1 2 /* pngwutil.c - utilities to write a PNG file 3 * 4 * Copyright (c) 2018-2022 Cosmin Truta 5 * Copyright (c) 1998-2002,2004,2006-2018 Glenn Randers-Pehrson 6 * Copyright (c) 1996-1997 Andreas Dilger 7 * 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 14 #include "pngpriv.h" 15 16 #ifdef PNG_WRITE_SUPPORTED 17 18 #ifdef PNG_WRITE_INT_FUNCTIONS_SUPPORTED 19 /* Place a 32-bit number into a buffer in PNG byte order. We work 20 * with unsigned numbers for convenience, although one supported 21 * ancillary chunk uses signed (two's complement) numbers. 22 */ 23 void PNGAPI 24 png_save_uint_32(png_bytep buf, png_uint_32 i) 25 { 26 buf[0] = (png_byte)((i >> 24) & 0xffU); 27 buf[1] = (png_byte)((i >> 16) & 0xffU); 28 buf[2] = (png_byte)((i >> 8) & 0xffU); 29 buf[3] = (png_byte)( i & 0xffU); 30 } 31 32 /* Place a 16-bit number into a buffer in PNG byte order. 33 * The parameter is declared unsigned int, not png_uint_16, 34 * just to avoid potential problems on pre-ANSI C compilers. 35 */ 36 void PNGAPI 37 png_save_uint_16(png_bytep buf, unsigned int i) 38 { 39 buf[0] = (png_byte)((i >> 8) & 0xffU); 40 buf[1] = (png_byte)( i & 0xffU); 41 } 42 #endif 43 44 /* Simple function to write the signature. If we have already written 45 * the magic bytes of the signature, or more likely, the PNG stream is 46 * being embedded into another stream and doesn't need its own signature, 47 * we should call png_set_sig_bytes() to tell libpng how many of the 48 * bytes have already been written. 49 */ 50 void PNGAPI 51 png_write_sig(png_structrp png_ptr) 52 { 53 png_byte png_signature[8] = {137, 80, 78, 71, 13, 10, 26, 10}; 54 55 #ifdef PNG_IO_STATE_SUPPORTED 56 /* Inform the I/O callback that the signature is being written */ 57 png_ptr->io_state = PNG_IO_WRITING | PNG_IO_SIGNATURE; 58 #endif 59 60 /* Write the rest of the 8 byte signature */ 61 png_write_data(png_ptr, &png_signature[png_ptr->sig_bytes], 62 (size_t)(8 - png_ptr->sig_bytes)); 63 64 if (png_ptr->sig_bytes < 3) 65 png_ptr->mode |= PNG_HAVE_PNG_SIGNATURE; 66 } 67 68 /* Write the start of a PNG chunk. The type is the chunk type. 69 * The total_length is the sum of the lengths of all the data you will be 70 * passing in png_write_chunk_data(). 71 */ 72 static void 73 png_write_chunk_header(png_structrp png_ptr, png_uint_32 chunk_name, 74 png_uint_32 length) 75 { 76 png_byte buf[8]; 77 78 #if defined(PNG_DEBUG) && (PNG_DEBUG > 0) 79 PNG_CSTRING_FROM_CHUNK(buf, chunk_name); 80 png_debug2(0, "Writing %s chunk, length = %lu", buf, (unsigned long)length); 81 #endif 82 83 if (png_ptr == NULL) 84 return; 85 86 #ifdef PNG_IO_STATE_SUPPORTED 87 /* Inform the I/O callback that the chunk header is being written. 88 * PNG_IO_CHUNK_HDR requires a single I/O call. 89 */ 90 png_ptr->io_state = PNG_IO_WRITING | PNG_IO_CHUNK_HDR; 91 #endif 92 93 /* Write the length and the chunk name */ 94 png_save_uint_32(buf, length); 95 png_save_uint_32(buf + 4, chunk_name); 96 png_write_data(png_ptr, buf, 8); 97 98 /* Put the chunk name into png_ptr->chunk_name */ 99 png_ptr->chunk_name = chunk_name; 100 101 /* Reset the crc and run it over the chunk name */ 102 png_reset_crc(png_ptr); 103 104 png_calculate_crc(png_ptr, buf + 4, 4); 105 106 #ifdef PNG_IO_STATE_SUPPORTED 107 /* Inform the I/O callback that chunk data will (possibly) be written. 108 * PNG_IO_CHUNK_DATA does NOT require a specific number of I/O calls. 109 */ 110 png_ptr->io_state = PNG_IO_WRITING | PNG_IO_CHUNK_DATA; 111 #endif 112 } 113 114 void PNGAPI 115 png_write_chunk_start(png_structrp png_ptr, png_const_bytep chunk_string, 116 png_uint_32 length) 117 { 118 png_write_chunk_header(png_ptr, PNG_CHUNK_FROM_STRING(chunk_string), length); 119 } 120 121 /* Write the data of a PNG chunk started with png_write_chunk_header(). 122 * Note that multiple calls to this function are allowed, and that the 123 * sum of the lengths from these calls *must* add up to the total_length 124 * given to png_write_chunk_header(). 125 */ 126 void PNGAPI 127 png_write_chunk_data(png_structrp png_ptr, png_const_bytep data, size_t length) 128 { 129 /* Write the data, and run the CRC over it */ 130 if (png_ptr == NULL) 131 return; 132 133 if (data != NULL && length > 0) 134 { 135 png_write_data(png_ptr, data, length); 136 137 /* Update the CRC after writing the data, 138 * in case the user I/O routine alters it. 139 */ 140 png_calculate_crc(png_ptr, data, length); 141 } 142 } 143 144 /* Finish a chunk started with png_write_chunk_header(). */ 145 void PNGAPI 146 png_write_chunk_end(png_structrp png_ptr) 147 { 148 png_byte buf[4]; 149 150 if (png_ptr == NULL) return; 151 152 #ifdef PNG_IO_STATE_SUPPORTED 153 /* Inform the I/O callback that the chunk CRC is being written. 154 * PNG_IO_CHUNK_CRC requires a single I/O function call. 155 */ 156 png_ptr->io_state = PNG_IO_WRITING | PNG_IO_CHUNK_CRC; 157 #endif 158 159 /* Write the crc in a single operation */ 160 png_save_uint_32(buf, png_ptr->crc); 161 162 png_write_data(png_ptr, buf, 4); 163 } 164 165 /* Write a PNG chunk all at once. The type is an array of ASCII characters 166 * representing the chunk name. The array must be at least 4 bytes in 167 * length, and does not need to be null terminated. To be safe, pass the 168 * pre-defined chunk names here, and if you need a new one, define it 169 * where the others are defined. The length is the length of the data. 170 * All the data must be present. If that is not possible, use the 171 * png_write_chunk_start(), png_write_chunk_data(), and png_write_chunk_end() 172 * functions instead. 173 */ 174 static void 175 png_write_complete_chunk(png_structrp png_ptr, png_uint_32 chunk_name, 176 png_const_bytep data, size_t length) 177 { 178 if (png_ptr == NULL) 179 return; 180 181 /* On 64-bit architectures 'length' may not fit in a png_uint_32. */ 182 if (length > PNG_UINT_31_MAX) 183 png_error(png_ptr, "length exceeds PNG maximum"); 184 185 png_write_chunk_header(png_ptr, chunk_name, (png_uint_32)length); 186 png_write_chunk_data(png_ptr, data, length); 187 png_write_chunk_end(png_ptr); 188 } 189 190 /* This is the API that calls the internal function above. */ 191 void PNGAPI 192 png_write_chunk(png_structrp png_ptr, png_const_bytep chunk_string, 193 png_const_bytep data, size_t length) 194 { 195 png_write_complete_chunk(png_ptr, PNG_CHUNK_FROM_STRING(chunk_string), data, 196 length); 197 } 198 199 /* This is used below to find the size of an image to pass to png_deflate_claim, 200 * so it only needs to be accurate if the size is less than 16384 bytes (the 201 * point at which a lower LZ window size can be used.) 202 */ 203 static png_alloc_size_t 204 png_image_size(png_structrp png_ptr) 205 { 206 /* Only return sizes up to the maximum of a png_uint_32; do this by limiting 207 * the width and height used to 15 bits. 208 */ 209 png_uint_32 h = png_ptr->height; 210 211 if (png_ptr->rowbytes < 32768 && h < 32768) 212 { 213 if (png_ptr->interlaced != 0) 214 { 215 /* Interlacing makes the image larger because of the replication of 216 * both the filter byte and the padding to a byte boundary. 217 */ 218 png_uint_32 w = png_ptr->width; 219 unsigned int pd = png_ptr->pixel_depth; 220 png_alloc_size_t cb_base; 221 int pass; 222 223 for (cb_base=0, pass=0; pass<=6; ++pass) 224 { 225 png_uint_32 pw = PNG_PASS_COLS(w, pass); 226 227 if (pw > 0) 228 cb_base += (PNG_ROWBYTES(pd, pw)+1) * PNG_PASS_ROWS(h, pass); 229 } 230 231 return cb_base; 232 } 233 234 else 235 return (png_ptr->rowbytes+1) * h; 236 } 237 238 else 239 return 0xffffffffU; 240 } 241 242 #ifdef PNG_WRITE_OPTIMIZE_CMF_SUPPORTED 243 /* This is the code to hack the first two bytes of the deflate stream (the 244 * deflate header) to correct the windowBits value to match the actual data 245 * size. Note that the second argument is the *uncompressed* size but the 246 * first argument is the *compressed* data (and it must be deflate 247 * compressed.) 248 */ 249 static void 250 optimize_cmf(png_bytep data, png_alloc_size_t data_size) 251 { 252 /* Optimize the CMF field in the zlib stream. The resultant zlib stream is 253 * still compliant to the stream specification. 254 */ 255 if (data_size <= 16384) /* else windowBits must be 15 */ 256 { 257 unsigned int z_cmf = data[0]; /* zlib compression method and flags */ 258 259 if ((z_cmf & 0x0f) == 8 && (z_cmf & 0xf0) <= 0x70) 260 { 261 unsigned int z_cinfo; 262 unsigned int half_z_window_size; 263 264 z_cinfo = z_cmf >> 4; 265 half_z_window_size = 1U << (z_cinfo + 7); 266 267 if (data_size <= half_z_window_size) /* else no change */ 268 { 269 unsigned int tmp; 270 271 do 272 { 273 half_z_window_size >>= 1; 274 --z_cinfo; 275 } 276 while (z_cinfo > 0 && data_size <= half_z_window_size); 277 278 z_cmf = (z_cmf & 0x0f) | (z_cinfo << 4); 279 280 data[0] = (png_byte)z_cmf; 281 tmp = data[1] & 0xe0; 282 tmp += 0x1f - ((z_cmf << 8) + tmp) % 0x1f; 283 data[1] = (png_byte)tmp; 284 } 285 } 286 } 287 } 288 #endif /* WRITE_OPTIMIZE_CMF */ 289 290 /* Initialize the compressor for the appropriate type of compression. */ 291 static int 292 png_deflate_claim(png_structrp png_ptr, png_uint_32 owner, 293 png_alloc_size_t data_size) 294 { 295 if (png_ptr->zowner != 0) 296 { 297 #if defined(PNG_WARNINGS_SUPPORTED) || defined(PNG_ERROR_TEXT_SUPPORTED) 298 char msg[64]; 299 300 PNG_STRING_FROM_CHUNK(msg, owner); 301 msg[4] = ':'; 302 msg[5] = ' '; 303 PNG_STRING_FROM_CHUNK(msg+6, png_ptr->zowner); 304 /* So the message that results is "<chunk> using zstream"; this is an 305 * internal error, but is very useful for debugging. i18n requirements 306 * are minimal. 307 */ 308 (void)png_safecat(msg, (sizeof msg), 10, " using zstream"); 309 #endif 310 #if PNG_RELEASE_BUILD 311 png_warning(png_ptr, msg); 312 313 /* Attempt sane error recovery */ 314 if (png_ptr->zowner == png_IDAT) /* don't steal from IDAT */ 315 { 316 png_ptr->zstream.msg = PNGZ_MSG_CAST("in use by IDAT"); 317 return Z_STREAM_ERROR; 318 } 319 320 png_ptr->zowner = 0; 321 #else 322 png_error(png_ptr, msg); 323 #endif 324 } 325 326 { 327 int level = png_ptr->zlib_level; 328 int method = png_ptr->zlib_method; 329 int windowBits = png_ptr->zlib_window_bits; 330 int memLevel = png_ptr->zlib_mem_level; 331 int strategy; /* set below */ 332 int ret; /* zlib return code */ 333 334 if (owner == png_IDAT) 335 { 336 if ((png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_STRATEGY) != 0) 337 strategy = png_ptr->zlib_strategy; 338 339 else if (png_ptr->do_filter != PNG_FILTER_NONE) 340 strategy = PNG_Z_DEFAULT_STRATEGY; 341 342 else 343 strategy = PNG_Z_DEFAULT_NOFILTER_STRATEGY; 344 } 345 346 else 347 { 348 #ifdef PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED 349 level = png_ptr->zlib_text_level; 350 method = png_ptr->zlib_text_method; 351 windowBits = png_ptr->zlib_text_window_bits; 352 memLevel = png_ptr->zlib_text_mem_level; 353 strategy = png_ptr->zlib_text_strategy; 354 #else 355 /* If customization is not supported the values all come from the 356 * IDAT values except for the strategy, which is fixed to the 357 * default. (This is the pre-1.6.0 behavior too, although it was 358 * implemented in a very different way.) 359 */ 360 strategy = Z_DEFAULT_STRATEGY; 361 #endif 362 } 363 364 /* Adjust 'windowBits' down if larger than 'data_size'; to stop this 365 * happening just pass 32768 as the data_size parameter. Notice that zlib 366 * requires an extra 262 bytes in the window in addition to the data to be 367 * able to see the whole of the data, so if data_size+262 takes us to the 368 * next windowBits size we need to fix up the value later. (Because even 369 * though deflate needs the extra window, inflate does not!) 370 */ 371 if (data_size <= 16384) 372 { 373 /* IMPLEMENTATION NOTE: this 'half_window_size' stuff is only here to 374 * work round a Microsoft Visual C misbehavior which, contrary to C-90, 375 * widens the result of the following shift to 64-bits if (and, 376 * apparently, only if) it is used in a test. 377 */ 378 unsigned int half_window_size = 1U << (windowBits-1); 379 380 while (data_size + 262 <= half_window_size) 381 { 382 half_window_size >>= 1; 383 --windowBits; 384 } 385 } 386 387 /* Check against the previous initialized values, if any. */ 388 if ((png_ptr->flags & PNG_FLAG_ZSTREAM_INITIALIZED) != 0 && 389 (png_ptr->zlib_set_level != level || 390 png_ptr->zlib_set_method != method || 391 png_ptr->zlib_set_window_bits != windowBits || 392 png_ptr->zlib_set_mem_level != memLevel || 393 png_ptr->zlib_set_strategy != strategy)) 394 { 395 if (deflateEnd(&png_ptr->zstream) != Z_OK) 396 png_warning(png_ptr, "deflateEnd failed (ignored)"); 397 398 png_ptr->flags &= ~PNG_FLAG_ZSTREAM_INITIALIZED; 399 } 400 401 /* For safety clear out the input and output pointers (currently zlib 402 * doesn't use them on Init, but it might in the future). 403 */ 404 png_ptr->zstream.next_in = NULL; 405 png_ptr->zstream.avail_in = 0; 406 png_ptr->zstream.next_out = NULL; 407 png_ptr->zstream.avail_out = 0; 408 409 /* Now initialize if required, setting the new parameters, otherwise just 410 * do a simple reset to the previous parameters. 411 */ 412 if ((png_ptr->flags & PNG_FLAG_ZSTREAM_INITIALIZED) != 0) 413 ret = deflateReset(&png_ptr->zstream); 414 415 else 416 { 417 ret = deflateInit2(&png_ptr->zstream, level, method, windowBits, 418 memLevel, strategy); 419 420 if (ret == Z_OK) 421 png_ptr->flags |= PNG_FLAG_ZSTREAM_INITIALIZED; 422 } 423 424 /* The return code is from either deflateReset or deflateInit2; they have 425 * pretty much the same set of error codes. 426 */ 427 if (ret == Z_OK) 428 png_ptr->zowner = owner; 429 430 else 431 png_zstream_error(png_ptr, ret); 432 433 return ret; 434 } 435 } 436 437 /* Clean up (or trim) a linked list of compression buffers. */ 438 void /* PRIVATE */ 439 png_free_buffer_list(png_structrp png_ptr, png_compression_bufferp *listp) 440 { 441 png_compression_bufferp list = *listp; 442 443 if (list != NULL) 444 { 445 *listp = NULL; 446 447 do 448 { 449 png_compression_bufferp next = list->next; 450 451 png_free(png_ptr, list); 452 list = next; 453 } 454 while (list != NULL); 455 } 456 } 457 458 #ifdef PNG_WRITE_COMPRESSED_TEXT_SUPPORTED 459 /* This pair of functions encapsulates the operation of (a) compressing a 460 * text string, and (b) issuing it later as a series of chunk data writes. 461 * The compression_state structure is shared context for these functions 462 * set up by the caller to allow access to the relevant local variables. 463 * 464 * compression_buffer (new in 1.6.0) is just a linked list of zbuffer_size 465 * temporary buffers. From 1.6.0 it is retained in png_struct so that it will 466 * be correctly freed in the event of a write error (previous implementations 467 * just leaked memory.) 468 */ 469 typedef struct 470 { 471 png_const_bytep input; /* The uncompressed input data */ 472 png_alloc_size_t input_len; /* Its length */ 473 png_uint_32 output_len; /* Final compressed length */ 474 png_byte output[1024]; /* First block of output */ 475 } compression_state; 476 477 static void 478 png_text_compress_init(compression_state *comp, png_const_bytep input, 479 png_alloc_size_t input_len) 480 { 481 comp->input = input; 482 comp->input_len = input_len; 483 comp->output_len = 0; 484 } 485 486 /* Compress the data in the compression state input */ 487 static int 488 png_text_compress(png_structrp png_ptr, png_uint_32 chunk_name, 489 compression_state *comp, png_uint_32 prefix_len) 490 { 491 int ret; 492 493 /* To find the length of the output it is necessary to first compress the 494 * input. The result is buffered rather than using the two-pass algorithm 495 * that is used on the inflate side; deflate is assumed to be slower and a 496 * PNG writer is assumed to have more memory available than a PNG reader. 497 * 498 * IMPLEMENTATION NOTE: the zlib API deflateBound() can be used to find an 499 * upper limit on the output size, but it is always bigger than the input 500 * size so it is likely to be more efficient to use this linked-list 501 * approach. 502 */ 503 ret = png_deflate_claim(png_ptr, chunk_name, comp->input_len); 504 505 if (ret != Z_OK) 506 return ret; 507 508 /* Set up the compression buffers, we need a loop here to avoid overflowing a 509 * uInt. Use ZLIB_IO_MAX to limit the input. The output is always limited 510 * by the output buffer size, so there is no need to check that. Since this 511 * is ANSI-C we know that an 'int', hence a uInt, is always at least 16 bits 512 * in size. 513 */ 514 { 515 png_compression_bufferp *end = &png_ptr->zbuffer_list; 516 png_alloc_size_t input_len = comp->input_len; /* may be zero! */ 517 png_uint_32 output_len; 518 519 /* zlib updates these for us: */ 520 png_ptr->zstream.next_in = PNGZ_INPUT_CAST(comp->input); 521 png_ptr->zstream.avail_in = 0; /* Set below */ 522 png_ptr->zstream.next_out = comp->output; 523 png_ptr->zstream.avail_out = (sizeof comp->output); 524 525 output_len = png_ptr->zstream.avail_out; 526 527 do 528 { 529 uInt avail_in = ZLIB_IO_MAX; 530 531 if (avail_in > input_len) 532 avail_in = (uInt)input_len; 533 534 input_len -= avail_in; 535 536 png_ptr->zstream.avail_in = avail_in; 537 538 if (png_ptr->zstream.avail_out == 0) 539 { 540 png_compression_buffer *next; 541 542 /* Chunk data is limited to 2^31 bytes in length, so the prefix 543 * length must be counted here. 544 */ 545 if (output_len + prefix_len > PNG_UINT_31_MAX) 546 { 547 ret = Z_MEM_ERROR; 548 break; 549 } 550 551 /* Need a new (malloc'ed) buffer, but there may be one present 552 * already. 553 */ 554 next = *end; 555 if (next == NULL) 556 { 557 next = png_voidcast(png_compression_bufferp, png_malloc_base 558 (png_ptr, PNG_COMPRESSION_BUFFER_SIZE(png_ptr))); 559 560 if (next == NULL) 561 { 562 ret = Z_MEM_ERROR; 563 break; 564 } 565 566 /* Link in this buffer (so that it will be freed later) */ 567 next->next = NULL; 568 *end = next; 569 } 570 571 png_ptr->zstream.next_out = next->output; 572 png_ptr->zstream.avail_out = png_ptr->zbuffer_size; 573 output_len += png_ptr->zstream.avail_out; 574 575 /* Move 'end' to the next buffer pointer. */ 576 end = &next->next; 577 } 578 579 /* Compress the data */ 580 ret = deflate(&png_ptr->zstream, 581 input_len > 0 ? Z_NO_FLUSH : Z_FINISH); 582 583 /* Claw back input data that was not consumed (because avail_in is 584 * reset above every time round the loop). 585 */ 586 input_len += png_ptr->zstream.avail_in; 587 png_ptr->zstream.avail_in = 0; /* safety */ 588 } 589 while (ret == Z_OK); 590 591 /* There may be some space left in the last output buffer. This needs to 592 * be subtracted from output_len. 593 */ 594 output_len -= png_ptr->zstream.avail_out; 595 png_ptr->zstream.avail_out = 0; /* safety */ 596 comp->output_len = output_len; 597 598 /* Now double check the output length, put in a custom message if it is 599 * too long. Otherwise ensure the z_stream::msg pointer is set to 600 * something. 601 */ 602 if (output_len + prefix_len >= PNG_UINT_31_MAX) 603 { 604 png_ptr->zstream.msg = PNGZ_MSG_CAST("compressed data too long"); 605 ret = Z_MEM_ERROR; 606 } 607 608 else 609 png_zstream_error(png_ptr, ret); 610 611 /* Reset zlib for another zTXt/iTXt or image data */ 612 png_ptr->zowner = 0; 613 614 /* The only success case is Z_STREAM_END, input_len must be 0; if not this 615 * is an internal error. 616 */ 617 if (ret == Z_STREAM_END && input_len == 0) 618 { 619 #ifdef PNG_WRITE_OPTIMIZE_CMF_SUPPORTED 620 /* Fix up the deflate header, if required */ 621 optimize_cmf(comp->output, comp->input_len); 622 #endif 623 /* But Z_OK is returned, not Z_STREAM_END; this allows the claim 624 * function above to return Z_STREAM_END on an error (though it never 625 * does in the current versions of zlib.) 626 */ 627 return Z_OK; 628 } 629 630 else 631 return ret; 632 } 633 } 634 635 /* Ship the compressed text out via chunk writes */ 636 static void 637 png_write_compressed_data_out(png_structrp png_ptr, compression_state *comp) 638 { 639 png_uint_32 output_len = comp->output_len; 640 png_const_bytep output = comp->output; 641 png_uint_32 avail = (sizeof comp->output); 642 png_compression_buffer *next = png_ptr->zbuffer_list; 643 644 for (;;) 645 { 646 if (avail > output_len) 647 avail = output_len; 648 649 png_write_chunk_data(png_ptr, output, avail); 650 651 output_len -= avail; 652 653 if (output_len == 0 || next == NULL) 654 break; 655 656 avail = png_ptr->zbuffer_size; 657 output = next->output; 658 next = next->next; 659 } 660 661 /* This is an internal error; 'next' must have been NULL! */ 662 if (output_len > 0) 663 png_error(png_ptr, "error writing ancillary chunked compressed data"); 664 } 665 #endif /* WRITE_COMPRESSED_TEXT */ 666 667 /* Write the IHDR chunk, and update the png_struct with the necessary 668 * information. Note that the rest of this code depends upon this 669 * information being correct. 670 */ 671 void /* PRIVATE */ 672 png_write_IHDR(png_structrp png_ptr, png_uint_32 width, png_uint_32 height, 673 int bit_depth, int color_type, int compression_type, int filter_type, 674 int interlace_type) 675 { 676 png_byte buf[13]; /* Buffer to store the IHDR info */ 677 int is_invalid_depth; 678 679 png_debug(1, "in png_write_IHDR"); 680 681 /* Check that we have valid input data from the application info */ 682 switch (color_type) 683 { 684 case PNG_COLOR_TYPE_GRAY: 685 switch (bit_depth) 686 { 687 case 1: 688 case 2: 689 case 4: 690 case 8: 691 #ifdef PNG_WRITE_16BIT_SUPPORTED 692 case 16: 693 #endif 694 png_ptr->channels = 1; break; 695 696 default: 697 png_error(png_ptr, 698 "Invalid bit depth for grayscale image"); 699 } 700 break; 701 702 case PNG_COLOR_TYPE_RGB: 703 is_invalid_depth = (bit_depth != 8); 704 #ifdef PNG_WRITE_16BIT_SUPPORTED 705 is_invalid_depth = (is_invalid_depth && bit_depth != 16); 706 #endif 707 if (is_invalid_depth) 708 png_error(png_ptr, "Invalid bit depth for RGB image"); 709 710 png_ptr->channels = 3; 711 break; 712 713 case PNG_COLOR_TYPE_PALETTE: 714 switch (bit_depth) 715 { 716 case 1: 717 case 2: 718 case 4: 719 case 8: 720 png_ptr->channels = 1; 721 break; 722 723 default: 724 png_error(png_ptr, "Invalid bit depth for paletted image"); 725 } 726 break; 727 728 case PNG_COLOR_TYPE_GRAY_ALPHA: 729 is_invalid_depth = (bit_depth != 8); 730 #ifdef PNG_WRITE_16BIT_SUPPORTED 731 is_invalid_depth = (is_invalid_depth && bit_depth != 16); 732 #endif 733 if (is_invalid_depth) 734 png_error(png_ptr, "Invalid bit depth for grayscale+alpha image"); 735 736 png_ptr->channels = 2; 737 break; 738 739 case PNG_COLOR_TYPE_RGB_ALPHA: 740 is_invalid_depth = (bit_depth != 8); 741 #ifdef PNG_WRITE_16BIT_SUPPORTED 742 is_invalid_depth = (is_invalid_depth && bit_depth != 16); 743 #endif 744 if (is_invalid_depth) 745 png_error(png_ptr, "Invalid bit depth for RGBA image"); 746 747 png_ptr->channels = 4; 748 break; 749 750 default: 751 png_error(png_ptr, "Invalid image color type specified"); 752 } 753 754 if (compression_type != PNG_COMPRESSION_TYPE_BASE) 755 { 756 png_warning(png_ptr, "Invalid compression type specified"); 757 compression_type = PNG_COMPRESSION_TYPE_BASE; 758 } 759 760 /* Write filter_method 64 (intrapixel differencing) only if 761 * 1. Libpng was compiled with PNG_MNG_FEATURES_SUPPORTED and 762 * 2. Libpng did not write a PNG signature (this filter_method is only 763 * used in PNG datastreams that are embedded in MNG datastreams) and 764 * 3. The application called png_permit_mng_features with a mask that 765 * included PNG_FLAG_MNG_FILTER_64 and 766 * 4. The filter_method is 64 and 767 * 5. The color_type is RGB or RGBA 768 */ 769 if ( 770 #ifdef PNG_MNG_FEATURES_SUPPORTED 771 !((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) != 0 && 772 ((png_ptr->mode & PNG_HAVE_PNG_SIGNATURE) == 0) && 773 (color_type == PNG_COLOR_TYPE_RGB || 774 color_type == PNG_COLOR_TYPE_RGB_ALPHA) && 775 (filter_type == PNG_INTRAPIXEL_DIFFERENCING)) && 776 #endif 777 filter_type != PNG_FILTER_TYPE_BASE) 778 { 779 png_warning(png_ptr, "Invalid filter type specified"); 780 filter_type = PNG_FILTER_TYPE_BASE; 781 } 782 783 #ifdef PNG_WRITE_INTERLACING_SUPPORTED 784 if (interlace_type != PNG_INTERLACE_NONE && 785 interlace_type != PNG_INTERLACE_ADAM7) 786 { 787 png_warning(png_ptr, "Invalid interlace type specified"); 788 interlace_type = PNG_INTERLACE_ADAM7; 789 } 790 #else 791 interlace_type=PNG_INTERLACE_NONE; 792 #endif 793 794 /* Save the relevant information */ 795 png_ptr->bit_depth = (png_byte)bit_depth; 796 png_ptr->color_type = (png_byte)color_type; 797 png_ptr->interlaced = (png_byte)interlace_type; 798 #ifdef PNG_MNG_FEATURES_SUPPORTED 799 png_ptr->filter_type = (png_byte)filter_type; 800 #endif 801 png_ptr->compression_type = (png_byte)compression_type; 802 png_ptr->width = width; 803 png_ptr->height = height; 804 805 png_ptr->pixel_depth = (png_byte)(bit_depth * png_ptr->channels); 806 png_ptr->rowbytes = PNG_ROWBYTES(png_ptr->pixel_depth, width); 807 /* Set the usr info, so any transformations can modify it */ 808 png_ptr->usr_width = png_ptr->width; 809 png_ptr->usr_bit_depth = png_ptr->bit_depth; 810 png_ptr->usr_channels = png_ptr->channels; 811 812 /* Pack the header information into the buffer */ 813 png_save_uint_32(buf, width); 814 png_save_uint_32(buf + 4, height); 815 buf[8] = (png_byte)bit_depth; 816 buf[9] = (png_byte)color_type; 817 buf[10] = (png_byte)compression_type; 818 buf[11] = (png_byte)filter_type; 819 buf[12] = (png_byte)interlace_type; 820 821 /* Write the chunk */ 822 png_write_complete_chunk(png_ptr, png_IHDR, buf, 13); 823 824 if ((png_ptr->do_filter) == PNG_NO_FILTERS) 825 { 826 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE || 827 png_ptr->bit_depth < 8) 828 png_ptr->do_filter = PNG_FILTER_NONE; 829 830 else 831 png_ptr->do_filter = PNG_ALL_FILTERS; 832 } 833 834 png_ptr->mode = PNG_HAVE_IHDR; /* not READY_FOR_ZTXT */ 835 } 836 837 /* Write the palette. We are careful not to trust png_color to be in the 838 * correct order for PNG, so people can redefine it to any convenient 839 * structure. 840 */ 841 void /* PRIVATE */ 842 png_write_PLTE(png_structrp png_ptr, png_const_colorp palette, 843 png_uint_32 num_pal) 844 { 845 png_uint_32 max_palette_length, i; 846 png_const_colorp pal_ptr; 847 png_byte buf[3]; 848 849 png_debug(1, "in png_write_PLTE"); 850 851 max_palette_length = (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) ? 852 (1 << png_ptr->bit_depth) : PNG_MAX_PALETTE_LENGTH; 853 854 if (( 855 #ifdef PNG_MNG_FEATURES_SUPPORTED 856 (png_ptr->mng_features_permitted & PNG_FLAG_MNG_EMPTY_PLTE) == 0 && 857 #endif 858 num_pal == 0) || num_pal > max_palette_length) 859 { 860 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) 861 { 862 png_error(png_ptr, "Invalid number of colors in palette"); 863 } 864 865 else 866 { 867 png_warning(png_ptr, "Invalid number of colors in palette"); 868 return; 869 } 870 } 871 872 if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) == 0) 873 { 874 png_warning(png_ptr, 875 "Ignoring request to write a PLTE chunk in grayscale PNG"); 876 877 return; 878 } 879 880 png_ptr->num_palette = (png_uint_16)num_pal; 881 png_debug1(3, "num_palette = %d", png_ptr->num_palette); 882 883 png_write_chunk_header(png_ptr, png_PLTE, (png_uint_32)(num_pal * 3)); 884 #ifdef PNG_POINTER_INDEXING_SUPPORTED 885 886 for (i = 0, pal_ptr = palette; i < num_pal; i++, pal_ptr++) 887 { 888 buf[0] = pal_ptr->red; 889 buf[1] = pal_ptr->green; 890 buf[2] = pal_ptr->blue; 891 png_write_chunk_data(png_ptr, buf, 3); 892 } 893 894 #else 895 /* This is a little slower but some buggy compilers need to do this 896 * instead 897 */ 898 pal_ptr=palette; 899 900 for (i = 0; i < num_pal; i++) 901 { 902 buf[0] = pal_ptr[i].red; 903 buf[1] = pal_ptr[i].green; 904 buf[2] = pal_ptr[i].blue; 905 png_write_chunk_data(png_ptr, buf, 3); 906 } 907 908 #endif 909 png_write_chunk_end(png_ptr); 910 png_ptr->mode |= PNG_HAVE_PLTE; 911 } 912 913 /* This is similar to png_text_compress, above, except that it does not require 914 * all of the data at once and, instead of buffering the compressed result, 915 * writes it as IDAT chunks. Unlike png_text_compress it *can* png_error out 916 * because it calls the write interface. As a result it does its own error 917 * reporting and does not return an error code. In the event of error it will 918 * just call png_error. The input data length may exceed 32-bits. The 'flush' 919 * parameter is exactly the same as that to deflate, with the following 920 * meanings: 921 * 922 * Z_NO_FLUSH: normal incremental output of compressed data 923 * Z_SYNC_FLUSH: do a SYNC_FLUSH, used by png_write_flush 924 * Z_FINISH: this is the end of the input, do a Z_FINISH and clean up 925 * 926 * The routine manages the acquire and release of the png_ptr->zstream by 927 * checking and (at the end) clearing png_ptr->zowner; it does some sanity 928 * checks on the 'mode' flags while doing this. 929 */ 930 void /* PRIVATE */ 931 png_compress_IDAT(png_structrp png_ptr, png_const_bytep input, 932 png_alloc_size_t input_len, int flush) 933 { 934 if (png_ptr->zowner != png_IDAT) 935 { 936 /* First time. Ensure we have a temporary buffer for compression and 937 * trim the buffer list if it has more than one entry to free memory. 938 * If 'WRITE_COMPRESSED_TEXT' is not set the list will never have been 939 * created at this point, but the check here is quick and safe. 940 */ 941 if (png_ptr->zbuffer_list == NULL) 942 { 943 png_ptr->zbuffer_list = png_voidcast(png_compression_bufferp, 944 png_malloc(png_ptr, PNG_COMPRESSION_BUFFER_SIZE(png_ptr))); 945 png_ptr->zbuffer_list->next = NULL; 946 } 947 948 else 949 png_free_buffer_list(png_ptr, &png_ptr->zbuffer_list->next); 950 951 /* It is a terminal error if we can't claim the zstream. */ 952 if (png_deflate_claim(png_ptr, png_IDAT, png_image_size(png_ptr)) != Z_OK) 953 png_error(png_ptr, png_ptr->zstream.msg); 954 955 /* The output state is maintained in png_ptr->zstream, so it must be 956 * initialized here after the claim. 957 */ 958 png_ptr->zstream.next_out = png_ptr->zbuffer_list->output; 959 png_ptr->zstream.avail_out = png_ptr->zbuffer_size; 960 } 961 962 /* Now loop reading and writing until all the input is consumed or an error 963 * terminates the operation. The _out values are maintained across calls to 964 * this function, but the input must be reset each time. 965 */ 966 png_ptr->zstream.next_in = PNGZ_INPUT_CAST(input); 967 png_ptr->zstream.avail_in = 0; /* set below */ 968 for (;;) 969 { 970 int ret; 971 972 /* INPUT: from the row data */ 973 uInt avail = ZLIB_IO_MAX; 974 975 if (avail > input_len) 976 avail = (uInt)input_len; /* safe because of the check */ 977 978 png_ptr->zstream.avail_in = avail; 979 input_len -= avail; 980 981 ret = deflate(&png_ptr->zstream, input_len > 0 ? Z_NO_FLUSH : flush); 982 983 /* Include as-yet unconsumed input */ 984 input_len += png_ptr->zstream.avail_in; 985 png_ptr->zstream.avail_in = 0; 986 987 /* OUTPUT: write complete IDAT chunks when avail_out drops to zero. Note 988 * that these two zstream fields are preserved across the calls, therefore 989 * there is no need to set these up on entry to the loop. 990 */ 991 if (png_ptr->zstream.avail_out == 0) 992 { 993 png_bytep data = png_ptr->zbuffer_list->output; 994 uInt size = png_ptr->zbuffer_size; 995 996 /* Write an IDAT containing the data then reset the buffer. The 997 * first IDAT may need deflate header optimization. 998 */ 999 #ifdef PNG_WRITE_OPTIMIZE_CMF_SUPPORTED 1000 if ((png_ptr->mode & PNG_HAVE_IDAT) == 0 && 1001 png_ptr->compression_type == PNG_COMPRESSION_TYPE_BASE) 1002 optimize_cmf(data, png_image_size(png_ptr)); 1003 #endif 1004 1005 if (size > 0) 1006 png_write_complete_chunk(png_ptr, png_IDAT, data, size); 1007 png_ptr->mode |= PNG_HAVE_IDAT; 1008 1009 png_ptr->zstream.next_out = data; 1010 png_ptr->zstream.avail_out = size; 1011 1012 /* For SYNC_FLUSH or FINISH it is essential to keep calling zlib with 1013 * the same flush parameter until it has finished output, for NO_FLUSH 1014 * it doesn't matter. 1015 */ 1016 if (ret == Z_OK && flush != Z_NO_FLUSH) 1017 continue; 1018 } 1019 1020 /* The order of these checks doesn't matter much; it just affects which 1021 * possible error might be detected if multiple things go wrong at once. 1022 */ 1023 if (ret == Z_OK) /* most likely return code! */ 1024 { 1025 /* If all the input has been consumed then just return. If Z_FINISH 1026 * was used as the flush parameter something has gone wrong if we get 1027 * here. 1028 */ 1029 if (input_len == 0) 1030 { 1031 if (flush == Z_FINISH) 1032 png_error(png_ptr, "Z_OK on Z_FINISH with output space"); 1033 1034 return; 1035 } 1036 } 1037 1038 else if (ret == Z_STREAM_END && flush == Z_FINISH) 1039 { 1040 /* This is the end of the IDAT data; any pending output must be 1041 * flushed. For small PNG files we may still be at the beginning. 1042 */ 1043 png_bytep data = png_ptr->zbuffer_list->output; 1044 uInt size = png_ptr->zbuffer_size - png_ptr->zstream.avail_out; 1045 1046 #ifdef PNG_WRITE_OPTIMIZE_CMF_SUPPORTED 1047 if ((png_ptr->mode & PNG_HAVE_IDAT) == 0 && 1048 png_ptr->compression_type == PNG_COMPRESSION_TYPE_BASE) 1049 optimize_cmf(data, png_image_size(png_ptr)); 1050 #endif 1051 1052 if (size > 0) 1053 png_write_complete_chunk(png_ptr, png_IDAT, data, size); 1054 png_ptr->zstream.avail_out = 0; 1055 png_ptr->zstream.next_out = NULL; 1056 png_ptr->mode |= PNG_HAVE_IDAT | PNG_AFTER_IDAT; 1057 1058 png_ptr->zowner = 0; /* Release the stream */ 1059 return; 1060 } 1061 1062 else 1063 { 1064 /* This is an error condition. */ 1065 png_zstream_error(png_ptr, ret); 1066 png_error(png_ptr, png_ptr->zstream.msg); 1067 } 1068 } 1069 } 1070 1071 /* Write an IEND chunk */ 1072 void /* PRIVATE */ 1073 png_write_IEND(png_structrp png_ptr) 1074 { 1075 png_debug(1, "in png_write_IEND"); 1076 1077 png_write_complete_chunk(png_ptr, png_IEND, NULL, 0); 1078 png_ptr->mode |= PNG_HAVE_IEND; 1079 } 1080 1081 #ifdef PNG_WRITE_gAMA_SUPPORTED 1082 /* Write a gAMA chunk */ 1083 void /* PRIVATE */ 1084 png_write_gAMA_fixed(png_structrp png_ptr, png_fixed_point file_gamma) 1085 { 1086 png_byte buf[4]; 1087 1088 png_debug(1, "in png_write_gAMA"); 1089 1090 /* file_gamma is saved in 1/100,000ths */ 1091 png_save_uint_32(buf, (png_uint_32)file_gamma); 1092 png_write_complete_chunk(png_ptr, png_gAMA, buf, 4); 1093 } 1094 #endif 1095 1096 #ifdef PNG_WRITE_sRGB_SUPPORTED 1097 /* Write a sRGB chunk */ 1098 void /* PRIVATE */ 1099 png_write_sRGB(png_structrp png_ptr, int srgb_intent) 1100 { 1101 png_byte buf[1]; 1102 1103 png_debug(1, "in png_write_sRGB"); 1104 1105 if (srgb_intent >= PNG_sRGB_INTENT_LAST) 1106 png_warning(png_ptr, 1107 "Invalid sRGB rendering intent specified"); 1108 1109 buf[0]=(png_byte)srgb_intent; 1110 png_write_complete_chunk(png_ptr, png_sRGB, buf, 1); 1111 } 1112 #endif 1113 1114 #ifdef PNG_WRITE_iCCP_SUPPORTED 1115 /* Write an iCCP chunk */ 1116 void /* PRIVATE */ 1117 png_write_iCCP(png_structrp png_ptr, png_const_charp name, 1118 png_const_bytep profile) 1119 { 1120 png_uint_32 name_len; 1121 png_uint_32 profile_len; 1122 png_byte new_name[81]; /* 1 byte for the compression byte */ 1123 compression_state comp; 1124 png_uint_32 temp; 1125 1126 png_debug(1, "in png_write_iCCP"); 1127 1128 /* These are all internal problems: the profile should have been checked 1129 * before when it was stored. 1130 */ 1131 if (profile == NULL) 1132 png_error(png_ptr, "No profile for iCCP chunk"); /* internal error */ 1133 1134 profile_len = png_get_uint_32(profile); 1135 1136 if (profile_len < 132) 1137 png_error(png_ptr, "ICC profile too short"); 1138 1139 temp = (png_uint_32) (*(profile+8)); 1140 if (temp > 3 && (profile_len & 0x03)) 1141 png_error(png_ptr, "ICC profile length invalid (not a multiple of 4)"); 1142 1143 { 1144 png_uint_32 embedded_profile_len = png_get_uint_32(profile); 1145 1146 if (profile_len != embedded_profile_len) 1147 png_error(png_ptr, "Profile length does not match profile"); 1148 } 1149 1150 name_len = png_check_keyword(png_ptr, name, new_name); 1151 1152 if (name_len == 0) 1153 png_error(png_ptr, "iCCP: invalid keyword"); 1154 1155 new_name[++name_len] = PNG_COMPRESSION_TYPE_BASE; 1156 1157 /* Make sure we include the NULL after the name and the compression type */ 1158 ++name_len; 1159 1160 png_text_compress_init(&comp, profile, profile_len); 1161 1162 /* Allow for keyword terminator and compression byte */ 1163 if (png_text_compress(png_ptr, png_iCCP, &comp, name_len) != Z_OK) 1164 png_error(png_ptr, png_ptr->zstream.msg); 1165 1166 png_write_chunk_header(png_ptr, png_iCCP, name_len + comp.output_len); 1167 1168 png_write_chunk_data(png_ptr, new_name, name_len); 1169 1170 png_write_compressed_data_out(png_ptr, &comp); 1171 1172 png_write_chunk_end(png_ptr); 1173 } 1174 #endif 1175 1176 #ifdef PNG_WRITE_sPLT_SUPPORTED 1177 /* Write a sPLT chunk */ 1178 void /* PRIVATE */ 1179 png_write_sPLT(png_structrp png_ptr, png_const_sPLT_tp spalette) 1180 { 1181 png_uint_32 name_len; 1182 png_byte new_name[80]; 1183 png_byte entrybuf[10]; 1184 size_t entry_size = (spalette->depth == 8 ? 6 : 10); 1185 size_t palette_size = entry_size * (size_t)spalette->nentries; 1186 png_sPLT_entryp ep; 1187 #ifndef PNG_POINTER_INDEXING_SUPPORTED 1188 int i; 1189 #endif 1190 1191 png_debug(1, "in png_write_sPLT"); 1192 1193 name_len = png_check_keyword(png_ptr, spalette->name, new_name); 1194 1195 if (name_len == 0) 1196 png_error(png_ptr, "sPLT: invalid keyword"); 1197 1198 /* Make sure we include the NULL after the name */ 1199 png_write_chunk_header(png_ptr, png_sPLT, 1200 (png_uint_32)(name_len + 2 + palette_size)); 1201 1202 png_write_chunk_data(png_ptr, (png_bytep)new_name, (size_t)(name_len + 1)); 1203 1204 png_write_chunk_data(png_ptr, &spalette->depth, 1); 1205 1206 /* Loop through each palette entry, writing appropriately */ 1207 #ifdef PNG_POINTER_INDEXING_SUPPORTED 1208 for (ep = spalette->entries; ep<spalette->entries + spalette->nentries; ep++) 1209 { 1210 if (spalette->depth == 8) 1211 { 1212 entrybuf[0] = (png_byte)ep->red; 1213 entrybuf[1] = (png_byte)ep->green; 1214 entrybuf[2] = (png_byte)ep->blue; 1215 entrybuf[3] = (png_byte)ep->alpha; 1216 png_save_uint_16(entrybuf + 4, ep->frequency); 1217 } 1218 1219 else 1220 { 1221 png_save_uint_16(entrybuf + 0, ep->red); 1222 png_save_uint_16(entrybuf + 2, ep->green); 1223 png_save_uint_16(entrybuf + 4, ep->blue); 1224 png_save_uint_16(entrybuf + 6, ep->alpha); 1225 png_save_uint_16(entrybuf + 8, ep->frequency); 1226 } 1227 1228 png_write_chunk_data(png_ptr, entrybuf, entry_size); 1229 } 1230 #else 1231 ep=spalette->entries; 1232 for (i = 0; i>spalette->nentries; i++) 1233 { 1234 if (spalette->depth == 8) 1235 { 1236 entrybuf[0] = (png_byte)ep[i].red; 1237 entrybuf[1] = (png_byte)ep[i].green; 1238 entrybuf[2] = (png_byte)ep[i].blue; 1239 entrybuf[3] = (png_byte)ep[i].alpha; 1240 png_save_uint_16(entrybuf + 4, ep[i].frequency); 1241 } 1242 1243 else 1244 { 1245 png_save_uint_16(entrybuf + 0, ep[i].red); 1246 png_save_uint_16(entrybuf + 2, ep[i].green); 1247 png_save_uint_16(entrybuf + 4, ep[i].blue); 1248 png_save_uint_16(entrybuf + 6, ep[i].alpha); 1249 png_save_uint_16(entrybuf + 8, ep[i].frequency); 1250 } 1251 1252 png_write_chunk_data(png_ptr, entrybuf, entry_size); 1253 } 1254 #endif 1255 1256 png_write_chunk_end(png_ptr); 1257 } 1258 #endif 1259 1260 #ifdef PNG_WRITE_sBIT_SUPPORTED 1261 /* Write the sBIT chunk */ 1262 void /* PRIVATE */ 1263 png_write_sBIT(png_structrp png_ptr, png_const_color_8p sbit, int color_type) 1264 { 1265 png_byte buf[4]; 1266 size_t size; 1267 1268 png_debug(1, "in png_write_sBIT"); 1269 1270 /* Make sure we don't depend upon the order of PNG_COLOR_8 */ 1271 if ((color_type & PNG_COLOR_MASK_COLOR) != 0) 1272 { 1273 png_byte maxbits; 1274 1275 maxbits = (png_byte)(color_type==PNG_COLOR_TYPE_PALETTE ? 8 : 1276 png_ptr->usr_bit_depth); 1277 1278 if (sbit->red == 0 || sbit->red > maxbits || 1279 sbit->green == 0 || sbit->green > maxbits || 1280 sbit->blue == 0 || sbit->blue > maxbits) 1281 { 1282 png_warning(png_ptr, "Invalid sBIT depth specified"); 1283 return; 1284 } 1285 1286 buf[0] = sbit->red; 1287 buf[1] = sbit->green; 1288 buf[2] = sbit->blue; 1289 size = 3; 1290 } 1291 1292 else 1293 { 1294 if (sbit->gray == 0 || sbit->gray > png_ptr->usr_bit_depth) 1295 { 1296 png_warning(png_ptr, "Invalid sBIT depth specified"); 1297 return; 1298 } 1299 1300 buf[0] = sbit->gray; 1301 size = 1; 1302 } 1303 1304 if ((color_type & PNG_COLOR_MASK_ALPHA) != 0) 1305 { 1306 if (sbit->alpha == 0 || sbit->alpha > png_ptr->usr_bit_depth) 1307 { 1308 png_warning(png_ptr, "Invalid sBIT depth specified"); 1309 return; 1310 } 1311 1312 buf[size++] = sbit->alpha; 1313 } 1314 1315 png_write_complete_chunk(png_ptr, png_sBIT, buf, size); 1316 } 1317 #endif 1318 1319 #ifdef PNG_WRITE_cHRM_SUPPORTED 1320 /* Write the cHRM chunk */ 1321 void /* PRIVATE */ 1322 png_write_cHRM_fixed(png_structrp png_ptr, const png_xy *xy) 1323 { 1324 png_byte buf[32]; 1325 1326 png_debug(1, "in png_write_cHRM"); 1327 1328 /* Each value is saved in 1/100,000ths */ 1329 png_save_int_32(buf, xy->whitex); 1330 png_save_int_32(buf + 4, xy->whitey); 1331 1332 png_save_int_32(buf + 8, xy->redx); 1333 png_save_int_32(buf + 12, xy->redy); 1334 1335 png_save_int_32(buf + 16, xy->greenx); 1336 png_save_int_32(buf + 20, xy->greeny); 1337 1338 png_save_int_32(buf + 24, xy->bluex); 1339 png_save_int_32(buf + 28, xy->bluey); 1340 1341 png_write_complete_chunk(png_ptr, png_cHRM, buf, 32); 1342 } 1343 #endif 1344 1345 #ifdef PNG_WRITE_tRNS_SUPPORTED 1346 /* Write the tRNS chunk */ 1347 void /* PRIVATE */ 1348 png_write_tRNS(png_structrp png_ptr, png_const_bytep trans_alpha, 1349 png_const_color_16p tran, int num_trans, int color_type) 1350 { 1351 png_byte buf[6]; 1352 1353 png_debug(1, "in png_write_tRNS"); 1354 1355 if (color_type == PNG_COLOR_TYPE_PALETTE) 1356 { 1357 if (num_trans <= 0 || num_trans > (int)png_ptr->num_palette) 1358 { 1359 png_app_warning(png_ptr, 1360 "Invalid number of transparent colors specified"); 1361 return; 1362 } 1363 1364 /* Write the chunk out as it is */ 1365 png_write_complete_chunk(png_ptr, png_tRNS, trans_alpha, 1366 (size_t)num_trans); 1367 } 1368 1369 else if (color_type == PNG_COLOR_TYPE_GRAY) 1370 { 1371 /* One 16-bit value */ 1372 if (tran->gray >= (1 << png_ptr->bit_depth)) 1373 { 1374 png_app_warning(png_ptr, 1375 "Ignoring attempt to write tRNS chunk out-of-range for bit_depth"); 1376 1377 return; 1378 } 1379 1380 png_save_uint_16(buf, tran->gray); 1381 png_write_complete_chunk(png_ptr, png_tRNS, buf, 2); 1382 } 1383 1384 else if (color_type == PNG_COLOR_TYPE_RGB) 1385 { 1386 /* Three 16-bit values */ 1387 png_save_uint_16(buf, tran->red); 1388 png_save_uint_16(buf + 2, tran->green); 1389 png_save_uint_16(buf + 4, tran->blue); 1390 #ifdef PNG_WRITE_16BIT_SUPPORTED 1391 if (png_ptr->bit_depth == 8 && (buf[0] | buf[2] | buf[4]) != 0) 1392 #else 1393 if ((buf[0] | buf[2] | buf[4]) != 0) 1394 #endif 1395 { 1396 png_app_warning(png_ptr, 1397 "Ignoring attempt to write 16-bit tRNS chunk when bit_depth is 8"); 1398 return; 1399 } 1400 1401 png_write_complete_chunk(png_ptr, png_tRNS, buf, 6); 1402 } 1403 1404 else 1405 { 1406 png_app_warning(png_ptr, "Can't write tRNS with an alpha channel"); 1407 } 1408 } 1409 #endif 1410 1411 #ifdef PNG_WRITE_bKGD_SUPPORTED 1412 /* Write the background chunk */ 1413 void /* PRIVATE */ 1414 png_write_bKGD(png_structrp png_ptr, png_const_color_16p back, int color_type) 1415 { 1416 png_byte buf[6]; 1417 1418 png_debug(1, "in png_write_bKGD"); 1419 1420 if (color_type == PNG_COLOR_TYPE_PALETTE) 1421 { 1422 if ( 1423 #ifdef PNG_MNG_FEATURES_SUPPORTED 1424 (png_ptr->num_palette != 0 || 1425 (png_ptr->mng_features_permitted & PNG_FLAG_MNG_EMPTY_PLTE) == 0) && 1426 #endif 1427 back->index >= png_ptr->num_palette) 1428 { 1429 png_warning(png_ptr, "Invalid background palette index"); 1430 return; 1431 } 1432 1433 buf[0] = back->index; 1434 png_write_complete_chunk(png_ptr, png_bKGD, buf, 1); 1435 } 1436 1437 else if ((color_type & PNG_COLOR_MASK_COLOR) != 0) 1438 { 1439 png_save_uint_16(buf, back->red); 1440 png_save_uint_16(buf + 2, back->green); 1441 png_save_uint_16(buf + 4, back->blue); 1442 #ifdef PNG_WRITE_16BIT_SUPPORTED 1443 if (png_ptr->bit_depth == 8 && (buf[0] | buf[2] | buf[4]) != 0) 1444 #else 1445 if ((buf[0] | buf[2] | buf[4]) != 0) 1446 #endif 1447 { 1448 png_warning(png_ptr, 1449 "Ignoring attempt to write 16-bit bKGD chunk " 1450 "when bit_depth is 8"); 1451 1452 return; 1453 } 1454 1455 png_write_complete_chunk(png_ptr, png_bKGD, buf, 6); 1456 } 1457 1458 else 1459 { 1460 if (back->gray >= (1 << png_ptr->bit_depth)) 1461 { 1462 png_warning(png_ptr, 1463 "Ignoring attempt to write bKGD chunk out-of-range for bit_depth"); 1464 1465 return; 1466 } 1467 1468 png_save_uint_16(buf, back->gray); 1469 png_write_complete_chunk(png_ptr, png_bKGD, buf, 2); 1470 } 1471 } 1472 #endif 1473 1474 #ifdef PNG_WRITE_eXIf_SUPPORTED 1475 /* Write the Exif data */ 1476 void /* PRIVATE */ 1477 png_write_eXIf(png_structrp png_ptr, png_bytep exif, int num_exif) 1478 { 1479 int i; 1480 png_byte buf[1]; 1481 1482 png_debug(1, "in png_write_eXIf"); 1483 1484 png_write_chunk_header(png_ptr, png_eXIf, (png_uint_32)(num_exif)); 1485 1486 for (i = 0; i < num_exif; i++) 1487 { 1488 buf[0] = exif[i]; 1489 png_write_chunk_data(png_ptr, buf, 1); 1490 } 1491 1492 png_write_chunk_end(png_ptr); 1493 } 1494 #endif 1495 1496 #ifdef PNG_WRITE_hIST_SUPPORTED 1497 /* Write the histogram */ 1498 void /* PRIVATE */ 1499 png_write_hIST(png_structrp png_ptr, png_const_uint_16p hist, int num_hist) 1500 { 1501 int i; 1502 png_byte buf[3]; 1503 1504 png_debug(1, "in png_write_hIST"); 1505 1506 if (num_hist > (int)png_ptr->num_palette) 1507 { 1508 png_debug2(3, "num_hist = %d, num_palette = %d", num_hist, 1509 png_ptr->num_palette); 1510 1511 png_warning(png_ptr, "Invalid number of histogram entries specified"); 1512 return; 1513 } 1514 1515 png_write_chunk_header(png_ptr, png_hIST, (png_uint_32)(num_hist * 2)); 1516 1517 for (i = 0; i < num_hist; i++) 1518 { 1519 png_save_uint_16(buf, hist[i]); 1520 png_write_chunk_data(png_ptr, buf, 2); 1521 } 1522 1523 png_write_chunk_end(png_ptr); 1524 } 1525 #endif 1526 1527 #ifdef PNG_WRITE_tEXt_SUPPORTED 1528 /* Write a tEXt chunk */ 1529 void /* PRIVATE */ 1530 png_write_tEXt(png_structrp png_ptr, png_const_charp key, png_const_charp text, 1531 size_t text_len) 1532 { 1533 png_uint_32 key_len; 1534 png_byte new_key[80]; 1535 1536 png_debug(1, "in png_write_tEXt"); 1537 1538 key_len = png_check_keyword(png_ptr, key, new_key); 1539 1540 if (key_len == 0) 1541 png_error(png_ptr, "tEXt: invalid keyword"); 1542 1543 if (text == NULL || *text == '\0') 1544 text_len = 0; 1545 1546 else 1547 text_len = strlen(text); 1548 1549 if (text_len > PNG_UINT_31_MAX - (key_len+1)) 1550 png_error(png_ptr, "tEXt: text too long"); 1551 1552 /* Make sure we include the 0 after the key */ 1553 png_write_chunk_header(png_ptr, png_tEXt, 1554 (png_uint_32)/*checked above*/(key_len + text_len + 1)); 1555 /* 1556 * We leave it to the application to meet PNG-1.0 requirements on the 1557 * contents of the text. PNG-1.0 through PNG-1.2 discourage the use of 1558 * any non-Latin-1 characters except for NEWLINE. ISO PNG will forbid them. 1559 * The NUL character is forbidden by PNG-1.0 through PNG-1.2 and ISO PNG. 1560 */ 1561 png_write_chunk_data(png_ptr, new_key, key_len + 1); 1562 1563 if (text_len != 0) 1564 png_write_chunk_data(png_ptr, (png_const_bytep)text, text_len); 1565 1566 png_write_chunk_end(png_ptr); 1567 } 1568 #endif 1569 1570 #ifdef PNG_WRITE_zTXt_SUPPORTED 1571 /* Write a compressed text chunk */ 1572 void /* PRIVATE */ 1573 png_write_zTXt(png_structrp png_ptr, png_const_charp key, png_const_charp text, 1574 int compression) 1575 { 1576 png_uint_32 key_len; 1577 png_byte new_key[81]; 1578 compression_state comp; 1579 1580 png_debug(1, "in png_write_zTXt"); 1581 1582 if (compression == PNG_TEXT_COMPRESSION_NONE) 1583 { 1584 png_write_tEXt(png_ptr, key, text, 0); 1585 return; 1586 } 1587 1588 if (compression != PNG_TEXT_COMPRESSION_zTXt) 1589 png_error(png_ptr, "zTXt: invalid compression type"); 1590 1591 key_len = png_check_keyword(png_ptr, key, new_key); 1592 1593 if (key_len == 0) 1594 png_error(png_ptr, "zTXt: invalid keyword"); 1595 1596 /* Add the compression method and 1 for the keyword separator. */ 1597 new_key[++key_len] = PNG_COMPRESSION_TYPE_BASE; 1598 ++key_len; 1599 1600 /* Compute the compressed data; do it now for the length */ 1601 png_text_compress_init(&comp, (png_const_bytep)text, 1602 text == NULL ? 0 : strlen(text)); 1603 1604 if (png_text_compress(png_ptr, png_zTXt, &comp, key_len) != Z_OK) 1605 png_error(png_ptr, png_ptr->zstream.msg); 1606 1607 /* Write start of chunk */ 1608 png_write_chunk_header(png_ptr, png_zTXt, key_len + comp.output_len); 1609 1610 /* Write key */ 1611 png_write_chunk_data(png_ptr, new_key, key_len); 1612 1613 /* Write the compressed data */ 1614 png_write_compressed_data_out(png_ptr, &comp); 1615 1616 /* Close the chunk */ 1617 png_write_chunk_end(png_ptr); 1618 } 1619 #endif 1620 1621 #ifdef PNG_WRITE_iTXt_SUPPORTED 1622 /* Write an iTXt chunk */ 1623 void /* PRIVATE */ 1624 png_write_iTXt(png_structrp png_ptr, int compression, png_const_charp key, 1625 png_const_charp lang, png_const_charp lang_key, png_const_charp text) 1626 { 1627 png_uint_32 key_len, prefix_len; 1628 size_t lang_len, lang_key_len; 1629 png_byte new_key[82]; 1630 compression_state comp; 1631 1632 png_debug(1, "in png_write_iTXt"); 1633 1634 key_len = png_check_keyword(png_ptr, key, new_key); 1635 1636 if (key_len == 0) 1637 png_error(png_ptr, "iTXt: invalid keyword"); 1638 1639 /* Set the compression flag */ 1640 switch (compression) 1641 { 1642 case PNG_ITXT_COMPRESSION_NONE: 1643 case PNG_TEXT_COMPRESSION_NONE: 1644 compression = new_key[++key_len] = 0; /* no compression */ 1645 break; 1646 1647 case PNG_TEXT_COMPRESSION_zTXt: 1648 case PNG_ITXT_COMPRESSION_zTXt: 1649 compression = new_key[++key_len] = 1; /* compressed */ 1650 break; 1651 1652 default: 1653 png_error(png_ptr, "iTXt: invalid compression"); 1654 } 1655 1656 new_key[++key_len] = PNG_COMPRESSION_TYPE_BASE; 1657 ++key_len; /* for the keywod separator */ 1658 1659 /* We leave it to the application to meet PNG-1.0 requirements on the 1660 * contents of the text. PNG-1.0 through PNG-1.2 discourage the use of 1661 * any non-Latin-1 characters except for NEWLINE. ISO PNG, however, 1662 * specifies that the text is UTF-8 and this really doesn't require any 1663 * checking. 1664 * 1665 * The NUL character is forbidden by PNG-1.0 through PNG-1.2 and ISO PNG. 1666 * 1667 * TODO: validate the language tag correctly (see the spec.) 1668 */ 1669 if (lang == NULL) lang = ""; /* empty language is valid */ 1670 lang_len = strlen(lang)+1; 1671 if (lang_key == NULL) lang_key = ""; /* may be empty */ 1672 lang_key_len = strlen(lang_key)+1; 1673 if (text == NULL) text = ""; /* may be empty */ 1674 1675 prefix_len = key_len; 1676 if (lang_len > PNG_UINT_31_MAX-prefix_len) 1677 prefix_len = PNG_UINT_31_MAX; 1678 else 1679 prefix_len = (png_uint_32)(prefix_len + lang_len); 1680 1681 if (lang_key_len > PNG_UINT_31_MAX-prefix_len) 1682 prefix_len = PNG_UINT_31_MAX; 1683 else 1684 prefix_len = (png_uint_32)(prefix_len + lang_key_len); 1685 1686 png_text_compress_init(&comp, (png_const_bytep)text, strlen(text)); 1687 1688 if (compression != 0) 1689 { 1690 if (png_text_compress(png_ptr, png_iTXt, &comp, prefix_len) != Z_OK) 1691 png_error(png_ptr, png_ptr->zstream.msg); 1692 } 1693 1694 else 1695 { 1696 if (comp.input_len > PNG_UINT_31_MAX-prefix_len) 1697 png_error(png_ptr, "iTXt: uncompressed text too long"); 1698 1699 /* So the string will fit in a chunk: */ 1700 comp.output_len = (png_uint_32)/*SAFE*/comp.input_len; 1701 } 1702 1703 png_write_chunk_header(png_ptr, png_iTXt, comp.output_len + prefix_len); 1704 1705 png_write_chunk_data(png_ptr, new_key, key_len); 1706 1707 png_write_chunk_data(png_ptr, (png_const_bytep)lang, lang_len); 1708 1709 png_write_chunk_data(png_ptr, (png_const_bytep)lang_key, lang_key_len); 1710 1711 if (compression != 0) 1712 png_write_compressed_data_out(png_ptr, &comp); 1713 1714 else 1715 png_write_chunk_data(png_ptr, (png_const_bytep)text, comp.output_len); 1716 1717 png_write_chunk_end(png_ptr); 1718 } 1719 #endif 1720 1721 #ifdef PNG_WRITE_oFFs_SUPPORTED 1722 /* Write the oFFs chunk */ 1723 void /* PRIVATE */ 1724 png_write_oFFs(png_structrp png_ptr, png_int_32 x_offset, png_int_32 y_offset, 1725 int unit_type) 1726 { 1727 png_byte buf[9]; 1728 1729 png_debug(1, "in png_write_oFFs"); 1730 1731 if (unit_type >= PNG_OFFSET_LAST) 1732 png_warning(png_ptr, "Unrecognized unit type for oFFs chunk"); 1733 1734 png_save_int_32(buf, x_offset); 1735 png_save_int_32(buf + 4, y_offset); 1736 buf[8] = (png_byte)unit_type; 1737 1738 png_write_complete_chunk(png_ptr, png_oFFs, buf, 9); 1739 } 1740 #endif 1741 #ifdef PNG_WRITE_pCAL_SUPPORTED 1742 /* Write the pCAL chunk (described in the PNG extensions document) */ 1743 void /* PRIVATE */ 1744 png_write_pCAL(png_structrp png_ptr, png_charp purpose, png_int_32 X0, 1745 png_int_32 X1, int type, int nparams, png_const_charp units, 1746 png_charpp params) 1747 { 1748 png_uint_32 purpose_len; 1749 size_t units_len, total_len; 1750 size_t *params_len; 1751 png_byte buf[10]; 1752 png_byte new_purpose[80]; 1753 int i; 1754 1755 png_debug1(1, "in png_write_pCAL (%d parameters)", nparams); 1756 1757 if (type >= PNG_EQUATION_LAST) 1758 png_error(png_ptr, "Unrecognized equation type for pCAL chunk"); 1759 1760 purpose_len = png_check_keyword(png_ptr, purpose, new_purpose); 1761 1762 if (purpose_len == 0) 1763 png_error(png_ptr, "pCAL: invalid keyword"); 1764 1765 ++purpose_len; /* terminator */ 1766 1767 png_debug1(3, "pCAL purpose length = %d", (int)purpose_len); 1768 units_len = strlen(units) + (nparams == 0 ? 0 : 1); 1769 png_debug1(3, "pCAL units length = %d", (int)units_len); 1770 total_len = purpose_len + units_len + 10; 1771 1772 params_len = (size_t *)png_malloc(png_ptr, 1773 (png_alloc_size_t)((png_alloc_size_t)nparams * (sizeof (size_t)))); 1774 1775 /* Find the length of each parameter, making sure we don't count the 1776 * null terminator for the last parameter. 1777 */ 1778 for (i = 0; i < nparams; i++) 1779 { 1780 params_len[i] = strlen(params[i]) + (i == nparams - 1 ? 0 : 1); 1781 png_debug2(3, "pCAL parameter %d length = %lu", i, 1782 (unsigned long)params_len[i]); 1783 total_len += params_len[i]; 1784 } 1785 1786 png_debug1(3, "pCAL total length = %d", (int)total_len); 1787 png_write_chunk_header(png_ptr, png_pCAL, (png_uint_32)total_len); 1788 png_write_chunk_data(png_ptr, new_purpose, purpose_len); 1789 png_save_int_32(buf, X0); 1790 png_save_int_32(buf + 4, X1); 1791 buf[8] = (png_byte)type; 1792 buf[9] = (png_byte)nparams; 1793 png_write_chunk_data(png_ptr, buf, 10); 1794 png_write_chunk_data(png_ptr, (png_const_bytep)units, (size_t)units_len); 1795 1796 for (i = 0; i < nparams; i++) 1797 { 1798 png_write_chunk_data(png_ptr, (png_const_bytep)params[i], params_len[i]); 1799 } 1800 1801 png_free(png_ptr, params_len); 1802 png_write_chunk_end(png_ptr); 1803 } 1804 #endif 1805 1806 #ifdef PNG_WRITE_sCAL_SUPPORTED 1807 /* Write the sCAL chunk */ 1808 void /* PRIVATE */ 1809 png_write_sCAL_s(png_structrp png_ptr, int unit, png_const_charp width, 1810 png_const_charp height) 1811 { 1812 png_byte buf[64]; 1813 size_t wlen, hlen, total_len; 1814 1815 png_debug(1, "in png_write_sCAL_s"); 1816 1817 wlen = strlen(width); 1818 hlen = strlen(height); 1819 total_len = wlen + hlen + 2; 1820 1821 if (total_len > 64) 1822 { 1823 png_warning(png_ptr, "Can't write sCAL (buffer too small)"); 1824 return; 1825 } 1826 1827 buf[0] = (png_byte)unit; 1828 memcpy(buf + 1, width, wlen + 1); /* Append the '\0' here */ 1829 memcpy(buf + wlen + 2, height, hlen); /* Do NOT append the '\0' here */ 1830 1831 png_debug1(3, "sCAL total length = %u", (unsigned int)total_len); 1832 png_write_complete_chunk(png_ptr, png_sCAL, buf, total_len); 1833 } 1834 #endif 1835 1836 #ifdef PNG_WRITE_pHYs_SUPPORTED 1837 /* Write the pHYs chunk */ 1838 void /* PRIVATE */ 1839 png_write_pHYs(png_structrp png_ptr, png_uint_32 x_pixels_per_unit, 1840 png_uint_32 y_pixels_per_unit, 1841 int unit_type) 1842 { 1843 png_byte buf[9]; 1844 1845 png_debug(1, "in png_write_pHYs"); 1846 1847 if (unit_type >= PNG_RESOLUTION_LAST) 1848 png_warning(png_ptr, "Unrecognized unit type for pHYs chunk"); 1849 1850 png_save_uint_32(buf, x_pixels_per_unit); 1851 png_save_uint_32(buf + 4, y_pixels_per_unit); 1852 buf[8] = (png_byte)unit_type; 1853 1854 png_write_complete_chunk(png_ptr, png_pHYs, buf, 9); 1855 } 1856 #endif 1857 1858 #ifdef PNG_WRITE_tIME_SUPPORTED 1859 /* Write the tIME chunk. Use either png_convert_from_struct_tm() 1860 * or png_convert_from_time_t(), or fill in the structure yourself. 1861 */ 1862 void /* PRIVATE */ 1863 png_write_tIME(png_structrp png_ptr, png_const_timep mod_time) 1864 { 1865 png_byte buf[7]; 1866 1867 png_debug(1, "in png_write_tIME"); 1868 1869 if (mod_time->month > 12 || mod_time->month < 1 || 1870 mod_time->day > 31 || mod_time->day < 1 || 1871 mod_time->hour > 23 || mod_time->second > 60) 1872 { 1873 png_warning(png_ptr, "Invalid time specified for tIME chunk"); 1874 return; 1875 } 1876 1877 png_save_uint_16(buf, mod_time->year); 1878 buf[2] = mod_time->month; 1879 buf[3] = mod_time->day; 1880 buf[4] = mod_time->hour; 1881 buf[5] = mod_time->minute; 1882 buf[6] = mod_time->second; 1883 1884 png_write_complete_chunk(png_ptr, png_tIME, buf, 7); 1885 } 1886 #endif 1887 1888 /* Initializes the row writing capability of libpng */ 1889 void /* PRIVATE */ 1890 png_write_start_row(png_structrp png_ptr) 1891 { 1892 #ifdef PNG_WRITE_INTERLACING_SUPPORTED 1893 /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */ 1894 1895 /* Start of interlace block */ 1896 static const png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0}; 1897 1898 /* Offset to next interlace block */ 1899 static const png_byte png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1}; 1900 1901 /* Start of interlace block in the y direction */ 1902 static const png_byte png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1}; 1903 1904 /* Offset to next interlace block in the y direction */ 1905 static const png_byte png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2}; 1906 #endif 1907 1908 png_alloc_size_t buf_size; 1909 int usr_pixel_depth; 1910 1911 #ifdef PNG_WRITE_FILTER_SUPPORTED 1912 png_byte filters; 1913 #endif 1914 1915 png_debug(1, "in png_write_start_row"); 1916 1917 usr_pixel_depth = png_ptr->usr_channels * png_ptr->usr_bit_depth; 1918 buf_size = PNG_ROWBYTES(usr_pixel_depth, png_ptr->width) + 1; 1919 1920 /* 1.5.6: added to allow checking in the row write code. */ 1921 png_ptr->transformed_pixel_depth = png_ptr->pixel_depth; 1922 png_ptr->maximum_pixel_depth = (png_byte)usr_pixel_depth; 1923 1924 /* Set up row buffer */ 1925 png_ptr->row_buf = png_voidcast(png_bytep, png_malloc(png_ptr, buf_size)); 1926 1927 png_ptr->row_buf[0] = PNG_FILTER_VALUE_NONE; 1928 1929 #ifdef PNG_WRITE_FILTER_SUPPORTED 1930 filters = png_ptr->do_filter; 1931 1932 if (png_ptr->height == 1) 1933 filters &= 0xff & ~(PNG_FILTER_UP|PNG_FILTER_AVG|PNG_FILTER_PAETH); 1934 1935 if (png_ptr->width == 1) 1936 filters &= 0xff & ~(PNG_FILTER_SUB|PNG_FILTER_AVG|PNG_FILTER_PAETH); 1937 1938 if (filters == 0) 1939 filters = PNG_FILTER_NONE; 1940 1941 png_ptr->do_filter = filters; 1942 1943 if (((filters & (PNG_FILTER_SUB | PNG_FILTER_UP | PNG_FILTER_AVG | 1944 PNG_FILTER_PAETH)) != 0) && png_ptr->try_row == NULL) 1945 { 1946 int num_filters = 0; 1947 1948 png_ptr->try_row = png_voidcast(png_bytep, png_malloc(png_ptr, buf_size)); 1949 1950 if (filters & PNG_FILTER_SUB) 1951 num_filters++; 1952 1953 if (filters & PNG_FILTER_UP) 1954 num_filters++; 1955 1956 if (filters & PNG_FILTER_AVG) 1957 num_filters++; 1958 1959 if (filters & PNG_FILTER_PAETH) 1960 num_filters++; 1961 1962 if (num_filters > 1) 1963 png_ptr->tst_row = png_voidcast(png_bytep, png_malloc(png_ptr, 1964 buf_size)); 1965 } 1966 1967 /* We only need to keep the previous row if we are using one of the following 1968 * filters. 1969 */ 1970 if ((filters & (PNG_FILTER_AVG | PNG_FILTER_UP | PNG_FILTER_PAETH)) != 0) 1971 png_ptr->prev_row = png_voidcast(png_bytep, 1972 png_calloc(png_ptr, buf_size)); 1973 #endif /* WRITE_FILTER */ 1974 1975 #ifdef PNG_WRITE_INTERLACING_SUPPORTED 1976 /* If interlaced, we need to set up width and height of pass */ 1977 if (png_ptr->interlaced != 0) 1978 { 1979 if ((png_ptr->transformations & PNG_INTERLACE) == 0) 1980 { 1981 png_ptr->num_rows = (png_ptr->height + png_pass_yinc[0] - 1 - 1982 png_pass_ystart[0]) / png_pass_yinc[0]; 1983 1984 png_ptr->usr_width = (png_ptr->width + png_pass_inc[0] - 1 - 1985 png_pass_start[0]) / png_pass_inc[0]; 1986 } 1987 1988 else 1989 { 1990 png_ptr->num_rows = png_ptr->height; 1991 png_ptr->usr_width = png_ptr->width; 1992 } 1993 } 1994 1995 else 1996 #endif 1997 { 1998 png_ptr->num_rows = png_ptr->height; 1999 png_ptr->usr_width = png_ptr->width; 2000 } 2001 } 2002 2003 /* Internal use only. Called when finished processing a row of data. */ 2004 void /* PRIVATE */ 2005 png_write_finish_row(png_structrp png_ptr) 2006 { 2007 #ifdef PNG_WRITE_INTERLACING_SUPPORTED 2008 /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */ 2009 2010 /* Start of interlace block */ 2011 static const png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0}; 2012 2013 /* Offset to next interlace block */ 2014 static const png_byte png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1}; 2015 2016 /* Start of interlace block in the y direction */ 2017 static const png_byte png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1}; 2018 2019 /* Offset to next interlace block in the y direction */ 2020 static const png_byte png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2}; 2021 #endif 2022 2023 png_debug(1, "in png_write_finish_row"); 2024 2025 /* Next row */ 2026 png_ptr->row_number++; 2027 2028 /* See if we are done */ 2029 if (png_ptr->row_number < png_ptr->num_rows) 2030 return; 2031 2032 #ifdef PNG_WRITE_INTERLACING_SUPPORTED 2033 /* If interlaced, go to next pass */ 2034 if (png_ptr->interlaced != 0) 2035 { 2036 png_ptr->row_number = 0; 2037 if ((png_ptr->transformations & PNG_INTERLACE) != 0) 2038 { 2039 png_ptr->pass++; 2040 } 2041 2042 else 2043 { 2044 /* Loop until we find a non-zero width or height pass */ 2045 do 2046 { 2047 png_ptr->pass++; 2048 2049 if (png_ptr->pass >= 7) 2050 break; 2051 2052 png_ptr->usr_width = (png_ptr->width + 2053 png_pass_inc[png_ptr->pass] - 1 - 2054 png_pass_start[png_ptr->pass]) / 2055 png_pass_inc[png_ptr->pass]; 2056 2057 png_ptr->num_rows = (png_ptr->height + 2058 png_pass_yinc[png_ptr->pass] - 1 - 2059 png_pass_ystart[png_ptr->pass]) / 2060 png_pass_yinc[png_ptr->pass]; 2061 2062 if ((png_ptr->transformations & PNG_INTERLACE) != 0) 2063 break; 2064 2065 } while (png_ptr->usr_width == 0 || png_ptr->num_rows == 0); 2066 2067 } 2068 2069 /* Reset the row above the image for the next pass */ 2070 if (png_ptr->pass < 7) 2071 { 2072 if (png_ptr->prev_row != NULL) 2073 memset(png_ptr->prev_row, 0, 2074 PNG_ROWBYTES(png_ptr->usr_channels * 2075 png_ptr->usr_bit_depth, png_ptr->width) + 1); 2076 2077 return; 2078 } 2079 } 2080 #endif 2081 2082 /* If we get here, we've just written the last row, so we need 2083 to flush the compressor */ 2084 png_compress_IDAT(png_ptr, NULL, 0, Z_FINISH); 2085 } 2086 2087 #ifdef PNG_WRITE_INTERLACING_SUPPORTED 2088 /* Pick out the correct pixels for the interlace pass. 2089 * The basic idea here is to go through the row with a source 2090 * pointer and a destination pointer (sp and dp), and copy the 2091 * correct pixels for the pass. As the row gets compacted, 2092 * sp will always be >= dp, so we should never overwrite anything. 2093 * See the default: case for the easiest code to understand. 2094 */ 2095 void /* PRIVATE */ 2096 png_do_write_interlace(png_row_infop row_info, png_bytep row, int pass) 2097 { 2098 /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */ 2099 2100 /* Start of interlace block */ 2101 static const png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0}; 2102 2103 /* Offset to next interlace block */ 2104 static const png_byte png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1}; 2105 2106 png_debug(1, "in png_do_write_interlace"); 2107 2108 /* We don't have to do anything on the last pass (6) */ 2109 if (pass < 6) 2110 { 2111 /* Each pixel depth is handled separately */ 2112 switch (row_info->pixel_depth) 2113 { 2114 case 1: 2115 { 2116 png_bytep sp; 2117 png_bytep dp; 2118 unsigned int shift; 2119 int d; 2120 int value; 2121 png_uint_32 i; 2122 png_uint_32 row_width = row_info->width; 2123 2124 dp = row; 2125 d = 0; 2126 shift = 7; 2127 2128 for (i = png_pass_start[pass]; i < row_width; 2129 i += png_pass_inc[pass]) 2130 { 2131 sp = row + (size_t)(i >> 3); 2132 value = (int)(*sp >> (7 - (int)(i & 0x07))) & 0x01; 2133 d |= (value << shift); 2134 2135 if (shift == 0) 2136 { 2137 shift = 7; 2138 *dp++ = (png_byte)d; 2139 d = 0; 2140 } 2141 2142 else 2143 shift--; 2144 2145 } 2146 if (shift != 7) 2147 *dp = (png_byte)d; 2148 2149 break; 2150 } 2151 2152 case 2: 2153 { 2154 png_bytep sp; 2155 png_bytep dp; 2156 unsigned int shift; 2157 int d; 2158 int value; 2159 png_uint_32 i; 2160 png_uint_32 row_width = row_info->width; 2161 2162 dp = row; 2163 shift = 6; 2164 d = 0; 2165 2166 for (i = png_pass_start[pass]; i < row_width; 2167 i += png_pass_inc[pass]) 2168 { 2169 sp = row + (size_t)(i >> 2); 2170 value = (*sp >> ((3 - (int)(i & 0x03)) << 1)) & 0x03; 2171 d |= (value << shift); 2172 2173 if (shift == 0) 2174 { 2175 shift = 6; 2176 *dp++ = (png_byte)d; 2177 d = 0; 2178 } 2179 2180 else 2181 shift -= 2; 2182 } 2183 if (shift != 6) 2184 *dp = (png_byte)d; 2185 2186 break; 2187 } 2188 2189 case 4: 2190 { 2191 png_bytep sp; 2192 png_bytep dp; 2193 unsigned int shift; 2194 int d; 2195 int value; 2196 png_uint_32 i; 2197 png_uint_32 row_width = row_info->width; 2198 2199 dp = row; 2200 shift = 4; 2201 d = 0; 2202 for (i = png_pass_start[pass]; i < row_width; 2203 i += png_pass_inc[pass]) 2204 { 2205 sp = row + (size_t)(i >> 1); 2206 value = (*sp >> ((1 - (int)(i & 0x01)) << 2)) & 0x0f; 2207 d |= (value << shift); 2208 2209 if (shift == 0) 2210 { 2211 shift = 4; 2212 *dp++ = (png_byte)d; 2213 d = 0; 2214 } 2215 2216 else 2217 shift -= 4; 2218 } 2219 if (shift != 4) 2220 *dp = (png_byte)d; 2221 2222 break; 2223 } 2224 2225 default: 2226 { 2227 png_bytep sp; 2228 png_bytep dp; 2229 png_uint_32 i; 2230 png_uint_32 row_width = row_info->width; 2231 size_t pixel_bytes; 2232 2233 /* Start at the beginning */ 2234 dp = row; 2235 2236 /* Find out how many bytes each pixel takes up */ 2237 pixel_bytes = (row_info->pixel_depth >> 3); 2238 2239 /* Loop through the row, only looking at the pixels that matter */ 2240 for (i = png_pass_start[pass]; i < row_width; 2241 i += png_pass_inc[pass]) 2242 { 2243 /* Find out where the original pixel is */ 2244 sp = row + (size_t)i * pixel_bytes; 2245 2246 /* Move the pixel */ 2247 if (dp != sp) 2248 memcpy(dp, sp, pixel_bytes); 2249 2250 /* Next pixel */ 2251 dp += pixel_bytes; 2252 } 2253 break; 2254 } 2255 } 2256 /* Set new row width */ 2257 row_info->width = (row_info->width + 2258 png_pass_inc[pass] - 1 - 2259 png_pass_start[pass]) / 2260 png_pass_inc[pass]; 2261 2262 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, 2263 row_info->width); 2264 } 2265 } 2266 #endif 2267 2268 2269 /* This filters the row, chooses which filter to use, if it has not already 2270 * been specified by the application, and then writes the row out with the 2271 * chosen filter. 2272 */ 2273 static void /* PRIVATE */ 2274 png_write_filtered_row(png_structrp png_ptr, png_bytep filtered_row, 2275 size_t row_bytes); 2276 2277 #ifdef PNG_WRITE_FILTER_SUPPORTED 2278 static size_t /* PRIVATE */ 2279 png_setup_sub_row(png_structrp png_ptr, png_uint_32 bpp, 2280 size_t row_bytes, size_t lmins) 2281 { 2282 png_bytep rp, dp, lp; 2283 size_t i; 2284 size_t sum = 0; 2285 unsigned int v; 2286 2287 png_ptr->try_row[0] = PNG_FILTER_VALUE_SUB; 2288 2289 for (i = 0, rp = png_ptr->row_buf + 1, dp = png_ptr->try_row + 1; i < bpp; 2290 i++, rp++, dp++) 2291 { 2292 v = *dp = *rp; 2293 #ifdef PNG_USE_ABS 2294 sum += 128 - abs((int)v - 128); 2295 #else 2296 sum += (v < 128) ? v : 256 - v; 2297 #endif 2298 } 2299 2300 for (lp = png_ptr->row_buf + 1; i < row_bytes; 2301 i++, rp++, lp++, dp++) 2302 { 2303 v = *dp = (png_byte)(((int)*rp - (int)*lp) & 0xff); 2304 #ifdef PNG_USE_ABS 2305 sum += 128 - abs((int)v - 128); 2306 #else 2307 sum += (v < 128) ? v : 256 - v; 2308 #endif 2309 2310 if (sum > lmins) /* We are already worse, don't continue. */ 2311 break; 2312 } 2313 2314 return (sum); 2315 } 2316 2317 static void /* PRIVATE */ 2318 png_setup_sub_row_only(png_structrp png_ptr, png_uint_32 bpp, 2319 size_t row_bytes) 2320 { 2321 png_bytep rp, dp, lp; 2322 size_t i; 2323 2324 png_ptr->try_row[0] = PNG_FILTER_VALUE_SUB; 2325 2326 for (i = 0, rp = png_ptr->row_buf + 1, dp = png_ptr->try_row + 1; i < bpp; 2327 i++, rp++, dp++) 2328 { 2329 *dp = *rp; 2330 } 2331 2332 for (lp = png_ptr->row_buf + 1; i < row_bytes; 2333 i++, rp++, lp++, dp++) 2334 { 2335 *dp = (png_byte)(((int)*rp - (int)*lp) & 0xff); 2336 } 2337 } 2338 2339 static size_t /* PRIVATE */ 2340 png_setup_up_row(png_structrp png_ptr, size_t row_bytes, size_t lmins) 2341 { 2342 png_bytep rp, dp, pp; 2343 size_t i; 2344 size_t sum = 0; 2345 unsigned int v; 2346 2347 png_ptr->try_row[0] = PNG_FILTER_VALUE_UP; 2348 2349 for (i = 0, rp = png_ptr->row_buf + 1, dp = png_ptr->try_row + 1, 2350 pp = png_ptr->prev_row + 1; i < row_bytes; 2351 i++, rp++, pp++, dp++) 2352 { 2353 v = *dp = (png_byte)(((int)*rp - (int)*pp) & 0xff); 2354 #ifdef PNG_USE_ABS 2355 sum += 128 - abs((int)v - 128); 2356 #else 2357 sum += (v < 128) ? v : 256 - v; 2358 #endif 2359 2360 if (sum > lmins) /* We are already worse, don't continue. */ 2361 break; 2362 } 2363 2364 return (sum); 2365 } 2366 static void /* PRIVATE */ 2367 png_setup_up_row_only(png_structrp png_ptr, size_t row_bytes) 2368 { 2369 png_bytep rp, dp, pp; 2370 size_t i; 2371 2372 png_ptr->try_row[0] = PNG_FILTER_VALUE_UP; 2373 2374 for (i = 0, rp = png_ptr->row_buf + 1, dp = png_ptr->try_row + 1, 2375 pp = png_ptr->prev_row + 1; i < row_bytes; 2376 i++, rp++, pp++, dp++) 2377 { 2378 *dp = (png_byte)(((int)*rp - (int)*pp) & 0xff); 2379 } 2380 } 2381 2382 static size_t /* PRIVATE */ 2383 png_setup_avg_row(png_structrp png_ptr, png_uint_32 bpp, 2384 size_t row_bytes, size_t lmins) 2385 { 2386 png_bytep rp, dp, pp, lp; 2387 png_uint_32 i; 2388 size_t sum = 0; 2389 unsigned int v; 2390 2391 png_ptr->try_row[0] = PNG_FILTER_VALUE_AVG; 2392 2393 for (i = 0, rp = png_ptr->row_buf + 1, dp = png_ptr->try_row + 1, 2394 pp = png_ptr->prev_row + 1; i < bpp; i++) 2395 { 2396 v = *dp++ = (png_byte)(((int)*rp++ - ((int)*pp++ / 2)) & 0xff); 2397 2398 #ifdef PNG_USE_ABS 2399 sum += 128 - abs((int)v - 128); 2400 #else 2401 sum += (v < 128) ? v : 256 - v; 2402 #endif 2403 } 2404 2405 for (lp = png_ptr->row_buf + 1; i < row_bytes; i++) 2406 { 2407 v = *dp++ = (png_byte)(((int)*rp++ - (((int)*pp++ + (int)*lp++) / 2)) 2408 & 0xff); 2409 2410 #ifdef PNG_USE_ABS 2411 sum += 128 - abs((int)v - 128); 2412 #else 2413 sum += (v < 128) ? v : 256 - v; 2414 #endif 2415 2416 if (sum > lmins) /* We are already worse, don't continue. */ 2417 break; 2418 } 2419 2420 return (sum); 2421 } 2422 static void /* PRIVATE */ 2423 png_setup_avg_row_only(png_structrp png_ptr, png_uint_32 bpp, 2424 size_t row_bytes) 2425 { 2426 png_bytep rp, dp, pp, lp; 2427 png_uint_32 i; 2428 2429 png_ptr->try_row[0] = PNG_FILTER_VALUE_AVG; 2430 2431 for (i = 0, rp = png_ptr->row_buf + 1, dp = png_ptr->try_row + 1, 2432 pp = png_ptr->prev_row + 1; i < bpp; i++) 2433 { 2434 *dp++ = (png_byte)(((int)*rp++ - ((int)*pp++ / 2)) & 0xff); 2435 } 2436 2437 for (lp = png_ptr->row_buf + 1; i < row_bytes; i++) 2438 { 2439 *dp++ = (png_byte)(((int)*rp++ - (((int)*pp++ + (int)*lp++) / 2)) 2440 & 0xff); 2441 } 2442 } 2443 2444 static size_t /* PRIVATE */ 2445 png_setup_paeth_row(png_structrp png_ptr, png_uint_32 bpp, 2446 size_t row_bytes, size_t lmins) 2447 { 2448 png_bytep rp, dp, pp, cp, lp; 2449 size_t i; 2450 size_t sum = 0; 2451 unsigned int v; 2452 2453 png_ptr->try_row[0] = PNG_FILTER_VALUE_PAETH; 2454 2455 for (i = 0, rp = png_ptr->row_buf + 1, dp = png_ptr->try_row + 1, 2456 pp = png_ptr->prev_row + 1; i < bpp; i++) 2457 { 2458 v = *dp++ = (png_byte)(((int)*rp++ - (int)*pp++) & 0xff); 2459 2460 #ifdef PNG_USE_ABS 2461 sum += 128 - abs((int)v - 128); 2462 #else 2463 sum += (v < 128) ? v : 256 - v; 2464 #endif 2465 } 2466 2467 for (lp = png_ptr->row_buf + 1, cp = png_ptr->prev_row + 1; i < row_bytes; 2468 i++) 2469 { 2470 int a, b, c, pa, pb, pc, p; 2471 2472 b = *pp++; 2473 c = *cp++; 2474 a = *lp++; 2475 2476 p = b - c; 2477 pc = a - c; 2478 2479 #ifdef PNG_USE_ABS 2480 pa = abs(p); 2481 pb = abs(pc); 2482 pc = abs(p + pc); 2483 #else 2484 pa = p < 0 ? -p : p; 2485 pb = pc < 0 ? -pc : pc; 2486 pc = (p + pc) < 0 ? -(p + pc) : p + pc; 2487 #endif 2488 2489 p = (pa <= pb && pa <=pc) ? a : (pb <= pc) ? b : c; 2490 2491 v = *dp++ = (png_byte)(((int)*rp++ - p) & 0xff); 2492 2493 #ifdef PNG_USE_ABS 2494 sum += 128 - abs((int)v - 128); 2495 #else 2496 sum += (v < 128) ? v : 256 - v; 2497 #endif 2498 2499 if (sum > lmins) /* We are already worse, don't continue. */ 2500 break; 2501 } 2502 2503 return (sum); 2504 } 2505 static void /* PRIVATE */ 2506 png_setup_paeth_row_only(png_structrp png_ptr, png_uint_32 bpp, 2507 size_t row_bytes) 2508 { 2509 png_bytep rp, dp, pp, cp, lp; 2510 size_t i; 2511 2512 png_ptr->try_row[0] = PNG_FILTER_VALUE_PAETH; 2513 2514 for (i = 0, rp = png_ptr->row_buf + 1, dp = png_ptr->try_row + 1, 2515 pp = png_ptr->prev_row + 1; i < bpp; i++) 2516 { 2517 *dp++ = (png_byte)(((int)*rp++ - (int)*pp++) & 0xff); 2518 } 2519 2520 for (lp = png_ptr->row_buf + 1, cp = png_ptr->prev_row + 1; i < row_bytes; 2521 i++) 2522 { 2523 int a, b, c, pa, pb, pc, p; 2524 2525 b = *pp++; 2526 c = *cp++; 2527 a = *lp++; 2528 2529 p = b - c; 2530 pc = a - c; 2531 2532 #ifdef PNG_USE_ABS 2533 pa = abs(p); 2534 pb = abs(pc); 2535 pc = abs(p + pc); 2536 #else 2537 pa = p < 0 ? -p : p; 2538 pb = pc < 0 ? -pc : pc; 2539 pc = (p + pc) < 0 ? -(p + pc) : p + pc; 2540 #endif 2541 2542 p = (pa <= pb && pa <=pc) ? a : (pb <= pc) ? b : c; 2543 2544 *dp++ = (png_byte)(((int)*rp++ - p) & 0xff); 2545 } 2546 } 2547 #endif /* WRITE_FILTER */ 2548 2549 void /* PRIVATE */ 2550 png_write_find_filter(png_structrp png_ptr, png_row_infop row_info) 2551 { 2552 #ifndef PNG_WRITE_FILTER_SUPPORTED 2553 png_write_filtered_row(png_ptr, png_ptr->row_buf, row_info->rowbytes+1); 2554 #else 2555 unsigned int filter_to_do = png_ptr->do_filter; 2556 png_bytep row_buf; 2557 png_bytep best_row; 2558 png_uint_32 bpp; 2559 size_t mins; 2560 size_t row_bytes = row_info->rowbytes; 2561 2562 png_debug(1, "in png_write_find_filter"); 2563 2564 /* Find out how many bytes offset each pixel is */ 2565 bpp = (row_info->pixel_depth + 7) >> 3; 2566 2567 row_buf = png_ptr->row_buf; 2568 mins = PNG_SIZE_MAX - 256/* so we can detect potential overflow of the 2569 running sum */; 2570 2571 /* The prediction method we use is to find which method provides the 2572 * smallest value when summing the absolute values of the distances 2573 * from zero, using anything >= 128 as negative numbers. This is known 2574 * as the "minimum sum of absolute differences" heuristic. Other 2575 * heuristics are the "weighted minimum sum of absolute differences" 2576 * (experimental and can in theory improve compression), and the "zlib 2577 * predictive" method (not implemented yet), which does test compressions 2578 * of lines using different filter methods, and then chooses the 2579 * (series of) filter(s) that give minimum compressed data size (VERY 2580 * computationally expensive). 2581 * 2582 * GRR 980525: consider also 2583 * 2584 * (1) minimum sum of absolute differences from running average (i.e., 2585 * keep running sum of non-absolute differences & count of bytes) 2586 * [track dispersion, too? restart average if dispersion too large?] 2587 * 2588 * (1b) minimum sum of absolute differences from sliding average, probably 2589 * with window size <= deflate window (usually 32K) 2590 * 2591 * (2) minimum sum of squared differences from zero or running average 2592 * (i.e., ~ root-mean-square approach) 2593 */ 2594 2595 2596 /* We don't need to test the 'no filter' case if this is the only filter 2597 * that has been chosen, as it doesn't actually do anything to the data. 2598 */ 2599 best_row = png_ptr->row_buf; 2600 2601 if (PNG_SIZE_MAX/128 <= row_bytes) 2602 { 2603 /* Overflow can occur in the calculation, just select the lowest set 2604 * filter. 2605 */ 2606 filter_to_do &= 0U-filter_to_do; 2607 } 2608 else if ((filter_to_do & PNG_FILTER_NONE) != 0 && 2609 filter_to_do != PNG_FILTER_NONE) 2610 { 2611 /* Overflow not possible and multiple filters in the list, including the 2612 * 'none' filter. 2613 */ 2614 png_bytep rp; 2615 size_t sum = 0; 2616 size_t i; 2617 unsigned int v; 2618 2619 { 2620 for (i = 0, rp = row_buf + 1; i < row_bytes; i++, rp++) 2621 { 2622 v = *rp; 2623 #ifdef PNG_USE_ABS 2624 sum += 128 - abs((int)v - 128); 2625 #else 2626 sum += (v < 128) ? v : 256 - v; 2627 #endif 2628 } 2629 } 2630 2631 mins = sum; 2632 } 2633 2634 /* Sub filter */ 2635 if (filter_to_do == PNG_FILTER_SUB) 2636 /* It's the only filter so no testing is needed */ 2637 { 2638 png_setup_sub_row_only(png_ptr, bpp, row_bytes); 2639 best_row = png_ptr->try_row; 2640 } 2641 2642 else if ((filter_to_do & PNG_FILTER_SUB) != 0) 2643 { 2644 size_t sum; 2645 size_t lmins = mins; 2646 2647 sum = png_setup_sub_row(png_ptr, bpp, row_bytes, lmins); 2648 2649 if (sum < mins) 2650 { 2651 mins = sum; 2652 best_row = png_ptr->try_row; 2653 if (png_ptr->tst_row != NULL) 2654 { 2655 png_ptr->try_row = png_ptr->tst_row; 2656 png_ptr->tst_row = best_row; 2657 } 2658 } 2659 } 2660 2661 /* Up filter */ 2662 if (filter_to_do == PNG_FILTER_UP) 2663 { 2664 png_setup_up_row_only(png_ptr, row_bytes); 2665 best_row = png_ptr->try_row; 2666 } 2667 2668 else if ((filter_to_do & PNG_FILTER_UP) != 0) 2669 { 2670 size_t sum; 2671 size_t lmins = mins; 2672 2673 sum = png_setup_up_row(png_ptr, row_bytes, lmins); 2674 2675 if (sum < mins) 2676 { 2677 mins = sum; 2678 best_row = png_ptr->try_row; 2679 if (png_ptr->tst_row != NULL) 2680 { 2681 png_ptr->try_row = png_ptr->tst_row; 2682 png_ptr->tst_row = best_row; 2683 } 2684 } 2685 } 2686 2687 /* Avg filter */ 2688 if (filter_to_do == PNG_FILTER_AVG) 2689 { 2690 png_setup_avg_row_only(png_ptr, bpp, row_bytes); 2691 best_row = png_ptr->try_row; 2692 } 2693 2694 else if ((filter_to_do & PNG_FILTER_AVG) != 0) 2695 { 2696 size_t sum; 2697 size_t lmins = mins; 2698 2699 sum= png_setup_avg_row(png_ptr, bpp, row_bytes, lmins); 2700 2701 if (sum < mins) 2702 { 2703 mins = sum; 2704 best_row = png_ptr->try_row; 2705 if (png_ptr->tst_row != NULL) 2706 { 2707 png_ptr->try_row = png_ptr->tst_row; 2708 png_ptr->tst_row = best_row; 2709 } 2710 } 2711 } 2712 2713 /* Paeth filter */ 2714 if (filter_to_do == PNG_FILTER_PAETH) 2715 { 2716 png_setup_paeth_row_only(png_ptr, bpp, row_bytes); 2717 best_row = png_ptr->try_row; 2718 } 2719 2720 else if ((filter_to_do & PNG_FILTER_PAETH) != 0) 2721 { 2722 size_t sum; 2723 size_t lmins = mins; 2724 2725 sum = png_setup_paeth_row(png_ptr, bpp, row_bytes, lmins); 2726 2727 if (sum < mins) 2728 { 2729 best_row = png_ptr->try_row; 2730 if (png_ptr->tst_row != NULL) 2731 { 2732 png_ptr->try_row = png_ptr->tst_row; 2733 png_ptr->tst_row = best_row; 2734 } 2735 } 2736 } 2737 2738 /* Do the actual writing of the filtered row data from the chosen filter. */ 2739 png_write_filtered_row(png_ptr, best_row, row_info->rowbytes+1); 2740 2741 #endif /* WRITE_FILTER */ 2742 } 2743 2744 2745 /* Do the actual writing of a previously filtered row. */ 2746 static void 2747 png_write_filtered_row(png_structrp png_ptr, png_bytep filtered_row, 2748 size_t full_row_length/*includes filter byte*/) 2749 { 2750 png_debug(1, "in png_write_filtered_row"); 2751 2752 png_debug1(2, "filter = %d", filtered_row[0]); 2753 2754 png_compress_IDAT(png_ptr, filtered_row, full_row_length, Z_NO_FLUSH); 2755 2756 #ifdef PNG_WRITE_FILTER_SUPPORTED 2757 /* Swap the current and previous rows */ 2758 if (png_ptr->prev_row != NULL) 2759 { 2760 png_bytep tptr; 2761 2762 tptr = png_ptr->prev_row; 2763 png_ptr->prev_row = png_ptr->row_buf; 2764 png_ptr->row_buf = tptr; 2765 } 2766 #endif /* WRITE_FILTER */ 2767 2768 /* Finish row - updates counters and flushes zlib if last row */ 2769 png_write_finish_row(png_ptr); 2770 2771 #ifdef PNG_WRITE_FLUSH_SUPPORTED 2772 png_ptr->flush_rows++; 2773 2774 if (png_ptr->flush_dist > 0 && 2775 png_ptr->flush_rows >= png_ptr->flush_dist) 2776 { 2777 png_write_flush(png_ptr); 2778 } 2779 #endif /* WRITE_FLUSH */ 2780 } 2781 #endif /* WRITE */ 2782