081#endif 2082 2083 if ((info_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0) 2084 info_ptr->channels++; 2085 2086#ifdef PNG_READ_FILLER_SUPPORTED 2087 /* STRIP_ALPHA and FILLER allowed: MASK_ALPHA bit stripped above */ 2088 if ((png_ptr->transformations & PNG_FILLER) != 0 && 2089 (info_ptr->color_type == PNG_COLOR_TYPE_RGB || 2090 info_ptr->color_type == PNG_COLOR_TYPE_GRAY)) 2091 { 2092 info_ptr->channels++; 2093 /* If adding a true alpha channel not just filler */ 2094 if ((png_ptr->transformations & PNG_ADD_ALPHA) != 0) 2095 info_ptr->color_type |= PNG_COLOR_MASK_ALPHA; 2096 } 2097#endif 2098 2099#if defined(PNG_USER_TRANSFORM_PTR_SUPPORTED) && \ 2100defined(PNG_READ_USER_TRANSFORM_SUPPORTED) 2101 if ((png_ptr->transformations & PNG_USER_TRANSFORM) != 0) 2102 { 2103 if (png_ptr->user_transform_depth != 0) 2104 info_ptr->bit_depth = png_ptr->user_transform_depth; 2105 2106 if (png_ptr->user_transform_channels != 0) 2107 info_ptr->channels = png_ptr->user_transform_channels; 2108 } 2109#endif 2110 2111 info_ptr->pixel_depth = (png_byte)(info_ptr->channels * 2112 info_ptr->bit_depth); 2113 2114 info_ptr->rowbytes = PNG_ROWBYTES(info_ptr->pixel_depth, info_ptr->width); 2115 2116 /* Adding in 1.5.4: cache the above value in png_struct so that we can later 2117 * check in png_rowbytes that the user buffer won't get overwritten. Note 2118 * that the field is not always set - if png_read_update_info isn't called 2119 * the application has to either not do any transforms or get the calculation 2120 * right itself. 2121 */ 2122 png_ptr->info_rowbytes = info_ptr->rowbytes; 2123 2124#ifndef PNG_READ_EXPAND_SUPPORTED 2125 if (png_ptr != NULL) 2126 return; 2127#endif 2128} 2129 2130#ifdef PNG_READ_PACK_SUPPORTED 2131/* Unpack pixels of 1, 2, or 4 bits per pixel into 1 byte per pixel, 2132 * without changing the actual values. Thus, if you had a row with 2133 * a bit depth of 1, you would end up with bytes that only contained 2134 * the numbers 0 or 1. If you would rather they contain 0 and 255, use 2135 * png_do_shift() after this. 2136 */ 2137static void 2138png_do_unpack(png_row_infop row_info, png_bytep row) 2139{ 2140 png_debug(1, "in png_do_unpack"); 2141 2142 if (row_info->bit_depth < 8) 2143 { 2144 png_uint_32 i; 2145 png_uint_32 row_width=row_info->width; 2146 2147 switch (row_info->bit_depth) 2148 { 2149 case 1: 2150 { 2151 png_bytep sp = row + (png_size_t)((row_width - 1) >> 3); 2152 png_bytep dp = row + (png_size_t)row_width - 1; 2153 png_uint_32 shift = 7 - (int)((row_width + 7) & 0x07); 2154 for (i = 0; i < row_width; i++) 2155 { 2156 *dp = (png_byte)((*sp >> shift) & 0x01); 2157 2158 if (shift == 7) 2159 { 2160 shift = 0; 2161 sp--; 2162 } 2163 2164 else 2165 shift++; 2166 2167 dp--; 2168 } 2169 break; 2170 } 2171 2172 case 2: 2173 { 2174 2175 png_bytep sp = row + (png_size_t)((row_width - 1) >> 2); 2176 png_bytep dp = row + (png_size_t)row_width - 1; 2177 png_uint_32 shift = (int)((3 - ((row_width + 3) & 0x03)) << 1); 2178 for (i = 0; i < row_width; i++) 2179 { 2180 *dp = (png_byte)((*sp >> shift) & 0x03); 2181 2182 if (shift == 6) 2183 { 2184 shift = 0; 2185 sp--; 2186 } 2187 2188 else 2189 shift += 2; 2190 2191 dp--; 2192 } 2193 break; 2194 } 2195 2196 case 4: 2197 { 2198 png_bytep sp = row + (png_size_t)((row_width - 1) >> 1); 2199 png_bytep dp = row + (png_size_t)row_width - 1; 2200 png_uint_32 shift = (int)((1 - ((row_width + 1) & 0x01)) << 2); 2201 for (i = 0; i < row_width; i++) 2202 { 2203 *dp = (png_byte)((*sp >> shift) & 0x0f); 2204 2205 if (shift == 4) 2206 { 2207 shift = 0; 2208 sp--; 2209 } 2210 2211 else 2212 shift = 4; 2213 2214 dp--; 2215 } 2216 break; 2217 } 2218 2219 default: 2220 break; 2221 } 2222 row_info->bit_depth = 8; 2223 row_info->pixel_depth = (png_byte)(8 * row_info->channels); 2224 row_info->rowbytes = row_width * row_info->channels; 2225 } 2226} 2227#endif 2228 2229#ifdef PNG_READ_SHIFT_SUPPORTED 2230/* Reverse the effects of png_do_shift. This routine merely shifts the 2231 * pixels back to their significant bits values. Thus, if you have 2232 * a row of bit depth 8, but only 5 are significant, this will shift 2233 * the values back to 0 through 31. 2234 */ 2235static void 2236png_do_unshift(png_row_infop row_info, png_bytep row, 2237 png_const_color_8p sig_bits) 2238{ 2239 int color_type; 2240 2241 png_debug(1, "in png_do_unshift"); 2242 2243 /* The palette case has already been handled in the _init routine. */ 2244 color_type = row_info->color_type; 2245 2246 if (color_type != PNG_COLOR_TYPE_PALETTE) 2247 { 2248 int shift[4]; 2249 int channels = 0; 2250 int bit_depth = row_info->bit_depth; 2251 2252 if ((color_type & PNG_COLOR_MASK_COLOR) != 0) 2253 { 2254 shift[channels++] = bit_depth - sig_bits->red; 2255 shift[channels++] = bit_depth - sig_bits->green; 2256 shift[channels++] = bit_depth - sig_bits->blue; 2257 } 2258 2259 else 2260 { 2261 shift[channels++] = bit_depth - sig_bits->gray; 2262 } 2263 2264 if ((color_type & PNG_COLOR_MASK_ALPHA) != 0) 2265 { 2266 shift[channels++] = bit_depth - sig_bits->alpha; 2267 } 2268 2269 { 2270 int c, have_shift; 2271 2272 for (c = have_shift = 0; c < channels; ++c) 2273 { 2274 /* A shift of more than the bit depth is an error condition but it 2275 * gets ignored here. 2276 */ 2277 if (shift[c] <= 0 || shift[c] >= bit_depth) 2278 shift[c] = 0; 2279 2280 else 2281 have_shift = 1; 2282 } 2283 2284 if (have_shift == 0) 2285 return; 2286 } 2287 2288 switch (bit_depth) 2289 { 2290 default: 2291 /* Must be 1bpp gray: should not be here! */ 2292 /* NOTREACHED */ 2293 break; 2294 2295 case 2: 2296 /* Must be 2bpp gray */ 2297 /* assert(channels == 1 && shift[0] == 1) */ 2298 { 2299 png_bytep bp = row; 2300 png_bytep bp_end = bp + row_info->rowbytes; 2301 2302 while (bp < bp_end) 2303 { 2304 int b = (*bp >> 1) & 0x55; 2305 *bp++ = (png_byte)b; 2306 } 2307 break; 2308 } 2309 2310 case 4: 2311 /* Must be 4bpp gray */ 2312 /* assert(channels == 1) */ 2313 { 2314 png_bytep bp = row; 2315 png_bytep bp_end = bp + row_info->rowbytes; 2316 int gray_shift = shift[0]; 2317 int mask = 0xf >> gray_shift; 2318 2319 mask |= mask << 4; 2320 2321 while (bp < bp_end) 2322 { 2323 int b = (*bp >> gray_shift) & mask; 2324 *bp++ = (png_byte)b; 2325 } 2326 break; 2327 } 2328 2329 case 8: 2330 /* Single byte components, G, GA, RGB, RGBA */ 2331 { 2332 png_bytep bp = row; 2333 png_bytep bp_end = bp + row_info->rowbytes; 2334 int channel = 0; 2335 2336 while (bp < bp_end) 2337 { 2338 int b = *bp >> shift[channel]; 2339 if (++channel >= channels) 2340 channel = 0; 2341 *bp++ = (png_byte)b; 2342 } 2343 break; 2344 } 2345 2346#ifdef PNG_READ_16BIT_SUPPORTED 2347 case 16: 2348 /* Double byte components, G, GA, RGB, RGBA */ 2349 { 2350 png_bytep bp = row; 2351 png_bytep bp_end = bp + row_info->rowbytes; 2352 int channel = 0; 2353 2354 while (bp < bp_end) 2355 { 2356 int value = (bp[0] << 8) + bp[1]; 2357 2358 value >>= shift[channel]; 2359 if (++channel >= channels) 2360 channel = 0; 2361 *bp++ = (png_byte)(value >> 8); 2362 *bp++ = (png_byte)value; 2363 } 2364 break; 2365 } 2366#endif 2367 } 2368 } 2369} 2370#endif 2371 2372#ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED 2373/* Scale rows of bit depth 16 down to 8 accurately */ 2374static void 2375png_do_scale_16_to_8(png_row_infop row_info, png_bytep row) 2376{ 2377 png_debug(1, "in png_do_scale_16_to_8"); 2378 2379 if (row_info->bit_depth == 16) 2380 { 2381 png_bytep sp = row; /* source */ 2382 png_bytep dp = row; /* destination */ 2383 png_bytep ep = sp + row_info->rowbytes; /* end+1 */ 2384 2385 while (sp < ep) 2386 { 2387 /* The input is an array of 16-bit components, these must be scaled to 2388 * 8 bits each. For a 16-bit value V the required value (from the PNG 2389 * specification) is: 2390 * 2391 * (V * 255) / 65535 2392 * 2393 * This reduces to round(V / 257), or floor((V + 128.5)/257) 2394 * 2395 * Represent V as the two byte value vhi.vlo. Make a guess that the 2396 * result is the top byte of V, vhi, then the correction to this value 2397 * is: 2398 * 2399 * error = floor(((V-vhi.vhi) + 128.5) / 257) 2400 * = floor(((vlo-vhi) + 128.5) / 257) 2401 * 2402 * This can be approximated using integer arithmetic (and a signed 2403 * shift): 2404 * 2405 * error = (vlo-vhi+128) >> 8; 2406 * 2407 * The approximate differs from the exact answer only when (vlo-vhi) is 2408 * 128; it then gives a correction of +1 when the exact correction is 2409 * 0. This gives 128 errors. The exact answer (correct for all 16-bit 2410 * input values) is: 2411 * 2412 * error = (vlo-vhi+128)*65535 >> 24; 2413 * 2414 * An alternative arithmetic calculation which also gives no errors is: 2415 * 2416 * (V * 255 + 32895) >> 16 2417 */ 2418 2419 png_int_32 tmp = *sp++; /* must be signed! */ 2420 tmp += (((int)*sp++ - tmp + 128) * 65535) >> 24; 2421 *dp++ = (png_byte)tmp; 2422 } 2423 2424 row_info->bit_depth = 8; 2425 row_info->pixel_depth = (png_byte)(8 * row_info->channels); 2426 row_info->rowbytes = row_info->width * row_info->channels; 2427 } 2428} 2429#endif 2430 2431#ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED 2432static void 2433/* Simply discard the low byte. This was the default behavior prior 2434 * to libpng-1.5.4. 2435 */ 2436png_do_chop(png_row_infop row_info, png_bytep row) 2437{ 2438 png_debug(1, "in png_do_chop"); 2439 2440 if (row_info->bit_depth == 16) 2441 { 2442 png_bytep sp = row; /* source */ 2443 png_bytep dp = row; /* destination */ 2444 png_bytep ep = sp + row_info->rowbytes; /* end+1 */ 2445 2446 while (sp < ep) 2447 { 2448 *dp++ = *sp; 2449 sp += 2; /* skip low byte */ 2450 } 2451 2452 row_info->bit_depth = 8; 2453 row_info->pixel_depth = (png_byte)(8 * row_info->channels); 2454 row_info->rowbytes = row_info->width * row_info->channels; 2455 } 2456} 2457#endif 2458 2459#ifdef PNG_READ_SWAP_ALPHA_SUPPORTED 2460static void 2461png_do_read_swap_alpha(png_row_infop row_info, png_bytep row) 2462{ 2463 png_debug(1, "in png_do_read_swap_alpha"); 2464 2465 { 2466 png_uint_32 row_width = row_info->width; 2467 if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA) 2468 { 2469 /* This converts from RGBA to ARGB */ 2470 if (row_info->bit_depth == 8) 2471 { 2472 png_bytep sp = row + row_info->rowbytes; 2473 png_bytep dp = sp; 2474 png_byte save; 2475 png_uint_32 i; 2476 2477 for (i = 0; i < row_width; i++) 2478 { 2479 save = *(--sp); 2480 *(--dp) = *(--sp); 2481 *(--dp) = *(--sp); 2482 *(--dp) = *(--sp); 2483 *(--dp) = save; 2484 } 2485 } 2486 2487#ifdef PNG_READ_16BIT_SUPPORTED 2488 /* This converts from RRGGBBAA to AARRGGBB */ 2489 else 2490 { 2491 png_bytep sp = row + row_info->rowbytes; 2492 png_bytep dp = sp; 2493 png_byte save[2]; 2494 png_uint_32 i; 2495 2496 for (i = 0; i < row_width; i++) 2497 { 2498 save[0] = *(--sp); 2499 save[1] = *(--sp); 2500 *(--dp) = *(--sp); 2501 *(--dp) = *(--sp); 2502 *(--dp) = *(--sp); 2503 *(--dp) = *(--sp); 2504 *(--dp) = *(--sp); 2505 *(--dp) = *(--sp); 2506 *(--dp) = save[0]; 2507 *(--dp) = save[1]; 2508 } 2509 } 2510#endif 2511 } 2512 2513 else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA) 2514 { 2515 /* This converts from GA to AG */ 2516 if (row_info->bit_depth == 8) 2517 { 2518 png_bytep sp = row + row_info->rowbytes; 2519 png_bytep dp = sp; 2520 png_byte save; 2521 png_uint_32 i; 2522 2523 for (i = 0; i < row_width; i++) 2524 { 2525 save = *(--sp); 2526 *(--dp) = *(--sp); 2527 *(--dp) = save; 2528 } 2529 } 2530 2531#ifdef PNG_READ_16BIT_SUPPORTED 2532 /* This converts from GGAA to AAGG */ 2533 else 2534 { 2535 png_bytep sp = row + row_info->rowbytes; 2536 png_bytep dp = sp; 2537 png_byte save[2]; 2538 png_uint_32 i; 2539 2540 for (i = 0; i < row_width; i++) 2541 { 2542 save[0] = *(--sp); 2543 save[1] = *(--sp); 2544 *(--dp) = *(--sp); 2545 *(--dp) = *(--sp); 2546 *(--dp) = save[0]; 2547 *(--dp) = save[1]; 2548 } 2549 } 2550#endif 2551 } 2552 } 2553} 2554#endif 2555 2556#ifdef PNG_READ_INVERT_ALPHA_SUPPORTED 2557static void 2558png_do_read_invert_alpha(png_row_infop row_info, png_bytep row) 2559{ 2560 png_uint_32 row_width; 2561 png_debug(1, "in png_do_read_invert_alpha"); 2562 2563 row_width = row_info->width; 2564 if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA) 2565 { 2566 if (row_info->bit_depth == 8) 2567 { 2568 /* This inverts the alpha channel in RGBA */ 2569 png_bytep sp = row + row_info->rowbytes; 2570 png_bytep dp = sp; 2571 png_uint_32 i; 2572 2573 for (i = 0; i < row_width; i++) 2574 { 2575 *(--dp) = (png_byte)(255 - *(--sp)); 2576 2577/* This does nothing: 2578 *(--dp) = *(--sp); 2579 *(--dp) = *(--sp); 2580 *(--dp) = *(--sp); 2581 We can replace it with: 2582*/ 2583 sp-=3; 2584 dp=sp; 2585 } 2586 } 2587 2588#ifdef PNG_READ_16BIT_SUPPORTED 2589 /* This inverts the alpha channel in RRGGBBAA */ 2590 else 2591 { 2592 png_bytep sp = row + row_info->rowbytes; 2593 png_bytep dp = sp; 2594 png_uint_32 i; 2595 2596 for (i = 0; i < row_width; i++) 2597 { 2598 *(--dp) = (png_byte)(255 - *(--sp)); 2599 *(--dp) = (png_byte)(255 - *(--sp)); 2600 2601/* This does nothing: 2602 *(--dp) = *(--sp); 2603 *(--dp) = *(--sp); 2604 *(--dp) = *(--sp); 2605 *(--dp) = *(--sp); 2606 *(--dp) = *(--sp); 2607 *(--dp) = *(--sp); 2608 We can replace it with: 2609*/ 2610 sp-=6; 2611 dp=sp; 2612 } 2613 } 2614#endif 2615 } 2616 else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA) 2617 { 2618 if (row_info->bit_depth == 8) 2619 { 2620 /* This inverts the alpha channel in GA */ 2621 png_bytep sp = row + row_info->rowbytes; 2622 png_bytep dp = sp; 2623 png_uint_32 i; 2624 2625 for (i = 0; i < row_width; i++) 2626 { 2627 *(--dp) = (png_byte)(255 - *(--sp)); 2628 *(--dp) = *(--sp); 2629 } 2630 } 2631 2632#ifdef PNG_READ_16BIT_SUPPORTED 2633 else 2634 { 2635 /* This inverts the alpha channel in GGAA */ 2636 png_bytep sp = row + row_info->rowbytes; 2637 png_bytep dp = sp; 2638 png_uint_32 i; 2639 2640 for (i = 0; i < row_width; i++) 2641 { 2642 *(--dp) = (png_byte)(255 - *(--sp)); 2643 *(--dp) = (png_byte)(255 - *(--sp)); 2644/* 2645 *(--dp) = *(--sp); 2646 *(--dp) = *(--sp); 2647*/ 2648 sp-=2; 2649 dp=sp; 2650 } 2651 } 2652#endif 2653 } 2654} 2655#endif 2656 2657#ifdef PNG_READ_FILLER_SUPPORTED 2658/* Add filler channel if we have RGB color */ 2659static void 2660png_do_read_filler(png_row_infop row_info, png_bytep row, 2661 png_uint_32 filler, png_uint_32 flags) 2662{ 2663 png_uint_32 i; 2664 png_uint_32 row_width = row_info->width; 2665 2666#ifdef PNG_READ_16BIT_SUPPORTED 2667 png_byte hi_filler = (png_byte)(filler>>8); 2668#endif 2669 png_byte lo_filler = (png_byte)filler; 2670 2671 png_debug(1, "in png_do_read_filler"); 2672 2673 if ( 2674 row_info->color_type == PNG_COLOR_TYPE_GRAY) 2675 { 2676 if (row_info->bit_depth == 8) 2677 { 2678 if ((flags & PNG_FLAG_FILLER_AFTER) != 0) 2679 { 2680 /* This changes the data from G to GX */ 2681 png_bytep sp = row + (png_size_t)row_width; 2682 png_bytep dp = sp + (png_size_t)row_width; 2683 for (i = 1; i < row_width; i++) 2684 { 2685 *(--dp) = lo_filler; 2686 *(--dp) = *(--sp); 2687 } 2688 *(--dp) = lo_filler; 2689 row_info->channels = 2; 2690 row_info->pixel_depth = 16; 2691 row_info->rowbytes = row_width * 2; 2692 } 2693 2694 else 2695 { 2696 /* This changes the data from G to XG */ 2697 png_bytep sp = row + (png_size_t)row_width; 2698 png_bytep dp = sp + (png_size_t)row_width; 2699 for (i = 0; i < row_width; i++) 2700 { 2701 *(--dp) = *(--sp); 2702 *(--dp) = lo_filler; 2703 } 2704 row_info->channels = 2; 2705 row_info->pixel_depth = 16; 2706 row_info->rowbytes = row_width * 2; 2707 } 2708 } 2709 2710#ifdef PNG_READ_16BIT_SUPPORTED 2711 else if (row_info->bit_depth == 16) 2712 { 2713 if ((flags & PNG_FLAG_FILLER_AFTER) != 0) 2714 { 2715 /* This changes the data from GG to GGXX */ 2716 png_bytep sp = row + (png_size_t)row_width * 2; 2717 png_bytep dp = sp + (png_size_t)row_width * 2; 2718 for (i = 1; i < row_width; i++) 2719 { 2720 *(--dp) = lo_filler; 2721 *(--dp) = hi_filler; 2722 *(--dp) = *(--sp); 2723 *(--dp) = *(--sp); 2724 } 2725 *(--dp) = lo_filler; 2726 *(--dp) = hi_filler; 2727 row_info->channels = 2; 2728 row_info->pixel_depth = 32; 2729 row_info->rowbytes = row_width * 4; 2730 } 2731 2732 else 2733 { 2734 /* This changes the data from GG to XXGG */ 2735 png_bytep sp = row + (png_size_t)row_width * 2; 2736 png_bytep dp = sp + (png_size_t)row_width * 2; 2737 for (i = 0; i < row_width; i++) 2738 { 2739 *(--dp) = *(--sp); 2740 *(--dp) = *(--sp); 2741 *(--dp) = lo_filler; 2742 *(--dp) = hi_filler; 2743 } 2744 row_info->channels = 2; 2745 row_info->pixel_depth = 32; 2746 row_info->rowbytes = row_width * 4; 2747 } 2748 } 2749#endif 2750 } /* COLOR_TYPE == GRAY */ 2751 else if (row_info->color_type == PNG_COLOR_TYPE_RGB) 2752 { 2753 if (row_info->bit_depth == 8) 2754 { 2755 if ((flags & PNG_FLAG_FILLER_AFTER) != 0) 2756 { 2757 /* This changes the data from RGB to RGBX */ 2758 png_bytep sp = row + (png_size_t)row_width * 3; 2759 png_bytep dp = sp + (png_size_t)row_width; 2760 for (i = 1; i < row_width; i++) 2761 { 2762 *(--dp) = lo_filler; 2763 *(--dp) = *(--sp); 2764 *(--dp) = *(--sp); 2765 *(--dp) = *(--sp); 2766 } 2767 *(--dp) = lo_filler; 2768 row_info->channels = 4; 2769 row_info->pixel_depth = 32; 2770 row_info->rowbytes = row_width * 4; 2771 } 2772 2773 else 2774 { 2775 /* This changes the data from RGB to XRGB */ 2776 png_bytep sp = row + (png_size_t)row_width * 3; 2777 png_bytep dp = sp + (png_size_t)row_width; 2778 for (i = 0; i < row_width; i++) 2779 { 2780 *(--dp) = *(--sp); 2781 *(--dp) = *(--sp); 2782 *(--dp) = *(--sp); 2783 *(--dp) = lo_filler; 2784 } 2785 row_info->channels = 4; 2786 row_info->pixel_depth = 32; 2787 row_info->rowbytes = row_width * 4; 2788 } 2789 } 2790 2791#ifdef PNG_READ_16BIT_SUPPORTED 2792 else if (row_info->bit_depth == 16) 2793 { 2794 if ((flags & PNG_FLAG_FILLER_AFTER) != 0) 2795 { 2796 /* This changes the data from RRGGBB to RRGGBBXX */ 2797 png_bytep sp = row + (png_size_t)row_width * 6; 2798 png_bytep dp = sp + (png_size_t)row_width * 2; 2799 for (i = 1; i < row_width; i++) 2800 { 2801 *(--dp) = lo_filler; 2802 *(--dp) = hi_filler; 2803 *(--dp) = *(--sp); 2804 *(--dp) = *(--sp); 2805 *(--dp) = *(--sp); 2806 *(--dp) = *(--sp); 2807 *(--dp) = *(--sp); 2808 *(--dp) = *(--sp); 2809 } 2810 *(--dp) = lo_filler; 2811 *(--dp) = hi_filler; 2812 row_info->channels = 4; 2813 row_info->pixel_depth = 64; 2814 row_info->rowbytes = row_width * 8; 2815 } 2816 2817 else 2818 { 2819 /* This changes the data from RRGGBB to XXRRGGBB */ 2820 png_bytep sp = row + (png_size_t)row_width * 6; 2821 png_bytep dp = sp + (png_size_t)row_width * 2; 2822 for (i = 0; i < row_width; i++) 2823 { 2824 *(--dp) = *(--sp); 2825 *(--dp) = *(--sp); 2826 *(--dp) = *(--sp); 2827 *(--dp) = *(--sp); 2828 *(--dp) = *(--sp); 2829 *(--dp) = *(--sp); 2830 *(--dp) = lo_filler; 2831 *(--dp) = hi_filler; 2832 } 2833 2834 row_info->channels = 4; 2835 row_info->pixel_depth = 64; 2836 row_info->rowbytes = row_width * 8; 2837 } 2838 } 2839#endif 2840 } /* COLOR_TYPE == RGB */ 2841} 2842#endif 2843 2844#ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED 2845/* Expand grayscale files to RGB, with or without alpha */ 2846static void 2847png_do_gray_to_rgb(png_row_infop row_info, png_bytep row) 2848{ 2849 png_uint_32 i; 2850 png_uint_32 row_width = row_info->width; 2851 2852 png_debug(1, "in png_do_gray_to_rgb"); 2853 2854 if (row_info->bit_depth >= 8 && 2855 (row_info->color_type & PNG_COLOR_MASK_COLOR) == 0) 2856 { 2857 if (row_info->color_type == PNG_COLOR_TYPE_GRAY) 2858 { 2859 if (row_info->bit_depth == 8) 2860 { 2861 /* This changes G to RGB */ 2862 png_bytep sp = row + (png_size_t)row_width - 1; 2863 png_bytep dp = sp + (png_size_t)row_width * 2; 2864 for (i = 0; i < row_width; i++) 2865 { 2866 *(dp--) = *sp; 2867 *(dp--) = *sp; 2868 *(dp--) = *(sp--); 2869 } 2870 } 2871 2872 else 2873 { 2874 /* This changes GG to RRGGBB */ 2875 png_bytep sp = row + (png_size_t)row_width * 2 - 1; 2876 png_bytep dp = sp + (png_size_t)row_width * 4; 2877 for (i = 0; i < row_width; i++) 2878 { 2879 *(dp--) = *sp; 2880 *(dp--) = *(sp - 1); 2881 *(dp--) = *sp; 2882 *(dp--) = *(sp - 1); 2883 *(dp--) = *(sp--); 2884 *(dp--) = *(sp--); 2885 } 2886 } 2887 } 2888 2889 else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA) 2890 { 2891 if (row_info->bit_depth == 8) 2892 { 2893 /* This changes GA to RGBA */ 2894 png_bytep sp = row + (png_size_t)row_width * 2 - 1; 2895 png_bytep dp = sp + (png_size_t)row_width * 2; 2896 for (i = 0; i < row_width; i++) 2897 { 2898 *(dp--) = *(sp--); 2899 *(dp--) = *sp; 2900 *(dp--) = *sp; 2901 *(dp--) = *(sp--); 2902 } 2903 } 2904 2905 else 2906 { 2907 /* This changes GGAA to RRGGBBAA */ 2908 png_bytep sp = row + (png_size_t)row_width * 4 - 1; 2909 png_bytep dp = sp + (png_size_t)row_width * 4; 2910 for (i = 0; i < row_width; i++) 2911 { 2912 *(dp--) = *(sp--); 2913 *(dp--) = *(sp--); 2914 *(dp--) = *sp; 2915 *(dp--) = *(sp - 1); 2916 *(dp--) = *sp; 2917 *(dp--) = *(sp - 1); 2918 *(dp--) = *(sp--); 2919 *(dp--) = *(sp--); 2920 } 2921 } 2922 } 2923 row_info->channels = (png_byte)(row_info->channels + 2); 2924 row_info->color_type |= PNG_COLOR_MASK_COLOR; 2925 row_info->pixel_depth = (png_byte)(row_info->channels * 2926 row_info->bit_depth); 2927 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width); 2928 } 2929} 2930#endif 2931 2932#ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED 2933/* Reduce RGB files to grayscale, with or without alpha 2934 * using the equation given in Poynton's ColorFAQ of 1998-01-04 at 2935 * <http://www.inforamp.net/~poynton/> (THIS LINK IS DEAD June 2008 but 2936 * versions dated 1998 through November 2002 have been archived at 2937 * http://web.archive.org/web/20000816232553/http://www.inforamp.net/ 2938 * ~poynton/notes/colour_and_gamma/ColorFAQ.txt ) 2939 * Charles Poynton poynton at poynton.com 2940 * 2941 * Y = 0.212671 * R + 0.715160 * G + 0.072169 * B 2942 * 2943 * which can be expressed with integers as 2944 * 2945 * Y = (6969 * R + 23434 * G + 2365 * B)/32768 2946 * 2947 * Poynton's current link (as of January 2003 through July 2011): 2948 * <http://www.poynton.com/notes/colour_and_gamma/> 2949 * has changed the numbers slightly: 2950 * 2951 * Y = 0.2126*R + 0.7152*G + 0.0722*B 2952 * 2953 * which can be expressed with integers as 2954 * 2955 * Y = (6966 * R + 23436 * G + 2366 * B)/32768 2956 * 2957 * Historically, however, libpng uses numbers derived from the ITU-R Rec 709 2958 * end point chromaticities and the D65 white point. Depending on the 2959 * precision used for the D65 white point this produces a variety of different 2960 * numbers, however if the four decimal place value used in ITU-R Rec 709 is 2961 * used (0.3127,0.3290) the Y calculation would be: 2962 * 2963 * Y = (6968 * R + 23435 * G + 2366 * B)/32768 2964 * 2965 * While this is correct the rounding results in an overflow for white, because 2966 * the sum of the rounded coefficients is 32769, not 32768. Consequently 2967 * libpng uses, instead, the closest non-overflowing approximation: 2968 * 2969 * Y = (6968 * R + 23434 * G + 2366 * B)/32768 2970 * 2971 * Starting with libpng-1.5.5, if the image being converted has a cHRM chunk 2972 * (including an sRGB chunk) then the chromaticities are used to calculate the 2973 * coefficients. See the chunk handling in pngrutil.c for more information. 2974 * 2975 * In all cases the calculation is to be done in a linear colorspace. If no 2976 * gamma information is available to correct the encoding of the original RGB 2977 * values this results in an implicit assumption that the original PNG RGB 2978 * values were linear. 2979 * 2980 * Other integer coefficents can be used via png_set_rgb_to_gray(). Because 2981 * the API takes just red and green coefficients the blue coefficient is 2982 * calculated to make the sum 32768. This will result in different rounding 2983 * to that used above. 2984 */ 2985static int 2986png_do_rgb_to_gray(png_structrp png_ptr, png_row_infop row_info, png_bytep row) 2987 2988{ 2989 int rgb_error = 0; 2990 2991 png_debug(1, "in png_do_rgb_to_gray"); 2992 2993 if ((row_info->color_type & PNG_COLOR_MASK_PALETTE) == 0 && 2994 (row_info->color_type & PNG_COLOR_MASK_COLOR) != 0) 2995 { 2996 PNG_CONST png_uint_32 rc = png_ptr->rgb_to_gray_red_coeff; 2997 PNG_CONST png_uint_32 gc = png_ptr->rgb_to_gray_green_coeff; 2998 PNG_CONST png_uint_32 bc = 32768 - rc - gc; 2999 PNG_CONST png_uint_32 row_width = row_info->width; 3000 PNG_CONST int have_alpha = 3001 (row_info->color_type & PNG_COLOR_MASK_ALPHA) != 0; 3002 3003 if (row_info->bit_depth == 8) 3004 { 3005#ifdef PNG_READ_GAMMA_SUPPORTED 3006 /* Notice that gamma to/from 1 are not necessarily inverses (if 3007 * there is an overall gamma correction). Prior to 1.5.5 this code 3008 * checked the linearized values for equality; this doesn't match 3009 * the documentation, the original values must be checked. 3010 */ 3011 if (png_ptr->gamma_from_1 != NULL && png_ptr->gamma_to_1 != NULL) 3012 { 3013 png_bytep sp = row; 3014 png_bytep dp = row; 3015 png_uint_32 i; 3016 3017 for (i = 0; i < row_width; i++) 3018 { 3019 png_byte red = *(sp++); 3020 png_byte green = *(sp++); 3021 png_byte blue = *(sp++); 3022 3023 if (red != green || red != blue) 3024 { 3025 red = png_ptr->gamma_to_1[red]; 3026 green = png_ptr->gamma_to_1[green]; 3027 blue = png_ptr->gamma_to_1[blue]; 3028 3029 rgb_error |= 1; 3030 *(dp++) = png_ptr->gamma_from_1[ 3031 (rc*red + gc*green + bc*blue + 16384)>>15]; 3032 } 3033 3034 else 3035 { 3036 /* If there is no overall correction the table will not be 3037 * set. 3038 */ 3039 if (png_ptr->gamma_table != NULL) 3040 red = png_ptr->gamma_table[red]; 3041 3042 *(dp++) = red; 3043 } 3044 3045 if (have_alpha != 0) 3046 *(dp++) = *(sp++); 3047 } 3048 } 3049 else 3050#endif 3051 { 3052 png_bytep sp = row; 3053 png_bytep dp = row; 3054 png_uint_32 i; 3055 3056 for (i = 0; i < row_width; i++) 3057 { 3058 png_byte red = *(sp++); 3059 png_byte green = *(sp++); 3060 png_byte blue = *(sp++); 3061 3062 if (red != green || red != blue) 3063 { 3064 rgb_error |= 1; 3065 /* NOTE: this is the historical approach which simply 3066 * truncates the results. 3067 */ 3068 *(dp++) = (png_byte)((rc*red + gc*green + bc*blue)>>15); 3069 } 3070 3071 else 3072 *(dp++) = red; 3073 3074 if (have_alpha != 0) 3075 *(dp++) = *(sp++); 3076 } 3077 } 3078 } 3079 3080 else /* RGB bit_depth == 16 */ 3081 { 3082#ifdef PNG_READ_GAMMA_SUPPORTED 3083 if (png_ptr->gamma_16_to_1 != NULL && png_ptr->gamma_16_from_1 != NULL) 3084 { 3085 png_bytep sp = row; 3086 png_bytep dp = row; 3087 png_uint_32 i; 3088 3089 for (i = 0; i < row_width; i++) 3090 { 3091 png_uint_16 red, green, blue, w; 3092 png_byte hi,lo; 3093 3094 hi=*(sp)++; lo=*(sp)++; red = (png_uint_16)((hi << 8) | (lo)); 3095 hi=*(sp)++; lo=*(sp)++; green = (png_uint_16)((hi << 8) | (lo)); 3096 hi=*(sp)++; lo=*(sp)++; blue = (png_uint_16)((hi << 8) | (lo)); 3097 3098 if (red == green && red == blue) 3099 { 3100 if (png_ptr->gamma_16_table != NULL) 3101 w = png_ptr->gamma_16_table[(red & 0xff) 3102 >> png_ptr->gamma_shift][red >> 8]; 3103 3104 else 3105 w = red; 3106 } 3107 3108 else 3109 { 3110 png_uint_16 red_1 = png_ptr->gamma_16_to_1[(red & 0xff) 3111 >> png_ptr->gamma_shift][red>>8]; 3112 png_uint_16 green_1 = 3113 png_ptr->gamma_16_to_1[(green & 0xff) >> 3114 png_ptr->gamma_shift][green>>8]; 3115 png_uint_16 blue_1 = png_ptr->gamma_16_to_1[(blue & 0xff) 3116 >> png_ptr->gamma_shift][blue>>8]; 3117 png_uint_16 gray16 = (png_uint_16)((rc*red_1 + gc*green_1 3118 + bc*blue_1 + 16384)>>15); 3119 w = png_ptr->gamma_16_from_1[(gray16 & 0xff) >> 3120 png_ptr->gamma_shift][gray16 >> 8]; 3121 rgb_error |= 1; 3122 } 3123 3124 *(dp++) = (png_byte)((w>>8) & 0xff); 3125 *(dp++) = (png_byte)(w & 0xff); 3126 3127 if (have_alpha != 0) 3128 { 3129 *(dp++) = *(sp++); 3130 *(dp++) = *(sp++); 3131 } 3132 } 3133 } 3134 else 3135#endif 3136 { 3137 png_bytep sp = row; 3138 png_bytep dp = row; 3139 png_uint_32 i; 3140 3141 for (i = 0; i < row_width; i++) 3142 { 3143 png_uint_16 red, green, blue, gray16; 3144 png_byte hi,lo; 3145 3146 hi=*(sp)++; lo=*(sp)++; red = (png_uint_16)((hi << 8) | (lo)); 3147 hi=*(sp)++; lo=*(sp)++; green = (png_uint_16)((hi << 8) | (lo)); 3148 hi=*(sp)++; lo=*(sp)++; blue = (png_uint_16)((hi << 8) | (lo)); 3149 3150 if (red != green || red != blue) 3151 rgb_error |= 1; 3152 3153 /* From 1.5.5 in the 16-bit case do the accurate conversion even 3154 * in the 'fast' case - this is because this is where the code 3155 * ends up when handling linear 16-bit data. 3156 */ 3157 gray16 = (png_uint_16)((rc*red + gc*green + bc*blue + 16384) >> 3158 15); 3159 *(dp++) = (png_byte)((gray16 >> 8) & 0xff); 3160 *(dp++) = (png_byte)(gray16 & 0xff); 3161 3162 if (have_alpha != 0) 3163 { 3164 *(dp++) = *(sp++); 3165 *(dp++) = *(sp++); 3166 } 3167 } 3168 } 3169 } 3170 3171 row_info->channels = (png_byte)(row_info->channels - 2); 3172 row_info->color_type = (png_byte)(row_info->color_type & 3173 ~PNG_COLOR_MASK_COLOR); 3174 row_info->pixel_depth = (png_byte)(row_info->channels * 3175 row_info->bit_depth); 3176 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width); 3177 } 3178 return rgb_error; 3179} 3180#endif 3181 3182#if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\ 3183 defined(PNG_READ_ALPHA_MODE_SUPPORTED) 3184/* Replace any alpha or transparency with the supplied background color. 3185 * "background" is already in the screen gamma, while "background_1" is 3186 * at a gamma of 1.0. Paletted files have already been taken care of. 3187 */ 3188static void 3189png_do_compose(png_row_infop row_info, png_bytep row, png_structrp png_ptr) 3190{ 3191#ifdef PNG_READ_GAMMA_SUPPORTED 3192 png_const_bytep gamma_table = png_ptr->gamma_table; 3193 png_const_bytep gamma_from_1 = png_ptr->gamma_from_1; 3194 png_const_bytep gamma_to_1 = png_ptr->gamma_to_1; 3195 png_const_uint_16pp gamma_16 = png_ptr->gamma_16_table; 3196 png_const_uint_16pp gamma_16_from_1 = png_ptr->gamma_16_from_1; 3197 png_const_uint_16pp gamma_16_to_1 = png_ptr->gamma_16_to_1; 3198 int gamma_shift = png_ptr->gamma_shift; 3199 int optimize = (png_ptr->flags & PNG_FLAG_OPTIMIZE_ALPHA) != 0; 3200#endif 3201 3202 png_bytep sp; 3203 png_uint_32 i; 3204 png_uint_32 row_width = row_info->width; 3205 int shift; 3206 3207 png_debug(1, "in png_do_compose"); 3208 3209 { 3210 switch (row_info->color_type) 3211 { 3212 case PNG_COLOR_TYPE_GRAY: 3213 { 3214 switch (row_info->bit_depth) 3215 { 3216 case 1: 3217 { 3218 sp = row; 3219 shift = 7; 3220 for (i = 0; i < row_width; i++) 3221 { 3222 if ((png_uint_16)((*sp >> shift) & 0x01) 3223 == png_ptr->trans_color.gray) 3224 { 3225 unsigned int tmp = *sp & (0x7f7f >> (7 - shift)); 3226 tmp |= png_ptr->background.gray << shift; 3227 *sp = (png_byte)(tmp & 0xff); 3228 } 3229 3230 if (shift == 0) 3231 { 3232 shift = 7; 3233 sp++; 3234 } 3235 3236 else 3237 shift--; 3238 } 3239 break; 3240 } 3241 3242 case 2: 3243 { 3244#ifdef PNG_READ_GAMMA_SUPPORTED 3245 if (gamma_table != NULL) 3246 { 3247 sp = row; 3248 shift = 6; 3249 for (i = 0; i < row_width; i++) 3250 { 3251 if ((png_uint_16)((*sp >> shift) & 0x03) 3252 == png_ptr->trans_color.gray) 3253 { 3254 unsigned int tmp = *sp & (0x3f3f >> (6 - shift)); 3255 tmp |= png_ptr->background.gray << shift; 3256 *sp = (png_byte)(tmp & 0xff); 3257 } 3258 3259 else 3260 { 3261 unsigned int p = (*sp >> shift) & 0x03; 3262 unsigned int g = (gamma_table [p | (p << 2) | 3263 (p << 4) | (p << 6)] >> 6) & 0x03; 3264 unsigned int tmp = *sp & (0x3f3f >> (6 - shift)); 3265 tmp |= g << shift; 3266 *sp = (png_byte)(tmp & 0xff); 3267 } 3268 3269 if (shift == 0) 3270 { 3271 shift = 6; 3272 sp++; 3273 } 3274 3275 else 3276 shift -= 2; 3277 } 3278 } 3279 3280 else 3281#endif 3282 { 3283 sp = row; 3284 shift = 6; 3285 for (i = 0; i < row_width; i++) 3286 { 3287 if ((png_uint_16)((*sp >> shift) & 0x03) 3288 == png_ptr->trans_color.gray) 3289 { 3290 unsigned int tmp = *sp & (0x3f3f >> (6 - shift)); 3291 tmp |= png_ptr->background.gray << shift; 3292 *sp = (png_byte)(tmp & 0xff); 3293 } 3294 3295 if (shift == 0) 3296 { 3297 shift = 6; 3298 sp++; 3299 } 3300 3301 else 3302 shift -= 2; 3303 } 3304 } 3305 break; 3306 } 3307 3308 case 4: 3309 { 3310#ifdef PNG_READ_GAMMA_SUPPORTED 3311 if (gamma_table != NULL) 3312 { 3313 sp = row; 3314 shift = 4; 3315 for (i = 0; i < row_width; i++) 3316 { 3317 if ((png_uint_16)((*sp >> shift) & 0x0f) 3318 == png_ptr->trans_color.gray) 3319 { 3320 unsigned int tmp = *sp & (0x0f0f >> (4 - shift)); 3321 tmp |= png_ptr->background.gray << shift; 3322 *sp = (png_byte)(tmp & 0xff); 3323 } 3324 3325 else 3326 { 3327 unsigned int p = (*sp >> shift) & 0x0f; 3328 unsigned int g = (gamma_table[p | (p << 4)] >> 4) & 3329 0x0f; 3330 unsigned int tmp = *sp & (0x0f0f >> (4 - shift)); 3331 tmp |= g << shift; 3332 *sp = (png_byte)(tmp & 0xff); 3333 } 3334 3335 if (shift == 0) 3336 { 3337 shift = 4; 3338 sp++; 3339 } 3340 3341 else 3342 shift -= 4; 3343 } 3344 } 3345 3346 else 3347#endif 3348 { 3349 sp = row; 3350 shift = 4; 3351 for (i = 0; i < row_width; i++) 3352 { 3353 if ((png_uint_16)((*sp >> shift) & 0x0f) 3354 == png_ptr->trans_color.gray) 3355 { 3356 unsigned int tmp = *sp & (0x0f0f >> (4 - shift)); 3357 tmp |= png_ptr->background.gray << shift; 3358 *sp = (png_byte)(tmp & 0xff); 3359 } 3360 3361 if (shift == 0) 3362 { 3363 shift = 4; 3364 sp++; 3365 } 3366 3367 else 3368 shift -= 4; 3369 } 3370 } 3371 break; 3372 } 3373 3374 case 8: 3375 { 3376#ifdef PNG_READ_GAMMA_SUPPORTED 3377 if (gamma_table != NULL) 3378 { 3379 sp = row; 3380 for (i = 0; i < row_width; i++, sp++) 3381 { 3382 if (*sp == png_ptr->trans_color.gray) 3383 *sp = (png_byte)png_ptr->background.gray; 3384 3385 else 3386 *sp = gamma_table[*sp]; 3387 } 3388 } 3389 else 3390#endif 3391 { 3392 sp = row; 3393 for (i = 0; i < row_width; i++, sp++) 3394 { 3395 if (*sp == png_ptr->trans_color.gray) 3396 *sp = (png_byte)png_ptr->background.gray; 3397 } 3398 } 3399 break; 3400 } 3401 3402 case 16: 3403 { 3404#ifdef PNG_READ_GAMMA_SUPPORTED 3405 if (gamma_16 != NULL) 3406 { 3407 sp = row; 3408 for (i = 0; i < row_width; i++, sp += 2) 3409 { 3410 png_uint_16 v; 3411 3412 v = (png_uint_16)(((*sp) << 8) + *(sp + 1)); 3413 3414 if (v == png_ptr->trans_color.gray) 3415 { 3416 /* Background is already in screen gamma */ 3417 *sp = (png_byte)((png_ptr->background.gray >> 8) 3418 & 0xff); 3419 *(sp + 1) = (png_byte)(png_ptr->background.gray 3420 & 0xff); 3421 } 3422 3423 else 3424 { 3425 v = gamma_16[*(sp + 1) >> gamma_shift][*sp]; 3426 *sp = (png_byte)((v >> 8) & 0xff); 3427 *(sp + 1) = (png_byte)(v & 0xff); 3428 } 3429 } 3430 } 3431 else 3432#endif 3433 { 3434 sp = row; 3435 for (i = 0; i < row_width; i++, sp += 2) 3436 { 3437 png_uint_16 v; 3438 3439 v = (png_uint_16)(((*sp) << 8) + *(sp + 1)); 3440 3441 if (v == png_ptr->trans_color.gray) 3442 { 3443 *sp = (png_byte)((png_ptr->background.gray >> 8) 3444 & 0xff); 3445 *(sp + 1) = (png_byte)(png_ptr->background.gray 3446 & 0xff); 3447 } 3448 } 3449 } 3450 break; 3451 } 3452 3453 default: 3454 break; 3455 } 3456 break; 3457 } 3458 3459 case PNG_COLOR_TYPE_RGB: 3460 { 3461 if (row_info->bit_depth == 8) 3462 { 3463#ifdef PNG_READ_GAMMA_SUPPORTED 3464 if (gamma_table != NULL) 3465 { 3466 sp = row; 3467 for (i = 0; i < row_width; i++, sp += 3) 3468 { 3469 if (*sp == png_ptr->trans_color.red && 3470 *(sp + 1) == png_ptr->trans_color.green && 3471 *(sp + 2) == png_ptr->trans_color.blue) 3472 { 3473 *sp = (png_byte)png_ptr->background.red; 3474 *(sp + 1) = (png_byte)png_ptr->background.green; 3475 *(sp + 2) = (png_byte)png_ptr->background.blue; 3476 } 3477 3478 else 3479 { 3480 *sp = gamma_table[*sp]; 3481 *(sp + 1) = gamma_table[*(sp + 1)]; 3482 *(sp + 2) = gamma_table[*(sp + 2)]; 3483 } 3484 } 3485 } 3486 else 3487#endif 3488 { 3489 sp = row; 3490 for (i = 0; i < row_width; i++, sp += 3) 3491 { 3492 if (*sp == png_ptr->trans_color.red && 3493 *(sp + 1) == png_ptr->trans_color.green && 3494 *(sp + 2) == png_ptr->trans_color.blue) 3495 { 3496 *sp = (png_byte)png_ptr->background.red; 3497 *(sp + 1) = (png_byte)png_ptr->background.green; 3498 *(sp + 2) = (png_byte)png_ptr->background.blue; 3499 } 3500 } 3501 } 3502 } 3503 else /* if (row_info->bit_depth == 16) */ 3504 { 3505#ifdef PNG_READ_GAMMA_SUPPORTED 3506 if (gamma_16 != NULL) 3507 { 3508 sp = row; 3509 for (i = 0; i < row_width; i++, sp += 6) 3510 { 3511 png_uint_16 r = (png_uint_16)(((*sp) << 8) + *(sp + 1)); 3512 3513 png_uint_16 g = (png_uint_16)(((*(sp + 2)) << 8) 3514 + *(sp + 3)); 3515 3516 png_uint_16 b = (png_uint_16)(((*(sp + 4)) << 8) 3517 + *(sp + 5)); 3518 3519 if (r == png_ptr->trans_color.red && 3520 g == png_ptr->trans_color.green && 3521 b == png_ptr->trans_color.blue) 3522 { 3523 /* Background is already in screen gamma */ 3524 *sp = (png_byte)((png_ptr->background.red >> 8) & 0xff); 3525 *(sp + 1) = (png_byte)(png_ptr->background.red & 0xff); 3526 *(sp + 2) = (png_byte)((png_ptr->background.green >> 8) 3527 & 0xff); 3528 *(sp + 3) = (png_byte)(png_ptr->background.green 3529 & 0xff); 3530 *(sp + 4) = (png_byte)((png_ptr->background.blue >> 8) 3531 & 0xff); 3532 *(sp + 5) = (png_byte)(png_ptr->background.blue & 0xff); 3533 } 3534 3535 else 3536 { 3537 png_uint_16 v = gamma_16[*(sp + 1) >> gamma_shift][*sp]; 3538 *sp = (png_byte)((v >> 8) & 0xff); 3539 *(sp + 1) = (png_byte)(v & 0xff); 3540 3541 v = gamma_16[*(sp + 3) >> gamma_shift][*(sp + 2)]; 3542 *(sp + 2) = (png_byte)((v >> 8) & 0xff); 3543 *(sp + 3) = (png_byte)(v & 0xff); 3544 3545 v = gamma_16[*(sp + 5) >> gamma_shift][*(sp + 4)]; 3546 *(sp + 4) = (png_byte)((v >> 8) & 0xff); 3547 *(sp + 5) = (png_byte)(v & 0xff); 3548 } 3549 } 3550 } 3551 3552 else 3553#endif 3554 { 3555 sp = row; 3556 for (i = 0; i < row_width; i++, sp += 6) 3557 { 3558 png_uint_16 r = (png_uint_16)(((*sp) << 8) + *(sp + 1)); 3559 3560 png_uint_16 g = (png_uint_16)(((*(sp + 2)) << 8) 3561 + *(sp + 3)); 3562 3563 png_uint_16 b = (png_uint_16)(((*(sp + 4)) << 8) 3564 + *(sp + 5)); 3565 3566 if (r == png_ptr->trans_color.red && 3567 g == png_ptr->trans_color.green && 3568 b == png_ptr->trans_color.blue) 3569 { 3570 *sp = (png_byte)((png_ptr->background.red >> 8) & 0xff); 3571 *(sp + 1) = (png_byte)(png_ptr->background.red & 0xff); 3572 *(sp + 2) = (png_byte)((png_ptr->background.green >> 8) 3573 & 0xff); 3574 *(sp + 3) = (png_byte)(png_ptr->background.green 3575 & 0xff); 3576 *(sp + 4) = (png_byte)((png_ptr->background.blue >> 8) 3577 & 0xff); 3578 *(sp + 5) = (png_byte)(png_ptr->background.blue & 0xff); 3579 } 3580 } 3581 } 3582 } 3583 break; 3584 } 3585 3586 case PNG_COLOR_TYPE_GRAY_ALPHA: 3587 { 3588 if (row_info->bit_depth == 8) 3589 { 3590#ifdef PNG_READ_GAMMA_SUPPORTED 3591 if (gamma_to_1 != NULL && gamma_from_1 != NULL && 3592 gamma_table != NULL) 3593 { 3594 sp = row; 3595 for (i = 0; i < row_width; i++, sp += 2) 3596 { 3597 png_uint_16 a = *(sp + 1); 3598 3599 if (a == 0xff) 3600 *sp = gamma_table[*sp]; 3601 3602 else if (a == 0) 3603 { 3604 /* Background is already in screen gamma */ 3605 *sp = (png_byte)png_ptr->background.gray; 3606 } 3607 3608 else 3609 { 3610 png_byte v, w; 3611 3612 v = gamma_to_1[*sp]; 3613 png_composite(w, v, a, png_ptr->background_1.gray); 3614 if (optimize == 0) 3615 w = gamma_from_1[w]; 3616 *sp = w; 3617 } 3618 } 3619 } 3620 else 3621#endif 3622 { 3623 sp = row; 3624 for (i = 0; i < row_width; i++, sp += 2) 3625 { 3626 png_byte a = *(sp + 1); 3627 3628 if (a == 0) 3629 *sp = (png_byte)png_ptr->background.gray; 3630 3631 else if (a < 0xff) 3632 png_composite(*sp, *sp, a, png_ptr->background.gray); 3633 } 3634 } 3635 } 3636 else /* if (png_ptr->bit_depth == 16) */ 3637 { 3638#ifdef PNG_READ_GAMMA_SUPPORTED 3639 if (gamma_16 != NULL && gamma_16_from_1 != NULL && 3640 gamma_16_to_1 != NULL) 3641 { 3642 sp = row; 3643 for (i = 0; i < row_width; i++, sp += 4) 3644 { 3645 png_uint_16 a = (png_uint_16)(((*(sp + 2)) << 8) 3646 + *(sp + 3)); 3647 3648 if (a == (png_uint_16)0xffff) 3649 { 3650 png_uint_16 v; 3651 3652 v = gamma_16[*(sp + 1) >> gamma_shift][*sp]; 3653 *sp = (png_byte)((v >> 8) & 0xff); 3654 *(sp + 1) = (png_byte)(v & 0xff); 3655 } 3656 3657 else if (a == 0) 3658 { 3659 /* Background is already in screen gamma */ 3660 *sp = (png_byte)((png_ptr->background.gray >> 8) 3661 & 0xff); 3662 *(sp + 1) = (png_byte)(png_ptr->background.gray & 0xff); 3663 } 3664 3665 else 3666 { 3667 png_uint_16 g, v, w; 3668 3669 g = gamma_16_to_1[*(sp + 1) >> gamma_shift][*sp]; 3670 png_composite_16(v, g, a, png_ptr->background_1.gray); 3671 if (optimize != 0) 3672 w = v; 3673 else 3674 w = gamma_16_from_1[(v & 0xff) >> 3675 gamma_shift][v >> 8]; 3676 *sp = (png_byte)((w >> 8) & 0xff); 3677 *(sp + 1) = (png_byte)(w & 0xff); 3678 } 3679 } 3680 } 3681 else 3682#endif 3683 { 3684 sp = row; 3685 for (i = 0; i < row_width; i++, sp += 4) 3686 { 3687 png_uint_16 a = (png_uint_16)(((*(sp + 2)) << 8) 3688 + *(sp + 3)); 3689 3690 if (a == 0) 3691 { 3692 *sp = (png_byte)((png_ptr->background.gray >> 8) 3693 & 0xff); 3694 *(sp + 1) = (png_byte)(png_ptr->background.gray & 0xff); 3695 } 3696 3697 else if (a < 0xffff) 3698 { 3699 png_uint_16 g, v; 3700 3701 g = (png_uint_16)(((*sp) << 8) + *(sp + 1)); 3702 png_composite_16(v, g, a, png_ptr->background.gray); 3703 *sp = (png_byte)((v >> 8) & 0xff); 3704 *(sp + 1) = (png_byte)(v & 0xff); 3705 } 3706 } 3707 } 3708 } 3709 break; 3710 } 3711 3712 case PNG_COLOR_TYPE_RGB_ALPHA: 3713 { 3714 if (row_info->bit_depth == 8) 3715 { 3716#ifdef PNG_READ_GAMMA_SUPPORTED 3717 if (gamma_to_1 != NULL && gamma_from_1 != NULL && 3718 gamma_table != NULL) 3719 { 3720 sp = row; 3721 for (i = 0; i < row_width; i++, sp += 4) 3722 { 3723 png_byte a = *(sp + 3); 3724 3725 if (a == 0xff) 3726 { 3727 *sp = gamma_table[*sp]; 3728 *(sp + 1) = gamma_table[*(sp + 1)]; 3729 *(sp + 2) = gamma_table[*(sp + 2)]; 3730 } 3731 3732 else if (a == 0) 3733 { 3734 /* Background is already in screen gamma */ 3735 *sp = (png_byte)png_ptr->background.red; 3736 *(sp + 1) = (png_byte)png_ptr->background.green; 3737 *(sp + 2) = (png_byte)png_ptr->background.blue; 3738 } 3739 3740 else 3741 { 3742 png_byte v, w; 3743 3744 v = gamma_to_1[*sp]; 3745 png_composite(w, v, a, png_ptr->background_1.red); 3746 if (optimize == 0) w = gamma_from_1[w]; 3747 *sp = w; 3748 3749 v = gamma_to_1[*(sp + 1)]; 3750 png_composite(w, v, a, png_ptr->background_1.green); 3751 if (optimize == 0) w = gamma_from_1[w]; 3752 *(sp + 1) = w; 3753 3754 v = gamma_to_1[*(sp + 2)]; 3755 png_composite(w, v, a, png_ptr->background_1.blue); 3756 if (optimize == 0) w = gamma_from_1[w]; 3757 *(sp + 2) = w; 3758 } 3759 } 3760 } 3761 else 3762#endif 3763 { 3764 sp = row; 3765 for (i = 0; i < row_width; i++, sp += 4) 3766 { 3767 png_byte a = *(sp + 3); 3768 3769 if (a == 0) 3770 { 3771 *sp = (png_byte)png_ptr->background.red; 3772 *(sp + 1) = (png_byte)png_ptr->background.green; 3773 *(sp + 2) = (png_byte)png_ptr->background.blue; 3774 } 3775 3776 else if (a < 0xff) 3777 { 3778 png_composite(*sp, *sp, a, png_ptr->background.red); 3779 3780 png_composite(*(sp + 1), *(sp + 1), a, 3781 png_ptr->background.green); 3782 3783 png_composite(*(sp + 2), *(sp + 2), a, 3784 png_ptr->background.blue); 3785 } 3786 } 3787 } 3788 } 3789 else /* if (row_info->bit_depth == 16) */ 3790 { 3791#ifdef PNG_READ_GAMMA_SUPPORTED 3792 if (gamma_16 != NULL && gamma_16_from_1 != NULL && 3793 gamma_16_to_1 != NULL) 3794 { 3795 sp = row; 3796 for (i = 0; i < row_width; i++, sp += 8) 3797 { 3798 png_uint_16 a = (png_uint_16)(((png_uint_16)(*(sp + 6)) 3799 << 8) + (png_uint_16)(*(sp + 7))); 3800 3801 if (a == (png_uint_16)0xffff) 3802 { 3803 png_uint_16 v; 3804 3805 v = gamma_16[*(sp + 1) >> gamma_shift][*sp]; 3806 *sp = (png_byte)((v >> 8) & 0xff); 3807 *(sp + 1) = (png_byte)(v & 0xff); 3808 3809 v = gamma_16[*(sp + 3) >> gamma_shift][*(sp + 2)]; 3810 *(sp + 2) = (png_byte)((v >> 8) & 0xff); 3811 *(sp + 3) = (png_byte)(v & 0xff); 3812 3813 v = gamma_16[*(sp + 5) >> gamma_shift][*(sp + 4)]; 3814 *(sp + 4) = (png_byte)((v >> 8) & 0xff); 3815 *(sp + 5) = (png_byte)(v & 0xff); 3816 } 3817 3818 else if (a == 0) 3819 { 3820 /* Background is already in screen gamma */ 3821 *sp = (png_byte)((png_ptr->background.red >> 8) & 0xff); 3822 *(sp + 1) = (png_byte)(png_ptr->background.red & 0xff); 3823 *(sp + 2) = (png_byte)((png_ptr->background.green >> 8) 3824 & 0xff); 3825 *(sp + 3) = (png_byte)(png_ptr->background.green 3826 & 0xff); 3827 *(sp + 4) = (png_byte)((png_ptr->background.blue >> 8) 3828 & 0xff); 3829 *(sp + 5) = (png_byte)(png_ptr->background.blue & 0xff); 3830 } 3831 3832 else 3833 { 3834 png_uint_16 v, w; 3835 3836 v = gamma_16_to_1[*(sp + 1) >> gamma_shift][*sp]; 3837 png_composite_16(w, v, a, png_ptr->background_1.red); 3838 if (optimize == 0) 3839 w = gamma_16_from_1[((w & 0xff) >> gamma_shift)][w >> 3840 8]; 3841 *sp = (png_byte)((w >> 8) & 0xff); 3842 *(sp + 1) = (png_byte)(w & 0xff); 3843 3844 v = gamma_16_to_1[*(sp + 3) >> gamma_shift][*(sp + 2)]; 3845 png_composite_16(w, v, a, png_ptr->background_1.green); 3846 if (optimize == 0) 3847 w = gamma_16_from_1[((w & 0xff) >> gamma_shift)][w >> 3848 8]; 3849 3850 *(sp + 2) = (png_byte)((w >> 8) & 0xff); 3851 *(sp + 3) = (png_byte)(w & 0xff); 3852 3853 v = gamma_16_to_1[*(sp + 5) >> gamma_shift][*(sp + 4)]; 3854 png_composite_16(w, v, a, png_ptr->background_1.blue); 3855 if (optimize == 0) 3856 w = gamma_16_from_1[((w & 0xff) >> gamma_shift)][w >> 3857 8]; 3858 3859 *(sp + 4) = (png_byte)((w >> 8) & 0xff); 3860 *(sp + 5) = (png_byte)(w & 0xff); 3861 } 3862 } 3863 } 3864 3865 else 3866#endif 3867 { 3868 sp = row; 3869 for (i = 0; i < row_width; i++, sp += 8) 3870 { 3871 png_uint_16 a = (png_uint_16)(((png_uint_16)(*(sp + 6)) 3872 << 8) + (png_uint_16)(*(sp + 7))); 3873 3874 if (a == 0) 3875 { 3876 *sp = (png_byte)((png_ptr->background.red >> 8) & 0xff); 3877 *(sp + 1) = (png_byte)(png_ptr->background.red & 0xff); 3878 *(sp + 2) = (png_byte)((png_ptr->background.green >> 8) 3879 & 0xff); 3880 *(sp + 3) = (png_byte)(png_ptr->background.green 3881 & 0xff); 3882 *(sp + 4) = (png_byte)((png_ptr->background.blue >> 8) 3883 & 0xff); 3884 *(sp + 5) = (png_byte)(png_ptr->background.blue & 0xff); 3885 } 3886 3887 else if (a < 0xffff) 3888 { 3889 png_uint_16 v; 3890 3891 png_uint_16 r = (png_uint_16)(((*sp) << 8) + *(sp + 1)); 3892 png_uint_16 g = (png_uint_16)(((*(sp + 2)) << 8) 3893 + *(sp + 3)); 3894 png_uint_16 b = (png_uint_16)(((*(sp + 4)) << 8) 3895 + *(sp + 5)); 3896 3897 png_composite_16(v, r, a, png_ptr->background.red); 3898 *sp = (png_byte)((v >> 8) & 0xff); 3899 *(sp + 1) = (png_byte)(v & 0xff); 3900 3901 png_composite_16(v, g, a, png_ptr->background.green); 3902 *(sp + 2) = (png_byte)((v >> 8) & 0xff); 3903 *(sp + 3) = (png_byte)(v & 0xff); 3904 3905 png_composite_16(v, b, a, png_ptr->background.blue); 3906 *(sp + 4) = (png_byte)((v >> 8) & 0xff); 3907 *(sp + 5) = (png_byte)(v & 0xff); 3908 } 3909 } 3910 } 3911 } 3912 break; 3913 } 3914 3915 default: 3916 break; 3917 } 3918 } 3919} 3920#endif /* READ_BACKGROUND || READ_ALPHA_MODE */ 3921 3922#ifdef PNG_READ_GAMMA_SUPPORTED 3923/* Gamma correct the image, avoiding the alpha channel. Make sure 3924 * you do this after you deal with the transparency issue on grayscale 3925 * or RGB images. If your bit depth is 8, use gamma_table, if it 3926 * is 16, use gamma_16_table and gamma_shift. Build these with 3927 * build_gamma_table(). 3928 */ 3929static void 3930png_do_gamma(png_row_infop row_info, png_bytep row, png_structrp png_ptr) 3931{ 3932 png_const_bytep gamma_table = png_ptr->gamma_table; 3933 png_const_uint_16pp gamma_16_table = png_ptr->gamma_16_table; 3934 int gamma_shift = png_ptr->gamma_shift; 3935 3936 png_bytep sp; 3937 png_uint_32 i; 3938 png_uint_32 row_width=row_info->width; 3939 3940 png_debug(1, "in png_do_gamma"); 3941 3942 if (((row_info->bit_depth <= 8 && gamma_table != NULL) || 3943 (row_info->bit_depth == 16 && gamma_16_table != NULL))) 3944 { 3945 switch (row_info->color_type) 3946 { 3947 case PNG_COLOR_TYPE_RGB: 3948 { 3949 if (row_info->bit_depth == 8) 3950 { 3951 sp = row; 3952 for (i = 0; i < row_width; i++) 3953 { 3954 *sp = gamma_table[*sp]; 3955 sp++; 3956 *sp = gamma_table[*sp]; 3957 sp++; 3958 *sp = gamma_table[*sp]; 3959 sp++; 3960 } 3961 } 3962 3963 else /* if (row_info->bit_depth == 16) */ 3964 { 3965 sp = row; 3966 for (i = 0; i < row_width; i++) 3967 { 3968 png_uint_16 v; 3969 3970 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp]; 3971 *sp = (png_byte)((v >> 8) & 0xff); 3972 *(sp + 1) = (png_byte)(v & 0xff); 3973 sp += 2; 3974 3975 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp]; 3976 *sp = (png_byte)((v >> 8) & 0xff); 3977 *(sp + 1) = (png_byte)(v & 0xff); 3978 sp += 2; 3979 3980 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp]; 3981 *sp = (png_byte)((v >> 8) & 0xff); 3982 *(sp + 1) = (png_byte)(v & 0xff); 3983 sp += 2; 3984 } 3985 } 3986 break; 3987 } 3988 3989 case PNG_COLOR_TYPE_RGB_ALPHA: 3990 { 3991 if (row_info->bit_depth == 8) 3992 { 3993 sp = row; 3994 for (i = 0; i < row_width; i++) 3995 { 3996 *sp = gamma_table[*sp]; 3997 sp++; 3998 3999 *sp = gamma_table[*sp]; 4000 sp++; 4001 4002 *sp = gamma_table[*sp]; 4003 sp++; 4004 4005 sp++; 4006 } 4007 } 4008 4009 else /* if (row_info->bit_depth == 16) */ 4010 { 4011 sp = row; 4012 for (i = 0; i < row_width; i++) 4013 { 4014 png_uint_16 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp]; 4015 *sp = (png_byte)((v >> 8) & 0xff); 4016 *(sp + 1) = (png_byte)(v & 0xff); 4017 sp += 2; 4018 4019 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp]; 4020 *sp = (png_byte)((v >> 8) & 0xff); 4021 *(sp + 1) = (png_byte)(v & 0xff); 4022 sp += 2; 4023 4024 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp]; 4025 *sp = (png_byte)((v >> 8) & 0xff); 4026 *(sp + 1) = (png_byte)(v & 0xff); 4027 sp += 4; 4028 } 4029 } 4030 break; 4031 } 4032 4033 case PNG_COLOR_TYPE_GRAY_ALPHA: 4034 { 4035 if (row_info->bit_depth == 8) 4036 { 4037 sp = row; 4038 for (i = 0; i < row_width; i++) 4039 { 4040 *sp = gamma_table[*sp]; 4041 sp += 2; 4042 } 4043 } 4044 4045 else /* if (row_info->bit_depth == 16) */ 4046 { 4047 sp = row; 4048 for (i = 0; i < row_width; i++) 4049 { 4050 png_uint_16 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp]; 4051 *sp = (png_byte)((v >> 8) & 0xff); 4052 *(sp + 1) = (png_byte)(v & 0xff); 4053 sp += 4; 4054 } 4055 } 4056 break; 4057 } 4058 4059 case PNG_COLOR_TYPE_GRAY: 4060 { 4061 if (row_info->bit_depth == 2) 4062 { 4063 sp = row; 4064 for (i = 0; i < row_width; i += 4) 4065 { 4066 int a = *sp & 0xc0; 4067 int b = *sp & 0x30; 4068 int c = *sp & 0x0c; 4069 int d = *sp & 0x03; 4070 4071 *sp = (png_byte)( 4072 ((((int)gamma_table[a|(a>>2)|(a>>4)|(a>>6)]) ) & 0xc0)| 4073 ((((int)gamma_table[(b<<2)|b|(b>>2)|(b>>4)])>>2) & 0x30)| 4074 ((((int)gamma_table[(c<<4)|(c<<2)|c|(c>>2)])>>4) & 0x0c)| 4075 ((((int)gamma_table[(d<<6)|(d<<4)|(d<<2)|d])>>6) )); 4076 sp++; 4077 } 4078 } 4079 4080 if (row_info->bit_depth == 4) 4081 { 4082 sp = row; 4083 for (i = 0; i < row_width; i += 2) 4084 { 4085 int msb = *sp & 0xf0; 4086 int lsb = *sp & 0x0f; 4087 4088 *sp = (png_byte)((((int)gamma_table[msb | (msb >> 4)]) & 0xf0) 4089 | (((int)gamma_table[(lsb << 4) | lsb]) >> 4)); 4090 sp++; 4091 } 4092 } 4093 4094 else if (row_info->bit_depth == 8) 4095 { 4096 sp = row; 4097 for (i = 0; i < row_width; i++) 4098 { 4099 *sp = gamma_table[*sp]; 4100 sp++; 4101 } 4102 } 4103 4104 else if (row_info->bit_depth == 16) 4105 { 4106 sp = row; 4107 for (i = 0; i < row_width; i++) 4108 { 4109 png_uint_16 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp]; 4110 *sp = (png_byte)((v >> 8) & 0xff); 4111 *(sp + 1) = (png_byte)(v & 0xff); 4112 sp += 2; 4113 } 4114 } 4115 break; 4116 } 4117 4118 default: 4119 break; 4120 } 4121 } 4122} 4123#endif 4124 4125#ifdef PNG_READ_ALPHA_MODE_SUPPORTED 4126/* Encode the alpha channel to the output gamma (the input channel is always 4127 * linear.) Called only with color types that have an alpha channel. Needs the 4128 * from_1 tables. 4129 */ 4130static void 4131png_do_encode_alpha(png_row_infop row_info, png_bytep row, png_structrp png_ptr) 4132{ 4133 png_uint_32 row_width = row_info->width; 4134 4135 png_debug(1, "in png_do_encode_alpha"); 4136 4137 if ((row_info->color_type & PNG_COLOR_MASK_ALPHA) != 0) 4138 { 4139 if (row_info->bit_depth == 8) 4140 { 4141 PNG_CONST png_bytep table = png_ptr->gamma_from_1; 4142 4143 if (table != NULL) 4144 { 4145 PNG_CONST int step = 4146 (row_info->color_type & PNG_COLOR_MASK_COLOR) ? 4 : 2; 4147 4148 /* The alpha channel is the last component: */ 4149 row += step - 1; 4150 4151 for (; row_width > 0; --row_width, row += step) 4152 *row = table[*row]; 4153 4154 return; 4155 } 4156 } 4157 4158 else if (row_info->bit_depth == 16) 4159 { 4160 PNG_CONST png_uint_16pp table = png_ptr->gamma_16_from_1; 4161 PNG_CONST int gamma_shift = png_ptr->gamma_shift; 4162 4163 if (table != NULL) 4164 { 4165 PNG_CONST int step = 4166 (row_info->color_type & PNG_COLOR_MASK_COLOR) ? 8 : 4; 4167 4168 /* The alpha channel is the last component: */ 4169 row += step - 2; 4170 4171 for (; row_width > 0; --row_width, row += step) 4172 { 4173 png_uint_16 v; 4174 4175 v = table[*(row + 1) >> gamma_shift][*row]; 4176 *row = (png_byte)((v >> 8) & 0xff); 4177 *(row + 1) = (png_byte)(v & 0xff); 4178 } 4179 4180 return; 4181 } 4182 } 4183 } 4184 4185 /* Only get to here if called with a weird row_info; no harm has been done, 4186 * so just issue a warning. 4187 */ 4188 png_warning(png_ptr, "png_do_encode_alpha: unexpected call"); 4189} 4190#endif 4191 4192#ifdef PNG_READ_EXPAND_SUPPORTED 4193/* Expands a palette row to an RGB or RGBA row depending 4194 * upon whether you supply trans and num_trans. 4195 */ 4196static void 4197png_do_expand_palette(png_row_infop row_info, png_bytep row, 4198 png_const_colorp palette, png_const_bytep trans_alpha, int num_trans) 4199{ 4200 int shift, value; 4201 png_bytep sp, dp; 4202 png_uint_32 i; 4203 png_uint_32 row_width=row_info->width; 4204 4205 png_debug(1, "in png_do_expand_palette"); 4206 4207 if (row_info->color_type == PNG_COLOR_TYPE_PALETTE) 4208 { 4209 if (row_info->bit_depth < 8) 4210 { 4211 switch (row_info->bit_depth) 4212 { 4213 case 1: 4214 { 4215 sp = row + (png_size_t)((row_width - 1) >> 3); 4216 dp = row + (png_size_t)row_width - 1; 4217 shift = 7 - (int)((row_width + 7) & 0x07); 4218 for (i = 0; i < row_width; i++) 4219 { 4220 if ((*sp >> shift) & 0x01) 4221 *dp = 1; 4222 4223 else 4224 *dp = 0; 4225 4226 if (shift == 7) 4227 { 4228 shift = 0; 4229 sp--; 4230 } 4231 4232 else 4233 shift++; 4234 4235 dp--; 4236 } 4237 break; 4238 } 4239 4240 case 2: 4241 { 4242 sp = row + (png_size_t)((row_width - 1) >> 2); 4243 dp = row + (png_size_t)row_width - 1; 4244 shift = (int)((3 - ((row_width + 3) & 0x03)) << 1); 4245 for (i = 0; i < row_width; i++) 4246 { 4247 value = (*sp >> shift) & 0x03; 4248 *dp = (png_byte)value; 4249 if (shift == 6) 4250 { 4251 shift = 0; 4252 sp--; 4253 } 4254 4255 else 4256 shift += 2; 4257 4258 dp--; 4259 } 4260 break; 4261 } 4262 4263 case 4: 4264 { 4265 sp = row + (png_size_t)((row_width - 1) >> 1); 4266 dp = row + (png_size_t)row_width - 1; 4267 shift = (int)((row_width & 0x01) << 2); 4268 for (i = 0; i < row_width; i++) 4269 { 4270 value = (*sp >> shift) & 0x0f; 4271 *dp = (png_byte)value; 4272 if (shift == 4) 4273 { 4274 shift = 0; 4275 sp--; 4276 } 4277 4278 else 4279 shift += 4; 4280 4281 dp--; 4282 } 4283 break; 4284 } 4285 4286 default: 4287 break; 4288 } 4289 row_info->bit_depth = 8; 4290 row_info->pixel_depth = 8; 4291 row_info->rowbytes = row_width; 4292 } 4293 4294 if (row_info->bit_depth == 8) 4295 { 4296 { 4297 if (num_trans > 0) 4298 { 4299 sp = row + (png_size_t)row_width - 1; 4300 dp = row + (png_size_t)(row_width << 2) - 1; 4301 4302 for (i = 0; i < row_width; i++) 4303 { 4304 if ((int)(*sp) >= num_trans) 4305 *dp-- = 0xff; 4306 4307 else 4308 *dp-- = trans_alpha[*sp]; 4309 4310 *dp-- = palette[*sp].blue; 4311 *dp-- = palette[*sp].green; 4312 *dp-- = palette[*sp].red; 4313 sp--; 4314 } 4315 row_info->bit_depth = 8; 4316 row_info->pixel_depth = 32; 4317 row_info->rowbytes = row_width * 4; 4318 row_info->color_type = 6; 4319 row_info->channels = 4; 4320 } 4321 4322 else 4323 { 4324 sp = row + (png_size_t)row_width - 1; 4325 dp = row + (png_size_t)(row_width * 3) - 1; 4326 4327 for (i = 0; i < row_width; i++) 4328 { 4329 *dp-- = palette[*sp].blue; 4330 *dp-- = palette[*sp].green; 4331 *dp-- = palette[*sp].red; 4332 sp--; 4333 } 4334 4335 row_info->bit_depth = 8; 4336 row_info->pixel_depth = 24; 4337 row_info->rowbytes = row_width * 3; 4338 row_info->color_type = 2; 4339 row_info->channels = 3; 4340 } 4341 } 4342 } 4343 } 4344} 4345 4346/* If the bit depth < 8, it is expanded to 8. Also, if the already 4347 * expanded transparency value is supplied, an alpha channel is built. 4348 */ 4349static void 4350png_do_expand(png_row_infop row_info, png_bytep row, 4351 png_const_color_16p trans_color) 4352{ 4353 int shift, value; 4354 png_bytep sp, dp; 4355 png_uint_32 i; 4356 png_uint_32 row_width=row_info->width; 4357 4358 png_debug(1, "in png_do_expand"); 4359 4360 { 4361 if (row_info->color_type == PNG_COLOR_TYPE_GRAY) 4362 { 4363 unsigned int gray = trans_color != NULL ? trans_color->gray : 0; 4364 4365 if (row_info->bit_depth < 8) 4366 { 4367 switch (row_info->bit_depth) 4368 { 4369 case 1: 4370 { 4371 gray = (gray & 0x01) * 0xff; 4372 sp = row + (png_size_t)((row_width - 1) >> 3); 4373 dp = row + (png_size_t)row_width - 1; 4374 shift = 7 - (int)((row_width + 7) & 0x07); 4375 for (i = 0; i < row_width; i++) 4376 { 4377 if ((*sp >> shift) & 0x01) 4378 *dp = 0xff; 4379 4380 else 4381 *dp = 0; 4382 4383 if (shift == 7) 4384 { 4385 shift = 0; 4386 sp--; 4387 } 4388 4389 else 4390 shift++; 4391 4392 dp--; 4393 } 4394 break; 4395 } 4396 4397 case 2: 4398 { 4399 gray = (gray & 0x03) * 0x55; 4400 sp = row + (png_size_t)((row_width - 1) >> 2); 4401 dp = row + (png_size_t)row_width - 1; 4402 shift = (int)((3 - ((row_width + 3) & 0x03)) << 1); 4403 for (i = 0; i < row_width; i++) 4404 { 4405 value = (*sp >> shift) & 0x03; 4406 *dp = (png_byte)(value | (value << 2) | (value << 4) | 4407 (value << 6)); 4408 if (shift == 6) 4409 { 4410 shift = 0; 4411 sp--; 4412 } 4413 4414 else 4415 shift += 2; 4416 4417 dp--; 4418 } 4419 break; 4420 } 4421 4422 case 4: 4423 { 4424 gray = (gray & 0x0f) * 0x11; 4425 sp = row + (png_size_t)((row_width - 1) >> 1); 4426 dp = row + (png_size_t)row_width - 1; 4427 shift = (int)((1 - ((row_width + 1) & 0x01)) << 2); 4428 for (i = 0; i < row_width; i++) 4429 { 4430 value = (*sp >> shift) & 0x0f; 4431 *dp = (png_byte)(value | (value << 4)); 4432 if (shift == 4) 4433 { 4434 shift = 0; 4435 sp--; 4436 } 4437 4438 else 4439 shift = 4; 4440 4441 dp--; 4442 } 4443 break; 4444 } 4445 4446 default: 4447 break; 4448 } 4449 4450 row_info->bit_depth = 8; 4451 row_info->pixel_depth = 8; 4452 row_info->rowbytes = row_width; 4453 } 4454 4455 if (trans_color != NULL) 4456 { 4457 if (row_info->bit_depth == 8) 4458 { 4459 gray = gray & 0xff; 4460 sp = row + (png_size_t)row_width - 1; 4461 dp = row + (png_size_t)(row_width << 1) - 1; 4462 4463 for (i = 0; i < row_width; i++) 4464 { 4465 if ((*sp & 0xffU) == gray) 4466 *dp-- = 0; 4467 4468 else 4469 *dp-- = 0xff; 4470 4471 *dp-- = *sp--; 4472 } 4473 } 4474 4475 else if (row_info->bit_depth == 16) 4476 { 4477 unsigned int gray_high = (gray >> 8) & 0xff; 4478 unsigned int gray_low = gray & 0xff; 4479 sp = row + row_info->rowbytes - 1; 4480 dp = row + (row_info->rowbytes << 1) - 1; 4481 for (i = 0; i < row_width; i++) 4482 { 4483 if ((*(sp - 1) & 0xffU) == gray_high && 4484 (*(sp) & 0xffU) == gray_low) 4485 { 4486 *dp-- = 0; 4487 *dp-- = 0; 4488 } 4489 4490 else 4491 { 4492 *dp-- = 0xff; 4493 *dp-- = 0xff; 4494 } 4495 4496 *dp-- = *sp--; 4497 *dp-- = *sp--; 4498 } 4499 } 4500 4501 row_info->color_type = PNG_COLOR_TYPE_GRAY_ALPHA; 4502 row_info->channels = 2; 4503 row_info->pixel_depth = (png_byte)(row_info->bit_depth << 1); 4504 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, 4505 row_width); 4506 } 4507 } 4508 else if (row_info->color_type == PNG_COLOR_TYPE_RGB && 4509 trans_color != NULL) 4510 { 4511 if (row_info->bit_depth == 8) 4512 { 4513 png_byte red = (png_byte)(trans_color->red & 0xff); 4514 png_byte green = (png_byte)(trans_color->green & 0xff); 4515 png_byte blue = (png_byte)(trans_color->blue & 0xff); 4516 sp = row + (png_size_t)row_info->rowbytes - 1; 4517 dp = row + (png_size_t)(row_width << 2) - 1; 4518 for (i = 0; i < row_width; i++) 4519 { 4520 if (*(sp - 2) == red && *(sp - 1) == green && *(sp) == blue) 4521 *dp-- = 0; 4522 4523 else 4524 *dp-- = 0xff; 4525 4526 *dp-- = *sp--; 4527 *dp-- = *sp--; 4528 *dp-- = *sp--; 4529 } 4530 } 4531 else if (row_info->bit_depth == 16) 4532 { 4533 png_byte red_high = (png_byte)((trans_color->red >> 8) & 0xff); 4534 png_byte green_high = (png_byte)((trans_color->green >> 8) & 0xff); 4535 png_byte blue_high = (png_byte)((trans_color->blue >> 8) & 0xff); 4536 png_byte red_low = (png_byte)(trans_color->red & 0xff); 4537 png_byte green_low = (png_byte)(trans_color->green & 0xff); 4538 png_byte blue_low = (png_byte)(trans_color->blue & 0xff); 4539 sp = row + row_info->rowbytes - 1; 4540 dp = row + (png_size_t)(row_width << 3) - 1; 4541 for (i = 0; i < row_width; i++) 4542 { 4543 if (*(sp - 5) == red_high && 4544 *(sp - 4) == red_low && 4545 *(sp - 3) == green_high && 4546 *(sp - 2) == green_low && 4547 *(sp - 1) == blue_high && 4548 *(sp ) == blue_low) 4549 { 4550 *dp-- = 0; 4551 *dp-- = 0; 4552 } 4553 4554 else 4555 { 4556 *dp-- = 0xff; 4557 *dp-- = 0xff; 4558 } 4559 4560 *dp-- = *sp--; 4561 *dp-- = *sp--; 4562 *dp-- = *sp--; 4563 *dp-- = *sp--; 4564 *dp-- = *sp--; 4565 *dp-- = *sp--; 4566 } 4567 } 4568 row_info->color_type = PNG_COLOR_TYPE_RGB_ALPHA; 4569 row_info->channels = 4; 4570 row_info->pixel_depth = (png_byte)(row_info->bit_depth << 2); 4571 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width); 4572 } 4573 } 4574} 4575#endif 4576 4577#ifdef PNG_READ_EXPAND_16_SUPPORTED 4578/* If the bit depth is 8 and the color type is not a palette type expand the 4579 * whole row to 16 bits. Has no effect otherwise. 4580 */ 4581static void 4582png_do_expand_16(png_row_infop row_info, png_bytep row) 4583{ 4584 if (row_info->bit_depth == 8 && 4585 row_info->color_type != PNG_COLOR_TYPE_PALETTE) 4586 { 4587 /* The row have a sequence of bytes containing [0..255] and we need 4588 * to turn it into another row containing [0..65535], to do this we 4589 * calculate: 4590 * 4591 * (input / 255) * 65535 4592 * 4593 * Which happens to be exactly input * 257 and this can be achieved 4594 * simply by byte replication in place (copying backwards). 4595 */ 4596 png_byte *sp = row + row_info->rowbytes; /* source, last byte + 1 */ 4597 png_byte *dp = sp + row_info->rowbytes; /* destination, end + 1 */ 4598 while (dp > sp) 4599 dp[-2] = dp[-1] = *--sp, dp -= 2; 4600 4601 row_info->rowbytes *= 2; 4602 row_info->bit_depth = 16; 4603 row_info->pixel_depth = (png_byte)(row_info->channels * 16); 4604 } 4605} 4606#endif 4607 4608#ifdef PNG_READ_QUANTIZE_SUPPORTED 4609static void 4610png_do_quantize(png_row_infop row_info, png_bytep row, 4611 png_const_bytep palette_lookup, png_const_bytep quantize_lookup) 4612{ 4613 png_bytep sp, dp; 4614 png_uint_32 i; 4615 png_uint_32 row_width=row_info->width; 4616 4617 png_debug(1, "in png_do_quantize"); 4618 4619 if (row_info->bit_depth == 8) 4620 { 4621 if (row_info->color_type == PNG_COLOR_TYPE_RGB && palette_lookup) 4622 { 4623 int r, g, b, p; 4624 sp = row; 4625 dp = row; 4626 for (i = 0; i < row_width; i++) 4627 { 4628 r = *sp++; 4629 g = *sp++; 4630 b = *sp++; 4631 4632 /* This looks real messy, but the compiler will reduce 4633 * it down to a reasonable formula. For example, with 4634 * 5 bits per color, we get: 4635 * p = (((r >> 3) & 0x1f) << 10) | 4636 * (((g >> 3) & 0x1f) << 5) | 4637 * ((b >> 3) & 0x1f); 4638 */ 4639 p = (((r >> (8 - PNG_QUANTIZE_RED_BITS)) & 4640 ((1 << PNG_QUANTIZE_RED_BITS) - 1)) << 4641 (PNG_QUANTIZE_GREEN_BITS + PNG_QUANTIZE_BLUE_BITS)) | 4642 (((g >> (8 - PNG_QUANTIZE_GREEN_BITS)) & 4643 ((1 << PNG_QUANTIZE_GREEN_BITS) - 1)) << 4644 (PNG_QUANTIZE_BLUE_BITS)) | 4645 ((b >> (8 - PNG_QUANTIZE_BLUE_BITS)) & 4646 ((1 << PNG_QUANTIZE_BLUE_BITS) - 1)); 4647 4648 *dp++ = palette_lookup[p]; 4649 } 4650 4651 row_info->color_type = PNG_COLOR_TYPE_PALETTE; 4652 row_info->channels = 1; 4653 row_info->pixel_depth = row_info->bit_depth; 4654 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width); 4655 } 4656 4657 else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA && 4658 palette_lookup != NULL) 4659 { 4660 int r, g, b, p; 4661 sp = row; 4662 dp = row; 4663 for (i = 0; i < row_width; i++) 4664 { 4665 r = *sp++; 4666 g = *sp++; 4667 b = *sp++; 4668 sp++; 4669 4670 p = (((r >> (8 - PNG_QUANTIZE_RED_BITS)) & 4671 ((1 << PNG_QUANTIZE_RED_BITS) - 1)) << 4672 (PNG_QUANTIZE_GREEN_BITS + PNG_QUANTIZE_BLUE_BITS)) | 4673 (((g >> (8 - PNG_QUANTIZE_GREEN_BITS)) & 4674 ((1 << PNG_QUANTIZE_GREEN_BITS) - 1)) << 4675 (PNG_QUANTIZE_BLUE_BITS)) | 4676 ((b >> (8 - PNG_QUANTIZE_BLUE_BITS)) & 4677 ((1 << PNG_QUANTIZE_BLUE_BITS) - 1)); 4678 4679 *dp++ = palette_lookup[p]; 4680 } 4681 4682 row_info->color_type = PNG_COLOR_TYPE_PALETTE; 4683 row_info->channels = 1; 4684 row_info->pixel_depth = row_info->bit_depth; 4685 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width); 4686 } 4687 4688 else if (row_info->color_type == PNG_COLOR_TYPE_PALETTE && 4689 quantize_lookup) 4690 { 4691 sp = row; 4692 4693 for (i = 0; i < row_width; i++, sp++) 4694 { 4695 *sp = quantize_lookup[*sp]; 4696 } 4697 } 4698 } 4699} 4700#endif /* READ_QUANTIZE */ 4701 4702/* Transform the row. The order of transformations is significant, 4703 * and is very touchy. If you add a transformation, take care to 4704 * decide how it fits in with the other transformations here. 4705 */ 4706void /* PRIVATE */ 4707png_do_read_transformations(png_structrp png_ptr, png_row_infop row_info) 4708{ 4709 png_debug(1, "in png_do_read_transformations"); 4710 4711 if (png_ptr->row_buf == NULL) 4712 { 4713 /* Prior to 1.5.4 this output row/pass where the NULL pointer is, but this 4714 * error is incredibly rare and incredibly easy to debug without this 4715 * information. 4716 */ 4717 png_error(png_ptr, "NULL row buffer"); 4718 } 4719 4720 /* The following is debugging; prior to 1.5.4 the code was never compiled in; 4721 * in 1.5.4 PNG_FLAG_DETECT_UNINITIALIZED was added and the macro 4722 * PNG_WARN_UNINITIALIZED_ROW removed. In 1.6 the new flag is set only for 4723 * all transformations, however in practice the ROW_INIT always gets done on 4724 * demand, if necessary. 4725 */ 4726 if ((png_ptr->flags & PNG_FLAG_DETECT_UNINITIALIZED) != 0 && 4727 (png_ptr->flags & PNG_FLAG_ROW_INIT) == 0) 4728 { 4729 /* Application has failed to call either png_read_start_image() or 4730 * png_read_update_info() after setting transforms that expand pixels. 4731 * This check added to libpng-1.2.19 (but not enabled until 1.5.4). 4732 */ 4733 png_error(png_ptr, "Uninitialized row"); 4734 } 4735 4736#ifdef PNG_READ_EXPAND_SUPPORTED 4737 if ((png_ptr->transformations & PNG_EXPAND) != 0) 4738 { 4739 if (row_info->color_type == PNG_COLOR_TYPE_PALETTE) 4740 { 4741 png_do_expand_palette(row_info, png_ptr->row_buf + 1, 4742 png_ptr->palette, png_ptr->trans_alpha, png_ptr->num_trans); 4743 } 4744 4745 else 4746 { 4747 if (png_ptr->num_trans != 0 && 4748 (png_ptr->transformations & PNG_EXPAND_tRNS) != 0) 4749 png_do_expand(row_info, png_ptr->row_buf + 1, 4750 &(png_ptr->trans_color)); 4751 4752 else 4753 png_do_expand(row_info, png_ptr->row_buf + 1, 4754 NULL); 4755 } 4756 } 4757#endif 4758 4759#ifdef PNG_READ_STRIP_ALPHA_SUPPORTED 4760 if ((png_ptr->transformations & PNG_STRIP_ALPHA) != 0 && 4761 (png_ptr->transformations & PNG_COMPOSE) == 0 && 4762 (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA || 4763 row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)) 4764 png_do_strip_channel(row_info, png_ptr->row_buf + 1, 4765 0 /* at_start == false, because SWAP_ALPHA happens later */); 4766#endif 4767 4768#ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED 4769 if ((png_ptr->transformations & PNG_RGB_TO_GRAY) != 0) 4770 { 4771 int rgb_error = 4772 png_do_rgb_to_gray(png_ptr, row_info, 4773 png_ptr->row_buf + 1); 4774 4775 if (rgb_error != 0) 4776 { 4777 png_ptr->rgb_to_gray_status=1; 4778 if ((png_ptr->transformations & PNG_RGB_TO_GRAY) == 4779 PNG_RGB_TO_GRAY_WARN) 4780 png_warning(png_ptr, "png_do_rgb_to_gray found nongray pixel"); 4781 4782 if ((png_ptr->transformations & PNG_RGB_TO_GRAY) == 4783 PNG_RGB_TO_GRAY_ERR) 4784 png_error(png_ptr, "png_do_rgb_to_gray found nongray pixel"); 4785 } 4786 } 4787#endif 4788 4789/* From Andreas Dilger e-mail to png-implement, 26 March 1998: 4790 * 4791 * In most cases, the "simple transparency" should be done prior to doing 4792 * gray-to-RGB, or you will have to test 3x as many bytes to check if a 4793 * pixel is transparent. You would also need to make sure that the 4794 * transparency information is upgraded to RGB. 4795 * 4796 * To summarize, the current flow is: 4797 * - Gray + simple transparency -> compare 1 or 2 gray bytes and composite 4798 * with background "in place" if transparent, 4799 * convert to RGB if necessary 4800 * - Gray + alpha -> composite with gray background and remove alpha bytes, 4801 * convert to RGB if necessary 4802 * 4803 * To support RGB backgrounds for gray images we need: 4804 * - Gray + simple transparency -> convert to RGB + simple transparency, 4805 * compare 3 or 6 bytes and composite with 4806 * background "in place" if transparent 4807 * (3x compare/pixel compared to doing 4808 * composite with gray bkgrnd) 4809 * - Gray + alpha -> convert to RGB + alpha, composite with background and 4810 * remove alpha bytes (3x float 4811 * operations/pixel compared with composite 4812 * on gray background) 4813 * 4814 * Greg's change will do this. The reason it wasn't done before is for 4815 * performance, as this increases the per-pixel operations. If we would check 4816 * in advance if the background was gray or RGB, and position the gray-to-RGB 4817 * transform appropriately, then it would save a lot of work/time. 4818 */ 4819 4820#ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED 4821 /* If gray -> RGB, do so now only if background is non-gray; else do later 4822 * for performance reasons 4823 */ 4824 if ((png_ptr->transformations & PNG_GRAY_TO_RGB) != 0 && 4825 (png_ptr->mode & PNG_BACKGROUND_IS_GRAY) == 0) 4826 png_do_gray_to_rgb(row_info, png_ptr->row_buf + 1); 4827#endif 4828 4829#if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\ 4830 defined(PNG_READ_ALPHA_MODE_SUPPORTED) 4831 if ((png_ptr->transformations & PNG_COMPOSE) != 0) 4832 png_do_compose(row_info, png_ptr->row_buf + 1, png_ptr); 4833#endif 4834 4835#ifdef PNG_READ_GAMMA_SUPPORTED 4836 if ((png_ptr->transformations & PNG_GAMMA) != 0 && 4837#ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED 4838 /* Because RGB_TO_GRAY does the gamma transform. */ 4839 (png_ptr->transformations & PNG_RGB_TO_GRAY) == 0 && 4840#endif 4841#if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\ 4842 defined(PNG_READ_ALPHA_MODE_SUPPORTED) 4843 /* Because PNG_COMPOSE does the gamma transform if there is something to 4844 * do (if there is an alpha channel or transparency.) 4845 */ 4846 !((png_ptr->transformations & PNG_COMPOSE) != 0 && 4847 ((png_ptr->num_trans != 0) || 4848 (png_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0)) && 4849#endif 4850 /* Because png_init_read_transformations transforms the palette, unless 4851 * RGB_TO_GRAY will do the transform. 4852 */ 4853 (png_ptr->color_type != PNG_COLOR_TYPE_PALETTE)) 4854 png_do_gamma(row_info, png_ptr->row_buf + 1, png_ptr); 4855#endif 4856 4857#ifdef PNG_READ_STRIP_ALPHA_SUPPORTED 4858 if ((png_ptr->transformations & PNG_STRIP_ALPHA) != 0 && 4859 (png_ptr->transformations & PNG_COMPOSE) != 0 && 4860 (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA || 4861 row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)) 4862 png_do_strip_channel(row_info, png_ptr->row_buf + 1, 4863 0 /* at_start == false, because SWAP_ALPHA happens later */); 4864#endif 4865 4866#ifdef PNG_READ_ALPHA_MODE_SUPPORTED 4867 if ((png_ptr->transformations & PNG_ENCODE_ALPHA) != 0 && 4868 (row_info->color_type & PNG_COLOR_MASK_ALPHA) != 0) 4869 png_do_encode_alpha(row_info, png_ptr->row_buf + 1, png_ptr); 4870#endif 4871 4872#ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED 4873 if ((png_ptr->transformations & PNG_SCALE_16_TO_8) != 0) 4874 png_do_scale_16_to_8(row_info, png_ptr->row_buf + 1); 4875#endif 4876 4877#ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED 4878 /* There is no harm in doing both of these because only one has any effect, 4879 * by putting the 'scale' option first if the app asks for scale (either by 4880 * calling the API or in a TRANSFORM flag) this is what happens. 4881 */ 4882 if ((png_ptr->transformations & PNG_16_TO_8) != 0) 4883 png_do_chop(row_info, png_ptr->row_buf + 1); 4884#endif 4885 4886#ifdef PNG_READ_QUANTIZE_SUPPORTED 4887 if ((png_ptr->transformations & PNG_QUANTIZE) != 0) 4888 { 4889 png_do_quantize(row_info, png_ptr->row_buf + 1, 4890 png_ptr->palette_lookup, png_ptr->quantize_index); 4891 4892 if (row_info->rowbytes == 0) 4893 png_error(png_ptr, "png_do_quantize returned rowbytes=0"); 4894 } 4895#endif /* READ_QUANTIZE */ 4896 4897#ifdef PNG_READ_EXPAND_16_SUPPORTED 4898 /* Do the expansion now, after all the arithmetic has been done. Notice 4899 * that previous transformations can handle the PNG_EXPAND_16 flag if this 4900 * is efficient (particularly true in the case of gamma correction, where 4901 * better accuracy results faster!) 4902 */ 4903 if ((png_ptr->transformations & PNG_EXPAND_16) != 0) 4904 png_do_expand_16(row_info, png_ptr->row_buf + 1); 4905#endif 4906 4907#ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED 4908 /* NOTE: moved here in 1.5.4 (from much later in this list.) */ 4909 if ((png_ptr->transformations & PNG_GRAY_TO_RGB) != 0 && 4910 (png_ptr->mode & PNG_BACKGROUND_IS_GRAY) != 0) 4911 png_do_gray_to_rgb(row_info, png_ptr->row_buf + 1); 4912#endif 4913 4914#ifdef PNG_READ_INVERT_SUPPORTED 4915 if ((png_ptr->transformations & PNG_INVERT_MONO) != 0) 4916 png_do_invert(row_info, png_ptr->row_buf + 1); 4917#endif 4918 4919#ifdef PNG_READ_INVERT_ALPHA_SUPPORTED 4920 if ((png_ptr->transformations & PNG_INVERT_ALPHA) != 0) 4921 png_do_read_invert_alpha(row_info, png_ptr->row_buf + 1); 4922#endif 4923 4924#ifdef PNG_READ_SHIFT_SUPPORTED 4925 if ((png_ptr->transformations & PNG_SHIFT) != 0) 4926 png_do_unshift(row_info, png_ptr->row_buf + 1, 4927 &(png_ptr->shift)); 4928#endif 4929 4930#ifdef PNG_READ_PACK_SUPPORTED 4931 if ((png_ptr->transformations & PNG_PACK) != 0) 4932 png_do_unpack(row_info, png_ptr->row_buf + 1); 4933#endif 4934 4935#ifdef PNG_READ_CHECK_FOR_INVALID_INDEX_SUPPORTED 4936 /* Added at libpng-1.5.10 */ 4937 if (row_info->color_type == PNG_COLOR_TYPE_PALETTE && 4938 png_ptr->num_palette_max >= 0) 4939 png_do_check_palette_indexes(png_ptr, row_info); 4940#endif 4941 4942#ifdef PNG_READ_BGR_SUPPORTED 4943 if ((png_ptr->transformations & PNG_BGR) != 0) 4944 png_do_bgr(row_info, png_ptr->row_buf + 1); 4945#endif 4946 4947#ifdef PNG_READ_PACKSWAP_SUPPORTED 4948 if ((png_ptr->transformations & PNG_PACKSWAP) != 0) 4949 png_do_packswap(row_info, png_ptr->row_buf + 1); 4950#endif 4951 4952#ifdef PNG_READ_FILLER_SUPPORTED 4953 if ((png_ptr->transformations & PNG_FILLER) != 0) 4954 png_do_read_filler(row_info, png_ptr->row_buf + 1, 4955 (png_uint_32)png_ptr->filler, png_ptr->flags); 4956#endif 4957 4958#ifdef PNG_READ_SWAP_ALPHA_SUPPORTED 4959 if ((png_ptr->transformations & PNG_SWAP_ALPHA) != 0) 4960 png_do_read_swap_alpha(row_info, png_ptr->row_buf + 1); 4961#endif 4962 4963#ifdef PNG_READ_16BIT_SUPPORTED 4964#ifdef PNG_READ_SWAP_SUPPORTED 4965 if ((png_ptr->transformations & PNG_SWAP_BYTES) != 0) 4966 png_do_swap(row_info, png_ptr->row_buf + 1); 4967#endif 4968#endif 4969 4970#ifdef PNG_READ_USER_TRANSFORM_SUPPORTED 4971 if ((png_ptr->transformations & PNG_USER_TRANSFORM) != 0) 4972 { 4973 if (png_ptr->read_user_transform_fn != NULL) 4974 (*(png_ptr->read_user_transform_fn)) /* User read transform function */ 4975 (png_ptr, /* png_ptr */ 4976 row_info, /* row_info: */ 4977 /* png_uint_32 width; width of row */ 4978 /* png_size_t rowbytes; number of bytes in row */ 4979 /* png_byte color_type; color type of pixels */ 4980 /* png_byte bit_depth; bit depth of samples */ 4981 /* png_byte channels; number of channels (1-4) */ 4982 /* png_byte pixel_depth; bits per pixel (depth*channels) */ 4983 png_ptr->row_buf + 1); /* start of pixel data for row */ 4984#ifdef PNG_USER_TRANSFORM_PTR_SUPPORTED 4985 if (png_ptr->user_transform_depth != 0) 4986 row_info->bit_depth = png_ptr->user_transform_depth; 4987 4988 if (png_ptr->user_transform_channels != 0) 4989 row_info->channels = png_ptr->user_transform_channels; 4990#endif 4991 row_info->pixel_depth = (png_byte)(row_info->bit_depth * 4992 row_info->channels); 4993 4994 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_info->width); 4995 } 4996#endif 4997} 4998 4999#endif /* READ_TRANSFORMS */ 5000#endif /* READ */ 5001