1 2 /* pngread.c - read a PNG file 3 * 4 * Last changed in libpng 1.6.17 [March 26, 2015] 5 * Copyright (c) 1998-2002,2004,2006-2015 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 routines that an application calls directly to 14 * read a PNG file or stream. 15 */ 16 17 #include "pngpriv.h" 18 #if defined(PNG_SIMPLIFIED_READ_SUPPORTED) && defined(PNG_STDIO_SUPPORTED) 19 # include <errno.h> 20 #endif 21 22 #ifdef PNG_READ_SUPPORTED 23 24 /* Create a PNG structure for reading, and allocate any memory needed. */ 25 PNG_FUNCTION(png_structp,PNGAPI 26 png_create_read_struct,(png_const_charp user_png_ver, png_voidp error_ptr, 27 png_error_ptr error_fn, png_error_ptr warn_fn),PNG_ALLOCATED) 28 { 29 #ifndef PNG_USER_MEM_SUPPORTED 30 png_structp png_ptr = png_create_png_struct(user_png_ver, error_ptr, 31 error_fn, warn_fn, NULL, NULL, NULL); 32 #else 33 return png_create_read_struct_2(user_png_ver, error_ptr, error_fn, 34 warn_fn, NULL, NULL, NULL); 35 } 36 37 /* Alternate create PNG structure for reading, and allocate any memory 38 * needed. 39 */ 40 PNG_FUNCTION(png_structp,PNGAPI 41 png_create_read_struct_2,(png_const_charp user_png_ver, png_voidp error_ptr, 42 png_error_ptr error_fn, png_error_ptr warn_fn, png_voidp mem_ptr, 43 png_malloc_ptr malloc_fn, png_free_ptr free_fn),PNG_ALLOCATED) 44 { 45 png_structp png_ptr = png_create_png_struct(user_png_ver, error_ptr, 46 error_fn, warn_fn, mem_ptr, malloc_fn, free_fn); 47 #endif /* USER_MEM */ 48 49 if (png_ptr != NULL) 50 { 51 png_ptr->mode = PNG_IS_READ_STRUCT; 52 53 /* Added in libpng-1.6.0; this can be used to detect a read structure if 54 * required (it will be zero in a write structure.) 55 */ 56 # ifdef PNG_SEQUENTIAL_READ_SUPPORTED 57 png_ptr->IDAT_read_size = PNG_IDAT_READ_SIZE; 58 # endif 59 60 # ifdef PNG_BENIGN_READ_ERRORS_SUPPORTED 61 png_ptr->flags |= PNG_FLAG_BENIGN_ERRORS_WARN; 62 63 /* In stable builds only warn if an application error can be completely 64 * handled. 65 */ 66 # if PNG_RELEASE_BUILD 67 png_ptr->flags |= PNG_FLAG_APP_WARNINGS_WARN; 68 # endif 69 # endif 70 71 /* TODO: delay this, it can be done in png_init_io (if the app doesn't 72 * do it itself) avoiding setting the default function if it is not 73 * required. 74 */ 75 png_set_read_fn(png_ptr, NULL, NULL); 76 } 77 78 return png_ptr; 79 } 80 81 82 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED 83 /* Read the information before the actual image data. This has been 84 * changed in v0.90 to allow reading a file that already has the magic 85 * bytes read from the stream. You can tell libpng how many bytes have 86 * been read from the beginning of the stream (up to the maximum of 8) 87 * via png_set_sig_bytes(), and we will only check the remaining bytes 88 * here. The application can then have access to the signature bytes we 89 * read if it is determined that this isn't a valid PNG file. 90 */ 91 void PNGAPI 92 png_read_info(png_structrp png_ptr, png_inforp info_ptr) 93 { 94 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED 95 int keep; 96 #endif 97 98 png_debug(1, "in png_read_info"); 99 100 if (png_ptr == NULL || info_ptr == NULL) 101 return; 102 103 /* Read and check the PNG file signature. */ 104 png_read_sig(png_ptr, info_ptr); 105 106 for (;;) 107 { 108 png_uint_32 length = png_read_chunk_header(png_ptr); 109 png_uint_32 chunk_name = png_ptr->chunk_name; 110 111 /* IDAT logic needs to happen here to simplify getting the two flags 112 * right. 113 */ 114 if (chunk_name == png_IDAT) 115 { 116 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0) 117 png_chunk_error(png_ptr, "Missing IHDR before IDAT"); 118 119 else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE && 120 (png_ptr->mode & PNG_HAVE_PLTE) == 0) 121 png_chunk_error(png_ptr, "Missing PLTE before IDAT"); 122 123 else if ((png_ptr->mode & PNG_AFTER_IDAT) != 0) 124 png_chunk_benign_error(png_ptr, "Too many IDATs found"); 125 126 png_ptr->mode |= PNG_HAVE_IDAT; 127 } 128 129 else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0) 130 png_ptr->mode |= PNG_AFTER_IDAT; 131 132 /* This should be a binary subdivision search or a hash for 133 * matching the chunk name rather than a linear search. 134 */ 135 if (chunk_name == png_IHDR) 136 png_handle_IHDR(png_ptr, info_ptr, length); 137 138 else if (chunk_name == png_IEND) 139 png_handle_IEND(png_ptr, info_ptr, length); 140 141 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED 142 else if ((keep = png_chunk_unknown_handling(png_ptr, chunk_name)) != 0) 143 { 144 png_handle_unknown(png_ptr, info_ptr, length, keep); 145 146 if (chunk_name == png_PLTE) 147 png_ptr->mode |= PNG_HAVE_PLTE; 148 149 else if (chunk_name == png_IDAT) 150 { 151 png_ptr->idat_size = 0; /* It has been consumed */ 152 break; 153 } 154 } 155 #endif 156 else if (chunk_name == png_PLTE) 157 png_handle_PLTE(png_ptr, info_ptr, length); 158 159 else if (chunk_name == png_IDAT) 160 { 161 png_ptr->idat_size = length; 162 break; 163 } 164 165 #ifdef PNG_READ_bKGD_SUPPORTED 166 else if (chunk_name == png_bKGD) 167 png_handle_bKGD(png_ptr, info_ptr, length); 168 #endif 169 170 #ifdef PNG_READ_cHRM_SUPPORTED 171 else if (chunk_name == png_cHRM) 172 png_handle_cHRM(png_ptr, info_ptr, length); 173 #endif 174 175 #ifdef PNG_READ_gAMA_SUPPORTED 176 else if (chunk_name == png_gAMA) 177 png_handle_gAMA(png_ptr, info_ptr, length); 178 #endif 179 180 #ifdef PNG_READ_hIST_SUPPORTED 181 else if (chunk_name == png_hIST) 182 png_handle_hIST(png_ptr, info_ptr, length); 183 #endif 184 185 #ifdef PNG_READ_oFFs_SUPPORTED 186 else if (chunk_name == png_oFFs) 187 png_handle_oFFs(png_ptr, info_ptr, length); 188 #endif 189 190 #ifdef PNG_READ_pCAL_SUPPORTED 191 else if (chunk_name == png_pCAL) 192 png_handle_pCAL(png_ptr, info_ptr, length); 193 #endif 194 195 #ifdef PNG_READ_sCAL_SUPPORTED 196 else if (chunk_name == png_sCAL) 197 png_handle_sCAL(png_ptr, info_ptr, length); 198 #endif 199 200 #ifdef PNG_READ_pHYs_SUPPORTED 201 else if (chunk_name == png_pHYs) 202 png_handle_pHYs(png_ptr, info_ptr, length); 203 #endif 204 205 #ifdef PNG_READ_sBIT_SUPPORTED 206 else if (chunk_name == png_sBIT) 207 png_handle_sBIT(png_ptr, info_ptr, length); 208 #endif 209 210 #ifdef PNG_READ_sRGB_SUPPORTED 211 else if (chunk_name == png_sRGB) 212 png_handle_sRGB(png_ptr, info_ptr, length); 213 #endif 214 215 #ifdef PNG_READ_iCCP_SUPPORTED 216 else if (chunk_name == png_iCCP) 217 png_handle_iCCP(png_ptr, info_ptr, length); 218 #endif 219 220 #ifdef PNG_READ_sPLT_SUPPORTED 221 else if (chunk_name == png_sPLT) 222 png_handle_sPLT(png_ptr, info_ptr, length); 223 #endif 224 225 #ifdef PNG_READ_tEXt_SUPPORTED 226 else if (chunk_name == png_tEXt) 227 png_handle_tEXt(png_ptr, info_ptr, length); 228 #endif 229 230 #ifdef PNG_READ_tIME_SUPPORTED 231 else if (chunk_name == png_tIME) 232 png_handle_tIME(png_ptr, info_ptr, length); 233 #endif 234 235 #ifdef PNG_READ_tRNS_SUPPORTED 236 else if (chunk_name == png_tRNS) 237 png_handle_tRNS(png_ptr, info_ptr, length); 238 #endif 239 240 #ifdef PNG_READ_zTXt_SUPPORTED 241 else if (chunk_name == png_zTXt) 242 png_handle_zTXt(png_ptr, info_ptr, length); 243 #endif 244 245 #ifdef PNG_READ_iTXt_SUPPORTED 246 else if (chunk_name == png_iTXt) 247 png_handle_iTXt(png_ptr, info_ptr, length); 248 #endif 249 250 else 251 png_handle_unknown(png_ptr, info_ptr, length, 252 PNG_HANDLE_CHUNK_AS_DEFAULT); 253 } 254 } 255 #endif /* SEQUENTIAL_READ */ 256 257 /* Optional call to update the users info_ptr structure */ 258 void PNGAPI 259 png_read_update_info(png_structrp png_ptr, png_inforp info_ptr) 260 { 261 png_debug(1, "in png_read_update_info"); 262 263 if (png_ptr != NULL) 264 { 265 if ((png_ptr->flags & PNG_FLAG_ROW_INIT) == 0) 266 { 267 png_read_start_row(png_ptr); 268 269 # ifdef PNG_READ_TRANSFORMS_SUPPORTED 270 png_read_transform_info(png_ptr, info_ptr); 271 # else 272 PNG_UNUSED(info_ptr) 273 # endif 274 } 275 276 /* New in 1.6.0 this avoids the bug of doing the initializations twice */ 277 else 278 png_app_error(png_ptr, 279 "png_read_update_info/png_start_read_image: duplicate call"); 280 } 281 } 282 283 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED 284 /* Initialize palette, background, etc, after transformations 285 * are set, but before any reading takes place. This allows 286 * the user to obtain a gamma-corrected palette, for example. 287 * If the user doesn't call this, we will do it ourselves. 288 */ 289 void PNGAPI 290 png_start_read_image(png_structrp png_ptr) 291 { 292 png_debug(1, "in png_start_read_image"); 293 294 if (png_ptr != NULL) 295 { 296 if ((png_ptr->flags & PNG_FLAG_ROW_INIT) == 0) 297 png_read_start_row(png_ptr); 298 299 /* New in 1.6.0 this avoids the bug of doing the initializations twice */ 300 else 301 png_app_error(png_ptr, 302 "png_start_read_image/png_read_update_info: duplicate call"); 303 } 304 } 305 #endif /* SEQUENTIAL_READ */ 306 307 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED 308 #ifdef PNG_MNG_FEATURES_SUPPORTED 309 /* Undoes intrapixel differencing, 310 * NOTE: this is apparently only supported in the 'sequential' reader. 311 */ 312 static void 313 png_do_read_intrapixel(png_row_infop row_info, png_bytep row) 314 { 315 png_debug(1, "in png_do_read_intrapixel"); 316 317 if ( 318 (row_info->color_type & PNG_COLOR_MASK_COLOR) != 0) 319 { 320 int bytes_per_pixel; 321 png_uint_32 row_width = row_info->width; 322 323 if (row_info->bit_depth == 8) 324 { 325 png_bytep rp; 326 png_uint_32 i; 327 328 if (row_info->color_type == PNG_COLOR_TYPE_RGB) 329 bytes_per_pixel = 3; 330 331 else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA) 332 bytes_per_pixel = 4; 333 334 else 335 return; 336 337 for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel) 338 { 339 *(rp) = (png_byte)((256 + *rp + *(rp + 1)) & 0xff); 340 *(rp+2) = (png_byte)((256 + *(rp + 2) + *(rp + 1)) & 0xff); 341 } 342 } 343 else if (row_info->bit_depth == 16) 344 { 345 png_bytep rp; 346 png_uint_32 i; 347 348 if (row_info->color_type == PNG_COLOR_TYPE_RGB) 349 bytes_per_pixel = 6; 350 351 else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA) 352 bytes_per_pixel = 8; 353 354 else 355 return; 356 357 for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel) 358 { 359 png_uint_32 s0 = (*(rp ) << 8) | *(rp + 1); 360 png_uint_32 s1 = (*(rp + 2) << 8) | *(rp + 3); 361 png_uint_32 s2 = (*(rp + 4) << 8) | *(rp + 5); 362 png_uint_32 red = (s0 + s1 + 65536) & 0xffff; 363 png_uint_32 blue = (s2 + s1 + 65536) & 0xffff; 364 *(rp ) = (png_byte)((red >> 8) & 0xff); 365 *(rp + 1) = (png_byte)(red & 0xff); 366 *(rp + 4) = (png_byte)((blue >> 8) & 0xff); 367 *(rp + 5) = (png_byte)(blue & 0xff); 368 } 369 } 370 } 371 } 372 #endif /* MNG_FEATURES */ 373 374 void PNGAPI 375 png_read_row(png_structrp png_ptr, png_bytep row, png_bytep dsp_row) 376 { 377 png_row_info row_info; 378 379 if (png_ptr == NULL) 380 return; 381 382 png_debug2(1, "in png_read_row (row %lu, pass %d)", 383 (unsigned long)png_ptr->row_number, png_ptr->pass); 384 385 /* png_read_start_row sets the information (in particular iwidth) for this 386 * interlace pass. 387 */ 388 if ((png_ptr->flags & PNG_FLAG_ROW_INIT) == 0) 389 png_read_start_row(png_ptr); 390 391 /* 1.5.6: row_info moved out of png_struct to a local here. */ 392 row_info.width = png_ptr->iwidth; /* NOTE: width of current interlaced row */ 393 row_info.color_type = png_ptr->color_type; 394 row_info.bit_depth = png_ptr->bit_depth; 395 row_info.channels = png_ptr->channels; 396 row_info.pixel_depth = png_ptr->pixel_depth; 397 row_info.rowbytes = PNG_ROWBYTES(row_info.pixel_depth, row_info.width); 398 399 #ifdef PNG_WARNINGS_SUPPORTED 400 if (png_ptr->row_number == 0 && png_ptr->pass == 0) 401 { 402 /* Check for transforms that have been set but were defined out */ 403 #if defined(PNG_WRITE_INVERT_SUPPORTED) && !defined(PNG_READ_INVERT_SUPPORTED) 404 if ((png_ptr->transformations & PNG_INVERT_MONO) != 0) 405 png_warning(png_ptr, "PNG_READ_INVERT_SUPPORTED is not defined"); 406 #endif 407 408 #if defined(PNG_WRITE_FILLER_SUPPORTED) && !defined(PNG_READ_FILLER_SUPPORTED) 409 if ((png_ptr->transformations & PNG_FILLER) != 0) 410 png_warning(png_ptr, "PNG_READ_FILLER_SUPPORTED is not defined"); 411 #endif 412 413 #if defined(PNG_WRITE_PACKSWAP_SUPPORTED) && \ 414 !defined(PNG_READ_PACKSWAP_SUPPORTED) 415 if ((png_ptr->transformations & PNG_PACKSWAP) != 0) 416 png_warning(png_ptr, "PNG_READ_PACKSWAP_SUPPORTED is not defined"); 417 #endif 418 419 #if defined(PNG_WRITE_PACK_SUPPORTED) && !defined(PNG_READ_PACK_SUPPORTED) 420 if ((png_ptr->transformations & PNG_PACK) != 0) 421 png_warning(png_ptr, "PNG_READ_PACK_SUPPORTED is not defined"); 422 #endif 423 424 #if defined(PNG_WRITE_SHIFT_SUPPORTED) && !defined(PNG_READ_SHIFT_SUPPORTED) 425 if ((png_ptr->transformations & PNG_SHIFT) != 0) 426 png_warning(png_ptr, "PNG_READ_SHIFT_SUPPORTED is not defined"); 427 #endif 428 429 #if defined(PNG_WRITE_BGR_SUPPORTED) && !defined(PNG_READ_BGR_SUPPORTED) 430 if ((png_ptr->transformations & PNG_BGR) != 0) 431 png_warning(png_ptr, "PNG_READ_BGR_SUPPORTED is not defined"); 432 #endif 433 434 #if defined(PNG_WRITE_SWAP_SUPPORTED) && !defined(PNG_READ_SWAP_SUPPORTED) 435 if ((png_ptr->transformations & PNG_SWAP_BYTES) != 0) 436 png_warning(png_ptr, "PNG_READ_SWAP_SUPPORTED is not defined"); 437 #endif 438 } 439 #endif /* WARNINGS */ 440 441 #ifdef PNG_READ_INTERLACING_SUPPORTED 442 /* If interlaced and we do not need a new row, combine row and return. 443 * Notice that the pixels we have from previous rows have been transformed 444 * already; we can only combine like with like (transformed or 445 * untransformed) and, because of the libpng API for interlaced images, this 446 * means we must transform before de-interlacing. 447 */ 448 if (png_ptr->interlaced != 0 && 449 (png_ptr->transformations & PNG_INTERLACE) != 0) 450 { 451 switch (png_ptr->pass) 452 { 453 case 0: 454 if (png_ptr->row_number & 0x07) 455 { 456 if (dsp_row != NULL) 457 png_combine_row(png_ptr, dsp_row, 1/*display*/); 458 png_read_finish_row(png_ptr); 459 return; 460 } 461 break; 462 463 case 1: 464 if ((png_ptr->row_number & 0x07) || png_ptr->width < 5) 465 { 466 if (dsp_row != NULL) 467 png_combine_row(png_ptr, dsp_row, 1/*display*/); 468 469 png_read_finish_row(png_ptr); 470 return; 471 } 472 break; 473 474 case 2: 475 if ((png_ptr->row_number & 0x07) != 4) 476 { 477 if (dsp_row != NULL && (png_ptr->row_number & 4)) 478 png_combine_row(png_ptr, dsp_row, 1/*display*/); 479 480 png_read_finish_row(png_ptr); 481 return; 482 } 483 break; 484 485 case 3: 486 if ((png_ptr->row_number & 3) || png_ptr->width < 3) 487 { 488 if (dsp_row != NULL) 489 png_combine_row(png_ptr, dsp_row, 1/*display*/); 490 491 png_read_finish_row(png_ptr); 492 return; 493 } 494 break; 495 496 case 4: 497 if ((png_ptr->row_number & 3) != 2) 498 { 499 if (dsp_row != NULL && (png_ptr->row_number & 2)) 500 png_combine_row(png_ptr, dsp_row, 1/*display*/); 501 502 png_read_finish_row(png_ptr); 503 return; 504 } 505 break; 506 507 case 5: 508 if ((png_ptr->row_number & 1) || png_ptr->width < 2) 509 { 510 if (dsp_row != NULL) 511 png_combine_row(png_ptr, dsp_row, 1/*display*/); 512 513 png_read_finish_row(png_ptr); 514 return; 515 } 516 break; 517 518 default: 519 case 6: 520 if ((png_ptr->row_number & 1) == 0) 521 { 522 png_read_finish_row(png_ptr); 523 return; 524 } 525 break; 526 } 527 } 528 #endif 529 530 if ((png_ptr->mode & PNG_HAVE_IDAT) == 0) 531 png_error(png_ptr, "Invalid attempt to read row data"); 532 533 /* Fill the row with IDAT data: */ 534 png_read_IDAT_data(png_ptr, png_ptr->row_buf, row_info.rowbytes + 1); 535 536 if (png_ptr->row_buf[0] > PNG_FILTER_VALUE_NONE) 537 { 538 if (png_ptr->row_buf[0] < PNG_FILTER_VALUE_LAST) 539 png_read_filter_row(png_ptr, &row_info, png_ptr->row_buf + 1, 540 png_ptr->prev_row + 1, png_ptr->row_buf[0]); 541 else 542 png_error(png_ptr, "bad adaptive filter value"); 543 } 544 545 /* libpng 1.5.6: the following line was copying png_ptr->rowbytes before 546 * 1.5.6, while the buffer really is this big in current versions of libpng 547 * it may not be in the future, so this was changed just to copy the 548 * interlaced count: 549 */ 550 memcpy(png_ptr->prev_row, png_ptr->row_buf, row_info.rowbytes + 1); 551 552 #ifdef PNG_MNG_FEATURES_SUPPORTED 553 if ((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) != 0 && 554 (png_ptr->filter_type == PNG_INTRAPIXEL_DIFFERENCING)) 555 { 556 /* Intrapixel differencing */ 557 png_do_read_intrapixel(&row_info, png_ptr->row_buf + 1); 558 } 559 #endif 560 561 #ifdef PNG_READ_TRANSFORMS_SUPPORTED 562 if (png_ptr->transformations) 563 png_do_read_transformations(png_ptr, &row_info); 564 #endif 565 566 /* The transformed pixel depth should match the depth now in row_info. */ 567 if (png_ptr->transformed_pixel_depth == 0) 568 { 569 png_ptr->transformed_pixel_depth = row_info.pixel_depth; 570 if (row_info.pixel_depth > png_ptr->maximum_pixel_depth) 571 png_error(png_ptr, "sequential row overflow"); 572 } 573 574 else if (png_ptr->transformed_pixel_depth != row_info.pixel_depth) 575 png_error(png_ptr, "internal sequential row size calculation error"); 576 577 #ifdef PNG_READ_INTERLACING_SUPPORTED 578 /* Expand interlaced rows to full size */ 579 if (png_ptr->interlaced != 0 && 580 (png_ptr->transformations & PNG_INTERLACE) != 0) 581 { 582 if (png_ptr->pass < 6) 583 png_do_read_interlace(&row_info, png_ptr->row_buf + 1, png_ptr->pass, 584 png_ptr->transformations); 585 586 if (dsp_row != NULL) 587 png_combine_row(png_ptr, dsp_row, 1/*display*/); 588 589 if (row != NULL) 590 png_combine_row(png_ptr, row, 0/*row*/); 591 } 592 593 else 594 #endif 595 { 596 if (row != NULL) 597 png_combine_row(png_ptr, row, -1/*ignored*/); 598 599 if (dsp_row != NULL) 600 png_combine_row(png_ptr, dsp_row, -1/*ignored*/); 601 } 602 png_read_finish_row(png_ptr); 603 604 if (png_ptr->read_row_fn != NULL) 605 (*(png_ptr->read_row_fn))(png_ptr, png_ptr->row_number, png_ptr->pass); 606 607 } 608 #endif /* SEQUENTIAL_READ */ 609 610 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED 611 /* Read one or more rows of image data. If the image is interlaced, 612 * and png_set_interlace_handling() has been called, the rows need to 613 * contain the contents of the rows from the previous pass. If the 614 * image has alpha or transparency, and png_handle_alpha()[*] has been 615 * called, the rows contents must be initialized to the contents of the 616 * screen. 617 * 618 * "row" holds the actual image, and pixels are placed in it 619 * as they arrive. If the image is displayed after each pass, it will 620 * appear to "sparkle" in. "display_row" can be used to display a 621 * "chunky" progressive image, with finer detail added as it becomes 622 * available. If you do not want this "chunky" display, you may pass 623 * NULL for display_row. If you do not want the sparkle display, and 624 * you have not called png_handle_alpha(), you may pass NULL for rows. 625 * If you have called png_handle_alpha(), and the image has either an 626 * alpha channel or a transparency chunk, you must provide a buffer for 627 * rows. In this case, you do not have to provide a display_row buffer 628 * also, but you may. If the image is not interlaced, or if you have 629 * not called png_set_interlace_handling(), the display_row buffer will 630 * be ignored, so pass NULL to it. 631 * 632 * [*] png_handle_alpha() does not exist yet, as of this version of libpng 633 */ 634 635 void PNGAPI 636 png_read_rows(png_structrp png_ptr, png_bytepp row, 637 png_bytepp display_row, png_uint_32 num_rows) 638 { 639 png_uint_32 i; 640 png_bytepp rp; 641 png_bytepp dp; 642 643 png_debug(1, "in png_read_rows"); 644 645 if (png_ptr == NULL) 646 return; 647 648 rp = row; 649 dp = display_row; 650 if (rp != NULL && dp != NULL) 651 for (i = 0; i < num_rows; i++) 652 { 653 png_bytep rptr = *rp++; 654 png_bytep dptr = *dp++; 655 656 png_read_row(png_ptr, rptr, dptr); 657 } 658 659 else if (rp != NULL) 660 for (i = 0; i < num_rows; i++) 661 { 662 png_bytep rptr = *rp; 663 png_read_row(png_ptr, rptr, NULL); 664 rp++; 665 } 666 667 else if (dp != NULL) 668 for (i = 0; i < num_rows; i++) 669 { 670 png_bytep dptr = *dp; 671 png_read_row(png_ptr, NULL, dptr); 672 dp++; 673 } 674 } 675 #endif /* SEQUENTIAL_READ */ 676 677 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED 678 /* Read the entire image. If the image has an alpha channel or a tRNS 679 * chunk, and you have called png_handle_alpha()[*], you will need to 680 * initialize the image to the current image that PNG will be overlaying. 681 * We set the num_rows again here, in case it was incorrectly set in 682 * png_read_start_row() by a call to png_read_update_info() or 683 * png_start_read_image() if png_set_interlace_handling() wasn't called 684 * prior to either of these functions like it should have been. You can 685 * only call this function once. If you desire to have an image for 686 * each pass of a interlaced image, use png_read_rows() instead. 687 * 688 * [*] png_handle_alpha() does not exist yet, as of this version of libpng 689 */ 690 void PNGAPI 691 png_read_image(png_structrp png_ptr, png_bytepp image) 692 { 693 png_uint_32 i, image_height; 694 int pass, j; 695 png_bytepp rp; 696 697 png_debug(1, "in png_read_image"); 698 699 if (png_ptr == NULL) 700 return; 701 702 #ifdef PNG_READ_INTERLACING_SUPPORTED 703 if ((png_ptr->flags & PNG_FLAG_ROW_INIT) == 0) 704 { 705 pass = png_set_interlace_handling(png_ptr); 706 /* And make sure transforms are initialized. */ 707 png_start_read_image(png_ptr); 708 } 709 else 710 { 711 if (png_ptr->interlaced != 0 && 712 (png_ptr->transformations & PNG_INTERLACE) == 0) 713 { 714 /* Caller called png_start_read_image or png_read_update_info without 715 * first turning on the PNG_INTERLACE transform. We can fix this here, 716 * but the caller should do it! 717 */ 718 png_warning(png_ptr, "Interlace handling should be turned on when " 719 "using png_read_image"); 720 /* Make sure this is set correctly */ 721 png_ptr->num_rows = png_ptr->height; 722 } 723 724 /* Obtain the pass number, which also turns on the PNG_INTERLACE flag in 725 * the above error case. 726 */ 727 pass = png_set_interlace_handling(png_ptr); 728 } 729 #else 730 if (png_ptr->interlaced) 731 png_error(png_ptr, 732 "Cannot read interlaced image -- interlace handler disabled"); 733 734 pass = 1; 735 #endif 736 737 image_height=png_ptr->height; 738 739 for (j = 0; j < pass; j++) 740 { 741 rp = image; 742 for (i = 0; i < image_height; i++) 743 { 744 png_read_row(png_ptr, *rp, NULL); 745 rp++; 746 } 747 } 748 } 749 #endif /* SEQUENTIAL_READ */ 750 751 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED 752 /* Read the end of the PNG file. Will not read past the end of the 753 * file, will verify the end is accurate, and will read any comments 754 * or time information at the end of the file, if info is not NULL. 755 */ 756 void PNGAPI 757 png_read_end(png_structrp png_ptr, png_inforp info_ptr) 758 { 759 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED 760 int keep; 761 #endif 762 763 png_debug(1, "in png_read_end"); 764 765 if (png_ptr == NULL) 766 return; 767 768 /* If png_read_end is called in the middle of reading the rows there may 769 * still be pending IDAT data and an owned zstream. Deal with this here. 770 */ 771 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED 772 if (png_chunk_unknown_handling(png_ptr, png_IDAT) == 0) 773 #endif 774 png_read_finish_IDAT(png_ptr); 775 776 #ifdef PNG_READ_CHECK_FOR_INVALID_INDEX_SUPPORTED 777 /* Report invalid palette index; added at libng-1.5.10 */ 778 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE && 779 png_ptr->num_palette_max > png_ptr->num_palette) 780 png_benign_error(png_ptr, "Read palette index exceeding num_palette"); 781 #endif 782 783 do 784 { 785 png_uint_32 length = png_read_chunk_header(png_ptr); 786 png_uint_32 chunk_name = png_ptr->chunk_name; 787 788 if (chunk_name == png_IEND) 789 png_handle_IEND(png_ptr, info_ptr, length); 790 791 else if (chunk_name == png_IHDR) 792 png_handle_IHDR(png_ptr, info_ptr, length); 793 794 else if (info_ptr == NULL) 795 png_crc_finish(png_ptr, length); 796 797 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED 798 else if ((keep = png_chunk_unknown_handling(png_ptr, chunk_name)) != 0) 799 { 800 if (chunk_name == png_IDAT) 801 { 802 if ((length > 0) || 803 (png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT) != 0) 804 png_benign_error(png_ptr, "Too many IDATs found"); 805 } 806 png_handle_unknown(png_ptr, info_ptr, length, keep); 807 if (chunk_name == png_PLTE) 808 png_ptr->mode |= PNG_HAVE_PLTE; 809 } 810 #endif 811 812 else if (chunk_name == png_IDAT) 813 { 814 /* Zero length IDATs are legal after the last IDAT has been 815 * read, but not after other chunks have been read. 816 */ 817 if ((length > 0) || (png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT) != 0) 818 png_benign_error(png_ptr, "Too many IDATs found"); 819 820 png_crc_finish(png_ptr, length); 821 } 822 else if (chunk_name == png_PLTE) 823 png_handle_PLTE(png_ptr, info_ptr, length); 824 825 #ifdef PNG_READ_bKGD_SUPPORTED 826 else if (chunk_name == png_bKGD) 827 png_handle_bKGD(png_ptr, info_ptr, length); 828 #endif 829 830 #ifdef PNG_READ_cHRM_SUPPORTED 831 else if (chunk_name == png_cHRM) 832 png_handle_cHRM(png_ptr, info_ptr, length); 833 #endif 834 835 #ifdef PNG_READ_gAMA_SUPPORTED 836 else if (chunk_name == png_gAMA) 837 png_handle_gAMA(png_ptr, info_ptr, length); 838 #endif 839 840 #ifdef PNG_READ_hIST_SUPPORTED 841 else if (chunk_name == png_hIST) 842 png_handle_hIST(png_ptr, info_ptr, length); 843 #endif 844 845 #ifdef PNG_READ_oFFs_SUPPORTED 846 else if (chunk_name == png_oFFs) 847 png_handle_oFFs(png_ptr, info_ptr, length); 848 #endif 849 850 #ifdef PNG_READ_pCAL_SUPPORTED 851 else if (chunk_name == png_pCAL) 852 png_handle_pCAL(png_ptr, info_ptr, length); 853 #endif 854 855 #ifdef PNG_READ_sCAL_SUPPORTED 856 else if (chunk_name == png_sCAL) 857 png_handle_sCAL(png_ptr, info_ptr, length); 858 #endif 859 860 #ifdef PNG_READ_pHYs_SUPPORTED 861 else if (chunk_name == png_pHYs) 862 png_handle_pHYs(png_ptr, info_ptr, length); 863 #endif 864 865 #ifdef PNG_READ_sBIT_SUPPORTED 866 else if (chunk_name == png_sBIT) 867 png_handle_sBIT(png_ptr, info_ptr, length); 868 #endif 869 870 #ifdef PNG_READ_sRGB_SUPPORTED 871 else if (chunk_name == png_sRGB) 872 png_handle_sRGB(png_ptr, info_ptr, length); 873 #endif 874 875 #ifdef PNG_READ_iCCP_SUPPORTED 876 else if (chunk_name == png_iCCP) 877 png_handle_iCCP(png_ptr, info_ptr, length); 878 #endif 879 880 #ifdef PNG_READ_sPLT_SUPPORTED 881 else if (chunk_name == png_sPLT) 882 png_handle_sPLT(png_ptr, info_ptr, length); 883 #endif 884 885 #ifdef PNG_READ_tEXt_SUPPORTED 886 else if (chunk_name == png_tEXt) 887 png_handle_tEXt(png_ptr, info_ptr, length); 888 #endif 889 890 #ifdef PNG_READ_tIME_SUPPORTED 891 else if (chunk_name == png_tIME) 892 png_handle_tIME(png_ptr, info_ptr, length); 893 #endif 894 895 #ifdef PNG_READ_tRNS_SUPPORTED 896 else if (chunk_name == png_tRNS) 897 png_handle_tRNS(png_ptr, info_ptr, length); 898 #endif 899 900 #ifdef PNG_READ_zTXt_SUPPORTED 901 else if (chunk_name == png_zTXt) 902 png_handle_zTXt(png_ptr, info_ptr, length); 903 #endif 904 905 #ifdef PNG_READ_iTXt_SUPPORTED 906 else if (chunk_name == png_iTXt) 907 png_handle_iTXt(png_ptr, info_ptr, length); 908 #endif 909 910 else 911 png_handle_unknown(png_ptr, info_ptr, length, 912 PNG_HANDLE_CHUNK_AS_DEFAULT); 913 } while ((png_ptr->mode & PNG_HAVE_IEND) == 0); 914 } 915 #endif /* SEQUENTIAL_READ */ 916 917 /* Free all memory used in the read struct */ 918 static void 919 png_read_destroy(png_structrp png_ptr) 920 { 921 png_debug(1, "in png_read_destroy"); 922 923 #ifdef PNG_READ_GAMMA_SUPPORTED 924 png_destroy_gamma_table(png_ptr); 925 #endif 926 927 png_free(png_ptr, png_ptr->big_row_buf); 928 png_ptr->big_row_buf = NULL; 929 png_free(png_ptr, png_ptr->big_prev_row); 930 png_ptr->big_prev_row = NULL; 931 png_free(png_ptr, png_ptr->read_buffer); 932 png_ptr->read_buffer = NULL; 933 934 #ifdef PNG_READ_QUANTIZE_SUPPORTED 935 png_free(png_ptr, png_ptr->palette_lookup); 936 png_ptr->palette_lookup = NULL; 937 png_free(png_ptr, png_ptr->quantize_index); 938 png_ptr->quantize_index = NULL; 939 #endif 940 941 if ((png_ptr->free_me & PNG_FREE_PLTE) != 0) 942 { 943 png_zfree(png_ptr, png_ptr->palette); 944 png_ptr->palette = NULL; 945 } 946 png_ptr->free_me &= ~PNG_FREE_PLTE; 947 948 #if defined(PNG_tRNS_SUPPORTED) || \ 949 defined(PNG_READ_EXPAND_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED) 950 if ((png_ptr->free_me & PNG_FREE_TRNS) != 0) 951 { 952 png_free(png_ptr, png_ptr->trans_alpha); 953 png_ptr->trans_alpha = NULL; 954 } 955 png_ptr->free_me &= ~PNG_FREE_TRNS; 956 #endif 957 958 inflateEnd(&png_ptr->zstream); 959 960 #ifdef PNG_PROGRESSIVE_READ_SUPPORTED 961 png_free(png_ptr, png_ptr->save_buffer); 962 png_ptr->save_buffer = NULL; 963 #endif 964 965 #if defined(PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED) && \ 966 defined(PNG_READ_UNKNOWN_CHUNKS_SUPPORTED) 967 png_free(png_ptr, png_ptr->unknown_chunk.data); 968 png_ptr->unknown_chunk.data = NULL; 969 #endif 970 971 #ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED 972 png_free(png_ptr, png_ptr->chunk_list); 973 png_ptr->chunk_list = NULL; 974 #endif 975 976 /* NOTE: the 'setjmp' buffer may still be allocated and the memory and error 977 * callbacks are still set at this point. They are required to complete the 978 * destruction of the png_struct itself. 979 */ 980 } 981 982 /* Free all memory used by the read */ 983 void PNGAPI 984 png_destroy_read_struct(png_structpp png_ptr_ptr, png_infopp info_ptr_ptr, 985 png_infopp end_info_ptr_ptr) 986 { 987 png_structrp png_ptr = NULL; 988 989 png_debug(1, "in png_destroy_read_struct"); 990 991 if (png_ptr_ptr != NULL) 992 png_ptr = *png_ptr_ptr; 993 994 if (png_ptr == NULL) 995 return; 996 997 /* libpng 1.6.0: use the API to destroy info structs to ensure consistent 998 * behavior. Prior to 1.6.0 libpng did extra 'info' destruction in this API. 999 * The extra was, apparently, unnecessary yet this hides memory leak bugs. 1000 */ 1001 png_destroy_info_struct(png_ptr, end_info_ptr_ptr); 1002 png_destroy_info_struct(png_ptr, info_ptr_ptr); 1003 1004 *png_ptr_ptr = NULL; 1005 png_read_destroy(png_ptr); 1006 png_destroy_png_struct(png_ptr); 1007 } 1008 1009 void PNGAPI 1010 png_set_read_status_fn(png_structrp png_ptr, png_read_status_ptr read_row_fn) 1011 { 1012 if (png_ptr == NULL) 1013 return; 1014 1015 png_ptr->read_row_fn = read_row_fn; 1016 } 1017 1018 1019 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED 1020 #ifdef PNG_INFO_IMAGE_SUPPORTED 1021 void PNGAPI 1022 png_read_png(png_structrp png_ptr, png_inforp info_ptr, 1023 int transforms, 1024 voidp params) 1025 { 1026 if (png_ptr == NULL || info_ptr == NULL) 1027 return; 1028 1029 /* png_read_info() gives us all of the information from the 1030 * PNG file before the first IDAT (image data chunk). 1031 */ 1032 png_read_info(png_ptr, info_ptr); 1033 if (info_ptr->height > PNG_UINT_32_MAX/(sizeof (png_bytep))) 1034 png_error(png_ptr, "Image is too high to process with png_read_png()"); 1035 1036 /* -------------- image transformations start here ------------------- */ 1037 /* libpng 1.6.10: add code to cause a png_app_error if a selected TRANSFORM 1038 * is not implemented. This will only happen in de-configured (non-default) 1039 * libpng builds. The results can be unexpected - png_read_png may return 1040 * short or mal-formed rows because the transform is skipped. 1041 */ 1042 1043 /* Tell libpng to strip 16-bit/color files down to 8 bits per color. 1044 */ 1045 if ((transforms & PNG_TRANSFORM_SCALE_16) != 0) 1046 /* Added at libpng-1.5.4. "strip_16" produces the same result that it 1047 * did in earlier versions, while "scale_16" is now more accurate. 1048 */ 1049 #ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED 1050 png_set_scale_16(png_ptr); 1051 #else 1052 png_app_error(png_ptr, "PNG_TRANSFORM_SCALE_16 not supported"); 1053 #endif 1054 1055 /* If both SCALE and STRIP are required pngrtran will effectively cancel the 1056 * latter by doing SCALE first. This is ok and allows apps not to check for 1057 * which is supported to get the right answer. 1058 */ 1059 if ((transforms & PNG_TRANSFORM_STRIP_16) != 0) 1060 #ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED 1061 png_set_strip_16(png_ptr); 1062 #else 1063 png_app_error(png_ptr, "PNG_TRANSFORM_STRIP_16 not supported"); 1064 #endif 1065 1066 /* Strip alpha bytes from the input data without combining with 1067 * the background (not recommended). 1068 */ 1069 if ((transforms & PNG_TRANSFORM_STRIP_ALPHA) != 0) 1070 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED 1071 png_set_strip_alpha(png_ptr); 1072 #else 1073 png_app_error(png_ptr, "PNG_TRANSFORM_STRIP_ALPHA not supported"); 1074 #endif 1075 1076 /* Extract multiple pixels with bit depths of 1, 2, or 4 from a single 1077 * byte into separate bytes (useful for paletted and grayscale images). 1078 */ 1079 if ((transforms & PNG_TRANSFORM_PACKING) != 0) 1080 #ifdef PNG_READ_PACK_SUPPORTED 1081 png_set_packing(png_ptr); 1082 #else 1083 png_app_error(png_ptr, "PNG_TRANSFORM_PACKING not supported"); 1084 #endif 1085 1086 /* Change the order of packed pixels to least significant bit first 1087 * (not useful if you are using png_set_packing). 1088 */ 1089 if ((transforms & PNG_TRANSFORM_PACKSWAP) != 0) 1090 #ifdef PNG_READ_PACKSWAP_SUPPORTED 1091 png_set_packswap(png_ptr); 1092 #else 1093 png_app_error(png_ptr, "PNG_TRANSFORM_PACKSWAP not supported"); 1094 #endif 1095 1096 /* Expand paletted colors into true RGB triplets 1097 * Expand grayscale images to full 8 bits from 1, 2, or 4 bits/pixel 1098 * Expand paletted or RGB images with transparency to full alpha 1099 * channels so the data will be available as RGBA quartets. 1100 */ 1101 if ((transforms & PNG_TRANSFORM_EXPAND) != 0) 1102 #ifdef PNG_READ_EXPAND_SUPPORTED 1103 png_set_expand(png_ptr); 1104 #else 1105 png_app_error(png_ptr, "PNG_TRANSFORM_EXPAND not supported"); 1106 #endif 1107 1108 /* We don't handle background color or gamma transformation or quantizing. 1109 */ 1110 1111 /* Invert monochrome files to have 0 as white and 1 as black 1112 */ 1113 if ((transforms & PNG_TRANSFORM_INVERT_MONO) != 0) 1114 #ifdef PNG_READ_INVERT_SUPPORTED 1115 png_set_invert_mono(png_ptr); 1116 #else 1117 png_app_error(png_ptr, "PNG_TRANSFORM_INVERT_MONO not supported"); 1118 #endif 1119 1120 /* If you want to shift the pixel values from the range [0,255] or 1121 * [0,65535] to the original [0,7] or [0,31], or whatever range the 1122 * colors were originally in: 1123 */ 1124 if ((transforms & PNG_TRANSFORM_SHIFT) != 0) 1125 #ifdef PNG_READ_SHIFT_SUPPORTED 1126 if ((info_ptr->valid & PNG_INFO_sBIT) != 0) 1127 png_set_shift(png_ptr, &info_ptr->sig_bit); 1128 #else 1129 png_app_error(png_ptr, "PNG_TRANSFORM_SHIFT not supported"); 1130 #endif 1131 1132 /* Flip the RGB pixels to BGR (or RGBA to BGRA) */ 1133 if ((transforms & PNG_TRANSFORM_BGR) != 0) 1134 #ifdef PNG_READ_BGR_SUPPORTED 1135 png_set_bgr(png_ptr); 1136 #else 1137 png_app_error(png_ptr, "PNG_TRANSFORM_BGR not supported"); 1138 #endif 1139 1140 /* Swap the RGBA or GA data to ARGB or AG (or BGRA to ABGR) */ 1141 if ((transforms & PNG_TRANSFORM_SWAP_ALPHA) != 0) 1142 #ifdef PNG_READ_SWAP_ALPHA_SUPPORTED 1143 png_set_swap_alpha(png_ptr); 1144 #else 1145 png_app_error(png_ptr, "PNG_TRANSFORM_SWAP_ALPHA not supported"); 1146 #endif 1147 1148 /* Swap bytes of 16-bit files to least significant byte first */ 1149 if ((transforms & PNG_TRANSFORM_SWAP_ENDIAN) != 0) 1150 #ifdef PNG_READ_SWAP_SUPPORTED 1151 png_set_swap(png_ptr); 1152 #else 1153 png_app_error(png_ptr, "PNG_TRANSFORM_SWAP_ENDIAN not supported"); 1154 #endif 1155 1156 /* Added at libpng-1.2.41 */ 1157 /* Invert the alpha channel from opacity to transparency */ 1158 if ((transforms & PNG_TRANSFORM_INVERT_ALPHA) != 0) 1159 #ifdef PNG_READ_INVERT_ALPHA_SUPPORTED 1160 png_set_invert_alpha(png_ptr); 1161 #else 1162 png_app_error(png_ptr, "PNG_TRANSFORM_INVERT_ALPHA not supported"); 1163 #endif 1164 1165 /* Added at libpng-1.2.41 */ 1166 /* Expand grayscale image to RGB */ 1167 if ((transforms & PNG_TRANSFORM_GRAY_TO_RGB) != 0) 1168 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED 1169 png_set_gray_to_rgb(png_ptr); 1170 #else 1171 png_app_error(png_ptr, "PNG_TRANSFORM_GRAY_TO_RGB not supported"); 1172 #endif 1173 1174 /* Added at libpng-1.5.4 */ 1175 if ((transforms & PNG_TRANSFORM_EXPAND_16) != 0) 1176 #ifdef PNG_READ_EXPAND_16_SUPPORTED 1177 png_set_expand_16(png_ptr); 1178 #else 1179 png_app_error(png_ptr, "PNG_TRANSFORM_EXPAND_16 not supported"); 1180 #endif 1181 1182 /* We don't handle adding filler bytes */ 1183 1184 /* We use png_read_image and rely on that for interlace handling, but we also 1185 * call png_read_update_info therefore must turn on interlace handling now: 1186 */ 1187 (void)png_set_interlace_handling(png_ptr); 1188 1189 /* Optional call to gamma correct and add the background to the palette 1190 * and update info structure. REQUIRED if you are expecting libpng to 1191 * update the palette for you (i.e., you selected such a transform above). 1192 */ 1193 png_read_update_info(png_ptr, info_ptr); 1194 1195 /* -------------- image transformations end here ------------------- */ 1196 1197 png_free_data(png_ptr, info_ptr, PNG_FREE_ROWS, 0); 1198 if (info_ptr->row_pointers == NULL) 1199 { 1200 png_uint_32 iptr; 1201 1202 info_ptr->row_pointers = png_voidcast(png_bytepp, png_malloc(png_ptr, 1203 info_ptr->height * (sizeof (png_bytep)))); 1204 1205 for (iptr=0; iptr<info_ptr->height; iptr++) 1206 info_ptr->row_pointers[iptr] = NULL; 1207 1208 info_ptr->free_me |= PNG_FREE_ROWS; 1209 1210 for (iptr = 0; iptr < info_ptr->height; iptr++) 1211 info_ptr->row_pointers[iptr] = png_voidcast(png_bytep, 1212 png_malloc(png_ptr, info_ptr->rowbytes)); 1213 } 1214 1215 png_read_image(png_ptr, info_ptr->row_pointers); 1216 info_ptr->valid |= PNG_INFO_IDAT; 1217 1218 /* Read rest of file, and get additional chunks in info_ptr - REQUIRED */ 1219 png_read_end(png_ptr, info_ptr); 1220 1221 PNG_UNUSED(params) 1222 } 1223 #endif /* INFO_IMAGE */ 1224 #endif /* SEQUENTIAL_READ */ 1225 1226 #ifdef PNG_SIMPLIFIED_READ_SUPPORTED 1227 /* SIMPLIFIED READ 1228 * 1229 * This code currently relies on the sequential reader, though it could easily 1230 * be made to work with the progressive one. 1231 */ 1232 /* Arguments to png_image_finish_read: */ 1233 1234 /* Encoding of PNG data (used by the color-map code) */ 1235 # define P_NOTSET 0 /* File encoding not yet known */ 1236 # define P_sRGB 1 /* 8-bit encoded to sRGB gamma */ 1237 # define P_LINEAR 2 /* 16-bit linear: not encoded, NOT pre-multiplied! */ 1238 # define P_FILE 3 /* 8-bit encoded to file gamma, not sRGB or linear */ 1239 # define P_LINEAR8 4 /* 8-bit linear: only from a file value */ 1240 1241 /* Color-map processing: after libpng has run on the PNG image further 1242 * processing may be needed to convert the data to color-map indices. 1243 */ 1244 #define PNG_CMAP_NONE 0 1245 #define PNG_CMAP_GA 1 /* Process GA data to a color-map with alpha */ 1246 #define PNG_CMAP_TRANS 2 /* Process GA data to a background index */ 1247 #define PNG_CMAP_RGB 3 /* Process RGB data */ 1248 #define PNG_CMAP_RGB_ALPHA 4 /* Process RGBA data */ 1249 1250 /* The following document where the background is for each processing case. */ 1251 #define PNG_CMAP_NONE_BACKGROUND 256 1252 #define PNG_CMAP_GA_BACKGROUND 231 1253 #define PNG_CMAP_TRANS_BACKGROUND 254 1254 #define PNG_CMAP_RGB_BACKGROUND 256 1255 #define PNG_CMAP_RGB_ALPHA_BACKGROUND 216 1256 1257 typedef struct 1258 { 1259 /* Arguments: */ 1260 png_imagep image; 1261 png_voidp buffer; 1262 png_int_32 row_stride; 1263 png_voidp colormap; 1264 png_const_colorp background; 1265 /* Local variables: */ 1266 png_voidp local_row; 1267 png_voidp first_row; 1268 ptrdiff_t row_bytes; /* step between rows */ 1269 int file_encoding; /* E_ values above */ 1270 png_fixed_point gamma_to_linear; /* For P_FILE, reciprocal of gamma */ 1271 int colormap_processing; /* PNG_CMAP_ values above */ 1272 } png_image_read_control; 1273 1274 /* Do all the *safe* initialization - 'safe' means that png_error won't be 1275 * called, so setting up the jmp_buf is not required. This means that anything 1276 * called from here must *not* call png_malloc - it has to call png_malloc_warn 1277 * instead so that control is returned safely back to this routine. 1278 */ 1279 static int 1280 png_image_read_init(png_imagep image) 1281 { 1282 if (image->opaque == NULL) 1283 { 1284 png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, image, 1285 png_safe_error, png_safe_warning); 1286 1287 /* And set the rest of the structure to NULL to ensure that the various 1288 * fields are consistent. 1289 */ 1290 memset(image, 0, (sizeof *image)); 1291 image->version = PNG_IMAGE_VERSION; 1292 1293 if (png_ptr != NULL) 1294 { 1295 png_infop info_ptr = png_create_info_struct(png_ptr); 1296 1297 if (info_ptr != NULL) 1298 { 1299 png_controlp control = png_voidcast(png_controlp, 1300 png_malloc_warn(png_ptr, (sizeof *control))); 1301 1302 if (control != NULL) 1303 { 1304 memset(control, 0, (sizeof *control)); 1305 1306 control->png_ptr = png_ptr; 1307 control->info_ptr = info_ptr; 1308 control->for_write = 0; 1309 1310 image->opaque = control; 1311 return 1; 1312 } 1313 1314 /* Error clean up */ 1315 png_destroy_info_struct(png_ptr, &info_ptr); 1316 } 1317 1318 png_destroy_read_struct(&png_ptr, NULL, NULL); 1319 } 1320 1321 return png_image_error(image, "png_image_read: out of memory"); 1322 } 1323 1324 return png_image_error(image, "png_image_read: opaque pointer not NULL"); 1325 } 1326 1327 /* Utility to find the base format of a PNG file from a png_struct. */ 1328 static png_uint_32 1329 png_image_format(png_structrp png_ptr) 1330 { 1331 png_uint_32 format = 0; 1332 1333 if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0) 1334 format |= PNG_FORMAT_FLAG_COLOR; 1335 1336 if ((png_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0) 1337 format |= PNG_FORMAT_FLAG_ALPHA; 1338 1339 /* Use png_ptr here, not info_ptr, because by examination png_handle_tRNS 1340 * sets the png_struct fields; that's all we are interested in here. The 1341 * precise interaction with an app call to png_set_tRNS and PNG file reading 1342 * is unclear. 1343 */ 1344 else if (png_ptr->num_trans > 0) 1345 format |= PNG_FORMAT_FLAG_ALPHA; 1346 1347 if (png_ptr->bit_depth == 16) 1348 format |= PNG_FORMAT_FLAG_LINEAR; 1349 1350 if ((png_ptr->color_type & PNG_COLOR_MASK_PALETTE) != 0) 1351 format |= PNG_FORMAT_FLAG_COLORMAP; 1352 1353 return format; 1354 } 1355 1356 /* Is the given gamma significantly different from sRGB? The test is the same 1357 * one used in pngrtran.c when deciding whether to do gamma correction. The 1358 * arithmetic optimizes the division by using the fact that the inverse of the 1359 * file sRGB gamma is 2.2 1360 */ 1361 static int 1362 png_gamma_not_sRGB(png_fixed_point g) 1363 { 1364 if (g < PNG_FP_1) 1365 { 1366 /* An uninitialized gamma is assumed to be sRGB for the simplified API. */ 1367 if (g == 0) 1368 return 0; 1369 1370 return png_gamma_significant((g * 11 + 2)/5 /* i.e. *2.2, rounded */); 1371 } 1372 1373 return 1; 1374 } 1375 1376 /* Do the main body of a 'png_image_begin_read' function; read the PNG file 1377 * header and fill in all the information. This is executed in a safe context, 1378 * unlike the init routine above. 1379 */ 1380 static int 1381 png_image_read_header(png_voidp argument) 1382 { 1383 png_imagep image = png_voidcast(png_imagep, argument); 1384 png_structrp png_ptr = image->opaque->png_ptr; 1385 png_inforp info_ptr = image->opaque->info_ptr; 1386 1387 png_set_benign_errors(png_ptr, 1/*warn*/); 1388 png_read_info(png_ptr, info_ptr); 1389 1390 /* Do this the fast way; just read directly out of png_struct. */ 1391 image->width = png_ptr->width; 1392 image->height = png_ptr->height; 1393 1394 { 1395 png_uint_32 format = png_image_format(png_ptr); 1396 1397 image->format = format; 1398 1399 #ifdef PNG_COLORSPACE_SUPPORTED 1400 /* Does the colorspace match sRGB? If there is no color endpoint 1401 * (colorant) information assume yes, otherwise require the 1402 * 'ENDPOINTS_MATCHP_sRGB' colorspace flag to have been set. If the 1403 * colorspace has been determined to be invalid ignore it. 1404 */ 1405 if ((format & PNG_FORMAT_FLAG_COLOR) != 0 && ((png_ptr->colorspace.flags 1406 & (PNG_COLORSPACE_HAVE_ENDPOINTS|PNG_COLORSPACE_ENDPOINTS_MATCH_sRGB| 1407 PNG_COLORSPACE_INVALID)) == PNG_COLORSPACE_HAVE_ENDPOINTS)) 1408 image->flags |= PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB; 1409 #endif 1410 } 1411 1412 /* We need the maximum number of entries regardless of the format the 1413 * application sets here. 1414 */ 1415 { 1416 png_uint_32 cmap_entries; 1417 1418 switch (png_ptr->color_type) 1419 { 1420 case PNG_COLOR_TYPE_GRAY: 1421 cmap_entries = 1U << png_ptr->bit_depth; 1422 break; 1423 1424 case PNG_COLOR_TYPE_PALETTE: 1425 cmap_entries = png_ptr->num_palette; 1426 break; 1427 1428 default: 1429 cmap_entries = 256; 1430 break; 1431 } 1432 1433 if (cmap_entries > 256) 1434 cmap_entries = 256; 1435 1436 image->colormap_entries = cmap_entries; 1437 } 1438 1439 return 1; 1440 } 1441 1442 #ifdef PNG_STDIO_SUPPORTED 1443 int PNGAPI 1444 png_image_begin_read_from_stdio(png_imagep image, FILE* file) 1445 { 1446 if (image != NULL && image->version == PNG_IMAGE_VERSION) 1447 { 1448 if (file != NULL) 1449 { 1450 if (png_image_read_init(image) != 0) 1451 { 1452 /* This is slightly evil, but png_init_io doesn't do anything other 1453 * than this and we haven't changed the standard IO functions so 1454 * this saves a 'safe' function. 1455 */ 1456 image->opaque->png_ptr->io_ptr = file; 1457 return png_safe_execute(image, png_image_read_header, image); 1458 } 1459 } 1460 1461 else 1462 return png_image_error(image, 1463 "png_image_begin_read_from_stdio: invalid argument"); 1464 } 1465 1466 else if (image != NULL) 1467 return png_image_error(image, 1468 "png_image_begin_read_from_stdio: incorrect PNG_IMAGE_VERSION"); 1469 1470 return 0; 1471 } 1472 1473 int PNGAPI 1474 png_image_begin_read_from_file(png_imagep image, const char *file_name) 1475 { 1476 if (image != NULL && image->version == PNG_IMAGE_VERSION) 1477 { 1478 if (file_name != NULL) 1479 { 1480 FILE *fp = fopen(file_name, "rb"); 1481 1482 if (fp != NULL) 1483 { 1484 if (png_image_read_init(image) != 0) 1485 { 1486 image->opaque->png_ptr->io_ptr = fp; 1487 image->opaque->owned_file = 1; 1488 return png_safe_execute(image, png_image_read_header, image); 1489 } 1490 1491 /* Clean up: just the opened file. */ 1492 (void)fclose(fp); 1493 } 1494 1495 else 1496 return png_image_error(image, strerror(errno)); 1497 } 1498 1499 else 1500 return png_image_error(image, 1501 "png_image_begin_read_from_file: invalid argument"); 1502 } 1503 1504 else if (image != NULL) 1505 return png_image_error(image, 1506 "png_image_begin_read_from_file: incorrect PNG_IMAGE_VERSION"); 1507 1508 return 0; 1509 } 1510 #endif /* STDIO */ 1511 1512 static void PNGCBAPI 1513 png_image_memory_read(png_structp png_ptr, png_bytep out, png_size_t need) 1514 { 1515 if (png_ptr != NULL) 1516 { 1517 png_imagep image = png_voidcast(png_imagep, png_ptr->io_ptr); 1518 if (image != NULL) 1519 { 1520 png_controlp cp = image->opaque; 1521 if (cp != NULL) 1522 { 1523 png_const_bytep memory = cp->memory; 1524 png_size_t size = cp->size; 1525 1526 if (memory != NULL && size >= need) 1527 { 1528 memcpy(out, memory, need); 1529 cp->memory = memory + need; 1530 cp->size = size - need; 1531 return; 1532 } 1533 1534 png_error(png_ptr, "read beyond end of data"); 1535 } 1536 } 1537 1538 png_error(png_ptr, "invalid memory read"); 1539 } 1540 } 1541 1542 int PNGAPI png_image_begin_read_from_memory(png_imagep image, 1543 png_const_voidp memory, png_size_t size) 1544 { 1545 if (image != NULL && image->version == PNG_IMAGE_VERSION) 1546 { 1547 if (memory != NULL && size > 0) 1548 { 1549 if (png_image_read_init(image) != 0) 1550 { 1551 /* Now set the IO functions to read from the memory buffer and 1552 * store it into io_ptr. Again do this in-place to avoid calling a 1553 * libpng function that requires error handling. 1554 */ 1555 image->opaque->memory = png_voidcast(png_const_bytep, memory); 1556 image->opaque->size = size; 1557 image->opaque->png_ptr->io_ptr = image; 1558 image->opaque->png_ptr->read_data_fn = png_image_memory_read; 1559 1560 return png_safe_execute(image, png_image_read_header, image); 1561 } 1562 } 1563 1564 else 1565 return png_image_error(image, 1566 "png_image_begin_read_from_memory: invalid argument"); 1567 } 1568 1569 else if (image != NULL) 1570 return png_image_error(image, 1571 "png_image_begin_read_from_memory: incorrect PNG_IMAGE_VERSION"); 1572 1573 return 0; 1574 } 1575 1576 /* Utility function to skip chunks that are not used by the simplified image 1577 * read functions and an appropriate macro to call it. 1578 */ 1579 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED 1580 static void 1581 png_image_skip_unused_chunks(png_structrp png_ptr) 1582 { 1583 /* Prepare the reader to ignore all recognized chunks whose data will not 1584 * be used, i.e., all chunks recognized by libpng except for those 1585 * involved in basic image reading: 1586 * 1587 * IHDR, PLTE, IDAT, IEND 1588 * 1589 * Or image data handling: 1590 * 1591 * tRNS, bKGD, gAMA, cHRM, sRGB, [iCCP] and sBIT. 1592 * 1593 * This provides a small performance improvement and eliminates any 1594 * potential vulnerability to security problems in the unused chunks. 1595 * 1596 * At present the iCCP chunk data isn't used, so iCCP chunk can be ignored 1597 * too. This allows the simplified API to be compiled without iCCP support, 1598 * however if the support is there the chunk is still checked to detect 1599 * errors (which are unfortunately quite common.) 1600 */ 1601 { 1602 static PNG_CONST png_byte chunks_to_process[] = { 1603 98, 75, 71, 68, '\0', /* bKGD */ 1604 99, 72, 82, 77, '\0', /* cHRM */ 1605 103, 65, 77, 65, '\0', /* gAMA */ 1606 # ifdef PNG_READ_iCCP_SUPPORTED 1607 105, 67, 67, 80, '\0', /* iCCP */ 1608 # endif 1609 115, 66, 73, 84, '\0', /* sBIT */ 1610 115, 82, 71, 66, '\0', /* sRGB */ 1611 }; 1612 1613 /* Ignore unknown chunks and all other chunks except for the 1614 * IHDR, PLTE, tRNS, IDAT, and IEND chunks. 1615 */ 1616 png_set_keep_unknown_chunks(png_ptr, PNG_HANDLE_CHUNK_NEVER, 1617 NULL, -1); 1618 1619 /* But do not ignore image data handling chunks */ 1620 png_set_keep_unknown_chunks(png_ptr, PNG_HANDLE_CHUNK_AS_DEFAULT, 1621 chunks_to_process, (int)/*SAFE*/(sizeof chunks_to_process)/5); 1622 } 1623 } 1624 1625 # define PNG_SKIP_CHUNKS(p) png_image_skip_unused_chunks(p) 1626 #else 1627 # define PNG_SKIP_CHUNKS(p) ((void)0) 1628 #endif /* HANDLE_AS_UNKNOWN */ 1629 1630 /* The following macro gives the exact rounded answer for all values in the 1631 * range 0..255 (it actually divides by 51.2, but the rounding still generates 1632 * the correct numbers 0..5 1633 */ 1634 #define PNG_DIV51(v8) (((v8) * 5 + 130) >> 8) 1635 1636 /* Utility functions to make particular color-maps */ 1637 static void 1638 set_file_encoding(png_image_read_control *display) 1639 { 1640 png_fixed_point g = display->image->opaque->png_ptr->colorspace.gamma; 1641 if (png_gamma_significant(g) != 0) 1642 { 1643 if (png_gamma_not_sRGB(g) != 0) 1644 { 1645 display->file_encoding = P_FILE; 1646 display->gamma_to_linear = png_reciprocal(g); 1647 } 1648 1649 else 1650 display->file_encoding = P_sRGB; 1651 } 1652 1653 else 1654 display->file_encoding = P_LINEAR8; 1655 } 1656 1657 static unsigned int 1658 decode_gamma(png_image_read_control *display, png_uint_32 value, int encoding) 1659 { 1660 if (encoding == P_FILE) /* double check */ 1661 encoding = display->file_encoding; 1662 1663 if (encoding == P_NOTSET) /* must be the file encoding */ 1664 { 1665 set_file_encoding(display); 1666 encoding = display->file_encoding; 1667 } 1668 1669 switch (encoding) 1670 { 1671 case P_FILE: 1672 value = png_gamma_16bit_correct(value*257, display->gamma_to_linear); 1673 break; 1674 1675 case P_sRGB: 1676 value = png_sRGB_table[value]; 1677 break; 1678 1679 case P_LINEAR: 1680 break; 1681 1682 case P_LINEAR8: 1683 value *= 257; 1684 break; 1685 1686 #ifdef __GNUC__ 1687 default: 1688 png_error(display->image->opaque->png_ptr, 1689 "unexpected encoding (internal error)"); 1690 #endif 1691 } 1692 1693 return value; 1694 } 1695 1696 static png_uint_32 1697 png_colormap_compose(png_image_read_control *display, 1698 png_uint_32 foreground, int foreground_encoding, png_uint_32 alpha, 1699 png_uint_32 background, int encoding) 1700 { 1701 /* The file value is composed on the background, the background has the given 1702 * encoding and so does the result, the file is encoded with P_FILE and the 1703 * file and alpha are 8-bit values. The (output) encoding will always be 1704 * P_LINEAR or P_sRGB. 1705 */ 1706 png_uint_32 f = decode_gamma(display, foreground, foreground_encoding); 1707 png_uint_32 b = decode_gamma(display, background, encoding); 1708 1709 /* The alpha is always an 8-bit value (it comes from the palette), the value 1710 * scaled by 255 is what PNG_sRGB_FROM_LINEAR requires. 1711 */ 1712 f = f * alpha + b * (255-alpha); 1713 1714 if (encoding == P_LINEAR) 1715 { 1716 /* Scale to 65535; divide by 255, approximately (in fact this is extremely 1717 * accurate, it divides by 255.00000005937181414556, with no overflow.) 1718 */ 1719 f *= 257; /* Now scaled by 65535 */ 1720 f += f >> 16; 1721 f = (f+32768) >> 16; 1722 } 1723 1724 else /* P_sRGB */ 1725 f = PNG_sRGB_FROM_LINEAR(f); 1726 1727 return f; 1728 } 1729 1730 /* NOTE: P_LINEAR values to this routine must be 16-bit, but P_FILE values must 1731 * be 8-bit. 1732 */ 1733 static void 1734 png_create_colormap_entry(png_image_read_control *display, 1735 png_uint_32 ip, png_uint_32 red, png_uint_32 green, png_uint_32 blue, 1736 png_uint_32 alpha, int encoding) 1737 { 1738 png_imagep image = display->image; 1739 const int output_encoding = (image->format & PNG_FORMAT_FLAG_LINEAR) != 0 ? 1740 P_LINEAR : P_sRGB; 1741 const int convert_to_Y = (image->format & PNG_FORMAT_FLAG_COLOR) == 0 && 1742 (red != green || green != blue); 1743 1744 if (ip > 255) 1745 png_error(image->opaque->png_ptr, "color-map index out of range"); 1746 1747 /* Update the cache with whether the file gamma is significantly different 1748 * from sRGB. 1749 */ 1750 if (encoding == P_FILE) 1751 { 1752 if (display->file_encoding == P_NOTSET) 1753 set_file_encoding(display); 1754 1755 /* Note that the cached value may be P_FILE too, but if it is then the 1756 * gamma_to_linear member has been set. 1757 */ 1758 encoding = display->file_encoding; 1759 } 1760 1761 if (encoding == P_FILE) 1762 { 1763 png_fixed_point g = display->gamma_to_linear; 1764 1765 red = png_gamma_16bit_correct(red*257, g); 1766 green = png_gamma_16bit_correct(green*257, g); 1767 blue = png_gamma_16bit_correct(blue*257, g); 1768 1769 if (convert_to_Y != 0 || output_encoding == P_LINEAR) 1770 { 1771 alpha *= 257; 1772 encoding = P_LINEAR; 1773 } 1774 1775 else 1776 { 1777 red = PNG_sRGB_FROM_LINEAR(red * 255); 1778 green = PNG_sRGB_FROM_LINEAR(green * 255); 1779 blue = PNG_sRGB_FROM_LINEAR(blue * 255); 1780 encoding = P_sRGB; 1781 } 1782 } 1783 1784 else if (encoding == P_LINEAR8) 1785 { 1786 /* This encoding occurs quite frequently in test cases because PngSuite 1787 * includes a gAMA 1.0 chunk with most images. 1788 */ 1789 red *= 257; 1790 green *= 257; 1791 blue *= 257; 1792 alpha *= 257; 1793 encoding = P_LINEAR; 1794 } 1795 1796 else if (encoding == P_sRGB && 1797 (convert_to_Y != 0 || output_encoding == P_LINEAR)) 1798 { 1799 /* The values are 8-bit sRGB values, but must be converted to 16-bit 1800 * linear. 1801 */ 1802 red = png_sRGB_table[red]; 1803 green = png_sRGB_table[green]; 1804 blue = png_sRGB_table[blue]; 1805 alpha *= 257; 1806 encoding = P_LINEAR; 1807 } 1808 1809 /* This is set if the color isn't gray but the output is. */ 1810 if (encoding == P_LINEAR) 1811 { 1812 if (convert_to_Y != 0) 1813 { 1814 /* NOTE: these values are copied from png_do_rgb_to_gray */ 1815 png_uint_32 y = (png_uint_32)6968 * red + (png_uint_32)23434 * green + 1816 (png_uint_32)2366 * blue; 1817 1818 if (output_encoding == P_LINEAR) 1819 y = (y + 16384) >> 15; 1820 1821 else 1822 { 1823 /* y is scaled by 32768, we need it scaled by 255: */ 1824 y = (y + 128) >> 8; 1825 y *= 255; 1826 y = PNG_sRGB_FROM_LINEAR((y + 64) >> 7); 1827 alpha = PNG_DIV257(alpha); 1828 encoding = P_sRGB; 1829 } 1830 1831 blue = red = green = y; 1832 } 1833 1834 else if (output_encoding == P_sRGB) 1835 { 1836 red = PNG_sRGB_FROM_LINEAR(red * 255); 1837 green = PNG_sRGB_FROM_LINEAR(green * 255); 1838 blue = PNG_sRGB_FROM_LINEAR(blue * 255); 1839 alpha = PNG_DIV257(alpha); 1840 encoding = P_sRGB; 1841 } 1842 } 1843 1844 if (encoding != output_encoding) 1845 png_error(image->opaque->png_ptr, "bad encoding (internal error)"); 1846 1847 /* Store the value. */ 1848 { 1849 # ifdef PNG_FORMAT_AFIRST_SUPPORTED 1850 const int afirst = (image->format & PNG_FORMAT_FLAG_AFIRST) != 0 && 1851 (image->format & PNG_FORMAT_FLAG_ALPHA) != 0; 1852 # else 1853 # define afirst 0 1854 # endif 1855 # ifdef PNG_FORMAT_BGR_SUPPORTED 1856 const int bgr = (image->format & PNG_FORMAT_FLAG_BGR) != 0 ? 2 : 0; 1857 # else 1858 # define bgr 0 1859 # endif 1860 1861 if (output_encoding == P_LINEAR) 1862 { 1863 png_uint_16p entry = png_voidcast(png_uint_16p, display->colormap); 1864 1865 entry += ip * PNG_IMAGE_SAMPLE_CHANNELS(image->format); 1866 1867 /* The linear 16-bit values must be pre-multiplied by the alpha channel 1868 * value, if less than 65535 (this is, effectively, composite on black 1869 * if the alpha channel is removed.) 1870 */ 1871 switch (PNG_IMAGE_SAMPLE_CHANNELS(image->format)) 1872 { 1873 case 4: 1874 entry[afirst ? 0 : 3] = (png_uint_16)alpha; 1875 /* FALL THROUGH */ 1876 1877 case 3: 1878 if (alpha < 65535) 1879 { 1880 if (alpha > 0) 1881 { 1882 blue = (blue * alpha + 32767U)/65535U; 1883 green = (green * alpha + 32767U)/65535U; 1884 red = (red * alpha + 32767U)/65535U; 1885 } 1886 1887 else 1888 red = green = blue = 0; 1889 } 1890 entry[afirst + (2 ^ bgr)] = (png_uint_16)blue; 1891 entry[afirst + 1] = (png_uint_16)green; 1892 entry[afirst + bgr] = (png_uint_16)red; 1893 break; 1894 1895 case 2: 1896 entry[1 ^ afirst] = (png_uint_16)alpha; 1897 /* FALL THROUGH */ 1898 1899 case 1: 1900 if (alpha < 65535) 1901 { 1902 if (alpha > 0) 1903 green = (green * alpha + 32767U)/65535U; 1904 1905 else 1906 green = 0; 1907 } 1908 entry[afirst] = (png_uint_16)green; 1909 break; 1910 1911 default: 1912 break; 1913 } 1914 } 1915 1916 else /* output encoding is P_sRGB */ 1917 { 1918 png_bytep entry = png_voidcast(png_bytep, display->colormap); 1919 1920 entry += ip * PNG_IMAGE_SAMPLE_CHANNELS(image->format); 1921 1922 switch (PNG_IMAGE_SAMPLE_CHANNELS(image->format)) 1923 { 1924 case 4: 1925 entry[afirst ? 0 : 3] = (png_byte)alpha; 1926 case 3: 1927 entry[afirst + (2 ^ bgr)] = (png_byte)blue; 1928 entry[afirst + 1] = (png_byte)green; 1929 entry[afirst + bgr] = (png_byte)red; 1930 break; 1931 1932 case 2: 1933 entry[1 ^ afirst] = (png_byte)alpha; 1934 case 1: 1935 entry[afirst] = (png_byte)green; 1936 break; 1937 1938 default: 1939 break; 1940 } 1941 } 1942 1943 # ifdef afirst 1944 # undef afirst 1945 # endif 1946 # ifdef bgr 1947 # undef bgr 1948 # endif 1949 } 1950 } 1951 1952 static int 1953 make_gray_file_colormap(png_image_read_control *display) 1954 { 1955 unsigned int i; 1956 1957 for (i=0; i<256; ++i) 1958 png_create_colormap_entry(display, i, i, i, i, 255, P_FILE); 1959 1960 return i; 1961 } 1962 1963 static int 1964 make_gray_colormap(png_image_read_control *display) 1965 { 1966 unsigned int i; 1967 1968 for (i=0; i<256; ++i) 1969 png_create_colormap_entry(display, i, i, i, i, 255, P_sRGB); 1970 1971 return i; 1972 } 1973 #define PNG_GRAY_COLORMAP_ENTRIES 256 1974 1975 static int 1976 make_ga_colormap(png_image_read_control *display) 1977 { 1978 unsigned int i, a; 1979 1980 /* Alpha is retained, the output will be a color-map with entries 1981 * selected by six levels of alpha. One transparent entry, 6 gray 1982 * levels for all the intermediate alpha values, leaving 230 entries 1983 * for the opaque grays. The color-map entries are the six values 1984 * [0..5]*51, the GA processing uses PNG_DIV51(value) to find the 1985 * relevant entry. 1986 * 1987 * if (alpha > 229) // opaque 1988 * { 1989 * // The 231 entries are selected to make the math below work: 1990 * base = 0; 1991 * entry = (231 * gray + 128) >> 8; 1992 * } 1993 * else if (alpha < 26) // transparent 1994 * { 1995 * base = 231; 1996 * entry = 0; 1997 * } 1998 * else // partially opaque 1999 * { 2000 * base = 226 + 6 * PNG_DIV51(alpha); 2001 * entry = PNG_DIV51(gray); 2002 * } 2003 */ 2004 i = 0; 2005 while (i < 231) 2006 { 2007 unsigned int gray = (i * 256 + 115) / 231; 2008 png_create_colormap_entry(display, i++, gray, gray, gray, 255, P_sRGB); 2009 } 2010 2011 /* 255 is used here for the component values for consistency with the code 2012 * that undoes premultiplication in pngwrite.c. 2013 */ 2014 png_create_colormap_entry(display, i++, 255, 255, 255, 0, P_sRGB); 2015 2016 for (a=1; a<5; ++a) 2017 { 2018 unsigned int g; 2019 2020 for (g=0; g<6; ++g) 2021 png_create_colormap_entry(display, i++, g*51, g*51, g*51, a*51, 2022 P_sRGB); 2023 } 2024 2025 return i; 2026 } 2027 2028 #define PNG_GA_COLORMAP_ENTRIES 256 2029 2030 static int 2031 make_rgb_colormap(png_image_read_control *display) 2032 { 2033 unsigned int i, r; 2034 2035 /* Build a 6x6x6 opaque RGB cube */ 2036 for (i=r=0; r<6; ++r) 2037 { 2038 unsigned int g; 2039 2040 for (g=0; g<6; ++g) 2041 { 2042 unsigned int b; 2043 2044 for (b=0; b<6; ++b) 2045 png_create_colormap_entry(display, i++, r*51, g*51, b*51, 255, 2046 P_sRGB); 2047 } 2048 } 2049 2050 return i; 2051 } 2052 2053 #define PNG_RGB_COLORMAP_ENTRIES 216 2054 2055 /* Return a palette index to the above palette given three 8-bit sRGB values. */ 2056 #define PNG_RGB_INDEX(r,g,b) \ 2057 ((png_byte)(6 * (6 * PNG_DIV51(r) + PNG_DIV51(g)) + PNG_DIV51(b))) 2058 2059 static int 2060 png_image_read_colormap(png_voidp argument) 2061 { 2062 png_image_read_control *display = 2063 png_voidcast(png_image_read_control*, argument); 2064 const png_imagep image = display->image; 2065 2066 const png_structrp png_ptr = image->opaque->png_ptr; 2067 const png_uint_32 output_format = image->format; 2068 const int output_encoding = (output_format & PNG_FORMAT_FLAG_LINEAR) != 0 ? 2069 P_LINEAR : P_sRGB; 2070 2071 unsigned int cmap_entries; 2072 unsigned int output_processing; /* Output processing option */ 2073 unsigned int data_encoding = P_NOTSET; /* Encoding libpng must produce */ 2074 2075 /* Background information; the background color and the index of this color 2076 * in the color-map if it exists (else 256). 2077 */ 2078 unsigned int background_index = 256; 2079 png_uint_32 back_r, back_g, back_b; 2080 2081 /* Flags to accumulate things that need to be done to the input. */ 2082 int expand_tRNS = 0; 2083 2084 /* Exclude the NYI feature of compositing onto a color-mapped buffer; it is 2085 * very difficult to do, the results look awful, and it is difficult to see 2086 * what possible use it is because the application can't control the 2087 * color-map. 2088 */ 2089 if (((png_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0 || 2090 png_ptr->num_trans > 0) /* alpha in input */ && 2091 ((output_format & PNG_FORMAT_FLAG_ALPHA) == 0) /* no alpha in output */) 2092 { 2093 if (output_encoding == P_LINEAR) /* compose on black */ 2094 back_b = back_g = back_r = 0; 2095 2096 else if (display->background == NULL /* no way to remove it */) 2097 png_error(png_ptr, 2098 "a background color must be supplied to remove alpha/transparency"); 2099 2100 /* Get a copy of the background color (this avoids repeating the checks 2101 * below.) The encoding is 8-bit sRGB or 16-bit linear, depending on the 2102 * output format. 2103 */ 2104 else 2105 { 2106 back_g = display->background->green; 2107 if ((output_format & PNG_FORMAT_FLAG_COLOR) != 0) 2108 { 2109 back_r = display->background->red; 2110 back_b = display->background->blue; 2111 } 2112 else 2113 back_b = back_r = back_g; 2114 } 2115 } 2116 2117 else if (output_encoding == P_LINEAR) 2118 back_b = back_r = back_g = 65535; 2119 2120 else 2121 back_b = back_r = back_g = 255; 2122 2123 /* Default the input file gamma if required - this is necessary because 2124 * libpng assumes that if no gamma information is present the data is in the 2125 * output format, but the simplified API deduces the gamma from the input 2126 * format. 2127 */ 2128 if ((png_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_GAMMA) == 0) 2129 { 2130 /* Do this directly, not using the png_colorspace functions, to ensure 2131 * that it happens even if the colorspace is invalid (though probably if 2132 * it is the setting will be ignored) Note that the same thing can be 2133 * achieved at the application interface with png_set_gAMA. 2134 */ 2135 if (png_ptr->bit_depth == 16 && 2136 (image->flags & PNG_IMAGE_FLAG_16BIT_sRGB) == 0) 2137 png_ptr->colorspace.gamma = PNG_GAMMA_LINEAR; 2138 2139 else 2140 png_ptr->colorspace.gamma = PNG_GAMMA_sRGB_INVERSE; 2141 2142 png_ptr->colorspace.flags |= PNG_COLORSPACE_HAVE_GAMMA; 2143 } 2144 2145 /* Decide what to do based on the PNG color type of the input data. The 2146 * utility function png_create_colormap_entry deals with most aspects of the 2147 * output transformations; this code works out how to produce bytes of 2148 * color-map entries from the original format. 2149 */ 2150 switch (png_ptr->color_type) 2151 { 2152 case PNG_COLOR_TYPE_GRAY: 2153 if (png_ptr->bit_depth <= 8) 2154 { 2155 /* There at most 256 colors in the output, regardless of 2156 * transparency. 2157 */ 2158 unsigned int step, i, val, trans = 256/*ignore*/, back_alpha = 0; 2159 2160 cmap_entries = 1U << png_ptr->bit_depth; 2161 if (cmap_entries > image->colormap_entries) 2162 png_error(png_ptr, "gray[8] color-map: too few entries"); 2163 2164 step = 255 / (cmap_entries - 1); 2165 output_processing = PNG_CMAP_NONE; 2166 2167 /* If there is a tRNS chunk then this either selects a transparent 2168 * value or, if the output has no alpha, the background color. 2169 */ 2170 if (png_ptr->num_trans > 0) 2171 { 2172 trans = png_ptr->trans_color.gray; 2173 2174 if ((output_format & PNG_FORMAT_FLAG_ALPHA) == 0) 2175 back_alpha = output_encoding == P_LINEAR ? 65535 : 255; 2176 } 2177 2178 /* png_create_colormap_entry just takes an RGBA and writes the 2179 * corresponding color-map entry using the format from 'image', 2180 * including the required conversion to sRGB or linear as 2181 * appropriate. The input values are always either sRGB (if the 2182 * gamma correction flag is 0) or 0..255 scaled file encoded values 2183 * (if the function must gamma correct them). 2184 */ 2185 for (i=val=0; i<cmap_entries; ++i, val += step) 2186 { 2187 /* 'i' is a file value. While this will result in duplicated 2188 * entries for 8-bit non-sRGB encoded files it is necessary to 2189 * have non-gamma corrected values to do tRNS handling. 2190 */ 2191 if (i != trans) 2192 png_create_colormap_entry(display, i, val, val, val, 255, 2193 P_FILE/*8-bit with file gamma*/); 2194 2195 /* Else this entry is transparent. The colors don't matter if 2196 * there is an alpha channel (back_alpha == 0), but it does no 2197 * harm to pass them in; the values are not set above so this 2198 * passes in white. 2199 * 2200 * NOTE: this preserves the full precision of the application 2201 * supplied background color when it is used. 2202 */ 2203 else 2204 png_create_colormap_entry(display, i, back_r, back_g, back_b, 2205 back_alpha, output_encoding); 2206 } 2207 2208 /* We need libpng to preserve the original encoding. */ 2209 data_encoding = P_FILE; 2210 2211 /* The rows from libpng, while technically gray values, are now also 2212 * color-map indices; however, they may need to be expanded to 1 2213 * byte per pixel. This is what png_set_packing does (i.e., it 2214 * unpacks the bit values into bytes.) 2215 */ 2216 if (png_ptr->bit_depth < 8) 2217 png_set_packing(png_ptr); 2218 } 2219 2220 else /* bit depth is 16 */ 2221 { 2222 /* The 16-bit input values can be converted directly to 8-bit gamma 2223 * encoded values; however, if a tRNS chunk is present 257 color-map 2224 * entries are required. This means that the extra entry requires 2225 * special processing; add an alpha channel, sacrifice gray level 2226 * 254 and convert transparent (alpha==0) entries to that. 2227 * 2228 * Use libpng to chop the data to 8 bits. Convert it to sRGB at the 2229 * same time to minimize quality loss. If a tRNS chunk is present 2230 * this means libpng must handle it too; otherwise it is impossible 2231 * to do the exact match on the 16-bit value. 2232 * 2233 * If the output has no alpha channel *and* the background color is 2234 * gray then it is possible to let libpng handle the substitution by 2235 * ensuring that the corresponding gray level matches the background 2236 * color exactly. 2237 */ 2238 data_encoding = P_sRGB; 2239 2240 if (PNG_GRAY_COLORMAP_ENTRIES > image->colormap_entries) 2241 png_error(png_ptr, "gray[16] color-map: too few entries"); 2242 2243 cmap_entries = make_gray_colormap(display); 2244 2245 if (png_ptr->num_trans > 0) 2246 { 2247 unsigned int back_alpha; 2248 2249 if ((output_format & PNG_FORMAT_FLAG_ALPHA) != 0) 2250 back_alpha = 0; 2251 2252 else 2253 { 2254 if (back_r == back_g && back_g == back_b) 2255 { 2256 /* Background is gray; no special processing will be 2257 * required. 2258 */ 2259 png_color_16 c; 2260 png_uint_32 gray = back_g; 2261 2262 if (output_encoding == P_LINEAR) 2263 { 2264 gray = PNG_sRGB_FROM_LINEAR(gray * 255); 2265 2266 /* And make sure the corresponding palette entry 2267 * matches. 2268 */ 2269 png_create_colormap_entry(display, gray, back_g, back_g, 2270 back_g, 65535, P_LINEAR); 2271 } 2272 2273 /* The background passed to libpng, however, must be the 2274 * sRGB value. 2275 */ 2276 c.index = 0; /*unused*/ 2277 c.gray = c.red = c.green = c.blue = (png_uint_16)gray; 2278 2279 /* NOTE: does this work without expanding tRNS to alpha? 2280 * It should be the color->gray case below apparently 2281 * doesn't. 2282 */ 2283 png_set_background_fixed(png_ptr, &c, 2284 PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/, 2285 0/*gamma: not used*/); 2286 2287 output_processing = PNG_CMAP_NONE; 2288 break; 2289 } 2290 #ifdef __COVERITY__ 2291 /* Coverity claims that output_encoding cannot be 2 (P_LINEAR) 2292 * here. 2293 */ 2294 back_alpha = 255; 2295 #else 2296 back_alpha = output_encoding == P_LINEAR ? 65535 : 255; 2297 #endif 2298 } 2299 2300 /* output_processing means that the libpng-processed row will be 2301 * 8-bit GA and it has to be processing to single byte color-map 2302 * values. Entry 254 is replaced by either a completely 2303 * transparent entry or by the background color at full 2304 * precision (and the background color is not a simple gray 2305 * level in this case.) 2306 */ 2307 expand_tRNS = 1; 2308 output_processing = PNG_CMAP_TRANS; 2309 background_index = 254; 2310 2311 /* And set (overwrite) color-map entry 254 to the actual 2312 * background color at full precision. 2313 */ 2314 png_create_colormap_entry(display, 254, back_r, back_g, back_b, 2315 back_alpha, output_encoding); 2316 } 2317 2318 else 2319 output_processing = PNG_CMAP_NONE; 2320 } 2321 break; 2322 2323 case PNG_COLOR_TYPE_GRAY_ALPHA: 2324 /* 8-bit or 16-bit PNG with two channels - gray and alpha. A minimum 2325 * of 65536 combinations. If, however, the alpha channel is to be 2326 * removed there are only 256 possibilities if the background is gray. 2327 * (Otherwise there is a subset of the 65536 possibilities defined by 2328 * the triangle between black, white and the background color.) 2329 * 2330 * Reduce 16-bit files to 8-bit and sRGB encode the result. No need to 2331 * worry about tRNS matching - tRNS is ignored if there is an alpha 2332 * channel. 2333 */ 2334 data_encoding = P_sRGB; 2335 2336 if ((output_format & PNG_FORMAT_FLAG_ALPHA) != 0) 2337 { 2338 if (PNG_GA_COLORMAP_ENTRIES > image->colormap_entries) 2339 png_error(png_ptr, "gray+alpha color-map: too few entries"); 2340 2341 cmap_entries = make_ga_colormap(display); 2342 2343 background_index = PNG_CMAP_GA_BACKGROUND; 2344 output_processing = PNG_CMAP_GA; 2345 } 2346 2347 else /* alpha is removed */ 2348 { 2349 /* Alpha must be removed as the PNG data is processed when the 2350 * background is a color because the G and A channels are 2351 * independent and the vector addition (non-parallel vectors) is a 2352 * 2-D problem. 2353 * 2354 * This can be reduced to the same algorithm as above by making a 2355 * colormap containing gray levels (for the opaque grays), a 2356 * background entry (for a transparent pixel) and a set of four six 2357 * level color values, one set for each intermediate alpha value. 2358 * See the comments in make_ga_colormap for how this works in the 2359 * per-pixel processing. 2360 * 2361 * If the background is gray, however, we only need a 256 entry gray 2362 * level color map. It is sufficient to make the entry generated 2363 * for the background color be exactly the color specified. 2364 */ 2365 if ((output_format & PNG_FORMAT_FLAG_COLOR) == 0 || 2366 (back_r == back_g && back_g == back_b)) 2367 { 2368 /* Background is gray; no special processing will be required. */ 2369 png_color_16 c; 2370 png_uint_32 gray = back_g; 2371 2372 if (PNG_GRAY_COLORMAP_ENTRIES > image->colormap_entries) 2373 png_error(png_ptr, "gray-alpha color-map: too few entries"); 2374 2375 cmap_entries = make_gray_colormap(display); 2376 2377 if (output_encoding == P_LINEAR) 2378 { 2379 gray = PNG_sRGB_FROM_LINEAR(gray * 255); 2380 2381 /* And make sure the corresponding palette entry matches. */ 2382 png_create_colormap_entry(display, gray, back_g, back_g, 2383 back_g, 65535, P_LINEAR); 2384 } 2385 2386 /* The background passed to libpng, however, must be the sRGB 2387 * value. 2388 */ 2389 c.index = 0; /*unused*/ 2390 c.gray = c.red = c.green = c.blue = (png_uint_16)gray; 2391 2392 png_set_background_fixed(png_ptr, &c, 2393 PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/, 2394 0/*gamma: not used*/); 2395 2396 output_processing = PNG_CMAP_NONE; 2397 } 2398 2399 else 2400 { 2401 png_uint_32 i, a; 2402 2403 /* This is the same as png_make_ga_colormap, above, except that 2404 * the entries are all opaque. 2405 */ 2406 if (PNG_GA_COLORMAP_ENTRIES > image->colormap_entries) 2407 png_error(png_ptr, "ga-alpha color-map: too few entries"); 2408 2409 i = 0; 2410 while (i < 231) 2411 { 2412 png_uint_32 gray = (i * 256 + 115) / 231; 2413 png_create_colormap_entry(display, i++, gray, gray, gray, 2414 255, P_sRGB); 2415 } 2416 2417 /* NOTE: this preserves the full precision of the application 2418 * background color. 2419 */ 2420 background_index = i; 2421 png_create_colormap_entry(display, i++, back_r, back_g, back_b, 2422 #ifdef __COVERITY__ 2423 /* Coverity claims that output_encoding cannot be 2 (P_LINEAR) 2424 * here. 2425 */ 255U, 2426 #else 2427 output_encoding == P_LINEAR ? 65535U : 255U, 2428 #endif 2429 output_encoding); 2430 2431 /* For non-opaque input composite on the sRGB background - this 2432 * requires inverting the encoding for each component. The input 2433 * is still converted to the sRGB encoding because this is a 2434 * reasonable approximate to the logarithmic curve of human 2435 * visual sensitivity, at least over the narrow range which PNG 2436 * represents. Consequently 'G' is always sRGB encoded, while 2437 * 'A' is linear. We need the linear background colors. 2438 */ 2439 if (output_encoding == P_sRGB) /* else already linear */ 2440 { 2441 /* This may produce a value not exactly matching the 2442 * background, but that's ok because these numbers are only 2443 * used when alpha != 0 2444 */ 2445 back_r = png_sRGB_table[back_r]; 2446 back_g = png_sRGB_table[back_g]; 2447 back_b = png_sRGB_table[back_b]; 2448 } 2449 2450 for (a=1; a<5; ++a) 2451 { 2452 unsigned int g; 2453 2454 /* PNG_sRGB_FROM_LINEAR expects a 16-bit linear value scaled 2455 * by an 8-bit alpha value (0..255). 2456 */ 2457 png_uint_32 alpha = 51 * a; 2458 png_uint_32 back_rx = (255-alpha) * back_r; 2459 png_uint_32 back_gx = (255-alpha) * back_g; 2460 png_uint_32 back_bx = (255-alpha) * back_b; 2461 2462 for (g=0; g<6; ++g) 2463 { 2464 png_uint_32 gray = png_sRGB_table[g*51] * alpha; 2465 2466 png_create_colormap_entry(display, i++, 2467 PNG_sRGB_FROM_LINEAR(gray + back_rx), 2468 PNG_sRGB_FROM_LINEAR(gray + back_gx), 2469 PNG_sRGB_FROM_LINEAR(gray + back_bx), 255, P_sRGB); 2470 } 2471 } 2472 2473 cmap_entries = i; 2474 output_processing = PNG_CMAP_GA; 2475 } 2476 } 2477 break; 2478 2479 case PNG_COLOR_TYPE_RGB: 2480 case PNG_COLOR_TYPE_RGB_ALPHA: 2481 /* Exclude the case where the output is gray; we can always handle this 2482 * with the cases above. 2483 */ 2484 if ((output_format & PNG_FORMAT_FLAG_COLOR) == 0) 2485 { 2486 /* The color-map will be grayscale, so we may as well convert the 2487 * input RGB values to a simple grayscale and use the grayscale 2488 * code above. 2489 * 2490 * NOTE: calling this apparently damages the recognition of the 2491 * transparent color in background color handling; call 2492 * png_set_tRNS_to_alpha before png_set_background_fixed. 2493 */ 2494 png_set_rgb_to_gray_fixed(png_ptr, PNG_ERROR_ACTION_NONE, -1, 2495 -1); 2496 data_encoding = P_sRGB; 2497 2498 /* The output will now be one or two 8-bit gray or gray+alpha 2499 * channels. The more complex case arises when the input has alpha. 2500 */ 2501 if ((png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA || 2502 png_ptr->num_trans > 0) && 2503 (output_format & PNG_FORMAT_FLAG_ALPHA) != 0) 2504 { 2505 /* Both input and output have an alpha channel, so no background 2506 * processing is required; just map the GA bytes to the right 2507 * color-map entry. 2508 */ 2509 expand_tRNS = 1; 2510 2511 if (PNG_GA_COLORMAP_ENTRIES > image->colormap_entries) 2512 png_error(png_ptr, "rgb[ga] color-map: too few entries"); 2513 2514 cmap_entries = make_ga_colormap(display); 2515 background_index = PNG_CMAP_GA_BACKGROUND; 2516 output_processing = PNG_CMAP_GA; 2517 } 2518 2519 else 2520 { 2521 /* Either the input or the output has no alpha channel, so there 2522 * will be no non-opaque pixels in the color-map; it will just be 2523 * grayscale. 2524 */ 2525 if (PNG_GRAY_COLORMAP_ENTRIES > image->colormap_entries) 2526 png_error(png_ptr, "rgb[gray] color-map: too few entries"); 2527 2528 /* Ideally this code would use libpng to do the gamma correction, 2529 * but if an input alpha channel is to be removed we will hit the 2530 * libpng bug in gamma+compose+rgb-to-gray (the double gamma 2531 * correction bug). Fix this by dropping the gamma correction in 2532 * this case and doing it in the palette; this will result in 2533 * duplicate palette entries, but that's better than the 2534 * alternative of double gamma correction. 2535 */ 2536 if ((png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA || 2537 png_ptr->num_trans > 0) && 2538 png_gamma_not_sRGB(png_ptr->colorspace.gamma) != 0) 2539 { 2540 cmap_entries = make_gray_file_colormap(display); 2541 data_encoding = P_FILE; 2542 } 2543 2544 else 2545 cmap_entries = make_gray_colormap(display); 2546 2547 /* But if the input has alpha or transparency it must be removed 2548 */ 2549 if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA || 2550 png_ptr->num_trans > 0) 2551 { 2552 png_color_16 c; 2553 png_uint_32 gray = back_g; 2554 2555 /* We need to ensure that the application background exists in 2556 * the colormap and that completely transparent pixels map to 2557 * it. Achieve this simply by ensuring that the entry 2558 * selected for the background really is the background color. 2559 */ 2560 if (data_encoding == P_FILE) /* from the fixup above */ 2561 { 2562 /* The app supplied a gray which is in output_encoding, we 2563 * need to convert it to a value of the input (P_FILE) 2564 * encoding then set this palette entry to the required 2565 * output encoding. 2566 */ 2567 if (output_encoding == P_sRGB) 2568 gray = png_sRGB_table[gray]; /* now P_LINEAR */ 2569 2570 gray = PNG_DIV257(png_gamma_16bit_correct(gray, 2571 png_ptr->colorspace.gamma)); /* now P_FILE */ 2572 2573 /* And make sure the corresponding palette entry contains 2574 * exactly the required sRGB value. 2575 */ 2576 png_create_colormap_entry(display, gray, back_g, back_g, 2577 back_g, 0/*unused*/, output_encoding); 2578 } 2579 2580 else if (output_encoding == P_LINEAR) 2581 { 2582 gray = PNG_sRGB_FROM_LINEAR(gray * 255); 2583 2584 /* And make sure the corresponding palette entry matches. 2585 */ 2586 png_create_colormap_entry(display, gray, back_g, back_g, 2587 back_g, 0/*unused*/, P_LINEAR); 2588 } 2589 2590 /* The background passed to libpng, however, must be the 2591 * output (normally sRGB) value. 2592 */ 2593 c.index = 0; /*unused*/ 2594 c.gray = c.red = c.green = c.blue = (png_uint_16)gray; 2595 2596 /* NOTE: the following is apparently a bug in libpng. Without 2597 * it the transparent color recognition in 2598 * png_set_background_fixed seems to go wrong. 2599 */ 2600 expand_tRNS = 1; 2601 png_set_background_fixed(png_ptr, &c, 2602 PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/, 2603 0/*gamma: not used*/); 2604 } 2605 2606 output_processing = PNG_CMAP_NONE; 2607 } 2608 } 2609 2610 else /* output is color */ 2611 { 2612 /* We could use png_quantize here so long as there is no transparent 2613 * color or alpha; png_quantize ignores alpha. Easier overall just 2614 * to do it once and using PNG_DIV51 on the 6x6x6 reduced RGB cube. 2615 * Consequently we always want libpng to produce sRGB data. 2616 */ 2617 data_encoding = P_sRGB; 2618 2619 /* Is there any transparency or alpha? */ 2620 if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA || 2621 png_ptr->num_trans > 0) 2622 { 2623 /* Is there alpha in the output too? If so all four channels are 2624 * processed into a special RGB cube with alpha support. 2625 */ 2626 if ((output_format & PNG_FORMAT_FLAG_ALPHA) != 0) 2627 { 2628 png_uint_32 r; 2629 2630 if (PNG_RGB_COLORMAP_ENTRIES+1+27 > image->colormap_entries) 2631 png_error(png_ptr, "rgb+alpha color-map: too few entries"); 2632 2633 cmap_entries = make_rgb_colormap(display); 2634 2635 /* Add a transparent entry. */ 2636 png_create_colormap_entry(display, cmap_entries, 255, 255, 2637 255, 0, P_sRGB); 2638 2639 /* This is stored as the background index for the processing 2640 * algorithm. 2641 */ 2642 background_index = cmap_entries++; 2643 2644 /* Add 27 r,g,b entries each with alpha 0.5. */ 2645 for (r=0; r<256; r = (r << 1) | 0x7f) 2646 { 2647 png_uint_32 g; 2648 2649 for (g=0; g<256; g = (g << 1) | 0x7f) 2650 { 2651 png_uint_32 b; 2652 2653 /* This generates components with the values 0, 127 and 2654 * 255 2655 */ 2656 for (b=0; b<256; b = (b << 1) | 0x7f) 2657 png_create_colormap_entry(display, cmap_entries++, 2658 r, g, b, 128, P_sRGB); 2659 } 2660 } 2661 2662 expand_tRNS = 1; 2663 output_processing = PNG_CMAP_RGB_ALPHA; 2664 } 2665 2666 else 2667 { 2668 /* Alpha/transparency must be removed. The background must 2669 * exist in the color map (achieved by setting adding it after 2670 * the 666 color-map). If the standard processing code will 2671 * pick up this entry automatically that's all that is 2672 * required; libpng can be called to do the background 2673 * processing. 2674 */ 2675 unsigned int sample_size = 2676 PNG_IMAGE_SAMPLE_SIZE(output_format); 2677 png_uint_32 r, g, b; /* sRGB background */ 2678 2679 if (PNG_RGB_COLORMAP_ENTRIES+1+27 > image->colormap_entries) 2680 png_error(png_ptr, "rgb-alpha color-map: too few entries"); 2681 2682 cmap_entries = make_rgb_colormap(display); 2683 2684 png_create_colormap_entry(display, cmap_entries, back_r, 2685 back_g, back_b, 0/*unused*/, output_encoding); 2686 2687 if (output_encoding == P_LINEAR) 2688 { 2689 r = PNG_sRGB_FROM_LINEAR(back_r * 255); 2690 g = PNG_sRGB_FROM_LINEAR(back_g * 255); 2691 b = PNG_sRGB_FROM_LINEAR(back_b * 255); 2692 } 2693 2694 else 2695 { 2696 r = back_r; 2697 g = back_g; 2698 b = back_g; 2699 } 2700 2701 /* Compare the newly-created color-map entry with the one the 2702 * PNG_CMAP_RGB algorithm will use. If the two entries don't 2703 * match, add the new one and set this as the background 2704 * index. 2705 */ 2706 if (memcmp((png_const_bytep)display->colormap + 2707 sample_size * cmap_entries, 2708 (png_const_bytep)display->colormap + 2709 sample_size * PNG_RGB_INDEX(r,g,b), 2710 sample_size) != 0) 2711 { 2712 /* The background color must be added. */ 2713 background_index = cmap_entries++; 2714 2715 /* Add 27 r,g,b entries each with created by composing with 2716 * the background at alpha 0.5. 2717 */ 2718 for (r=0; r<256; r = (r << 1) | 0x7f) 2719 { 2720 for (g=0; g<256; g = (g << 1) | 0x7f) 2721 { 2722 /* This generates components with the values 0, 127 2723 * and 255 2724 */ 2725 for (b=0; b<256; b = (b << 1) | 0x7f) 2726 png_create_colormap_entry(display, cmap_entries++, 2727 png_colormap_compose(display, r, P_sRGB, 128, 2728 back_r, output_encoding), 2729 png_colormap_compose(display, g, P_sRGB, 128, 2730 back_g, output_encoding), 2731 png_colormap_compose(display, b, P_sRGB, 128, 2732 back_b, output_encoding), 2733 0/*unused*/, output_encoding); 2734 } 2735 } 2736 2737 expand_tRNS = 1; 2738 output_processing = PNG_CMAP_RGB_ALPHA; 2739 } 2740 2741 else /* background color is in the standard color-map */ 2742 { 2743 png_color_16 c; 2744 2745 c.index = 0; /*unused*/ 2746 c.red = (png_uint_16)back_r; 2747 c.gray = c.green = (png_uint_16)back_g; 2748 c.blue = (png_uint_16)back_b; 2749 2750 png_set_background_fixed(png_ptr, &c, 2751 PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/, 2752 0/*gamma: not used*/); 2753 2754 output_processing = PNG_CMAP_RGB; 2755 } 2756 } 2757 } 2758 2759 else /* no alpha or transparency in the input */ 2760 { 2761 /* Alpha in the output is irrelevant, simply map the opaque input 2762 * pixels to the 6x6x6 color-map. 2763 */ 2764 if (PNG_RGB_COLORMAP_ENTRIES > image->colormap_entries) 2765 png_error(png_ptr, "rgb color-map: too few entries"); 2766 2767 cmap_entries = make_rgb_colormap(display); 2768 output_processing = PNG_CMAP_RGB; 2769 } 2770 } 2771 break; 2772 2773 case PNG_COLOR_TYPE_PALETTE: 2774 /* It's already got a color-map. It may be necessary to eliminate the 2775 * tRNS entries though. 2776 */ 2777 { 2778 unsigned int num_trans = png_ptr->num_trans; 2779 png_const_bytep trans = num_trans > 0 ? png_ptr->trans_alpha : NULL; 2780 png_const_colorp colormap = png_ptr->palette; 2781 const int do_background = trans != NULL && 2782 (output_format & PNG_FORMAT_FLAG_ALPHA) == 0; 2783 unsigned int i; 2784 2785 /* Just in case: */ 2786 if (trans == NULL) 2787 num_trans = 0; 2788 2789 output_processing = PNG_CMAP_NONE; 2790 data_encoding = P_FILE; /* Don't change from color-map indices */ 2791 cmap_entries = png_ptr->num_palette; 2792 if (cmap_entries > 256) 2793 cmap_entries = 256; 2794 2795 if (cmap_entries > image->colormap_entries) 2796 png_error(png_ptr, "palette color-map: too few entries"); 2797 2798 for (i=0; i < cmap_entries; ++i) 2799 { 2800 if (do_background != 0 && i < num_trans && trans[i] < 255) 2801 { 2802 if (trans[i] == 0) 2803 png_create_colormap_entry(display, i, back_r, back_g, 2804 back_b, 0, output_encoding); 2805 2806 else 2807 { 2808 /* Must compose the PNG file color in the color-map entry 2809 * on the sRGB color in 'back'. 2810 */ 2811 png_create_colormap_entry(display, i, 2812 png_colormap_compose(display, colormap[i].red, P_FILE, 2813 trans[i], back_r, output_encoding), 2814 png_colormap_compose(display, colormap[i].green, P_FILE, 2815 trans[i], back_g, output_encoding), 2816 png_colormap_compose(display, colormap[i].blue, P_FILE, 2817 trans[i], back_b, output_encoding), 2818 output_encoding == P_LINEAR ? trans[i] * 257U : 2819 trans[i], 2820 output_encoding); 2821 } 2822 } 2823 2824 else 2825 png_create_colormap_entry(display, i, colormap[i].red, 2826 colormap[i].green, colormap[i].blue, 2827 i < num_trans ? trans[i] : 255U, P_FILE/*8-bit*/); 2828 } 2829 2830 /* The PNG data may have indices packed in fewer than 8 bits, it 2831 * must be expanded if so. 2832 */ 2833 if (png_ptr->bit_depth < 8) 2834 png_set_packing(png_ptr); 2835 } 2836 break; 2837 2838 default: 2839 png_error(png_ptr, "invalid PNG color type"); 2840 /*NOT REACHED*/ 2841 } 2842 2843 /* Now deal with the output processing */ 2844 if (expand_tRNS != 0 && png_ptr->num_trans > 0 && 2845 (png_ptr->color_type & PNG_COLOR_MASK_ALPHA) == 0) 2846 png_set_tRNS_to_alpha(png_ptr); 2847 2848 switch (data_encoding) 2849 { 2850 case P_sRGB: 2851 /* Change to 8-bit sRGB */ 2852 png_set_alpha_mode_fixed(png_ptr, PNG_ALPHA_PNG, PNG_GAMMA_sRGB); 2853 /* FALL THROUGH */ 2854 2855 case P_FILE: 2856 if (png_ptr->bit_depth > 8) 2857 png_set_scale_16(png_ptr); 2858 break; 2859 2860 #ifdef __GNUC__ 2861 default: 2862 png_error(png_ptr, "bad data option (internal error)"); 2863 #endif 2864 } 2865 2866 if (cmap_entries > 256 || cmap_entries > image->colormap_entries) 2867 png_error(png_ptr, "color map overflow (BAD internal error)"); 2868 2869 image->colormap_entries = cmap_entries; 2870 2871 /* Double check using the recorded background index */ 2872 switch (output_processing) 2873 { 2874 case PNG_CMAP_NONE: 2875 if (background_index != PNG_CMAP_NONE_BACKGROUND) 2876 goto bad_background; 2877 break; 2878 2879 case PNG_CMAP_GA: 2880 if (background_index != PNG_CMAP_GA_BACKGROUND) 2881 goto bad_background; 2882 break; 2883 2884 case PNG_CMAP_TRANS: 2885 if (background_index >= cmap_entries || 2886 background_index != PNG_CMAP_TRANS_BACKGROUND) 2887 goto bad_background; 2888 break; 2889 2890 case PNG_CMAP_RGB: 2891 if (background_index != PNG_CMAP_RGB_BACKGROUND) 2892 goto bad_background; 2893 break; 2894 2895 case PNG_CMAP_RGB_ALPHA: 2896 if (background_index != PNG_CMAP_RGB_ALPHA_BACKGROUND) 2897 goto bad_background; 2898 break; 2899 2900 default: 2901 png_error(png_ptr, "bad processing option (internal error)"); 2902 2903 bad_background: 2904 png_error(png_ptr, "bad background index (internal error)"); 2905 } 2906 2907 display->colormap_processing = output_processing; 2908 2909 return 1/*ok*/; 2910 } 2911 2912 /* The final part of the color-map read called from png_image_finish_read. */ 2913 static int 2914 png_image_read_and_map(png_voidp argument) 2915 { 2916 png_image_read_control *display = png_voidcast(png_image_read_control*, 2917 argument); 2918 png_imagep image = display->image; 2919 png_structrp png_ptr = image->opaque->png_ptr; 2920 int passes; 2921 2922 /* Called when the libpng data must be transformed into the color-mapped 2923 * form. There is a local row buffer in display->local and this routine must 2924 * do the interlace handling. 2925 */ 2926 switch (png_ptr->interlaced) 2927 { 2928 case PNG_INTERLACE_NONE: 2929 passes = 1; 2930 break; 2931 2932 case PNG_INTERLACE_ADAM7: 2933 passes = PNG_INTERLACE_ADAM7_PASSES; 2934 break; 2935 2936 default: 2937 png_error(png_ptr, "unknown interlace type"); 2938 } 2939 2940 { 2941 png_uint_32 height = image->height; 2942 png_uint_32 width = image->width; 2943 int proc = display->colormap_processing; 2944 png_bytep first_row = png_voidcast(png_bytep, display->first_row); 2945 ptrdiff_t step_row = display->row_bytes; 2946 int pass; 2947 2948 for (pass = 0; pass < passes; ++pass) 2949 { 2950 unsigned int startx, stepx, stepy; 2951 png_uint_32 y; 2952 2953 if (png_ptr->interlaced == PNG_INTERLACE_ADAM7) 2954 { 2955 /* The row may be empty for a short image: */ 2956 if (PNG_PASS_COLS(width, pass) == 0) 2957 continue; 2958 2959 startx = PNG_PASS_START_COL(pass); 2960 stepx = PNG_PASS_COL_OFFSET(pass); 2961 y = PNG_PASS_START_ROW(pass); 2962 stepy = PNG_PASS_ROW_OFFSET(pass); 2963 } 2964 2965 else 2966 { 2967 y = 0; 2968 startx = 0; 2969 stepx = stepy = 1; 2970 } 2971 2972 for (; y<height; y += stepy) 2973 { 2974 png_bytep inrow = png_voidcast(png_bytep, display->local_row); 2975 png_bytep outrow = first_row + y * step_row; 2976 png_const_bytep end_row = outrow + width; 2977 2978 /* Read read the libpng data into the temporary buffer. */ 2979 png_read_row(png_ptr, inrow, NULL); 2980 2981 /* Now process the row according to the processing option, note 2982 * that the caller verifies that the format of the libpng output 2983 * data is as required. 2984 */ 2985 outrow += startx; 2986 switch (proc) 2987 { 2988 case PNG_CMAP_GA: 2989 for (; outrow < end_row; outrow += stepx) 2990 { 2991 /* The data is always in the PNG order */ 2992 unsigned int gray = *inrow++; 2993 unsigned int alpha = *inrow++; 2994 unsigned int entry; 2995 2996 /* NOTE: this code is copied as a comment in 2997 * make_ga_colormap above. Please update the 2998 * comment if you change this code! 2999 */ 3000 if (alpha > 229) /* opaque */ 3001 { 3002 entry = (231 * gray + 128) >> 8; 3003 } 3004 else if (alpha < 26) /* transparent */ 3005 { 3006 entry = 231; 3007 } 3008 else /* partially opaque */ 3009 { 3010 entry = 226 + 6 * PNG_DIV51(alpha) + PNG_DIV51(gray); 3011 } 3012 3013 *outrow = (png_byte)entry; 3014 } 3015 break; 3016 3017 case PNG_CMAP_TRANS: 3018 for (; outrow < end_row; outrow += stepx) 3019 { 3020 png_byte gray = *inrow++; 3021 png_byte alpha = *inrow++; 3022 3023 if (alpha == 0) 3024 *outrow = PNG_CMAP_TRANS_BACKGROUND; 3025 3026 else if (gray != PNG_CMAP_TRANS_BACKGROUND) 3027 *outrow = gray; 3028 3029 else 3030 *outrow = (png_byte)(PNG_CMAP_TRANS_BACKGROUND+1); 3031 } 3032 break; 3033 3034 case PNG_CMAP_RGB: 3035 for (; outrow < end_row; outrow += stepx) 3036 { 3037 *outrow = PNG_RGB_INDEX(inrow[0], inrow[1], inrow[2]); 3038 inrow += 3; 3039 } 3040 break; 3041 3042 case PNG_CMAP_RGB_ALPHA: 3043 for (; outrow < end_row; outrow += stepx) 3044 { 3045 unsigned int alpha = inrow[3]; 3046 3047 /* Because the alpha entries only hold alpha==0.5 values 3048 * split the processing at alpha==0.25 (64) and 0.75 3049 * (196). 3050 */ 3051 3052 if (alpha >= 196) 3053 *outrow = PNG_RGB_INDEX(inrow[0], inrow[1], 3054 inrow[2]); 3055 3056 else if (alpha < 64) 3057 *outrow = PNG_CMAP_RGB_ALPHA_BACKGROUND; 3058 3059 else 3060 { 3061 /* Likewise there are three entries for each of r, g 3062 * and b. We could select the entry by popcount on 3063 * the top two bits on those architectures that 3064 * support it, this is what the code below does, 3065 * crudely. 3066 */ 3067 unsigned int back_i = PNG_CMAP_RGB_ALPHA_BACKGROUND+1; 3068 3069 /* Here are how the values map: 3070 * 3071 * 0x00 .. 0x3f -> 0 3072 * 0x40 .. 0xbf -> 1 3073 * 0xc0 .. 0xff -> 2 3074 * 3075 * So, as above with the explicit alpha checks, the 3076 * breakpoints are at 64 and 196. 3077 */ 3078 if (inrow[0] & 0x80) back_i += 9; /* red */ 3079 if (inrow[0] & 0x40) back_i += 9; 3080 if (inrow[0] & 0x80) back_i += 3; /* green */ 3081 if (inrow[0] & 0x40) back_i += 3; 3082 if (inrow[0] & 0x80) back_i += 1; /* blue */ 3083 if (inrow[0] & 0x40) back_i += 1; 3084 3085 *outrow = (png_byte)back_i; 3086 } 3087 3088 inrow += 4; 3089 } 3090 break; 3091 3092 default: 3093 break; 3094 } 3095 } 3096 } 3097 } 3098 3099 return 1; 3100 } 3101 3102 static int 3103 png_image_read_colormapped(png_voidp argument) 3104 { 3105 png_image_read_control *display = png_voidcast(png_image_read_control*, 3106 argument); 3107 png_imagep image = display->image; 3108 png_controlp control = image->opaque; 3109 png_structrp png_ptr = control->png_ptr; 3110 png_inforp info_ptr = control->info_ptr; 3111 3112 int passes = 0; /* As a flag */ 3113 3114 PNG_SKIP_CHUNKS(png_ptr); 3115 3116 /* Update the 'info' structure and make sure the result is as required; first 3117 * make sure to turn on the interlace handling if it will be required 3118 * (because it can't be turned on *after* the call to png_read_update_info!) 3119 */ 3120 if (display->colormap_processing == PNG_CMAP_NONE) 3121 passes = png_set_interlace_handling(png_ptr); 3122 3123 png_read_update_info(png_ptr, info_ptr); 3124 3125 /* The expected output can be deduced from the colormap_processing option. */ 3126 switch (display->colormap_processing) 3127 { 3128 case PNG_CMAP_NONE: 3129 /* Output must be one channel and one byte per pixel, the output 3130 * encoding can be anything. 3131 */ 3132 if ((info_ptr->color_type == PNG_COLOR_TYPE_PALETTE || 3133 info_ptr->color_type == PNG_COLOR_TYPE_GRAY) && 3134 info_ptr->bit_depth == 8) 3135 break; 3136 3137 goto bad_output; 3138 3139 case PNG_CMAP_TRANS: 3140 case PNG_CMAP_GA: 3141 /* Output must be two channels and the 'G' one must be sRGB, the latter 3142 * can be checked with an exact number because it should have been set 3143 * to this number above! 3144 */ 3145 if (info_ptr->color_type == PNG_COLOR_TYPE_GRAY_ALPHA && 3146 info_ptr->bit_depth == 8 && 3147 png_ptr->screen_gamma == PNG_GAMMA_sRGB && 3148 image->colormap_entries == 256) 3149 break; 3150 3151 goto bad_output; 3152 3153 case PNG_CMAP_RGB: 3154 /* Output must be 8-bit sRGB encoded RGB */ 3155 if (info_ptr->color_type == PNG_COLOR_TYPE_RGB && 3156 info_ptr->bit_depth == 8 && 3157 png_ptr->screen_gamma == PNG_GAMMA_sRGB && 3158 image->colormap_entries == 216) 3159 break; 3160 3161 goto bad_output; 3162 3163 case PNG_CMAP_RGB_ALPHA: 3164 /* Output must be 8-bit sRGB encoded RGBA */ 3165 if (info_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA && 3166 info_ptr->bit_depth == 8 && 3167 png_ptr->screen_gamma == PNG_GAMMA_sRGB && 3168 image->colormap_entries == 244 /* 216 + 1 + 27 */) 3169 break; 3170 3171 /* goto bad_output; */ 3172 /* FALL THROUGH */ 3173 3174 default: 3175 bad_output: 3176 png_error(png_ptr, "bad color-map processing (internal error)"); 3177 } 3178 3179 /* Now read the rows. Do this here if it is possible to read directly into 3180 * the output buffer, otherwise allocate a local row buffer of the maximum 3181 * size libpng requires and call the relevant processing routine safely. 3182 */ 3183 { 3184 png_voidp first_row = display->buffer; 3185 ptrdiff_t row_bytes = display->row_stride; 3186 3187 /* The following expression is designed to work correctly whether it gives 3188 * a signed or an unsigned result. 3189 */ 3190 if (row_bytes < 0) 3191 { 3192 char *ptr = png_voidcast(char*, first_row); 3193 ptr += (image->height-1) * (-row_bytes); 3194 first_row = png_voidcast(png_voidp, ptr); 3195 } 3196 3197 display->first_row = first_row; 3198 display->row_bytes = row_bytes; 3199 } 3200 3201 if (passes == 0) 3202 { 3203 int result; 3204 png_voidp row = png_malloc(png_ptr, png_get_rowbytes(png_ptr, info_ptr)); 3205 3206 display->local_row = row; 3207 result = png_safe_execute(image, png_image_read_and_map, display); 3208 display->local_row = NULL; 3209 png_free(png_ptr, row); 3210 3211 return result; 3212 } 3213 3214 else 3215 { 3216 png_alloc_size_t row_bytes = display->row_bytes; 3217 3218 while (--passes >= 0) 3219 { 3220 png_uint_32 y = image->height; 3221 png_bytep row = png_voidcast(png_bytep, display->first_row); 3222 3223 while (y-- > 0) 3224 { 3225 png_read_row(png_ptr, row, NULL); 3226 row += row_bytes; 3227 } 3228 } 3229 3230 return 1; 3231 } 3232 } 3233 3234 /* Just the row reading part of png_image_read. */ 3235 static int 3236 png_image_read_composite(png_voidp argument) 3237 { 3238 png_image_read_control *display = png_voidcast(png_image_read_control*, 3239 argument); 3240 png_imagep image = display->image; 3241 png_structrp png_ptr = image->opaque->png_ptr; 3242 int passes; 3243 3244 switch (png_ptr->interlaced) 3245 { 3246 case PNG_INTERLACE_NONE: 3247 passes = 1; 3248 break; 3249 3250 case PNG_INTERLACE_ADAM7: 3251 passes = PNG_INTERLACE_ADAM7_PASSES; 3252 break; 3253 3254 default: 3255 png_error(png_ptr, "unknown interlace type"); 3256 } 3257 3258 { 3259 png_uint_32 height = image->height; 3260 png_uint_32 width = image->width; 3261 ptrdiff_t step_row = display->row_bytes; 3262 unsigned int channels = 3263 (image->format & PNG_FORMAT_FLAG_COLOR) != 0 ? 3 : 1; 3264 int pass; 3265 3266 for (pass = 0; pass < passes; ++pass) 3267 { 3268 unsigned int startx, stepx, stepy; 3269 png_uint_32 y; 3270 3271 if (png_ptr->interlaced == PNG_INTERLACE_ADAM7) 3272 { 3273 /* The row may be empty for a short image: */ 3274 if (PNG_PASS_COLS(width, pass) == 0) 3275 continue; 3276 3277 startx = PNG_PASS_START_COL(pass) * channels; 3278 stepx = PNG_PASS_COL_OFFSET(pass) * channels; 3279 y = PNG_PASS_START_ROW(pass); 3280 stepy = PNG_PASS_ROW_OFFSET(pass); 3281 } 3282 3283 else 3284 { 3285 y = 0; 3286 startx = 0; 3287 stepx = channels; 3288 stepy = 1; 3289 } 3290 3291 for (; y<height; y += stepy) 3292 { 3293 png_bytep inrow = png_voidcast(png_bytep, display->local_row); 3294 png_bytep outrow; 3295 png_const_bytep end_row; 3296 3297 /* Read the row, which is packed: */ 3298 png_read_row(png_ptr, inrow, NULL); 3299 3300 outrow = png_voidcast(png_bytep, display->first_row); 3301 outrow += y * step_row; 3302 end_row = outrow + width * channels; 3303 3304 /* Now do the composition on each pixel in this row. */ 3305 outrow += startx; 3306 for (; outrow < end_row; outrow += stepx) 3307 { 3308 png_byte alpha = inrow[channels]; 3309 3310 if (alpha > 0) /* else no change to the output */ 3311 { 3312 unsigned int c; 3313 3314 for (c=0; c<channels; ++c) 3315 { 3316 png_uint_32 component = inrow[c]; 3317 3318 if (alpha < 255) /* else just use component */ 3319 { 3320 /* This is PNG_OPTIMIZED_ALPHA, the component value 3321 * is a linear 8-bit value. Combine this with the 3322 * current outrow[c] value which is sRGB encoded. 3323 * Arithmetic here is 16-bits to preserve the output 3324 * values correctly. 3325 */ 3326 component *= 257*255; /* =65535 */ 3327 component += (255-alpha)*png_sRGB_table[outrow[c]]; 3328 3329 /* So 'component' is scaled by 255*65535 and is 3330 * therefore appropriate for the sRGB to linear 3331 * conversion table. 3332 */ 3333 component = PNG_sRGB_FROM_LINEAR(component); 3334 } 3335 3336 outrow[c] = (png_byte)component; 3337 } 3338 } 3339 3340 inrow += channels+1; /* components and alpha channel */ 3341 } 3342 } 3343 } 3344 } 3345 3346 return 1; 3347 } 3348 3349 /* The do_local_background case; called when all the following transforms are to 3350 * be done: 3351 * 3352 * PNG_RGB_TO_GRAY 3353 * PNG_COMPOSITE 3354 * PNG_GAMMA 3355 * 3356 * This is a work-around for the fact that both the PNG_RGB_TO_GRAY and 3357 * PNG_COMPOSITE code performs gamma correction, so we get double gamma 3358 * correction. The fix-up is to prevent the PNG_COMPOSITE operation from 3359 * happening inside libpng, so this routine sees an 8 or 16-bit gray+alpha 3360 * row and handles the removal or pre-multiplication of the alpha channel. 3361 */ 3362 static int 3363 png_image_read_background(png_voidp argument) 3364 { 3365 png_image_read_control *display = png_voidcast(png_image_read_control*, 3366 argument); 3367 png_imagep image = display->image; 3368 png_structrp png_ptr = image->opaque->png_ptr; 3369 png_inforp info_ptr = image->opaque->info_ptr; 3370 png_uint_32 height = image->height; 3371 png_uint_32 width = image->width; 3372 int pass, passes; 3373 3374 /* Double check the convoluted logic below. We expect to get here with 3375 * libpng doing rgb to gray and gamma correction but background processing 3376 * left to the png_image_read_background function. The rows libpng produce 3377 * might be 8 or 16-bit but should always have two channels; gray plus alpha. 3378 */ 3379 if ((png_ptr->transformations & PNG_RGB_TO_GRAY) == 0) 3380 png_error(png_ptr, "lost rgb to gray"); 3381 3382 if ((png_ptr->transformations & PNG_COMPOSE) != 0) 3383 png_error(png_ptr, "unexpected compose"); 3384 3385 if (png_get_channels(png_ptr, info_ptr) != 2) 3386 png_error(png_ptr, "lost/gained channels"); 3387 3388 /* Expect the 8-bit case to always remove the alpha channel */ 3389 if ((image->format & PNG_FORMAT_FLAG_LINEAR) == 0 && 3390 (image->format & PNG_FORMAT_FLAG_ALPHA) != 0) 3391 png_error(png_ptr, "unexpected 8-bit transformation"); 3392 3393 switch (png_ptr->interlaced) 3394 { 3395 case PNG_INTERLACE_NONE: 3396 passes = 1; 3397 break; 3398 3399 case PNG_INTERLACE_ADAM7: 3400 passes = PNG_INTERLACE_ADAM7_PASSES; 3401 break; 3402 3403 default: 3404 png_error(png_ptr, "unknown interlace type"); 3405 } 3406 3407 /* Use direct access to info_ptr here because otherwise the simplified API 3408 * would require PNG_EASY_ACCESS_SUPPORTED (just for this.) Note this is 3409 * checking the value after libpng expansions, not the original value in the 3410 * PNG. 3411 */ 3412 switch (info_ptr->bit_depth) 3413 { 3414 case 8: 3415 /* 8-bit sRGB gray values with an alpha channel; the alpha channel is 3416 * to be removed by composing on a background: either the row if 3417 * display->background is NULL or display->background->green if not. 3418 * Unlike the code above ALPHA_OPTIMIZED has *not* been done. 3419 */ 3420 { 3421 png_bytep first_row = png_voidcast(png_bytep, display->first_row); 3422 ptrdiff_t step_row = display->row_bytes; 3423 3424 for (pass = 0; pass < passes; ++pass) 3425 { 3426 png_bytep row = png_voidcast(png_bytep, 3427 display->first_row); 3428 unsigned int startx, stepx, stepy; 3429 png_uint_32 y; 3430 3431 if (png_ptr->interlaced == PNG_INTERLACE_ADAM7) 3432 { 3433 /* The row may be empty for a short image: */ 3434 if (PNG_PASS_COLS(width, pass) == 0) 3435 continue; 3436 3437 startx = PNG_PASS_START_COL(pass); 3438 stepx = PNG_PASS_COL_OFFSET(pass); 3439 y = PNG_PASS_START_ROW(pass); 3440 stepy = PNG_PASS_ROW_OFFSET(pass); 3441 } 3442 3443 else 3444 { 3445 y = 0; 3446 startx = 0; 3447 stepx = stepy = 1; 3448 } 3449 3450 if (display->background == NULL) 3451 { 3452 for (; y<height; y += stepy) 3453 { 3454 png_bytep inrow = png_voidcast(png_bytep, 3455 display->local_row); 3456 png_bytep outrow = first_row + y * step_row; 3457 png_const_bytep end_row = outrow + width; 3458 3459 /* Read the row, which is packed: */ 3460 png_read_row(png_ptr, inrow, NULL); 3461 3462 /* Now do the composition on each pixel in this row. */ 3463 outrow += startx; 3464 for (; outrow < end_row; outrow += stepx) 3465 { 3466 png_byte alpha = inrow[1]; 3467 3468 if (alpha > 0) /* else no change to the output */ 3469 { 3470 png_uint_32 component = inrow[0]; 3471 3472 if (alpha < 255) /* else just use component */ 3473 { 3474 /* Since PNG_OPTIMIZED_ALPHA was not set it is 3475 * necessary to invert the sRGB transfer 3476 * function and multiply the alpha out. 3477 */ 3478 component = png_sRGB_table[component] * alpha; 3479 component += png_sRGB_table[outrow[0]] * 3480 (255-alpha); 3481 component = PNG_sRGB_FROM_LINEAR(component); 3482 } 3483 3484 outrow[0] = (png_byte)component; 3485 } 3486 3487 inrow += 2; /* gray and alpha channel */ 3488 } 3489 } 3490 } 3491 3492 else /* constant background value */ 3493 { 3494 png_byte background8 = display->background->green; 3495 png_uint_16 background = png_sRGB_table[background8]; 3496 3497 for (; y<height; y += stepy) 3498 { 3499 png_bytep inrow = png_voidcast(png_bytep, 3500 display->local_row); 3501 png_bytep outrow = first_row + y * step_row; 3502 png_const_bytep end_row = outrow + width; 3503 3504 /* Read the row, which is packed: */ 3505 png_read_row(png_ptr, inrow, NULL); 3506 3507 /* Now do the composition on each pixel in this row. */ 3508 outrow += startx; 3509 for (; outrow < end_row; outrow += stepx) 3510 { 3511 png_byte alpha = inrow[1]; 3512 3513 if (alpha > 0) /* else use background */ 3514 { 3515 png_uint_32 component = inrow[0]; 3516 3517 if (alpha < 255) /* else just use component */ 3518 { 3519 component = png_sRGB_table[component] * alpha; 3520 component += background * (255-alpha); 3521 component = PNG_sRGB_FROM_LINEAR(component); 3522 } 3523 3524 outrow[0] = (png_byte)component; 3525 } 3526 3527 else 3528 outrow[0] = background8; 3529 3530 inrow += 2; /* gray and alpha channel */ 3531 } 3532 3533 row += display->row_bytes; 3534 } 3535 } 3536 } 3537 } 3538 break; 3539 3540 case 16: 3541 /* 16-bit linear with pre-multiplied alpha; the pre-multiplication must 3542 * still be done and, maybe, the alpha channel removed. This code also 3543 * handles the alpha-first option. 3544 */ 3545 { 3546 png_uint_16p first_row = png_voidcast(png_uint_16p, 3547 display->first_row); 3548 /* The division by two is safe because the caller passed in a 3549 * stride which was multiplied by 2 (below) to get row_bytes. 3550 */ 3551 ptrdiff_t step_row = display->row_bytes / 2; 3552 int preserve_alpha = (image->format & PNG_FORMAT_FLAG_ALPHA) != 0; 3553 unsigned int outchannels = 1+preserve_alpha; 3554 int swap_alpha = 0; 3555 3556 # ifdef PNG_SIMPLIFIED_READ_AFIRST_SUPPORTED 3557 if (preserve_alpha != 0 && 3558 (image->format & PNG_FORMAT_FLAG_AFIRST) != 0) 3559 swap_alpha = 1; 3560 # endif 3561 3562 for (pass = 0; pass < passes; ++pass) 3563 { 3564 unsigned int startx, stepx, stepy; 3565 png_uint_32 y; 3566 3567 /* The 'x' start and step are adjusted to output components here. 3568 */ 3569 if (png_ptr->interlaced == PNG_INTERLACE_ADAM7) 3570 { 3571 /* The row may be empty for a short image: */ 3572 if (PNG_PASS_COLS(width, pass) == 0) 3573 continue; 3574 3575 startx = PNG_PASS_START_COL(pass) * outchannels; 3576 stepx = PNG_PASS_COL_OFFSET(pass) * outchannels; 3577 y = PNG_PASS_START_ROW(pass); 3578 stepy = PNG_PASS_ROW_OFFSET(pass); 3579 } 3580 3581 else 3582 { 3583 y = 0; 3584 startx = 0; 3585 stepx = outchannels; 3586 stepy = 1; 3587 } 3588 3589 for (; y<height; y += stepy) 3590 { 3591 png_const_uint_16p inrow; 3592 png_uint_16p outrow = first_row + y*step_row; 3593 png_uint_16p end_row = outrow + width * outchannels; 3594 3595 /* Read the row, which is packed: */ 3596 png_read_row(png_ptr, png_voidcast(png_bytep, 3597 display->local_row), NULL); 3598 inrow = png_voidcast(png_const_uint_16p, display->local_row); 3599 3600 /* Now do the pre-multiplication on each pixel in this row. 3601 */ 3602 outrow += startx; 3603 for (; outrow < end_row; outrow += stepx) 3604 { 3605 png_uint_32 component = inrow[0]; 3606 png_uint_16 alpha = inrow[1]; 3607 3608 if (alpha > 0) /* else 0 */ 3609 { 3610 if (alpha < 65535) /* else just use component */ 3611 { 3612 component *= alpha; 3613 component += 32767; 3614 component /= 65535; 3615 } 3616 } 3617 3618 else 3619 component = 0; 3620 3621 outrow[swap_alpha] = (png_uint_16)component; 3622 if (preserve_alpha != 0) 3623 outrow[1 ^ swap_alpha] = alpha; 3624 3625 inrow += 2; /* components and alpha channel */ 3626 } 3627 } 3628 } 3629 } 3630 break; 3631 3632 #ifdef __GNUC__ 3633 default: 3634 png_error(png_ptr, "unexpected bit depth"); 3635 #endif 3636 } 3637 3638 return 1; 3639 } 3640 3641 /* The guts of png_image_finish_read as a png_safe_execute callback. */ 3642 static int 3643 png_image_read_direct(png_voidp argument) 3644 { 3645 png_image_read_control *display = png_voidcast(png_image_read_control*, 3646 argument); 3647 png_imagep image = display->image; 3648 png_structrp png_ptr = image->opaque->png_ptr; 3649 png_inforp info_ptr = image->opaque->info_ptr; 3650 3651 png_uint_32 format = image->format; 3652 int linear = (format & PNG_FORMAT_FLAG_LINEAR) != 0; 3653 int do_local_compose = 0; 3654 int do_local_background = 0; /* to avoid double gamma correction bug */ 3655 int passes = 0; 3656 3657 /* Add transforms to ensure the correct output format is produced then check 3658 * that the required implementation support is there. Always expand; always 3659 * need 8 bits minimum, no palette and expanded tRNS. 3660 */ 3661 png_set_expand(png_ptr); 3662 3663 /* Now check the format to see if it was modified. */ 3664 { 3665 png_uint_32 base_format = png_image_format(png_ptr) & 3666 ~PNG_FORMAT_FLAG_COLORMAP /* removed by png_set_expand */; 3667 png_uint_32 change = format ^ base_format; 3668 png_fixed_point output_gamma; 3669 int mode; /* alpha mode */ 3670 3671 /* Do this first so that we have a record if rgb to gray is happening. */ 3672 if ((change & PNG_FORMAT_FLAG_COLOR) != 0) 3673 { 3674 /* gray<->color transformation required. */ 3675 if ((format & PNG_FORMAT_FLAG_COLOR) != 0) 3676 png_set_gray_to_rgb(png_ptr); 3677 3678 else 3679 { 3680 /* libpng can't do both rgb to gray and 3681 * background/pre-multiplication if there is also significant gamma 3682 * correction, because both operations require linear colors and 3683 * the code only supports one transform doing the gamma correction. 3684 * Handle this by doing the pre-multiplication or background 3685 * operation in this code, if necessary. 3686 * 3687 * TODO: fix this by rewriting pngrtran.c (!) 3688 * 3689 * For the moment (given that fixing this in pngrtran.c is an 3690 * enormous change) 'do_local_background' is used to indicate that 3691 * the problem exists. 3692 */ 3693 if ((base_format & PNG_FORMAT_FLAG_ALPHA) != 0) 3694 do_local_background = 1/*maybe*/; 3695 3696 png_set_rgb_to_gray_fixed(png_ptr, PNG_ERROR_ACTION_NONE, 3697 PNG_RGB_TO_GRAY_DEFAULT, PNG_RGB_TO_GRAY_DEFAULT); 3698 } 3699 3700 change &= ~PNG_FORMAT_FLAG_COLOR; 3701 } 3702 3703 /* Set the gamma appropriately, linear for 16-bit input, sRGB otherwise. 3704 */ 3705 { 3706 png_fixed_point input_gamma_default; 3707 3708 if ((base_format & PNG_FORMAT_FLAG_LINEAR) != 0 && 3709 (image->flags & PNG_IMAGE_FLAG_16BIT_sRGB) == 0) 3710 input_gamma_default = PNG_GAMMA_LINEAR; 3711 else 3712 input_gamma_default = PNG_DEFAULT_sRGB; 3713 3714 /* Call png_set_alpha_mode to set the default for the input gamma; the 3715 * output gamma is set by a second call below. 3716 */ 3717 png_set_alpha_mode_fixed(png_ptr, PNG_ALPHA_PNG, input_gamma_default); 3718 } 3719 3720 if (linear != 0) 3721 { 3722 /* If there *is* an alpha channel in the input it must be multiplied 3723 * out; use PNG_ALPHA_STANDARD, otherwise just use PNG_ALPHA_PNG. 3724 */ 3725 if ((base_format & PNG_FORMAT_FLAG_ALPHA) != 0) 3726 mode = PNG_ALPHA_STANDARD; /* associated alpha */ 3727 3728 else 3729 mode = PNG_ALPHA_PNG; 3730 3731 output_gamma = PNG_GAMMA_LINEAR; 3732 } 3733 3734 else 3735 { 3736 mode = PNG_ALPHA_PNG; 3737 output_gamma = PNG_DEFAULT_sRGB; 3738 } 3739 3740 /* If 'do_local_background' is set check for the presence of gamma 3741 * correction; this is part of the work-round for the libpng bug 3742 * described above. 3743 * 3744 * TODO: fix libpng and remove this. 3745 */ 3746 if (do_local_background != 0) 3747 { 3748 png_fixed_point gtest; 3749 3750 /* This is 'png_gamma_threshold' from pngrtran.c; the test used for 3751 * gamma correction, the screen gamma hasn't been set on png_struct 3752 * yet; it's set below. png_struct::gamma, however, is set to the 3753 * final value. 3754 */ 3755 if (png_muldiv(>est, output_gamma, png_ptr->colorspace.gamma, 3756 PNG_FP_1) != 0 && png_gamma_significant(gtest) == 0) 3757 do_local_background = 0; 3758 3759 else if (mode == PNG_ALPHA_STANDARD) 3760 { 3761 do_local_background = 2/*required*/; 3762 mode = PNG_ALPHA_PNG; /* prevent libpng doing it */ 3763 } 3764 3765 /* else leave as 1 for the checks below */ 3766 } 3767 3768 /* If the bit-depth changes then handle that here. */ 3769 if ((change & PNG_FORMAT_FLAG_LINEAR) != 0) 3770 { 3771 if (linear != 0 /*16-bit output*/) 3772 png_set_expand_16(png_ptr); 3773 3774 else /* 8-bit output */ 3775 png_set_scale_16(png_ptr); 3776 3777 change &= ~PNG_FORMAT_FLAG_LINEAR; 3778 } 3779 3780 /* Now the background/alpha channel changes. */ 3781 if ((change & PNG_FORMAT_FLAG_ALPHA) != 0) 3782 { 3783 /* Removing an alpha channel requires composition for the 8-bit 3784 * formats; for the 16-bit it is already done, above, by the 3785 * pre-multiplication and the channel just needs to be stripped. 3786 */ 3787 if ((base_format & PNG_FORMAT_FLAG_ALPHA) != 0) 3788 { 3789 /* If RGB->gray is happening the alpha channel must be left and the 3790 * operation completed locally. 3791 * 3792 * TODO: fix libpng and remove this. 3793 */ 3794 if (do_local_background != 0) 3795 do_local_background = 2/*required*/; 3796 3797 /* 16-bit output: just remove the channel */ 3798 else if (linear != 0) /* compose on black (well, pre-multiply) */ 3799 png_set_strip_alpha(png_ptr); 3800 3801 /* 8-bit output: do an appropriate compose */ 3802 else if (display->background != NULL) 3803 { 3804 png_color_16 c; 3805 3806 c.index = 0; /*unused*/ 3807 c.red = display->background->red; 3808 c.green = display->background->green; 3809 c.blue = display->background->blue; 3810 c.gray = display->background->green; 3811 3812 /* This is always an 8-bit sRGB value, using the 'green' channel 3813 * for gray is much better than calculating the luminance here; 3814 * we can get off-by-one errors in that calculation relative to 3815 * the app expectations and that will show up in transparent 3816 * pixels. 3817 */ 3818 png_set_background_fixed(png_ptr, &c, 3819 PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/, 3820 0/*gamma: not used*/); 3821 } 3822 3823 else /* compose on row: implemented below. */ 3824 { 3825 do_local_compose = 1; 3826 /* This leaves the alpha channel in the output, so it has to be 3827 * removed by the code below. Set the encoding to the 'OPTIMIZE' 3828 * one so the code only has to hack on the pixels that require 3829 * composition. 3830 */ 3831 mode = PNG_ALPHA_OPTIMIZED; 3832 } 3833 } 3834 3835 else /* output needs an alpha channel */ 3836 { 3837 /* This is tricky because it happens before the swap operation has 3838 * been accomplished; however, the swap does *not* swap the added 3839 * alpha channel (weird API), so it must be added in the correct 3840 * place. 3841 */ 3842 png_uint_32 filler; /* opaque filler */ 3843 int where; 3844 3845 if (linear != 0) 3846 filler = 65535; 3847 3848 else 3849 filler = 255; 3850 3851 # ifdef PNG_FORMAT_AFIRST_SUPPORTED 3852 if ((format & PNG_FORMAT_FLAG_AFIRST) != 0) 3853 { 3854 where = PNG_FILLER_BEFORE; 3855 change &= ~PNG_FORMAT_FLAG_AFIRST; 3856 } 3857 3858 else 3859 # endif 3860 where = PNG_FILLER_AFTER; 3861 3862 png_set_add_alpha(png_ptr, filler, where); 3863 } 3864 3865 /* This stops the (irrelevant) call to swap_alpha below. */ 3866 change &= ~PNG_FORMAT_FLAG_ALPHA; 3867 } 3868 3869 /* Now set the alpha mode correctly; this is always done, even if there is 3870 * no alpha channel in either the input or the output because it correctly 3871 * sets the output gamma. 3872 */ 3873 png_set_alpha_mode_fixed(png_ptr, mode, output_gamma); 3874 3875 # ifdef PNG_FORMAT_BGR_SUPPORTED 3876 if ((change & PNG_FORMAT_FLAG_BGR) != 0) 3877 { 3878 /* Check only the output format; PNG is never BGR; don't do this if 3879 * the output is gray, but fix up the 'format' value in that case. 3880 */ 3881 if ((format & PNG_FORMAT_FLAG_COLOR) != 0) 3882 png_set_bgr(png_ptr); 3883 3884 else 3885 format &= ~PNG_FORMAT_FLAG_BGR; 3886 3887 change &= ~PNG_FORMAT_FLAG_BGR; 3888 } 3889 # endif 3890 3891 # ifdef PNG_FORMAT_AFIRST_SUPPORTED 3892 if ((change & PNG_FORMAT_FLAG_AFIRST) != 0) 3893 { 3894 /* Only relevant if there is an alpha channel - it's particularly 3895 * important to handle this correctly because do_local_compose may 3896 * be set above and then libpng will keep the alpha channel for this 3897 * code to remove. 3898 */ 3899 if ((format & PNG_FORMAT_FLAG_ALPHA) != 0) 3900 { 3901 /* Disable this if doing a local background, 3902 * TODO: remove this when local background is no longer required. 3903 */ 3904 if (do_local_background != 2) 3905 png_set_swap_alpha(png_ptr); 3906 } 3907 3908 else 3909 format &= ~PNG_FORMAT_FLAG_AFIRST; 3910 3911 change &= ~PNG_FORMAT_FLAG_AFIRST; 3912 } 3913 # endif 3914 3915 /* If the *output* is 16-bit then we need to check for a byte-swap on this 3916 * architecture. 3917 */ 3918 if (linear != 0) 3919 { 3920 PNG_CONST png_uint_16 le = 0x0001; 3921 3922 if ((*(png_const_bytep) & le) != 0) 3923 png_set_swap(png_ptr); 3924 } 3925 3926 /* If change is not now 0 some transformation is missing - error out. */ 3927 if (change != 0) 3928 png_error(png_ptr, "png_read_image: unsupported transformation"); 3929 } 3930 3931 PNG_SKIP_CHUNKS(png_ptr); 3932 3933 /* Update the 'info' structure and make sure the result is as required; first 3934 * make sure to turn on the interlace handling if it will be required 3935 * (because it can't be turned on *after* the call to png_read_update_info!) 3936 * 3937 * TODO: remove the do_local_background fixup below. 3938 */ 3939 if (do_local_compose == 0 && do_local_background != 2) 3940 passes = png_set_interlace_handling(png_ptr); 3941 3942 png_read_update_info(png_ptr, info_ptr); 3943 3944 { 3945 png_uint_32 info_format = 0; 3946 3947 if ((info_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0) 3948 info_format |= PNG_FORMAT_FLAG_COLOR; 3949 3950 if ((info_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0) 3951 { 3952 /* do_local_compose removes this channel below. */ 3953 if (do_local_compose == 0) 3954 { 3955 /* do_local_background does the same if required. */ 3956 if (do_local_background != 2 || 3957 (format & PNG_FORMAT_FLAG_ALPHA) != 0) 3958 info_format |= PNG_FORMAT_FLAG_ALPHA; 3959 } 3960 } 3961 3962 else if (do_local_compose != 0) /* internal error */ 3963 png_error(png_ptr, "png_image_read: alpha channel lost"); 3964 3965 if (info_ptr->bit_depth == 16) 3966 info_format |= PNG_FORMAT_FLAG_LINEAR; 3967 3968 # ifdef PNG_FORMAT_BGR_SUPPORTED 3969 if ((png_ptr->transformations & PNG_BGR) != 0) 3970 info_format |= PNG_FORMAT_FLAG_BGR; 3971 # endif 3972 3973 # ifdef PNG_FORMAT_AFIRST_SUPPORTED 3974 if (do_local_background == 2) 3975 { 3976 if ((format & PNG_FORMAT_FLAG_AFIRST) != 0) 3977 info_format |= PNG_FORMAT_FLAG_AFIRST; 3978 } 3979 3980 if ((png_ptr->transformations & PNG_SWAP_ALPHA) != 0 || 3981 ((png_ptr->transformations & PNG_ADD_ALPHA) != 0 && 3982 (png_ptr->flags & PNG_FLAG_FILLER_AFTER) == 0)) 3983 { 3984 if (do_local_background == 2) 3985 png_error(png_ptr, "unexpected alpha swap transformation"); 3986 3987 info_format |= PNG_FORMAT_FLAG_AFIRST; 3988 } 3989 # endif 3990 3991 /* This is actually an internal error. */ 3992 if (info_format != format) 3993 png_error(png_ptr, "png_read_image: invalid transformations"); 3994 } 3995 3996 /* Now read the rows. If do_local_compose is set then it is necessary to use 3997 * a local row buffer. The output will be GA, RGBA or BGRA and must be 3998 * converted to G, RGB or BGR as appropriate. The 'local_row' member of the 3999 * display acts as a flag. 4000 */ 4001 { 4002 png_voidp first_row = display->buffer; 4003 ptrdiff_t row_bytes = display->row_stride; 4004 4005 if (linear != 0) 4006 row_bytes *= 2; 4007 4008 /* The following expression is designed to work correctly whether it gives 4009 * a signed or an unsigned result. 4010 */ 4011 if (row_bytes < 0) 4012 { 4013 char *ptr = png_voidcast(char*, first_row); 4014 ptr += (image->height-1) * (-row_bytes); 4015 first_row = png_voidcast(png_voidp, ptr); 4016 } 4017 4018 display->first_row = first_row; 4019 display->row_bytes = row_bytes; 4020 } 4021 4022 if (do_local_compose != 0) 4023 { 4024 int result; 4025 png_voidp row = png_malloc(png_ptr, png_get_rowbytes(png_ptr, info_ptr)); 4026 4027 display->local_row = row; 4028 result = png_safe_execute(image, png_image_read_composite, display); 4029 display->local_row = NULL; 4030 png_free(png_ptr, row); 4031 4032 return result; 4033 } 4034 4035 else if (do_local_background == 2) 4036 { 4037 int result; 4038 png_voidp row = png_malloc(png_ptr, png_get_rowbytes(png_ptr, info_ptr)); 4039 4040 display->local_row = row; 4041 result = png_safe_execute(image, png_image_read_background, display); 4042 display->local_row = NULL; 4043 png_free(png_ptr, row); 4044 4045 return result; 4046 } 4047 4048 else 4049 { 4050 png_alloc_size_t row_bytes = display->row_bytes; 4051 4052 while (--passes >= 0) 4053 { 4054 png_uint_32 y = image->height; 4055 png_bytep row = png_voidcast(png_bytep, display->first_row); 4056 4057 while (y-- > 0) 4058 { 4059 png_read_row(png_ptr, row, NULL); 4060 row += row_bytes; 4061 } 4062 } 4063 4064 return 1; 4065 } 4066 } 4067 4068 int PNGAPI 4069 png_image_finish_read(png_imagep image, png_const_colorp background, 4070 void *buffer, png_int_32 row_stride, void *colormap) 4071 { 4072 if (image != NULL && image->version == PNG_IMAGE_VERSION) 4073 { 4074 /* Check for row_stride overflow. This check is not performed on the 4075 * original PNG format because it may not occur in the output PNG format 4076 * and libpng deals with the issues of reading the original. 4077 */ 4078 const unsigned int channels = PNG_IMAGE_PIXEL_CHANNELS(image->format); 4079 4080 if (image->width <= 0x7FFFFFFFU/channels) /* no overflow */ 4081 { 4082 png_uint_32 check; 4083 const png_uint_32 png_row_stride = image->width * channels; 4084 4085 if (row_stride == 0) 4086 row_stride = (png_int_32)/*SAFE*/png_row_stride; 4087 4088 if (row_stride < 0) 4089 check = -row_stride; 4090 4091 else 4092 check = row_stride; 4093 4094 if (image->opaque != NULL && buffer != NULL && check >= png_row_stride) 4095 { 4096 /* Now check for overflow of the image buffer calculation; this 4097 * limits the whole image size to 32 bits for API compatibility with 4098 * the current, 32-bit, PNG_IMAGE_BUFFER_SIZE macro. 4099 */ 4100 if (image->height <= 0xFFFFFFFF/png_row_stride) 4101 { 4102 if ((image->format & PNG_FORMAT_FLAG_COLORMAP) == 0 || 4103 (image->colormap_entries > 0 && colormap != NULL)) 4104 { 4105 int result; 4106 png_image_read_control display; 4107 4108 memset(&display, 0, (sizeof display)); 4109 display.image = image; 4110 display.buffer = buffer; 4111 display.row_stride = row_stride; 4112 display.colormap = colormap; 4113 display.background = background; 4114 display.local_row = NULL; 4115 4116 /* Choose the correct 'end' routine; for the color-map case 4117 * all the setup has already been done. 4118 */ 4119 if ((image->format & PNG_FORMAT_FLAG_COLORMAP) != 0) 4120 result = png_safe_execute(image, 4121 png_image_read_colormap, &display) && 4122 png_safe_execute(image, 4123 png_image_read_colormapped, &display); 4124 4125 else 4126 result = 4127 png_safe_execute(image, 4128 png_image_read_direct, &display); 4129 4130 png_image_free(image); 4131 return result; 4132 } 4133 4134 else 4135 return png_image_error(image, 4136 "png_image_finish_read[color-map]: no color-map"); 4137 } 4138 4139 else 4140 return png_image_error(image, 4141 "png_image_finish_read: image too large"); 4142 } 4143 4144 else 4145 return png_image_error(image, 4146 "png_image_finish_read: invalid argument"); 4147 } 4148 4149 else 4150 return png_image_error(image, 4151 "png_image_finish_read: row_stride too large"); 4152 } 4153 4154 else if (image != NULL) 4155 return png_image_error(image, 4156 "png_image_finish_read: damaged PNG_IMAGE_VERSION"); 4157 4158 return 0; 4159 } 4160 4161 #endif /* SIMPLIFIED_READ */ 4162 #endif /* READ */ 4163
