1 /* 2 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 3 * 4 * This code is free software; you can redistribute it and/or modify it 5 * under the terms of the GNU General Public License version 2 only, as 6 * published by the Free Software Foundation. Oracle designates this 7 * particular file as subject to the "Classpath" exception as provided 8 * by Oracle in the LICENSE file that accompanied this code. 9 * 10 * This code is distributed in the hope that it will be useful, but WITHOUT 11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 13 * version 2 for more details (a copy is included in the LICENSE file that 14 * accompanied this code). 15 * 16 * You should have received a copy of the GNU General Public License version 17 * 2 along with this work; if not, write to the Free Software Foundation, 18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 19 * 20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 21 * or visit www.oracle.com if you need additional information or have any 22 * questions. 23 */ 24 25 /* pngwutil.c - utilities to write a PNG file 26 * 27 * This file is available under and governed by the GNU General Public 28 * License version 2 only, as published by the Free Software Foundation. 29 * However, the following notice accompanied the original version of this 30 * file and, per its terms, should not be removed: 31 * 32 * Last changed in libpng 1.6.22 [May 26, 2016] 33 * Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson 34 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger) 35 * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.) 36 * 37 * This code is released under the libpng license. 38 * For conditions of distribution and use, see the disclaimer 39 * and license in png.h 40 */ 41 42 #include "pngpriv.h" 43 44 #ifdef PNG_WRITE_SUPPORTED 45 46 #ifdef PNG_WRITE_INT_FUNCTIONS_SUPPORTED 47 /* Place a 32-bit number into a buffer in PNG byte order. We work 48 * with unsigned numbers for convenience, although one supported 49 * ancillary chunk uses signed (two's complement) numbers. 50 */ 51 void PNGAPI 52 png_save_uint_32(png_bytep buf, png_uint_32 i) 53 { 54 buf[0] = (png_byte)((i >> 24) & 0xffU); 55 buf[1] = (png_byte)((i >> 16) & 0xffU); 56 buf[2] = (png_byte)((i >> 8) & 0xffU); 57 buf[3] = (png_byte)( i & 0xffU); 58 } 59 60 /* Place a 16-bit number into a buffer in PNG byte order. 61 * The parameter is declared unsigned int, not png_uint_16, 62 * just to avoid potential problems on pre-ANSI C compilers. 63 */ 64 void PNGAPI 65 png_save_uint_16(png_bytep buf, unsigned int i) 66 { 67 buf[0] = (png_byte)((i >> 8) & 0xffU); 68 buf[1] = (png_byte)( i & 0xffU); 69 } 70 #endif 71 72 /* Simple function to write the signature. If we have already written 73 * the magic bytes of the signature, or more likely, the PNG stream is 74 * being embedded into another stream and doesn't need its own signature, 75 * we should call png_set_sig_bytes() to tell libpng how many of the 76 * bytes have already been written. 77 */ 78 void PNGAPI 79 png_write_sig(png_structrp png_ptr) 80 { 81 png_byte png_signature[8] = {137, 80, 78, 71, 13, 10, 26, 10}; 82 83 #ifdef PNG_IO_STATE_SUPPORTED 84 /* Inform the I/O callback that the signature is being written */ 85 png_ptr->io_state = PNG_IO_WRITING | PNG_IO_SIGNATURE; 86 #endif 87 88 /* Write the rest of the 8 byte signature */ 89 png_write_data(png_ptr, &png_signature[png_ptr->sig_bytes], 90 (png_size_t)(8 - png_ptr->sig_bytes)); 91 92 if (png_ptr->sig_bytes < 3) 93 png_ptr->mode |= PNG_HAVE_PNG_SIGNATURE; 94 } 95 96 /* Write the start of a PNG chunk. The type is the chunk type. 97 * The total_length is the sum of the lengths of all the data you will be 98 * passing in png_write_chunk_data(). 99 */ 100 static void 101 png_write_chunk_header(png_structrp png_ptr, png_uint_32 chunk_name, 102 png_uint_32 length) 103 { 104 png_byte buf[8]; 105 106 #if defined(PNG_DEBUG) && (PNG_DEBUG > 0) 107 PNG_CSTRING_FROM_CHUNK(buf, chunk_name); 108 png_debug2(0, "Writing %s chunk, length = %lu", buf, (unsigned long)length); 109 #endif 110 111 if (png_ptr == NULL) 112 return; 113 114 #ifdef PNG_IO_STATE_SUPPORTED 115 /* Inform the I/O callback that the chunk header is being written. 116 * PNG_IO_CHUNK_HDR requires a single I/O call. 117 */ 118 png_ptr->io_state = PNG_IO_WRITING | PNG_IO_CHUNK_HDR; 119 #endif 120 121 /* Write the length and the chunk name */ 122 png_save_uint_32(buf, length); 123 png_save_uint_32(buf + 4, chunk_name); 124 png_write_data(png_ptr, buf, 8); 125 126 /* Put the chunk name into png_ptr->chunk_name */ 127 png_ptr->chunk_name = chunk_name; 128 129 /* Reset the crc and run it over the chunk name */ 130 png_reset_crc(png_ptr); 131 132 png_calculate_crc(png_ptr, buf + 4, 4); 133 134 #ifdef PNG_IO_STATE_SUPPORTED 135 /* Inform the I/O callback that chunk data will (possibly) be written. 136 * PNG_IO_CHUNK_DATA does NOT require a specific number of I/O calls. 137 */ 138 png_ptr->io_state = PNG_IO_WRITING | PNG_IO_CHUNK_DATA; 139 #endif 140 } 141 142 void PNGAPI 143 png_write_chunk_start(png_structrp png_ptr, png_const_bytep chunk_string, 144 png_uint_32 length) 145 { 146 png_write_chunk_header(png_ptr, PNG_CHUNK_FROM_STRING(chunk_string), length); 147 } 148 149 /* Write the data of a PNG chunk started with png_write_chunk_header(). 150 * Note that multiple calls to this function are allowed, and that the 151 * sum of the lengths from these calls *must* add up to the total_length 152 * given to png_write_chunk_header(). 153 */ 154 void PNGAPI 155 png_write_chunk_data(png_structrp png_ptr, png_const_bytep data, 156 png_size_t length) 157 { 158 /* Write the data, and run the CRC over it */ 159 if (png_ptr == NULL) 160 return; 161 162 if (data != NULL && length > 0) 163 { 164 png_write_data(png_ptr, data, length); 165 166 /* Update the CRC after writing the data, 167 * in case the user I/O routine alters it. 168 */ 169 png_calculate_crc(png_ptr, data, length); 170 } 171 } 172 173 /* Finish a chunk started with png_write_chunk_header(). */ 174 void PNGAPI 175 png_write_chunk_end(png_structrp png_ptr) 176 { 177 png_byte buf[4]; 178 179 if (png_ptr == NULL) return; 180 181 #ifdef PNG_IO_STATE_SUPPORTED 182 /* Inform the I/O callback that the chunk CRC is being written. 183 * PNG_IO_CHUNK_CRC requires a single I/O function call. 184 */ 185 png_ptr->io_state = PNG_IO_WRITING | PNG_IO_CHUNK_CRC; 186 #endif 187 188 /* Write the crc in a single operation */ 189 png_save_uint_32(buf, png_ptr->crc); 190 191 png_write_data(png_ptr, buf, (png_size_t)4); 192 } 193 194 /* Write a PNG chunk all at once. The type is an array of ASCII characters 195 * representing the chunk name. The array must be at least 4 bytes in 196 * length, and does not need to be null terminated. To be safe, pass the 197 * pre-defined chunk names here, and if you need a new one, define it 198 * where the others are defined. The length is the length of the data. 199 * All the data must be present. If that is not possible, use the 200 * png_write_chunk_start(), png_write_chunk_data(), and png_write_chunk_end() 201 * functions instead. 202 */ 203 static void 204 png_write_complete_chunk(png_structrp png_ptr, png_uint_32 chunk_name, 205 png_const_bytep data, png_size_t length) 206 { 207 if (png_ptr == NULL) 208 return; 209 210 /* On 64-bit architectures 'length' may not fit in a png_uint_32. */ 211 if (length > PNG_UINT_31_MAX) 212 png_error(png_ptr, "length exceeds PNG maximum"); 213 214 png_write_chunk_header(png_ptr, chunk_name, (png_uint_32)length); 215 png_write_chunk_data(png_ptr, data, length); 216 png_write_chunk_end(png_ptr); 217 } 218 219 /* This is the API that calls the internal function above. */ 220 void PNGAPI 221 png_write_chunk(png_structrp png_ptr, png_const_bytep chunk_string, 222 png_const_bytep data, png_size_t length) 223 { 224 png_write_complete_chunk(png_ptr, PNG_CHUNK_FROM_STRING(chunk_string), data, 225 length); 226 } 227 228 /* This is used below to find the size of an image to pass to png_deflate_claim, 229 * so it only needs to be accurate if the size is less than 16384 bytes (the 230 * point at which a lower LZ window size can be used.) 231 */ 232 static png_alloc_size_t 233 png_image_size(png_structrp png_ptr) 234 { 235 /* Only return sizes up to the maximum of a png_uint_32; do this by limiting 236 * the width and height used to 15 bits. 237 */ 238 png_uint_32 h = png_ptr->height; 239 240 if (png_ptr->rowbytes < 32768 && h < 32768) 241 { 242 if (png_ptr->interlaced != 0) 243 { 244 /* Interlacing makes the image larger because of the replication of 245 * both the filter byte and the padding to a byte boundary. 246 */ 247 png_uint_32 w = png_ptr->width; 248 unsigned int pd = png_ptr->pixel_depth; 249 png_alloc_size_t cb_base; 250 int pass; 251 252 for (cb_base=0, pass=0; pass<=6; ++pass) 253 { 254 png_uint_32 pw = PNG_PASS_COLS(w, pass); 255 256 if (pw > 0) 257 cb_base += (PNG_ROWBYTES(pd, pw)+1) * PNG_PASS_ROWS(h, pass); 258 } 259 260 return cb_base; 261 } 262 263 else 264 return (png_ptr->rowbytes+1) * h; 265 } 266 267 else 268 return 0xffffffffU; 269 } 270 271 #ifdef PNG_WRITE_OPTIMIZE_CMF_SUPPORTED 272 /* This is the code to hack the first two bytes of the deflate stream (the 273 * deflate header) to correct the windowBits value to match the actual data 274 * size. Note that the second argument is the *uncompressed* size but the 275 * first argument is the *compressed* data (and it must be deflate 276 * compressed.) 277 */ 278 static void 279 optimize_cmf(png_bytep data, png_alloc_size_t data_size) 280 { 281 /* Optimize the CMF field in the zlib stream. The resultant zlib stream is 282 * still compliant to the stream specification. 283 */ 284 if (data_size <= 16384) /* else windowBits must be 15 */ 285 { 286 unsigned int z_cmf = data[0]; /* zlib compression method and flags */ 287 288 if ((z_cmf & 0x0f) == 8 && (z_cmf & 0xf0) <= 0x70) 289 { 290 unsigned int z_cinfo; 291 unsigned int half_z_window_size; 292 293 z_cinfo = z_cmf >> 4; 294 half_z_window_size = 1U << (z_cinfo + 7); 295 296 if (data_size <= half_z_window_size) /* else no change */ 297 { 298 unsigned int tmp; 299 300 do 301 { 302 half_z_window_size >>= 1; 303 --z_cinfo; 304 } 305 while (z_cinfo > 0 && data_size <= half_z_window_size); 306 307 z_cmf = (z_cmf & 0x0f) | (z_cinfo << 4); 308 309 data[0] = (png_byte)z_cmf; 310 tmp = data[1] & 0xe0; 311 tmp += 0x1f - ((z_cmf << 8) + tmp) % 0x1f; 312 data[1] = (png_byte)tmp; 313 } 314 } 315 } 316 } 317 #endif /* WRITE_OPTIMIZE_CMF */ 318 319 /* Initialize the compressor for the appropriate type of compression. */ 320 static int 321 png_deflate_claim(png_structrp png_ptr, png_uint_32 owner, 322 png_alloc_size_t data_size) 323 { 324 if (png_ptr->zowner != 0) 325 { 326 #if defined(PNG_WARNINGS_SUPPORTED) || defined(PNG_ERROR_TEXT_SUPPORTED) 327 char msg[64]; 328 329 PNG_STRING_FROM_CHUNK(msg, owner); 330 msg[4] = ':'; 331 msg[5] = ' '; 332 PNG_STRING_FROM_CHUNK(msg+6, png_ptr->zowner); 333 /* So the message that results is "<chunk> using zstream"; this is an 334 * internal error, but is very useful for debugging. i18n requirements 335 * are minimal. 336 */ 337 (void)png_safecat(msg, (sizeof msg), 10, " using zstream"); 338 #endif 339 #if PNG_RELEASE_BUILD 340 png_warning(png_ptr, msg); 341 342 /* Attempt sane error recovery */ 343 if (png_ptr->zowner == png_IDAT) /* don't steal from IDAT */ 344 { 345 png_ptr->zstream.msg = PNGZ_MSG_CAST("in use by IDAT"); 346 return Z_STREAM_ERROR; 347 } 348 349 png_ptr->zowner = 0; 350 #else 351 png_error(png_ptr, msg); 352 #endif 353 } 354 355 { 356 int level = png_ptr->zlib_level; 357 int method = png_ptr->zlib_method; 358 int windowBits = png_ptr->zlib_window_bits; 359 int memLevel = png_ptr->zlib_mem_level; 360 int strategy; /* set below */ 361 int ret; /* zlib return code */ 362 363 if (owner == png_IDAT) 364 { 365 if ((png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_STRATEGY) != 0) 366 strategy = png_ptr->zlib_strategy; 367 368 else if (png_ptr->do_filter != PNG_FILTER_NONE) 369 strategy = PNG_Z_DEFAULT_STRATEGY; 370 371 else 372 strategy = PNG_Z_DEFAULT_NOFILTER_STRATEGY; 373 } 374 375 else 376 { 377 #ifdef PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED 378 level = png_ptr->zlib_text_level; 379 method = png_ptr->zlib_text_method; 380 windowBits = png_ptr->zlib_text_window_bits; 381 memLevel = png_ptr->zlib_text_mem_level; 382 strategy = png_ptr->zlib_text_strategy; 383 #else 384 /* If customization is not supported the values all come from the 385 * IDAT values except for the strategy, which is fixed to the 386 * default. (This is the pre-1.6.0 behavior too, although it was 387 * implemented in a very different way.) 388 */ 389 strategy = Z_DEFAULT_STRATEGY; 390 #endif 391 } 392 393 /* Adjust 'windowBits' down if larger than 'data_size'; to stop this 394 * happening just pass 32768 as the data_size parameter. Notice that zlib 395 * requires an extra 262 bytes in the window in addition to the data to be 396 * able to see the whole of the data, so if data_size+262 takes us to the 397 * next windowBits size we need to fix up the value later. (Because even 398 * though deflate needs the extra window, inflate does not!) 399 */ 400 if (data_size <= 16384) 401 { 402 /* IMPLEMENTATION NOTE: this 'half_window_size' stuff is only here to 403 * work round a Microsoft Visual C misbehavior which, contrary to C-90, 404 * widens the result of the following shift to 64-bits if (and, 405 * apparently, only if) it is used in a test. 406 */ 407 unsigned int half_window_size = 1U << (windowBits-1); 408 409 while (data_size + 262 <= half_window_size) 410 { 411 half_window_size >>= 1; 412 --windowBits; 413 } 414 } 415 416 /* Check against the previous initialized values, if any. */ 417 if ((png_ptr->flags & PNG_FLAG_ZSTREAM_INITIALIZED) != 0 && 418 (png_ptr->zlib_set_level != level || 419 png_ptr->zlib_set_method != method || 420 png_ptr->zlib_set_window_bits != windowBits || 421 png_ptr->zlib_set_mem_level != memLevel || 422 png_ptr->zlib_set_strategy != strategy)) 423 { 424 if (deflateEnd(&png_ptr->zstream) != Z_OK) 425 png_warning(png_ptr, "deflateEnd failed (ignored)"); 426 427 png_ptr->flags &= ~PNG_FLAG_ZSTREAM_INITIALIZED; 428 } 429 430 /* For safety clear out the input and output pointers (currently zlib 431 * doesn't use them on Init, but it might in the future). 432 */ 433 png_ptr->zstream.next_in = NULL; 434 png_ptr->zstream.avail_in = 0; 435 png_ptr->zstream.next_out = NULL; 436 png_ptr->zstream.avail_out = 0; 437 438 /* Now initialize if required, setting the new parameters, otherwise just 439 * to a simple reset to the previous parameters. 440 */ 441 if ((png_ptr->flags & PNG_FLAG_ZSTREAM_INITIALIZED) != 0) 442 ret = deflateReset(&png_ptr->zstream); 443 444 else 445 { 446 ret = deflateInit2(&png_ptr->zstream, level, method, windowBits, 447 memLevel, strategy); 448 449 if (ret == Z_OK) 450 png_ptr->flags |= PNG_FLAG_ZSTREAM_INITIALIZED; 451 } 452 453 /* The return code is from either deflateReset or deflateInit2; they have 454 * pretty much the same set of error codes. 455 */ 456 if (ret == Z_OK) 457 png_ptr->zowner = owner; 458 459 else 460 png_zstream_error(png_ptr, ret); 461 462 return ret; 463 } 464 } 465 466 /* Clean up (or trim) a linked list of compression buffers. */ 467 void /* PRIVATE */ 468 png_free_buffer_list(png_structrp png_ptr, png_compression_bufferp *listp) 469 { 470 png_compression_bufferp list = *listp; 471 472 if (list != NULL) 473 { 474 *listp = NULL; 475 476 do 477 { 478 png_compression_bufferp next = list->next; 479 480 png_free(png_ptr, list); 481 list = next; 482 } 483 while (list != NULL); 484 } 485 } 486 487 #ifdef PNG_WRITE_COMPRESSED_TEXT_SUPPORTED 488 /* This pair of functions encapsulates the operation of (a) compressing a 489 * text string, and (b) issuing it later as a series of chunk data writes. 490 * The compression_state structure is shared context for these functions 491 * set up by the caller to allow access to the relevant local variables. 492 * 493 * compression_buffer (new in 1.6.0) is just a linked list of zbuffer_size 494 * temporary buffers. From 1.6.0 it is retained in png_struct so that it will 495 * be correctly freed in the event of a write error (previous implementations 496 * just leaked memory.) 497 */ 498 typedef struct 499 { 500 png_const_bytep input; /* The uncompressed input data */ 501 png_alloc_size_t input_len; /* Its length */ 502 png_uint_32 output_len; /* Final compressed length */ 503 png_byte output[1024]; /* First block of output */ 504 } compression_state; 505 506 static void 507 png_text_compress_init(compression_state *comp, png_const_bytep input, 508 png_alloc_size_t input_len) 509 { 510 comp->input = input; 511 comp->input_len = input_len; 512 comp->output_len = 0; 513 } 514 515 /* Compress the data in the compression state input */ 516 static int 517 png_text_compress(png_structrp png_ptr, png_uint_32 chunk_name, 518 compression_state *comp, png_uint_32 prefix_len) 519 { 520 int ret; 521 522 /* To find the length of the output it is necessary to first compress the 523 * input. The result is buffered rather than using the two-pass algorithm 524 * that is used on the inflate side; deflate is assumed to be slower and a 525 * PNG writer is assumed to have more memory available than a PNG reader. 526 * 527 * IMPLEMENTATION NOTE: the zlib API deflateBound() can be used to find an 528 * upper limit on the output size, but it is always bigger than the input 529 * size so it is likely to be more efficient to use this linked-list 530 * approach. 531 */ 532 ret = png_deflate_claim(png_ptr, chunk_name, comp->input_len); 533 534 if (ret != Z_OK) 535 return ret; 536 537 /* Set up the compression buffers, we need a loop here to avoid overflowing a 538 * uInt. Use ZLIB_IO_MAX to limit the input. The output is always limited 539 * by the output buffer size, so there is no need to check that. Since this 540 * is ANSI-C we know that an 'int', hence a uInt, is always at least 16 bits 541 * in size. 542 */ 543 { 544 png_compression_bufferp *end = &png_ptr->zbuffer_list; 545 png_alloc_size_t input_len = comp->input_len; /* may be zero! */ 546 png_uint_32 output_len; 547 548 /* zlib updates these for us: */ 549 png_ptr->zstream.next_in = PNGZ_INPUT_CAST(comp->input); 550 png_ptr->zstream.avail_in = 0; /* Set below */ 551 png_ptr->zstream.next_out = comp->output; 552 png_ptr->zstream.avail_out = (sizeof comp->output); 553 554 output_len = png_ptr->zstream.avail_out; 555 556 do 557 { 558 uInt avail_in = ZLIB_IO_MAX; 559 560 if (avail_in > input_len) 561 avail_in = (uInt)input_len; 562 563 input_len -= avail_in; 564 565 png_ptr->zstream.avail_in = avail_in; 566 567 if (png_ptr->zstream.avail_out == 0) 568 { 569 png_compression_buffer *next; 570 571 /* Chunk data is limited to 2^31 bytes in length, so the prefix 572 * length must be counted here. 573 */ 574 if (output_len + prefix_len > PNG_UINT_31_MAX) 575 { 576 ret = Z_MEM_ERROR; 577 break; 578 } 579 580 /* Need a new (malloc'ed) buffer, but there may be one present 581 * already. 582 */ 583 next = *end; 584 if (next == NULL) 585 { 586 next = png_voidcast(png_compression_bufferp, png_malloc_base 587 (png_ptr, PNG_COMPRESSION_BUFFER_SIZE(png_ptr))); 588 589 if (next == NULL) 590 { 591 ret = Z_MEM_ERROR; 592 break; 593 } 594 595 /* Link in this buffer (so that it will be freed later) */ 596 next->next = NULL; 597 *end = next; 598 } 599 600 png_ptr->zstream.next_out = next->output; 601 png_ptr->zstream.avail_out = png_ptr->zbuffer_size; 602 output_len += png_ptr->zstream.avail_out; 603 604 /* Move 'end' to the next buffer pointer. */ 605 end = &next->next; 606 } 607 608 /* Compress the data */ 609 ret = deflate(&png_ptr->zstream, 610 input_len > 0 ? Z_NO_FLUSH : Z_FINISH); 611 612 /* Claw back input data that was not consumed (because avail_in is 613 * reset above every time round the loop). 614 */ 615 input_len += png_ptr->zstream.avail_in; 616 png_ptr->zstream.avail_in = 0; /* safety */ 617 } 618 while (ret == Z_OK); 619 620 /* There may be some space left in the last output buffer. This needs to 621 * be subtracted from output_len. 622 */ 623 output_len -= png_ptr->zstream.avail_out; 624 png_ptr->zstream.avail_out = 0; /* safety */ 625 comp->output_len = output_len; 626 627 /* Now double check the output length, put in a custom message if it is 628 * too long. Otherwise ensure the z_stream::msg pointer is set to 629 * something. 630 */ 631 if (output_len + prefix_len >= PNG_UINT_31_MAX) 632 { 633 png_ptr->zstream.msg = PNGZ_MSG_CAST("compressed data too long"); 634 ret = Z_MEM_ERROR; 635 } 636 637 else 638 png_zstream_error(png_ptr, ret); 639 640 /* Reset zlib for another zTXt/iTXt or image data */ 641 png_ptr->zowner = 0; 642 643 /* The only success case is Z_STREAM_END, input_len must be 0; if not this 644 * is an internal error. 645 */ 646 if (ret == Z_STREAM_END && input_len == 0) 647 { 648 #ifdef PNG_WRITE_OPTIMIZE_CMF_SUPPORTED 649 /* Fix up the deflate header, if required */ 650 optimize_cmf(comp->output, comp->input_len); 651 #endif 652 /* But Z_OK is returned, not Z_STREAM_END; this allows the claim 653 * function above to return Z_STREAM_END on an error (though it never 654 * does in the current versions of zlib.) 655 */ 656 return Z_OK; 657 } 658 659 else 660 return ret; 661 } 662 } 663 664 /* Ship the compressed text out via chunk writes */ 665 static void 666 png_write_compressed_data_out(png_structrp png_ptr, compression_state *comp) 667 { 668 png_uint_32 output_len = comp->output_len; 669 png_const_bytep output = comp->output; 670 png_uint_32 avail = (sizeof comp->output); 671 png_compression_buffer *next = png_ptr->zbuffer_list; 672 673 for (;;) 674 { 675 if (avail > output_len) 676 avail = output_len; 677 678 png_write_chunk_data(png_ptr, output, avail); 679 680 output_len -= avail; 681 682 if (output_len == 0 || next == NULL) 683 break; 684 685 avail = png_ptr->zbuffer_size; 686 output = next->output; 687 next = next->next; 688 } 689 690 /* This is an internal error; 'next' must have been NULL! */ 691 if (output_len > 0) 692 png_error(png_ptr, "error writing ancillary chunked compressed data"); 693 } 694 #endif /* WRITE_COMPRESSED_TEXT */ 695 696 /* Write the IHDR chunk, and update the png_struct with the necessary 697 * information. Note that the rest of this code depends upon this 698 * information being correct. 699 */ 700 void /* PRIVATE */ 701 png_write_IHDR(png_structrp png_ptr, png_uint_32 width, png_uint_32 height, 702 int bit_depth, int color_type, int compression_type, int filter_type, 703 int interlace_type) 704 { 705 png_byte buf[13]; /* Buffer to store the IHDR info */ 706 707 png_debug(1, "in png_write_IHDR"); 708 709 /* Check that we have valid input data from the application info */ 710 switch (color_type) 711 { 712 case PNG_COLOR_TYPE_GRAY: 713 switch (bit_depth) 714 { 715 case 1: 716 case 2: 717 case 4: 718 case 8: 719 #ifdef PNG_WRITE_16BIT_SUPPORTED 720 case 16: 721 #endif 722 png_ptr->channels = 1; break; 723 724 default: 725 png_error(png_ptr, 726 "Invalid bit depth for grayscale image"); 727 } 728 break; 729 730 case PNG_COLOR_TYPE_RGB: 731 #ifdef PNG_WRITE_16BIT_SUPPORTED 732 if (bit_depth != 8 && bit_depth != 16) 733 #else 734 if (bit_depth != 8) 735 #endif 736 png_error(png_ptr, "Invalid bit depth for RGB image"); 737 738 png_ptr->channels = 3; 739 break; 740 741 case PNG_COLOR_TYPE_PALETTE: 742 switch (bit_depth) 743 { 744 case 1: 745 case 2: 746 case 4: 747 case 8: 748 png_ptr->channels = 1; 749 break; 750 751 default: 752 png_error(png_ptr, "Invalid bit depth for paletted image"); 753 } 754 break; 755 756 case PNG_COLOR_TYPE_GRAY_ALPHA: 757 if (bit_depth != 8 && bit_depth != 16) 758 png_error(png_ptr, "Invalid bit depth for grayscale+alpha image"); 759 760 png_ptr->channels = 2; 761 break; 762 763 case PNG_COLOR_TYPE_RGB_ALPHA: 764 #ifdef PNG_WRITE_16BIT_SUPPORTED 765 if (bit_depth != 8 && bit_depth != 16) 766 #else 767 if (bit_depth != 8) 768 #endif 769 png_error(png_ptr, "Invalid bit depth for RGBA image"); 770 771 png_ptr->channels = 4; 772 break; 773 774 default: 775 png_error(png_ptr, "Invalid image color type specified"); 776 } 777 778 if (compression_type != PNG_COMPRESSION_TYPE_BASE) 779 { 780 png_warning(png_ptr, "Invalid compression type specified"); 781 compression_type = PNG_COMPRESSION_TYPE_BASE; 782 } 783 784 /* Write filter_method 64 (intrapixel differencing) only if 785 * 1. Libpng was compiled with PNG_MNG_FEATURES_SUPPORTED and 786 * 2. Libpng did not write a PNG signature (this filter_method is only 787 * used in PNG datastreams that are embedded in MNG datastreams) and 788 * 3. The application called png_permit_mng_features with a mask that 789 * included PNG_FLAG_MNG_FILTER_64 and 790 * 4. The filter_method is 64 and 791 * 5. The color_type is RGB or RGBA 792 */ 793 if ( 794 #ifdef PNG_MNG_FEATURES_SUPPORTED 795 !((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) != 0 && 796 ((png_ptr->mode & PNG_HAVE_PNG_SIGNATURE) == 0) && 797 (color_type == PNG_COLOR_TYPE_RGB || 798 color_type == PNG_COLOR_TYPE_RGB_ALPHA) && 799 (filter_type == PNG_INTRAPIXEL_DIFFERENCING)) && 800 #endif 801 filter_type != PNG_FILTER_TYPE_BASE) 802 { 803 png_warning(png_ptr, "Invalid filter type specified"); 804 filter_type = PNG_FILTER_TYPE_BASE; 805 } 806 807 #ifdef PNG_WRITE_INTERLACING_SUPPORTED 808 if (interlace_type != PNG_INTERLACE_NONE && 809 interlace_type != PNG_INTERLACE_ADAM7) 810 { 811 png_warning(png_ptr, "Invalid interlace type specified"); 812 interlace_type = PNG_INTERLACE_ADAM7; 813 } 814 #else 815 interlace_type=PNG_INTERLACE_NONE; 816 #endif 817 818 /* Save the relevant information */ 819 png_ptr->bit_depth = (png_byte)bit_depth; 820 png_ptr->color_type = (png_byte)color_type; 821 png_ptr->interlaced = (png_byte)interlace_type; 822 #ifdef PNG_MNG_FEATURES_SUPPORTED 823 png_ptr->filter_type = (png_byte)filter_type; 824 #endif 825 png_ptr->compression_type = (png_byte)compression_type; 826 png_ptr->width = width; 827 png_ptr->height = height; 828 829 png_ptr->pixel_depth = (png_byte)(bit_depth * png_ptr->channels); 830 png_ptr->rowbytes = PNG_ROWBYTES(png_ptr->pixel_depth, width); 831 /* Set the usr info, so any transformations can modify it */ 832 png_ptr->usr_width = png_ptr->width; 833 png_ptr->usr_bit_depth = png_ptr->bit_depth; 834 png_ptr->usr_channels = png_ptr->channels; 835 836 /* Pack the header information into the buffer */ 837 png_save_uint_32(buf, width); 838 png_save_uint_32(buf + 4, height); 839 buf[8] = (png_byte)bit_depth; 840 buf[9] = (png_byte)color_type; 841 buf[10] = (png_byte)compression_type; 842 buf[11] = (png_byte)filter_type; 843 buf[12] = (png_byte)interlace_type; 844 845 /* Write the chunk */ 846 png_write_complete_chunk(png_ptr, png_IHDR, buf, (png_size_t)13); 847 848 if ((png_ptr->do_filter) == PNG_NO_FILTERS) 849 { 850 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE || 851 png_ptr->bit_depth < 8) 852 png_ptr->do_filter = PNG_FILTER_NONE; 853 854 else 855 png_ptr->do_filter = PNG_ALL_FILTERS; 856 } 857 858 png_ptr->mode = PNG_HAVE_IHDR; /* not READY_FOR_ZTXT */ 859 } 860 861 /* Write the palette. We are careful not to trust png_color to be in the 862 * correct order for PNG, so people can redefine it to any convenient 863 * structure. 864 */ 865 void /* PRIVATE */ 866 png_write_PLTE(png_structrp png_ptr, png_const_colorp palette, 867 png_uint_32 num_pal) 868 { 869 png_uint_32 max_palette_length, i; 870 png_const_colorp pal_ptr; 871 png_byte buf[3]; 872 873 png_debug(1, "in png_write_PLTE"); 874 875 max_palette_length = (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) ? 876 (1 << png_ptr->bit_depth) : PNG_MAX_PALETTE_LENGTH; 877 878 if (( 879 #ifdef PNG_MNG_FEATURES_SUPPORTED 880 (png_ptr->mng_features_permitted & PNG_FLAG_MNG_EMPTY_PLTE) == 0 && 881 #endif 882 num_pal == 0) || num_pal > max_palette_length) 883 { 884 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) 885 { 886 png_error(png_ptr, "Invalid number of colors in palette"); 887 } 888 889 else 890 { 891 png_warning(png_ptr, "Invalid number of colors in palette"); 892 return; 893 } 894 } 895 896 if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) == 0) 897 { 898 png_warning(png_ptr, 899 "Ignoring request to write a PLTE chunk in grayscale PNG"); 900 901 return; 902 } 903 904 png_ptr->num_palette = (png_uint_16)num_pal; 905 png_debug1(3, "num_palette = %d", png_ptr->num_palette); 906 907 png_write_chunk_header(png_ptr, png_PLTE, (png_uint_32)(num_pal * 3)); 908 #ifdef PNG_POINTER_INDEXING_SUPPORTED 909 910 for (i = 0, pal_ptr = palette; i < num_pal; i++, pal_ptr++) 911 { 912 buf[0] = pal_ptr->red; 913 buf[1] = pal_ptr->green; 914 buf[2] = pal_ptr->blue; 915 png_write_chunk_data(png_ptr, buf, (png_size_t)3); 916 } 917 918 #else 919 /* This is a little slower but some buggy compilers need to do this 920 * instead 921 */ 922 pal_ptr=palette; 923 924 for (i = 0; i < num_pal; i++) 925 { 926 buf[0] = pal_ptr[i].red; 927 buf[1] = pal_ptr[i].green; 928 buf[2] = pal_ptr[i].blue; 929 png_write_chunk_data(png_ptr, buf, (png_size_t)3); 930 } 931 932 #endif 933 png_write_chunk_end(png_ptr); 934 png_ptr->mode |= PNG_HAVE_PLTE; 935 } 936 937 /* This is similar to png_text_compress, above, except that it does not require 938 * all of the data at once and, instead of buffering the compressed result, 939 * writes it as IDAT chunks. Unlike png_text_compress it *can* png_error out 940 * because it calls the write interface. As a result it does its own error 941 * reporting and does not return an error code. In the event of error it will 942 * just call png_error. The input data length may exceed 32-bits. The 'flush' 943 * parameter is exactly the same as that to deflate, with the following 944 * meanings: 945 * 946 * Z_NO_FLUSH: normal incremental output of compressed data 947 * Z_SYNC_FLUSH: do a SYNC_FLUSH, used by png_write_flush 948 * Z_FINISH: this is the end of the input, do a Z_FINISH and clean up 949 * 950 * The routine manages the acquire and release of the png_ptr->zstream by 951 * checking and (at the end) clearing png_ptr->zowner; it does some sanity 952 * checks on the 'mode' flags while doing this. 953 */ 954 void /* PRIVATE */ 955 png_compress_IDAT(png_structrp png_ptr, png_const_bytep input, 956 png_alloc_size_t input_len, int flush) 957 { 958 if (png_ptr->zowner != png_IDAT) 959 { 960 /* First time. Ensure we have a temporary buffer for compression and 961 * trim the buffer list if it has more than one entry to free memory. 962 * If 'WRITE_COMPRESSED_TEXT' is not set the list will never have been 963 * created at this point, but the check here is quick and safe. 964 */ 965 if (png_ptr->zbuffer_list == NULL) 966 { 967 png_ptr->zbuffer_list = png_voidcast(png_compression_bufferp, 968 png_malloc(png_ptr, PNG_COMPRESSION_BUFFER_SIZE(png_ptr))); 969 png_ptr->zbuffer_list->next = NULL; 970 } 971 972 else 973 png_free_buffer_list(png_ptr, &png_ptr->zbuffer_list->next); 974 975 /* It is a terminal error if we can't claim the zstream. */ 976 if (png_deflate_claim(png_ptr, png_IDAT, png_image_size(png_ptr)) != Z_OK) 977 png_error(png_ptr, png_ptr->zstream.msg); 978 979 /* The output state is maintained in png_ptr->zstream, so it must be 980 * initialized here after the claim. 981 */ 982 png_ptr->zstream.next_out = png_ptr->zbuffer_list->output; 983 png_ptr->zstream.avail_out = png_ptr->zbuffer_size; 984 } 985 986 /* Now loop reading and writing until all the input is consumed or an error 987 * terminates the operation. The _out values are maintained across calls to 988 * this function, but the input must be reset each time. 989 */ 990 png_ptr->zstream.next_in = PNGZ_INPUT_CAST(input); 991 png_ptr->zstream.avail_in = 0; /* set below */ 992 for (;;) 993 { 994 int ret; 995 996 /* INPUT: from the row data */ 997 uInt avail = ZLIB_IO_MAX; 998 999 if (avail > input_len) 1000 avail = (uInt)input_len; /* safe because of the check */ 1001 1002 png_ptr->zstream.avail_in = avail; 1003 input_len -= avail; 1004 1005 ret = deflate(&png_ptr->zstream, input_len > 0 ? Z_NO_FLUSH : flush); 1006 1007 /* Include as-yet unconsumed input */ 1008 input_len += png_ptr->zstream.avail_in; 1009 png_ptr->zstream.avail_in = 0; 1010 1011 /* OUTPUT: write complete IDAT chunks when avail_out drops to zero. Note 1012 * that these two zstream fields are preserved across the calls, therefore 1013 * there is no need to set these up on entry to the loop. 1014 */ 1015 if (png_ptr->zstream.avail_out == 0) 1016 { 1017 png_bytep data = png_ptr->zbuffer_list->output; 1018 uInt size = png_ptr->zbuffer_size; 1019 1020 /* Write an IDAT containing the data then reset the buffer. The 1021 * first IDAT may need deflate header optimization. 1022 */ 1023 #ifdef PNG_WRITE_OPTIMIZE_CMF_SUPPORTED 1024 if ((png_ptr->mode & PNG_HAVE_IDAT) == 0 && 1025 png_ptr->compression_type == PNG_COMPRESSION_TYPE_BASE) 1026 optimize_cmf(data, png_image_size(png_ptr)); 1027 #endif 1028 1029 png_write_complete_chunk(png_ptr, png_IDAT, data, size); 1030 png_ptr->mode |= PNG_HAVE_IDAT; 1031 1032 png_ptr->zstream.next_out = data; 1033 png_ptr->zstream.avail_out = size; 1034 1035 /* For SYNC_FLUSH or FINISH it is essential to keep calling zlib with 1036 * the same flush parameter until it has finished output, for NO_FLUSH 1037 * it doesn't matter. 1038 */ 1039 if (ret == Z_OK && flush != Z_NO_FLUSH) 1040 continue; 1041 } 1042 1043 /* The order of these checks doesn't matter much; it just affects which 1044 * possible error might be detected if multiple things go wrong at once. 1045 */ 1046 if (ret == Z_OK) /* most likely return code! */ 1047 { 1048 /* If all the input has been consumed then just return. If Z_FINISH 1049 * was used as the flush parameter something has gone wrong if we get 1050 * here. 1051 */ 1052 if (input_len == 0) 1053 { 1054 if (flush == Z_FINISH) 1055 png_error(png_ptr, "Z_OK on Z_FINISH with output space"); 1056 1057 return; 1058 } 1059 } 1060 1061 else if (ret == Z_STREAM_END && flush == Z_FINISH) 1062 { 1063 /* This is the end of the IDAT data; any pending output must be 1064 * flushed. For small PNG files we may still be at the beginning. 1065 */ 1066 png_bytep data = png_ptr->zbuffer_list->output; 1067 uInt size = png_ptr->zbuffer_size - png_ptr->zstream.avail_out; 1068 1069 #ifdef PNG_WRITE_OPTIMIZE_CMF_SUPPORTED 1070 if ((png_ptr->mode & PNG_HAVE_IDAT) == 0 && 1071 png_ptr->compression_type == PNG_COMPRESSION_TYPE_BASE) 1072 optimize_cmf(data, png_image_size(png_ptr)); 1073 #endif 1074 1075 png_write_complete_chunk(png_ptr, png_IDAT, data, size); 1076 png_ptr->zstream.avail_out = 0; 1077 png_ptr->zstream.next_out = NULL; 1078 png_ptr->mode |= PNG_HAVE_IDAT | PNG_AFTER_IDAT; 1079 1080 png_ptr->zowner = 0; /* Release the stream */ 1081 return; 1082 } 1083 1084 else 1085 { 1086 /* This is an error condition. */ 1087 png_zstream_error(png_ptr, ret); 1088 png_error(png_ptr, png_ptr->zstream.msg); 1089 } 1090 } 1091 } 1092 1093 /* Write an IEND chunk */ 1094 void /* PRIVATE */ 1095 png_write_IEND(png_structrp png_ptr) 1096 { 1097 png_debug(1, "in png_write_IEND"); 1098 1099 png_write_complete_chunk(png_ptr, png_IEND, NULL, (png_size_t)0); 1100 png_ptr->mode |= PNG_HAVE_IEND; 1101 } 1102 1103 #ifdef PNG_WRITE_gAMA_SUPPORTED 1104 /* Write a gAMA chunk */ 1105 void /* PRIVATE */ 1106 png_write_gAMA_fixed(png_structrp png_ptr, png_fixed_point file_gamma) 1107 { 1108 png_byte buf[4]; 1109 1110 png_debug(1, "in png_write_gAMA"); 1111 1112 /* file_gamma is saved in 1/100,000ths */ 1113 png_save_uint_32(buf, (png_uint_32)file_gamma); 1114 png_write_complete_chunk(png_ptr, png_gAMA, buf, (png_size_t)4); 1115 } 1116 #endif 1117 1118 #ifdef PNG_WRITE_sRGB_SUPPORTED 1119 /* Write a sRGB chunk */ 1120 void /* PRIVATE */ 1121 png_write_sRGB(png_structrp png_ptr, int srgb_intent) 1122 { 1123 png_byte buf[1]; 1124 1125 png_debug(1, "in png_write_sRGB"); 1126 1127 if (srgb_intent >= PNG_sRGB_INTENT_LAST) 1128 png_warning(png_ptr, 1129 "Invalid sRGB rendering intent specified"); 1130 1131 buf[0]=(png_byte)srgb_intent; 1132 png_write_complete_chunk(png_ptr, png_sRGB, buf, (png_size_t)1); 1133 } 1134 #endif 1135 1136 #ifdef PNG_WRITE_iCCP_SUPPORTED 1137 /* Write an iCCP chunk */ 1138 void /* PRIVATE */ 1139 png_write_iCCP(png_structrp png_ptr, png_const_charp name, 1140 png_const_bytep profile) 1141 { 1142 png_uint_32 name_len; 1143 png_uint_32 profile_len; 1144 png_byte new_name[81]; /* 1 byte for the compression byte */ 1145 compression_state comp; 1146 png_uint_32 temp; 1147 1148 png_debug(1, "in png_write_iCCP"); 1149 1150 /* These are all internal problems: the profile should have been checked 1151 * before when it was stored. 1152 */ 1153 if (profile == NULL) 1154 png_error(png_ptr, "No profile for iCCP chunk"); /* internal error */ 1155 1156 profile_len = png_get_uint_32(profile); 1157 1158 if (profile_len < 132) 1159 png_error(png_ptr, "ICC profile too short"); 1160 1161 temp = (png_uint_32) (*(profile+8)); 1162 if (temp > 3 && (profile_len & 0x03)) 1163 png_error(png_ptr, "ICC profile length invalid (not a multiple of 4)"); 1164 1165 { 1166 png_uint_32 embedded_profile_len = png_get_uint_32(profile); 1167 1168 if (profile_len != embedded_profile_len) 1169 png_error(png_ptr, "Profile length does not match profile"); 1170 } 1171 1172 name_len = png_check_keyword(png_ptr, name, new_name); 1173 1174 if (name_len == 0) 1175 png_error(png_ptr, "iCCP: invalid keyword"); 1176 1177 new_name[++name_len] = PNG_COMPRESSION_TYPE_BASE; 1178 1179 /* Make sure we include the NULL after the name and the compression type */ 1180 ++name_len; 1181 1182 png_text_compress_init(&comp, profile, profile_len); 1183 1184 /* Allow for keyword terminator and compression byte */ 1185 if (png_text_compress(png_ptr, png_iCCP, &comp, name_len) != Z_OK) 1186 png_error(png_ptr, png_ptr->zstream.msg); 1187 1188 png_write_chunk_header(png_ptr, png_iCCP, name_len + comp.output_len); 1189 1190 png_write_chunk_data(png_ptr, new_name, name_len); 1191 1192 png_write_compressed_data_out(png_ptr, &comp); 1193 1194 png_write_chunk_end(png_ptr); 1195 } 1196 #endif 1197 1198 #ifdef PNG_WRITE_sPLT_SUPPORTED 1199 /* Write a sPLT chunk */ 1200 void /* PRIVATE */ 1201 png_write_sPLT(png_structrp png_ptr, png_const_sPLT_tp spalette) 1202 { 1203 png_uint_32 name_len; 1204 png_byte new_name[80]; 1205 png_byte entrybuf[10]; 1206 png_size_t entry_size = (spalette->depth == 8 ? 6 : 10); 1207 png_size_t palette_size = entry_size * spalette->nentries; 1208 png_sPLT_entryp ep; 1209 #ifndef PNG_POINTER_INDEXING_SUPPORTED 1210 int i; 1211 #endif 1212 1213 png_debug(1, "in png_write_sPLT"); 1214 1215 name_len = png_check_keyword(png_ptr, spalette->name, new_name); 1216 1217 if (name_len == 0) 1218 png_error(png_ptr, "sPLT: invalid keyword"); 1219 1220 /* Make sure we include the NULL after the name */ 1221 png_write_chunk_header(png_ptr, png_sPLT, 1222 (png_uint_32)(name_len + 2 + palette_size)); 1223 1224 png_write_chunk_data(png_ptr, (png_bytep)new_name, 1225 (png_size_t)(name_len + 1)); 1226 1227 png_write_chunk_data(png_ptr, &spalette->depth, (png_size_t)1); 1228 1229 /* Loop through each palette entry, writing appropriately */ 1230 #ifdef PNG_POINTER_INDEXING_SUPPORTED 1231 for (ep = spalette->entries; ep<spalette->entries + spalette->nentries; ep++) 1232 { 1233 if (spalette->depth == 8) 1234 { 1235 entrybuf[0] = (png_byte)ep->red; 1236 entrybuf[1] = (png_byte)ep->green; 1237 entrybuf[2] = (png_byte)ep->blue; 1238 entrybuf[3] = (png_byte)ep->alpha; 1239 png_save_uint_16(entrybuf + 4, ep->frequency); 1240 } 1241 1242 else 1243 { 1244 png_save_uint_16(entrybuf + 0, ep->red); 1245 png_save_uint_16(entrybuf + 2, ep->green); 1246 png_save_uint_16(entrybuf + 4, ep->blue); 1247 png_save_uint_16(entrybuf + 6, ep->alpha); 1248 png_save_uint_16(entrybuf + 8, ep->frequency); 1249 } 1250 1251 png_write_chunk_data(png_ptr, entrybuf, entry_size); 1252 } 1253 #else 1254 ep=spalette->entries; 1255 for (i = 0; i>spalette->nentries; i++) 1256 { 1257 if (spalette->depth == 8) 1258 { 1259 entrybuf[0] = (png_byte)ep[i].red; 1260 entrybuf[1] = (png_byte)ep[i].green; 1261 entrybuf[2] = (png_byte)ep[i].blue; 1262 entrybuf[3] = (png_byte)ep[i].alpha; 1263 png_save_uint_16(entrybuf + 4, ep[i].frequency); 1264 } 1265 1266 else 1267 { 1268 png_save_uint_16(entrybuf + 0, ep[i].red); 1269 png_save_uint_16(entrybuf + 2, ep[i].green); 1270 png_save_uint_16(entrybuf + 4, ep[i].blue); 1271 png_save_uint_16(entrybuf + 6, ep[i].alpha); 1272 png_save_uint_16(entrybuf + 8, ep[i].frequency); 1273 } 1274 1275 png_write_chunk_data(png_ptr, entrybuf, entry_size); 1276 } 1277 #endif 1278 1279 png_write_chunk_end(png_ptr); 1280 } 1281 #endif 1282 1283 #ifdef PNG_WRITE_sBIT_SUPPORTED 1284 /* Write the sBIT chunk */ 1285 void /* PRIVATE */ 1286 png_write_sBIT(png_structrp png_ptr, png_const_color_8p sbit, int color_type) 1287 { 1288 png_byte buf[4]; 1289 png_size_t size; 1290 1291 png_debug(1, "in png_write_sBIT"); 1292 1293 /* Make sure we don't depend upon the order of PNG_COLOR_8 */ 1294 if ((color_type & PNG_COLOR_MASK_COLOR) != 0) 1295 { 1296 png_byte maxbits; 1297 1298 maxbits = (png_byte)(color_type==PNG_COLOR_TYPE_PALETTE ? 8 : 1299 png_ptr->usr_bit_depth); 1300 1301 if (sbit->red == 0 || sbit->red > maxbits || 1302 sbit->green == 0 || sbit->green > maxbits || 1303 sbit->blue == 0 || sbit->blue > maxbits) 1304 { 1305 png_warning(png_ptr, "Invalid sBIT depth specified"); 1306 return; 1307 } 1308 1309 buf[0] = sbit->red; 1310 buf[1] = sbit->green; 1311 buf[2] = sbit->blue; 1312 size = 3; 1313 } 1314 1315 else 1316 { 1317 if (sbit->gray == 0 || sbit->gray > png_ptr->usr_bit_depth) 1318 { 1319 png_warning(png_ptr, "Invalid sBIT depth specified"); 1320 return; 1321 } 1322 1323 buf[0] = sbit->gray; 1324 size = 1; 1325 } 1326 1327 if ((color_type & PNG_COLOR_MASK_ALPHA) != 0) 1328 { 1329 if (sbit->alpha == 0 || sbit->alpha > png_ptr->usr_bit_depth) 1330 { 1331 png_warning(png_ptr, "Invalid sBIT depth specified"); 1332 return; 1333 } 1334 1335 buf[size++] = sbit->alpha; 1336 } 1337 1338 png_write_complete_chunk(png_ptr, png_sBIT, buf, size); 1339 } 1340 #endif 1341 1342 #ifdef PNG_WRITE_cHRM_SUPPORTED 1343 /* Write the cHRM chunk */ 1344 void /* PRIVATE */ 1345 png_write_cHRM_fixed(png_structrp png_ptr, const png_xy *xy) 1346 { 1347 png_byte buf[32]; 1348 1349 png_debug(1, "in png_write_cHRM"); 1350 1351 /* Each value is saved in 1/100,000ths */ 1352 png_save_int_32(buf, xy->whitex); 1353 png_save_int_32(buf + 4, xy->whitey); 1354 1355 png_save_int_32(buf + 8, xy->redx); 1356 png_save_int_32(buf + 12, xy->redy); 1357 1358 png_save_int_32(buf + 16, xy->greenx); 1359 png_save_int_32(buf + 20, xy->greeny); 1360 1361 png_save_int_32(buf + 24, xy->bluex); 1362 png_save_int_32(buf + 28, xy->bluey); 1363 1364 png_write_complete_chunk(png_ptr, png_cHRM, buf, 32); 1365 } 1366 #endif 1367 1368 #ifdef PNG_WRITE_tRNS_SUPPORTED 1369 /* Write the tRNS chunk */ 1370 void /* PRIVATE */ 1371 png_write_tRNS(png_structrp png_ptr, png_const_bytep trans_alpha, 1372 png_const_color_16p tran, int num_trans, int color_type) 1373 { 1374 png_byte buf[6]; 1375 1376 png_debug(1, "in png_write_tRNS"); 1377 1378 if (color_type == PNG_COLOR_TYPE_PALETTE) 1379 { 1380 if (num_trans <= 0 || num_trans > (int)png_ptr->num_palette) 1381 { 1382 png_app_warning(png_ptr, 1383 "Invalid number of transparent colors specified"); 1384 return; 1385 } 1386 1387 /* Write the chunk out as it is */ 1388 png_write_complete_chunk(png_ptr, png_tRNS, trans_alpha, 1389 (png_size_t)num_trans); 1390 } 1391 1392 else if (color_type == PNG_COLOR_TYPE_GRAY) 1393 { 1394 /* One 16-bit value */ 1395 if (tran->gray >= (1 << png_ptr->bit_depth)) 1396 { 1397 png_app_warning(png_ptr, 1398 "Ignoring attempt to write tRNS chunk out-of-range for bit_depth"); 1399 1400 return; 1401 } 1402 1403 png_save_uint_16(buf, tran->gray); 1404 png_write_complete_chunk(png_ptr, png_tRNS, buf, (png_size_t)2); 1405 } 1406 1407 else if (color_type == PNG_COLOR_TYPE_RGB) 1408 { 1409 /* Three 16-bit values */ 1410 png_save_uint_16(buf, tran->red); 1411 png_save_uint_16(buf + 2, tran->green); 1412 png_save_uint_16(buf + 4, tran->blue); 1413 #ifdef PNG_WRITE_16BIT_SUPPORTED 1414 if (png_ptr->bit_depth == 8 && (buf[0] | buf[2] | buf[4]) != 0) 1415 #else 1416 if ((buf[0] | buf[2] | buf[4]) != 0) 1417 #endif 1418 { 1419 png_app_warning(png_ptr, 1420 "Ignoring attempt to write 16-bit tRNS chunk when bit_depth is 8"); 1421 return; 1422 } 1423 1424 png_write_complete_chunk(png_ptr, png_tRNS, buf, (png_size_t)6); 1425 } 1426 1427 else 1428 { 1429 png_app_warning(png_ptr, "Can't write tRNS with an alpha channel"); 1430 } 1431 } 1432 #endif 1433 1434 #ifdef PNG_WRITE_bKGD_SUPPORTED 1435 /* Write the background chunk */ 1436 void /* PRIVATE */ 1437 png_write_bKGD(png_structrp png_ptr, png_const_color_16p back, int color_type) 1438 { 1439 png_byte buf[6]; 1440 1441 png_debug(1, "in png_write_bKGD"); 1442 1443 if (color_type == PNG_COLOR_TYPE_PALETTE) 1444 { 1445 if ( 1446 #ifdef PNG_MNG_FEATURES_SUPPORTED 1447 (png_ptr->num_palette != 0 || 1448 (png_ptr->mng_features_permitted & PNG_FLAG_MNG_EMPTY_PLTE) == 0) && 1449 #endif 1450 back->index >= png_ptr->num_palette) 1451 { 1452 png_warning(png_ptr, "Invalid background palette index"); 1453 return; 1454 } 1455 1456 buf[0] = back->index; 1457 png_write_complete_chunk(png_ptr, png_bKGD, buf, (png_size_t)1); 1458 } 1459 1460 else if ((color_type & PNG_COLOR_MASK_COLOR) != 0) 1461 { 1462 png_save_uint_16(buf, back->red); 1463 png_save_uint_16(buf + 2, back->green); 1464 png_save_uint_16(buf + 4, back->blue); 1465 #ifdef PNG_WRITE_16BIT_SUPPORTED 1466 if (png_ptr->bit_depth == 8 && (buf[0] | buf[2] | buf[4]) != 0) 1467 #else 1468 if ((buf[0] | buf[2] | buf[4]) != 0) 1469 #endif 1470 { 1471 png_warning(png_ptr, 1472 "Ignoring attempt to write 16-bit bKGD chunk when bit_depth is 8"); 1473 1474 return; 1475 } 1476 1477 png_write_complete_chunk(png_ptr, png_bKGD, buf, (png_size_t)6); 1478 } 1479 1480 else 1481 { 1482 if (back->gray >= (1 << png_ptr->bit_depth)) 1483 { 1484 png_warning(png_ptr, 1485 "Ignoring attempt to write bKGD chunk out-of-range for bit_depth"); 1486 1487 return; 1488 } 1489 1490 png_save_uint_16(buf, back->gray); 1491 png_write_complete_chunk(png_ptr, png_bKGD, buf, (png_size_t)2); 1492 } 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, (png_size_t)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 png_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 png_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, (png_size_t)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 png_size_t units_len, total_len; 1750 png_size_tp 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 = (png_size_tp)png_malloc(png_ptr, 1773 (png_alloc_size_t)(nparams * (sizeof (png_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, (png_size_t)10); 1794 png_write_chunk_data(png_ptr, (png_const_bytep)units, (png_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 png_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, (png_size_t)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, (png_size_t)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 PNG_CONST png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0}; 1897 1898 /* Offset to next interlace block */ 1899 static PNG_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 PNG_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 PNG_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 PNG_CONST png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0}; 2012 2013 /* Offset to next interlace block */ 2014 static PNG_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 PNG_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 PNG_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_size_t)(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 PNG_CONST png_byte png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0}; 2102 2103 /* Offset to next interlace block */ 2104 static PNG_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 + (png_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 + (png_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 + (png_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 png_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 + (png_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 png_size_t row_bytes); 2276 2277 #ifdef PNG_WRITE_FILTER_SUPPORTED 2278 static png_size_t /* PRIVATE */ 2279 png_setup_sub_row(png_structrp png_ptr, const png_uint_32 bpp, 2280 const png_size_t row_bytes, const png_size_t lmins) 2281 { 2282 png_bytep rp, dp, lp; 2283 png_size_t i; 2284 png_size_t sum = 0; 2285 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 sum += (v < 128) ? v : 256 - v; 2294 } 2295 2296 for (lp = png_ptr->row_buf + 1; i < row_bytes; 2297 i++, rp++, lp++, dp++) 2298 { 2299 v = *dp = (png_byte)(((int)*rp - (int)*lp) & 0xff); 2300 sum += (v < 128) ? v : 256 - v; 2301 2302 if (sum > lmins) /* We are already worse, don't continue. */ 2303 break; 2304 } 2305 2306 return (sum); 2307 } 2308 2309 static png_size_t /* PRIVATE */ 2310 png_setup_up_row(png_structrp png_ptr, const png_size_t row_bytes, 2311 const png_size_t lmins) 2312 { 2313 png_bytep rp, dp, pp; 2314 png_size_t i; 2315 png_size_t sum = 0; 2316 int v; 2317 2318 png_ptr->try_row[0] = PNG_FILTER_VALUE_UP; 2319 2320 for (i = 0, rp = png_ptr->row_buf + 1, dp = png_ptr->try_row + 1, 2321 pp = png_ptr->prev_row + 1; i < row_bytes; 2322 i++, rp++, pp++, dp++) 2323 { 2324 v = *dp = (png_byte)(((int)*rp - (int)*pp) & 0xff); 2325 sum += (v < 128) ? v : 256 - v; 2326 2327 if (sum > lmins) /* We are already worse, don't continue. */ 2328 break; 2329 } 2330 2331 return (sum); 2332 } 2333 2334 static png_size_t /* PRIVATE */ 2335 png_setup_avg_row(png_structrp png_ptr, const png_uint_32 bpp, 2336 const png_size_t row_bytes, const png_size_t lmins) 2337 { 2338 png_bytep rp, dp, pp, lp; 2339 png_uint_32 i; 2340 png_size_t sum = 0; 2341 int v; 2342 2343 png_ptr->try_row[0] = PNG_FILTER_VALUE_AVG; 2344 2345 for (i = 0, rp = png_ptr->row_buf + 1, dp = png_ptr->try_row + 1, 2346 pp = png_ptr->prev_row + 1; i < bpp; i++) 2347 { 2348 v = *dp++ = (png_byte)(((int)*rp++ - ((int)*pp++ / 2)) & 0xff); 2349 2350 sum += (v < 128) ? v : 256 - v; 2351 } 2352 2353 for (lp = png_ptr->row_buf + 1; i < row_bytes; i++) 2354 { 2355 v = *dp++ = (png_byte)(((int)*rp++ - (((int)*pp++ + (int)*lp++) / 2)) 2356 & 0xff); 2357 2358 sum += (v < 128) ? v : 256 - v; 2359 2360 if (sum > lmins) /* We are already worse, don't continue. */ 2361 break; 2362 } 2363 2364 return (sum); 2365 } 2366 2367 static png_size_t /* PRIVATE */ 2368 png_setup_paeth_row(png_structrp png_ptr, const png_uint_32 bpp, 2369 const png_size_t row_bytes, const png_size_t lmins) 2370 { 2371 png_bytep rp, dp, pp, cp, lp; 2372 png_size_t i; 2373 png_size_t sum = 0; 2374 int v; 2375 2376 png_ptr->try_row[0] = PNG_FILTER_VALUE_PAETH; 2377 2378 for (i = 0, rp = png_ptr->row_buf + 1, dp = png_ptr->try_row + 1, 2379 pp = png_ptr->prev_row + 1; i < bpp; i++) 2380 { 2381 v = *dp++ = (png_byte)(((int)*rp++ - (int)*pp++) & 0xff); 2382 2383 sum += (v < 128) ? v : 256 - v; 2384 } 2385 2386 for (lp = png_ptr->row_buf + 1, cp = png_ptr->prev_row + 1; i < row_bytes; 2387 i++) 2388 { 2389 int a, b, c, pa, pb, pc, p; 2390 2391 b = *pp++; 2392 c = *cp++; 2393 a = *lp++; 2394 2395 p = b - c; 2396 pc = a - c; 2397 2398 #ifdef PNG_USE_ABS 2399 pa = abs(p); 2400 pb = abs(pc); 2401 pc = abs(p + pc); 2402 #else 2403 pa = p < 0 ? -p : p; 2404 pb = pc < 0 ? -pc : pc; 2405 pc = (p + pc) < 0 ? -(p + pc) : p + pc; 2406 #endif 2407 2408 p = (pa <= pb && pa <=pc) ? a : (pb <= pc) ? b : c; 2409 2410 v = *dp++ = (png_byte)(((int)*rp++ - p) & 0xff); 2411 2412 sum += (v < 128) ? v : 256 - v; 2413 2414 if (sum > lmins) /* We are already worse, don't continue. */ 2415 break; 2416 } 2417 2418 return (sum); 2419 } 2420 #endif /* WRITE_FILTER */ 2421 2422 void /* PRIVATE */ 2423 png_write_find_filter(png_structrp png_ptr, png_row_infop row_info) 2424 { 2425 #ifndef PNG_WRITE_FILTER_SUPPORTED 2426 png_write_filtered_row(png_ptr, png_ptr->row_buf, row_info->rowbytes+1); 2427 #else 2428 png_byte filter_to_do = png_ptr->do_filter; 2429 png_bytep row_buf; 2430 png_bytep best_row; 2431 png_uint_32 bpp; 2432 png_size_t mins; 2433 png_size_t row_bytes = row_info->rowbytes; 2434 2435 png_debug(1, "in png_write_find_filter"); 2436 2437 /* Find out how many bytes offset each pixel is */ 2438 bpp = (row_info->pixel_depth + 7) >> 3; 2439 2440 row_buf = png_ptr->row_buf; 2441 mins = PNG_SIZE_MAX - 256/* so we can detect potential overflow of the 2442 running sum */; 2443 2444 /* The prediction method we use is to find which method provides the 2445 * smallest value when summing the absolute values of the distances 2446 * from zero, using anything >= 128 as negative numbers. This is known 2447 * as the "minimum sum of absolute differences" heuristic. Other 2448 * heuristics are the "weighted minimum sum of absolute differences" 2449 * (experimental and can in theory improve compression), and the "zlib 2450 * predictive" method (not implemented yet), which does test compressions 2451 * of lines using different filter methods, and then chooses the 2452 * (series of) filter(s) that give minimum compressed data size (VERY 2453 * computationally expensive). 2454 * 2455 * GRR 980525: consider also 2456 * 2457 * (1) minimum sum of absolute differences from running average (i.e., 2458 * keep running sum of non-absolute differences & count of bytes) 2459 * [track dispersion, too? restart average if dispersion too large?] 2460 * 2461 * (1b) minimum sum of absolute differences from sliding average, probably 2462 * with window size <= deflate window (usually 32K) 2463 * 2464 * (2) minimum sum of squared differences from zero or running average 2465 * (i.e., ~ root-mean-square approach) 2466 */ 2467 2468 2469 /* We don't need to test the 'no filter' case if this is the only filter 2470 * that has been chosen, as it doesn't actually do anything to the data. 2471 */ 2472 best_row = png_ptr->row_buf; 2473 2474 2475 if ((filter_to_do & PNG_FILTER_NONE) != 0 && filter_to_do != PNG_FILTER_NONE) 2476 { 2477 png_bytep rp; 2478 png_size_t sum = 0; 2479 png_size_t i; 2480 int v; 2481 2482 if (PNG_SIZE_MAX/128 <= row_bytes) 2483 { 2484 for (i = 0, rp = row_buf + 1; i < row_bytes; i++, rp++) 2485 { 2486 /* Check for overflow */ 2487 if (sum > PNG_SIZE_MAX/128 - 256) 2488 break; 2489 2490 v = *rp; 2491 sum += (v < 128) ? v : 256 - v; 2492 } 2493 } 2494 else /* Overflow is not possible */ 2495 { 2496 for (i = 0, rp = row_buf + 1; i < row_bytes; i++, rp++) 2497 { 2498 v = *rp; 2499 sum += (v < 128) ? v : 256 - v; 2500 } 2501 } 2502 2503 mins = sum; 2504 } 2505 2506 /* Sub filter */ 2507 if (filter_to_do == PNG_FILTER_SUB) 2508 /* It's the only filter so no testing is needed */ 2509 { 2510 (void) png_setup_sub_row(png_ptr, bpp, row_bytes, mins); 2511 best_row = png_ptr->try_row; 2512 } 2513 2514 else if ((filter_to_do & PNG_FILTER_SUB) != 0) 2515 { 2516 png_size_t sum; 2517 png_size_t lmins = mins; 2518 2519 sum = png_setup_sub_row(png_ptr, bpp, row_bytes, lmins); 2520 2521 if (sum < mins) 2522 { 2523 mins = sum; 2524 best_row = png_ptr->try_row; 2525 if (png_ptr->tst_row != NULL) 2526 { 2527 png_ptr->try_row = png_ptr->tst_row; 2528 png_ptr->tst_row = best_row; 2529 } 2530 } 2531 } 2532 2533 /* Up filter */ 2534 if (filter_to_do == PNG_FILTER_UP) 2535 { 2536 (void) png_setup_up_row(png_ptr, row_bytes, mins); 2537 best_row = png_ptr->try_row; 2538 } 2539 2540 else if ((filter_to_do & PNG_FILTER_UP) != 0) 2541 { 2542 png_size_t sum; 2543 png_size_t lmins = mins; 2544 2545 sum = png_setup_up_row(png_ptr, row_bytes, lmins); 2546 2547 if (sum < mins) 2548 { 2549 mins = sum; 2550 best_row = png_ptr->try_row; 2551 if (png_ptr->tst_row != NULL) 2552 { 2553 png_ptr->try_row = png_ptr->tst_row; 2554 png_ptr->tst_row = best_row; 2555 } 2556 } 2557 } 2558 2559 /* Avg filter */ 2560 if (filter_to_do == PNG_FILTER_AVG) 2561 { 2562 (void) png_setup_avg_row(png_ptr, bpp, row_bytes, mins); 2563 best_row = png_ptr->try_row; 2564 } 2565 2566 else if ((filter_to_do & PNG_FILTER_AVG) != 0) 2567 { 2568 png_size_t sum; 2569 png_size_t lmins = mins; 2570 2571 sum= png_setup_avg_row(png_ptr, bpp, row_bytes, lmins); 2572 2573 if (sum < mins) 2574 { 2575 mins = sum; 2576 best_row = png_ptr->try_row; 2577 if (png_ptr->tst_row != NULL) 2578 { 2579 png_ptr->try_row = png_ptr->tst_row; 2580 png_ptr->tst_row = best_row; 2581 } 2582 } 2583 } 2584 2585 /* Paeth filter */ 2586 if ((filter_to_do == PNG_FILTER_PAETH) != 0) 2587 { 2588 (void) png_setup_paeth_row(png_ptr, bpp, row_bytes, mins); 2589 best_row = png_ptr->try_row; 2590 } 2591 2592 else if ((filter_to_do & PNG_FILTER_PAETH) != 0) 2593 { 2594 png_size_t sum; 2595 png_size_t lmins = mins; 2596 2597 sum = png_setup_paeth_row(png_ptr, bpp, row_bytes, lmins); 2598 2599 if (sum < mins) 2600 { 2601 best_row = png_ptr->try_row; 2602 if (png_ptr->tst_row != NULL) 2603 { 2604 png_ptr->try_row = png_ptr->tst_row; 2605 png_ptr->tst_row = best_row; 2606 } 2607 } 2608 } 2609 2610 /* Do the actual writing of the filtered row data from the chosen filter. */ 2611 png_write_filtered_row(png_ptr, best_row, row_info->rowbytes+1); 2612 2613 #endif /* WRITE_FILTER */ 2614 } 2615 2616 2617 /* Do the actual writing of a previously filtered row. */ 2618 static void 2619 png_write_filtered_row(png_structrp png_ptr, png_bytep filtered_row, 2620 png_size_t full_row_length/*includes filter byte*/) 2621 { 2622 png_debug(1, "in png_write_filtered_row"); 2623 2624 png_debug1(2, "filter = %d", filtered_row[0]); 2625 2626 png_compress_IDAT(png_ptr, filtered_row, full_row_length, Z_NO_FLUSH); 2627 2628 #ifdef PNG_WRITE_FILTER_SUPPORTED 2629 /* Swap the current and previous rows */ 2630 if (png_ptr->prev_row != NULL) 2631 { 2632 png_bytep tptr; 2633 2634 tptr = png_ptr->prev_row; 2635 png_ptr->prev_row = png_ptr->row_buf; 2636 png_ptr->row_buf = tptr; 2637 } 2638 #endif /* WRITE_FILTER */ 2639 2640 /* Finish row - updates counters and flushes zlib if last row */ 2641 png_write_finish_row(png_ptr); 2642 2643 #ifdef PNG_WRITE_FLUSH_SUPPORTED 2644 png_ptr->flush_rows++; 2645 2646 if (png_ptr->flush_dist > 0 && 2647 png_ptr->flush_rows >= png_ptr->flush_dist) 2648 { 2649 png_write_flush(png_ptr); 2650 } 2651 #endif /* WRITE_FLUSH */ 2652 } 2653 #endif /* WRITE */ --- EOF ---