1 // Copyright 2012 Google Inc. All Rights Reserved. 2 // 3 // Use of this source code is governed by a BSD-style license 4 // that can be found in the COPYING file in the root of the source 5 // tree. An additional intellectual property rights grant can be found 6 // in the file PATENTS. All contributing project authors may 7 // be found in the AUTHORS file in the root of the source tree. 8 // ----------------------------------------------------------------------------- 9 // 10 // main entry for the decoder 11 // 12 // Authors: Vikas Arora (vikaas.arora (at) gmail.com) 13 // Jyrki Alakuijala (jyrki (at) google.com) 14 15 #include <stdio.h> 16 #include <stdlib.h> 17 #include "./vp8li.h" 18 #include "../dsp/lossless.h" 19 #include "../dsp/yuv.h" 20 #include "../utils/huffman.h" 21 #include "../utils/utils.h" 22 23 #if defined(__cplusplus) || defined(c_plusplus) 24 extern "C" { 25 #endif 26 27 #define NUM_ARGB_CACHE_ROWS 16 28 29 static const int kCodeLengthLiterals = 16; 30 static const int kCodeLengthRepeatCode = 16; 31 static const int kCodeLengthExtraBits[3] = { 2, 3, 7 }; 32 static const int kCodeLengthRepeatOffsets[3] = { 3, 3, 11 }; 33 34 // ----------------------------------------------------------------------------- 35 // Five Huffman codes are used at each meta code: 36 // 1. green + length prefix codes + color cache codes, 37 // 2. alpha, 38 // 3. red, 39 // 4. blue, and, 40 // 5. distance prefix codes. 41 typedef enum { 42 GREEN = 0, 43 RED = 1, 44 BLUE = 2, 45 ALPHA = 3, 46 DIST = 4 47 } HuffIndex; 48 49 static const uint16_t kAlphabetSize[HUFFMAN_CODES_PER_META_CODE] = { 50 NUM_LITERAL_CODES + NUM_LENGTH_CODES, 51 NUM_LITERAL_CODES, NUM_LITERAL_CODES, NUM_LITERAL_CODES, 52 NUM_DISTANCE_CODES 53 }; 54 55 56 #define NUM_CODE_LENGTH_CODES 19 57 static const uint8_t kCodeLengthCodeOrder[NUM_CODE_LENGTH_CODES] = { 58 17, 18, 0, 1, 2, 3, 4, 5, 16, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 59 }; 60 61 #define CODE_TO_PLANE_CODES 120 62 static const uint8_t code_to_plane_lut[CODE_TO_PLANE_CODES] = { 63 0x18, 0x07, 0x17, 0x19, 0x28, 0x06, 0x27, 0x29, 0x16, 0x1a, 64 0x26, 0x2a, 0x38, 0x05, 0x37, 0x39, 0x15, 0x1b, 0x36, 0x3a, 65 0x25, 0x2b, 0x48, 0x04, 0x47, 0x49, 0x14, 0x1c, 0x35, 0x3b, 66 0x46, 0x4a, 0x24, 0x2c, 0x58, 0x45, 0x4b, 0x34, 0x3c, 0x03, 67 0x57, 0x59, 0x13, 0x1d, 0x56, 0x5a, 0x23, 0x2d, 0x44, 0x4c, 68 0x55, 0x5b, 0x33, 0x3d, 0x68, 0x02, 0x67, 0x69, 0x12, 0x1e, 69 0x66, 0x6a, 0x22, 0x2e, 0x54, 0x5c, 0x43, 0x4d, 0x65, 0x6b, 70 0x32, 0x3e, 0x78, 0x01, 0x77, 0x79, 0x53, 0x5d, 0x11, 0x1f, 71 0x64, 0x6c, 0x42, 0x4e, 0x76, 0x7a, 0x21, 0x2f, 0x75, 0x7b, 72 0x31, 0x3f, 0x63, 0x6d, 0x52, 0x5e, 0x00, 0x74, 0x7c, 0x41, 73 0x4f, 0x10, 0x20, 0x62, 0x6e, 0x30, 0x73, 0x7d, 0x51, 0x5f, 74 0x40, 0x72, 0x7e, 0x61, 0x6f, 0x50, 0x71, 0x7f, 0x60, 0x70 75 }; 76 77 static int DecodeImageStream(int xsize, int ysize, 78 int is_level0, 79 VP8LDecoder* const dec, 80 uint32_t** const decoded_data); 81 82 //------------------------------------------------------------------------------ 83 84 int VP8LCheckSignature(const uint8_t* const data, size_t size) { 85 return (size >= 1) && (data[0] == VP8L_MAGIC_BYTE); 86 } 87 88 static int ReadImageInfo(VP8LBitReader* const br, 89 int* const width, int* const height, 90 int* const has_alpha) { 91 const uint8_t signature = VP8LReadBits(br, 8); 92 if (!VP8LCheckSignature(&signature, 1)) { 93 return 0; 94 } 95 *width = VP8LReadBits(br, VP8L_IMAGE_SIZE_BITS) + 1; 96 *height = VP8LReadBits(br, VP8L_IMAGE_SIZE_BITS) + 1; 97 *has_alpha = VP8LReadBits(br, 1); 98 VP8LReadBits(br, VP8L_VERSION_BITS); // Read/ignore the version number. 99 return 1; 100 } 101 102 int VP8LGetInfo(const uint8_t* data, size_t data_size, 103 int* const width, int* const height, int* const has_alpha) { 104 if (data == NULL || data_size < VP8L_FRAME_HEADER_SIZE) { 105 return 0; // not enough data 106 } else { 107 int w, h, a; 108 VP8LBitReader br; 109 VP8LInitBitReader(&br, data, data_size); 110 if (!ReadImageInfo(&br, &w, &h, &a)) { 111 return 0; 112 } 113 if (width != NULL) *width = w; 114 if (height != NULL) *height = h; 115 if (has_alpha != NULL) *has_alpha = a; 116 return 1; 117 } 118 } 119 120 //------------------------------------------------------------------------------ 121 122 static WEBP_INLINE int GetCopyDistance(int distance_symbol, 123 VP8LBitReader* const br) { 124 int extra_bits, offset; 125 if (distance_symbol < 4) { 126 return distance_symbol + 1; 127 } 128 extra_bits = (distance_symbol - 2) >> 1; 129 offset = (2 + (distance_symbol & 1)) << extra_bits; 130 return offset + VP8LReadBits(br, extra_bits) + 1; 131 } 132 133 static WEBP_INLINE int GetCopyLength(int length_symbol, 134 VP8LBitReader* const br) { 135 // Length and distance prefixes are encoded the same way. 136 return GetCopyDistance(length_symbol, br); 137 } 138 139 static WEBP_INLINE int PlaneCodeToDistance(int xsize, int plane_code) { 140 if (plane_code > CODE_TO_PLANE_CODES) { 141 return plane_code - CODE_TO_PLANE_CODES; 142 } else { 143 const int dist_code = code_to_plane_lut[plane_code - 1]; 144 const int yoffset = dist_code >> 4; 145 const int xoffset = 8 - (dist_code & 0xf); 146 const int dist = yoffset * xsize + xoffset; 147 return (dist >= 1) ? dist : 1; 148 } 149 } 150 151 //------------------------------------------------------------------------------ 152 // Decodes the next Huffman code from bit-stream. 153 // FillBitWindow(br) needs to be called at minimum every second call 154 // to ReadSymbol, in order to pre-fetch enough bits. 155 static WEBP_INLINE int ReadSymbol(const HuffmanTree* tree, 156 VP8LBitReader* const br) { 157 const HuffmanTreeNode* node = tree->root_; 158 int num_bits = 0; 159 uint32_t bits = VP8LPrefetchBits(br); 160 assert(node != NULL); 161 while (!HuffmanTreeNodeIsLeaf(node)) { 162 node = HuffmanTreeNextNode(node, bits & 1); 163 bits >>= 1; 164 ++num_bits; 165 } 166 VP8LDiscardBits(br, num_bits); 167 return node->symbol_; 168 } 169 170 static int ReadHuffmanCodeLengths( 171 VP8LDecoder* const dec, const int* const code_length_code_lengths, 172 int num_symbols, int* const code_lengths) { 173 int ok = 0; 174 VP8LBitReader* const br = &dec->br_; 175 int symbol; 176 int max_symbol; 177 int prev_code_len = DEFAULT_CODE_LENGTH; 178 HuffmanTree tree; 179 180 if (!HuffmanTreeBuildImplicit(&tree, code_length_code_lengths, 181 NUM_CODE_LENGTH_CODES)) { 182 dec->status_ = VP8_STATUS_BITSTREAM_ERROR; 183 return 0; 184 } 185 186 if (VP8LReadBits(br, 1)) { // use length 187 const int length_nbits = 2 + 2 * VP8LReadBits(br, 3); 188 max_symbol = 2 + VP8LReadBits(br, length_nbits); 189 if (max_symbol > num_symbols) { 190 dec->status_ = VP8_STATUS_BITSTREAM_ERROR; 191 goto End; 192 } 193 } else { 194 max_symbol = num_symbols; 195 } 196 197 symbol = 0; 198 while (symbol < num_symbols) { 199 int code_len; 200 if (max_symbol-- == 0) break; 201 VP8LFillBitWindow(br); 202 code_len = ReadSymbol(&tree, br); 203 if (code_len < kCodeLengthLiterals) { 204 code_lengths[symbol++] = code_len; 205 if (code_len != 0) prev_code_len = code_len; 206 } else { 207 const int use_prev = (code_len == kCodeLengthRepeatCode); 208 const int slot = code_len - kCodeLengthLiterals; 209 const int extra_bits = kCodeLengthExtraBits[slot]; 210 const int repeat_offset = kCodeLengthRepeatOffsets[slot]; 211 int repeat = VP8LReadBits(br, extra_bits) + repeat_offset; 212 if (symbol + repeat > num_symbols) { 213 dec->status_ = VP8_STATUS_BITSTREAM_ERROR; 214 goto End; 215 } else { 216 const int length = use_prev ? prev_code_len : 0; 217 while (repeat-- > 0) code_lengths[symbol++] = length; 218 } 219 } 220 } 221 ok = 1; 222 223 End: 224 HuffmanTreeRelease(&tree); 225 return ok; 226 } 227 228 static int ReadHuffmanCode(int alphabet_size, VP8LDecoder* const dec, 229 HuffmanTree* const tree) { 230 int ok = 0; 231 VP8LBitReader* const br = &dec->br_; 232 const int simple_code = VP8LReadBits(br, 1); 233 234 if (simple_code) { // Read symbols, codes & code lengths directly. 235 int symbols[2]; 236 int codes[2]; 237 int code_lengths[2]; 238 const int num_symbols = VP8LReadBits(br, 1) + 1; 239 const int first_symbol_len_code = VP8LReadBits(br, 1); 240 // The first code is either 1 bit or 8 bit code. 241 symbols[0] = VP8LReadBits(br, (first_symbol_len_code == 0) ? 1 : 8); 242 codes[0] = 0; 243 code_lengths[0] = num_symbols - 1; 244 // The second code (if present), is always 8 bit long. 245 if (num_symbols == 2) { 246 symbols[1] = VP8LReadBits(br, 8); 247 codes[1] = 1; 248 code_lengths[1] = num_symbols - 1; 249 } 250 ok = HuffmanTreeBuildExplicit(tree, code_lengths, codes, symbols, 251 alphabet_size, num_symbols); 252 } else { // Decode Huffman-coded code lengths. 253 int* code_lengths = NULL; 254 int i; 255 int code_length_code_lengths[NUM_CODE_LENGTH_CODES] = { 0 }; 256 const int num_codes = VP8LReadBits(br, 4) + 4; 257 if (num_codes > NUM_CODE_LENGTH_CODES) { 258 dec->status_ = VP8_STATUS_BITSTREAM_ERROR; 259 return 0; 260 } 261 262 code_lengths = 263 (int*)WebPSafeCalloc((uint64_t)alphabet_size, sizeof(*code_lengths)); 264 if (code_lengths == NULL) { 265 dec->status_ = VP8_STATUS_OUT_OF_MEMORY; 266 return 0; 267 } 268 269 for (i = 0; i < num_codes; ++i) { 270 code_length_code_lengths[kCodeLengthCodeOrder[i]] = VP8LReadBits(br, 3); 271 } 272 ok = ReadHuffmanCodeLengths(dec, code_length_code_lengths, alphabet_size, 273 code_lengths); 274 if (ok) { 275 ok = HuffmanTreeBuildImplicit(tree, code_lengths, alphabet_size); 276 } 277 free(code_lengths); 278 } 279 ok = ok && !br->error_; 280 if (!ok) { 281 dec->status_ = VP8_STATUS_BITSTREAM_ERROR; 282 return 0; 283 } 284 return 1; 285 } 286 287 static void DeleteHtreeGroups(HTreeGroup* htree_groups, int num_htree_groups) { 288 if (htree_groups != NULL) { 289 int i, j; 290 for (i = 0; i < num_htree_groups; ++i) { 291 HuffmanTree* const htrees = htree_groups[i].htrees_; 292 for (j = 0; j < HUFFMAN_CODES_PER_META_CODE; ++j) { 293 HuffmanTreeRelease(&htrees[j]); 294 } 295 } 296 free(htree_groups); 297 } 298 } 299 300 static int ReadHuffmanCodes(VP8LDecoder* const dec, int xsize, int ysize, 301 int color_cache_bits, int allow_recursion) { 302 int i, j; 303 VP8LBitReader* const br = &dec->br_; 304 VP8LMetadata* const hdr = &dec->hdr_; 305 uint32_t* huffman_image = NULL; 306 HTreeGroup* htree_groups = NULL; 307 int num_htree_groups = 1; 308 309 if (allow_recursion && VP8LReadBits(br, 1)) { 310 // use meta Huffman codes. 311 const int huffman_precision = VP8LReadBits(br, 3) + 2; 312 const int huffman_xsize = VP8LSubSampleSize(xsize, huffman_precision); 313 const int huffman_ysize = VP8LSubSampleSize(ysize, huffman_precision); 314 const int huffman_pixs = huffman_xsize * huffman_ysize; 315 if (!DecodeImageStream(huffman_xsize, huffman_ysize, 0, dec, 316 &huffman_image)) { 317 dec->status_ = VP8_STATUS_BITSTREAM_ERROR; 318 goto Error; 319 } 320 hdr->huffman_subsample_bits_ = huffman_precision; 321 for (i = 0; i < huffman_pixs; ++i) { 322 // The huffman data is stored in red and green bytes. 323 const int group = (huffman_image[i] >> 8) & 0xffff; 324 huffman_image[i] = group; 325 if (group >= num_htree_groups) { 326 num_htree_groups = group + 1; 327 } 328 } 329 } 330 331 if (br->error_) goto Error; 332 333 assert(num_htree_groups <= 0x10000); 334 htree_groups = 335 (HTreeGroup*)WebPSafeCalloc((uint64_t)num_htree_groups, 336 sizeof(*htree_groups)); 337 if (htree_groups == NULL) { 338 dec->status_ = VP8_STATUS_OUT_OF_MEMORY; 339 goto Error; 340 } 341 342 for (i = 0; i < num_htree_groups; ++i) { 343 HuffmanTree* const htrees = htree_groups[i].htrees_; 344 for (j = 0; j < HUFFMAN_CODES_PER_META_CODE; ++j) { 345 int alphabet_size = kAlphabetSize[j]; 346 if (j == 0 && color_cache_bits > 0) { 347 alphabet_size += 1 << color_cache_bits; 348 } 349 if (!ReadHuffmanCode(alphabet_size, dec, htrees + j)) goto Error; 350 } 351 } 352 353 // All OK. Finalize pointers and return. 354 hdr->huffman_image_ = huffman_image; 355 hdr->num_htree_groups_ = num_htree_groups; 356 hdr->htree_groups_ = htree_groups; 357 return 1; 358 359 Error: 360 free(huffman_image); 361 DeleteHtreeGroups(htree_groups, num_htree_groups); 362 return 0; 363 } 364 365 //------------------------------------------------------------------------------ 366 // Scaling. 367 368 static int AllocateAndInitRescaler(VP8LDecoder* const dec, VP8Io* const io) { 369 const int num_channels = 4; 370 const int in_width = io->mb_w; 371 const int out_width = io->scaled_width; 372 const int in_height = io->mb_h; 373 const int out_height = io->scaled_height; 374 const uint64_t work_size = 2 * num_channels * (uint64_t)out_width; 375 int32_t* work; // Rescaler work area. 376 const uint64_t scaled_data_size = num_channels * (uint64_t)out_width; 377 uint32_t* scaled_data; // Temporary storage for scaled BGRA data. 378 const uint64_t memory_size = sizeof(*dec->rescaler) + 379 work_size * sizeof(*work) + 380 scaled_data_size * sizeof(*scaled_data); 381 uint8_t* memory = (uint8_t*)WebPSafeCalloc(memory_size, sizeof(*memory)); 382 if (memory == NULL) { 383 dec->status_ = VP8_STATUS_OUT_OF_MEMORY; 384 return 0; 385 } 386 assert(dec->rescaler_memory == NULL); 387 dec->rescaler_memory = memory; 388 389 dec->rescaler = (WebPRescaler*)memory; 390 memory += sizeof(*dec->rescaler); 391 work = (int32_t*)memory; 392 memory += work_size * sizeof(*work); 393 scaled_data = (uint32_t*)memory; 394 395 WebPRescalerInit(dec->rescaler, in_width, in_height, (uint8_t*)scaled_data, 396 out_width, out_height, 0, num_channels, 397 in_width, out_width, in_height, out_height, work); 398 return 1; 399 } 400 401 //------------------------------------------------------------------------------ 402 // Export to ARGB 403 404 // We have special "export" function since we need to convert from BGRA 405 static int Export(WebPRescaler* const rescaler, WEBP_CSP_MODE colorspace, 406 int rgba_stride, uint8_t* const rgba) { 407 const uint32_t* const src = (const uint32_t*)rescaler->dst; 408 const int dst_width = rescaler->dst_width; 409 int num_lines_out = 0; 410 while (WebPRescalerHasPendingOutput(rescaler)) { 411 uint8_t* const dst = rgba + num_lines_out * rgba_stride; 412 WebPRescalerExportRow(rescaler); 413 VP8LConvertFromBGRA(src, dst_width, colorspace, dst); 414 ++num_lines_out; 415 } 416 return num_lines_out; 417 } 418 419 // Emit scaled rows. 420 static int EmitRescaledRows(const VP8LDecoder* const dec, 421 const uint32_t* const data, int in_stride, int mb_h, 422 uint8_t* const out, int out_stride) { 423 const WEBP_CSP_MODE colorspace = dec->output_->colorspace; 424 const uint8_t* const in = (const uint8_t*)data; 425 int num_lines_in = 0; 426 int num_lines_out = 0; 427 while (num_lines_in < mb_h) { 428 const uint8_t* const row_in = in + num_lines_in * in_stride; 429 uint8_t* const row_out = out + num_lines_out * out_stride; 430 num_lines_in += WebPRescalerImport(dec->rescaler, mb_h - num_lines_in, 431 row_in, in_stride); 432 num_lines_out += Export(dec->rescaler, colorspace, out_stride, row_out); 433 } 434 return num_lines_out; 435 } 436 437 // Emit rows without any scaling. 438 static int EmitRows(WEBP_CSP_MODE colorspace, 439 const uint32_t* const data, int in_stride, 440 int mb_w, int mb_h, 441 uint8_t* const out, int out_stride) { 442 int lines = mb_h; 443 const uint8_t* row_in = (const uint8_t*)data; 444 uint8_t* row_out = out; 445 while (lines-- > 0) { 446 VP8LConvertFromBGRA((const uint32_t*)row_in, mb_w, colorspace, row_out); 447 row_in += in_stride; 448 row_out += out_stride; 449 } 450 return mb_h; // Num rows out == num rows in. 451 } 452 453 //------------------------------------------------------------------------------ 454 // Export to YUVA 455 456 static void ConvertToYUVA(const uint32_t* const src, int width, int y_pos, 457 const WebPDecBuffer* const output) { 458 const WebPYUVABuffer* const buf = &output->u.YUVA; 459 // first, the luma plane 460 { 461 int i; 462 uint8_t* const y = buf->y + y_pos * buf->y_stride; 463 for (i = 0; i < width; ++i) { 464 const uint32_t p = src[i]; 465 y[i] = VP8RGBToY((p >> 16) & 0xff, (p >> 8) & 0xff, (p >> 0) & 0xff); 466 } 467 } 468 469 // then U/V planes 470 { 471 uint8_t* const u = buf->u + (y_pos >> 1) * buf->u_stride; 472 uint8_t* const v = buf->v + (y_pos >> 1) * buf->v_stride; 473 const int uv_width = width >> 1; 474 int i; 475 for (i = 0; i < uv_width; ++i) { 476 const uint32_t v0 = src[2 * i + 0]; 477 const uint32_t v1 = src[2 * i + 1]; 478 // VP8RGBToU/V expects four accumulated pixels. Hence we need to 479 // scale r/g/b value by a factor 2. We just shift v0/v1 one bit less. 480 const int r = ((v0 >> 15) & 0x1fe) + ((v1 >> 15) & 0x1fe); 481 const int g = ((v0 >> 7) & 0x1fe) + ((v1 >> 7) & 0x1fe); 482 const int b = ((v0 << 1) & 0x1fe) + ((v1 << 1) & 0x1fe); 483 if (!(y_pos & 1)) { // even lines: store values 484 u[i] = VP8RGBToU(r, g, b); 485 v[i] = VP8RGBToV(r, g, b); 486 } else { // odd lines: average with previous values 487 const int tmp_u = VP8RGBToU(r, g, b); 488 const int tmp_v = VP8RGBToV(r, g, b); 489 // Approximated average-of-four. But it's an acceptable diff. 490 u[i] = (u[i] + tmp_u + 1) >> 1; 491 v[i] = (v[i] + tmp_v + 1) >> 1; 492 } 493 } 494 if (width & 1) { // last pixel 495 const uint32_t v0 = src[2 * i + 0]; 496 const int r = (v0 >> 14) & 0x3fc; 497 const int g = (v0 >> 6) & 0x3fc; 498 const int b = (v0 << 2) & 0x3fc; 499 if (!(y_pos & 1)) { // even lines 500 u[i] = VP8RGBToU(r, g, b); 501 v[i] = VP8RGBToV(r, g, b); 502 } else { // odd lines (note: we could just skip this) 503 const int tmp_u = VP8RGBToU(r, g, b); 504 const int tmp_v = VP8RGBToV(r, g, b); 505 u[i] = (u[i] + tmp_u + 1) >> 1; 506 v[i] = (v[i] + tmp_v + 1) >> 1; 507 } 508 } 509 } 510 // Lastly, store alpha if needed. 511 if (buf->a != NULL) { 512 int i; 513 uint8_t* const a = buf->a + y_pos * buf->a_stride; 514 for (i = 0; i < width; ++i) a[i] = (src[i] >> 24); 515 } 516 } 517 518 static int ExportYUVA(const VP8LDecoder* const dec, int y_pos) { 519 WebPRescaler* const rescaler = dec->rescaler; 520 const uint32_t* const src = (const uint32_t*)rescaler->dst; 521 const int dst_width = rescaler->dst_width; 522 int num_lines_out = 0; 523 while (WebPRescalerHasPendingOutput(rescaler)) { 524 WebPRescalerExportRow(rescaler); 525 ConvertToYUVA(src, dst_width, y_pos, dec->output_); 526 ++y_pos; 527 ++num_lines_out; 528 } 529 return num_lines_out; 530 } 531 532 static int EmitRescaledRowsYUVA(const VP8LDecoder* const dec, 533 const uint32_t* const data, 534 int in_stride, int mb_h) { 535 const uint8_t* const in = (const uint8_t*)data; 536 int num_lines_in = 0; 537 int y_pos = dec->last_out_row_; 538 while (num_lines_in < mb_h) { 539 const uint8_t* const row_in = in + num_lines_in * in_stride; 540 num_lines_in += WebPRescalerImport(dec->rescaler, mb_h - num_lines_in, 541 row_in, in_stride); 542 y_pos += ExportYUVA(dec, y_pos); 543 } 544 return y_pos; 545 } 546 547 static int EmitRowsYUVA(const VP8LDecoder* const dec, 548 const uint32_t* const data, int in_stride, 549 int mb_w, int num_rows) { 550 int y_pos = dec->last_out_row_; 551 const uint8_t* row_in = (const uint8_t*)data; 552 while (num_rows-- > 0) { 553 ConvertToYUVA((const uint32_t*)row_in, mb_w, y_pos, dec->output_); 554 row_in += in_stride; 555 ++y_pos; 556 } 557 return y_pos; 558 } 559 560 //------------------------------------------------------------------------------ 561 // Cropping. 562 563 // Sets io->mb_y, io->mb_h & io->mb_w according to start row, end row and 564 // crop options. Also updates the input data pointer, so that it points to the 565 // start of the cropped window. 566 // Note that 'pixel_stride' is in units of 'uint32_t' (and not 'bytes). 567 // Returns true if the crop window is not empty. 568 static int SetCropWindow(VP8Io* const io, int y_start, int y_end, 569 const uint32_t** const in_data, int pixel_stride) { 570 assert(y_start < y_end); 571 assert(io->crop_left < io->crop_right); 572 if (y_end > io->crop_bottom) { 573 y_end = io->crop_bottom; // make sure we don't overflow on last row. 574 } 575 if (y_start < io->crop_top) { 576 const int delta = io->crop_top - y_start; 577 y_start = io->crop_top; 578 *in_data += pixel_stride * delta; 579 } 580 if (y_start >= y_end) return 0; // Crop window is empty. 581 582 *in_data += io->crop_left; 583 584 io->mb_y = y_start - io->crop_top; 585 io->mb_w = io->crop_right - io->crop_left; 586 io->mb_h = y_end - y_start; 587 return 1; // Non-empty crop window. 588 } 589 590 //------------------------------------------------------------------------------ 591 592 static WEBP_INLINE int GetMetaIndex( 593 const uint32_t* const image, int xsize, int bits, int x, int y) { 594 if (bits == 0) return 0; 595 return image[xsize * (y >> bits) + (x >> bits)]; 596 } 597 598 static WEBP_INLINE HTreeGroup* GetHtreeGroupForPos(VP8LMetadata* const hdr, 599 int x, int y) { 600 const int meta_index = GetMetaIndex(hdr->huffman_image_, hdr->huffman_xsize_, 601 hdr->huffman_subsample_bits_, x, y); 602 assert(meta_index < hdr->num_htree_groups_); 603 return hdr->htree_groups_ + meta_index; 604 } 605 606 //------------------------------------------------------------------------------ 607 // Main loop, with custom row-processing function 608 609 typedef void (*ProcessRowsFunc)(VP8LDecoder* const dec, int row); 610 611 static void ApplyInverseTransforms(VP8LDecoder* const dec, int num_rows, 612 const uint32_t* const rows) { 613 int n = dec->next_transform_; 614 const int cache_pixs = dec->width_ * num_rows; 615 const int start_row = dec->last_row_; 616 const int end_row = start_row + num_rows; 617 const uint32_t* rows_in = rows; 618 uint32_t* const rows_out = dec->argb_cache_; 619 620 // Inverse transforms. 621 // TODO: most transforms only need to operate on the cropped region only. 622 memcpy(rows_out, rows_in, cache_pixs * sizeof(*rows_out)); 623 while (n-- > 0) { 624 VP8LTransform* const transform = &dec->transforms_[n]; 625 VP8LInverseTransform(transform, start_row, end_row, rows_in, rows_out); 626 rows_in = rows_out; 627 } 628 } 629 630 // Special method for paletted alpha data. 631 static void ApplyInverseTransformsAlpha(VP8LDecoder* const dec, int num_rows, 632 const uint8_t* const rows) { 633 const int start_row = dec->last_row_; 634 const int end_row = start_row + num_rows; 635 const uint8_t* rows_in = rows; 636 uint8_t* rows_out = (uint8_t*)dec->io_->opaque + dec->io_->width * start_row; 637 VP8LTransform* const transform = &dec->transforms_[0]; 638 assert(dec->next_transform_ == 1); 639 assert(transform->type_ == COLOR_INDEXING_TRANSFORM); 640 VP8LColorIndexInverseTransformAlpha(transform, start_row, end_row, rows_in, 641 rows_out); 642 } 643 644 // Processes (transforms, scales & color-converts) the rows decoded after the 645 // last call. 646 static void ProcessRows(VP8LDecoder* const dec, int row) { 647 const uint32_t* const rows = dec->pixels_ + dec->width_ * dec->last_row_; 648 const int num_rows = row - dec->last_row_; 649 650 if (num_rows <= 0) return; // Nothing to be done. 651 ApplyInverseTransforms(dec, num_rows, rows); 652 653 // Emit output. 654 { 655 VP8Io* const io = dec->io_; 656 const uint32_t* rows_data = dec->argb_cache_; 657 if (!SetCropWindow(io, dec->last_row_, row, &rows_data, io->width)) { 658 // Nothing to output (this time). 659 } else { 660 const WebPDecBuffer* const output = dec->output_; 661 const int in_stride = io->width * sizeof(*rows_data); 662 if (output->colorspace < MODE_YUV) { // convert to RGBA 663 const WebPRGBABuffer* const buf = &output->u.RGBA; 664 uint8_t* const rgba = buf->rgba + dec->last_out_row_ * buf->stride; 665 const int num_rows_out = io->use_scaling ? 666 EmitRescaledRows(dec, rows_data, in_stride, io->mb_h, 667 rgba, buf->stride) : 668 EmitRows(output->colorspace, rows_data, in_stride, 669 io->mb_w, io->mb_h, rgba, buf->stride); 670 // Update 'last_out_row_'. 671 dec->last_out_row_ += num_rows_out; 672 } else { // convert to YUVA 673 dec->last_out_row_ = io->use_scaling ? 674 EmitRescaledRowsYUVA(dec, rows_data, in_stride, io->mb_h) : 675 EmitRowsYUVA(dec, rows_data, in_stride, io->mb_w, io->mb_h); 676 } 677 assert(dec->last_out_row_ <= output->height); 678 } 679 } 680 681 // Update 'last_row_'. 682 dec->last_row_ = row; 683 assert(dec->last_row_ <= dec->height_); 684 } 685 686 #define DECODE_DATA_FUNC(FUNC_NAME, TYPE, STORE_PIXEL) \ 687 static int FUNC_NAME(VP8LDecoder* const dec, TYPE* const data, int width, \ 688 int height, ProcessRowsFunc process_func) { \ 689 int ok = 1; \ 690 int col = 0, row = 0; \ 691 VP8LBitReader* const br = &dec->br_; \ 692 VP8LMetadata* const hdr = &dec->hdr_; \ 693 HTreeGroup* htree_group = hdr->htree_groups_; \ 694 TYPE* src = data; \ 695 TYPE* last_cached = data; \ 696 TYPE* const src_end = data + width * height; \ 697 const int len_code_limit = NUM_LITERAL_CODES + NUM_LENGTH_CODES; \ 698 const int color_cache_limit = len_code_limit + hdr->color_cache_size_; \ 699 VP8LColorCache* const color_cache = \ 700 (hdr->color_cache_size_ > 0) ? &hdr->color_cache_ : NULL; \ 701 const int mask = hdr->huffman_mask_; \ 702 assert(htree_group != NULL); \ 703 while (!br->eos_ && src < src_end) { \ 704 int code; \ 705 /* Only update when changing tile. Note we could use this test: */ \ 706 /* if "((((prev_col ^ col) | prev_row ^ row)) > mask)" -> tile changed */ \ 707 /* but that's actually slower and needs storing the previous col/row. */ \ 708 if ((col & mask) == 0) { \ 709 htree_group = GetHtreeGroupForPos(hdr, col, row); \ 710 } \ 711 VP8LFillBitWindow(br); \ 712 code = ReadSymbol(&htree_group->htrees_[GREEN], br); \ 713 if (code < NUM_LITERAL_CODES) { /* Literal*/ \ 714 int red, green, blue, alpha; \ 715 red = ReadSymbol(&htree_group->htrees_[RED], br); \ 716 green = code; \ 717 VP8LFillBitWindow(br); \ 718 blue = ReadSymbol(&htree_group->htrees_[BLUE], br); \ 719 alpha = ReadSymbol(&htree_group->htrees_[ALPHA], br); \ 720 *src = STORE_PIXEL(alpha, red, green, blue); \ 721 AdvanceByOne: \ 722 ++src; \ 723 ++col; \ 724 if (col >= width) { \ 725 col = 0; \ 726 ++row; \ 727 if ((process_func != NULL) && (row % NUM_ARGB_CACHE_ROWS == 0)) { \ 728 process_func(dec, row); \ 729 } \ 730 if (color_cache != NULL) { \ 731 while (last_cached < src) { \ 732 VP8LColorCacheInsert(color_cache, *last_cached++); \ 733 } \ 734 } \ 735 } \ 736 } else if (code < len_code_limit) { /* Backward reference */ \ 737 int dist_code, dist; \ 738 const int length_sym = code - NUM_LITERAL_CODES; \ 739 const int length = GetCopyLength(length_sym, br); \ 740 const int dist_symbol = ReadSymbol(&htree_group->htrees_[DIST], br); \ 741 VP8LFillBitWindow(br); \ 742 dist_code = GetCopyDistance(dist_symbol, br); \ 743 dist = PlaneCodeToDistance(width, dist_code); \ 744 if (src - data < dist || src_end - src < length) { \ 745 ok = 0; \ 746 goto End; \ 747 } \ 748 { \ 749 int i; \ 750 for (i = 0; i < length; ++i) src[i] = src[i - dist]; \ 751 src += length; \ 752 } \ 753 col += length; \ 754 while (col >= width) { \ 755 col -= width; \ 756 ++row; \ 757 if ((process_func != NULL) && (row % NUM_ARGB_CACHE_ROWS == 0)) { \ 758 process_func(dec, row); \ 759 } \ 760 } \ 761 if (src < src_end) { \ 762 htree_group = GetHtreeGroupForPos(hdr, col, row); \ 763 if (color_cache != NULL) { \ 764 while (last_cached < src) { \ 765 VP8LColorCacheInsert(color_cache, *last_cached++); \ 766 } \ 767 } \ 768 } \ 769 } else if (code < color_cache_limit) { /* Color cache */ \ 770 const int key = code - len_code_limit; \ 771 assert(color_cache != NULL); \ 772 while (last_cached < src) { \ 773 VP8LColorCacheInsert(color_cache, *last_cached++); \ 774 } \ 775 *src = VP8LColorCacheLookup(color_cache, key); \ 776 goto AdvanceByOne; \ 777 } else { /* Not reached */ \ 778 ok = 0; \ 779 goto End; \ 780 } \ 781 ok = !br->error_; \ 782 if (!ok) goto End; \ 783 } \ 784 /* Process the remaining rows corresponding to last row-block. */ \ 785 if (process_func != NULL) process_func(dec, row); \ 786 End: \ 787 if (br->error_ || !ok || (br->eos_ && src < src_end)) { \ 788 ok = 0; \ 789 dec->status_ = \ 790 (!br->eos_) ? VP8_STATUS_BITSTREAM_ERROR : VP8_STATUS_SUSPENDED; \ 791 } else if (src == src_end) { \ 792 dec->state_ = READ_DATA; \ 793 } \ 794 return ok; \ 795 } 796 797 static WEBP_INLINE uint32_t GetARGBPixel(int alpha, int red, int green, 798 int blue) { 799 return (alpha << 24) | (red << 16) | (green << 8) | blue; 800 } 801 802 static WEBP_INLINE uint8_t GetAlphaPixel(int alpha, int red, int green, 803 int blue) { 804 (void)alpha; 805 (void)red; 806 (void)blue; 807 return green; // Alpha value is stored in green channel. 808 } 809 810 DECODE_DATA_FUNC(DecodeImageData, uint32_t, GetARGBPixel) 811 DECODE_DATA_FUNC(DecodeAlphaData, uint8_t, GetAlphaPixel) 812 813 #undef DECODE_DATA_FUNC 814 815 // ----------------------------------------------------------------------------- 816 // VP8LTransform 817 818 static void ClearTransform(VP8LTransform* const transform) { 819 free(transform->data_); 820 transform->data_ = NULL; 821 } 822 823 // For security reason, we need to remap the color map to span 824 // the total possible bundled values, and not just the num_colors. 825 static int ExpandColorMap(int num_colors, VP8LTransform* const transform) { 826 int i; 827 const int final_num_colors = 1 << (8 >> transform->bits_); 828 uint32_t* const new_color_map = 829 (uint32_t*)WebPSafeMalloc((uint64_t)final_num_colors, 830 sizeof(*new_color_map)); 831 if (new_color_map == NULL) { 832 return 0; 833 } else { 834 uint8_t* const data = (uint8_t*)transform->data_; 835 uint8_t* const new_data = (uint8_t*)new_color_map; 836 new_color_map[0] = transform->data_[0]; 837 for (i = 4; i < 4 * num_colors; ++i) { 838 // Equivalent to AddPixelEq(), on a byte-basis. 839 new_data[i] = (data[i] + new_data[i - 4]) & 0xff; 840 } 841 for (; i < 4 * final_num_colors; ++i) 842 new_data[i] = 0; // black tail. 843 free(transform->data_); 844 transform->data_ = new_color_map; 845 } 846 return 1; 847 } 848 849 static int ReadTransform(int* const xsize, int const* ysize, 850 VP8LDecoder* const dec) { 851 int ok = 1; 852 VP8LBitReader* const br = &dec->br_; 853 VP8LTransform* transform = &dec->transforms_[dec->next_transform_]; 854 const VP8LImageTransformType type = 855 (VP8LImageTransformType)VP8LReadBits(br, 2); 856 857 // Each transform type can only be present once in the stream. 858 if (dec->transforms_seen_ & (1U << type)) { 859 return 0; // Already there, let's not accept the second same transform. 860 } 861 dec->transforms_seen_ |= (1U << type); 862 863 transform->type_ = type; 864 transform->xsize_ = *xsize; 865 transform->ysize_ = *ysize; 866 transform->data_ = NULL; 867 ++dec->next_transform_; 868 assert(dec->next_transform_ <= NUM_TRANSFORMS); 869 870 switch (type) { 871 case PREDICTOR_TRANSFORM: 872 case CROSS_COLOR_TRANSFORM: 873 transform->bits_ = VP8LReadBits(br, 3) + 2; 874 ok = DecodeImageStream(VP8LSubSampleSize(transform->xsize_, 875 transform->bits_), 876 VP8LSubSampleSize(transform->ysize_, 877 transform->bits_), 878 0, dec, &transform->data_); 879 break; 880 case COLOR_INDEXING_TRANSFORM: { 881 const int num_colors = VP8LReadBits(br, 8) + 1; 882 const int bits = (num_colors > 16) ? 0 883 : (num_colors > 4) ? 1 884 : (num_colors > 2) ? 2 885 : 3; 886 *xsize = VP8LSubSampleSize(transform->xsize_, bits); 887 transform->bits_ = bits; 888 ok = DecodeImageStream(num_colors, 1, 0, dec, &transform->data_); 889 ok = ok && ExpandColorMap(num_colors, transform); 890 break; 891 } 892 case SUBTRACT_GREEN: 893 break; 894 default: 895 assert(0); // can't happen 896 break; 897 } 898 899 return ok; 900 } 901 902 // ----------------------------------------------------------------------------- 903 // VP8LMetadata 904 905 static void InitMetadata(VP8LMetadata* const hdr) { 906 assert(hdr); 907 memset(hdr, 0, sizeof(*hdr)); 908 } 909 910 static void ClearMetadata(VP8LMetadata* const hdr) { 911 assert(hdr); 912 913 free(hdr->huffman_image_); 914 DeleteHtreeGroups(hdr->htree_groups_, hdr->num_htree_groups_); 915 VP8LColorCacheClear(&hdr->color_cache_); 916 InitMetadata(hdr); 917 } 918 919 // ----------------------------------------------------------------------------- 920 // VP8LDecoder 921 922 VP8LDecoder* VP8LNew(void) { 923 VP8LDecoder* const dec = (VP8LDecoder*)calloc(1, sizeof(*dec)); 924 if (dec == NULL) return NULL; 925 dec->status_ = VP8_STATUS_OK; 926 dec->action_ = READ_DIM; 927 dec->state_ = READ_DIM; 928 return dec; 929 } 930 931 void VP8LClear(VP8LDecoder* const dec) { 932 int i; 933 if (dec == NULL) return; 934 ClearMetadata(&dec->hdr_); 935 936 free(dec->pixels_); 937 dec->pixels_ = NULL; 938 for (i = 0; i < dec->next_transform_; ++i) { 939 ClearTransform(&dec->transforms_[i]); 940 } 941 dec->next_transform_ = 0; 942 dec->transforms_seen_ = 0; 943 944 free(dec->rescaler_memory); 945 dec->rescaler_memory = NULL; 946 947 dec->output_ = NULL; // leave no trace behind 948 } 949 950 void VP8LDelete(VP8LDecoder* const dec) { 951 if (dec != NULL) { 952 VP8LClear(dec); 953 free(dec); 954 } 955 } 956 957 static void UpdateDecoder(VP8LDecoder* const dec, int width, int height) { 958 VP8LMetadata* const hdr = &dec->hdr_; 959 const int num_bits = hdr->huffman_subsample_bits_; 960 dec->width_ = width; 961 dec->height_ = height; 962 963 hdr->huffman_xsize_ = VP8LSubSampleSize(width, num_bits); 964 hdr->huffman_mask_ = (num_bits == 0) ? ~0 : (1 << num_bits) - 1; 965 } 966 967 static int DecodeImageStream(int xsize, int ysize, 968 int is_level0, 969 VP8LDecoder* const dec, 970 uint32_t** const decoded_data) { 971 int ok = 1; 972 int transform_xsize = xsize; 973 int transform_ysize = ysize; 974 VP8LBitReader* const br = &dec->br_; 975 VP8LMetadata* const hdr = &dec->hdr_; 976 uint32_t* data = NULL; 977 int color_cache_bits = 0; 978 979 // Read the transforms (may recurse). 980 if (is_level0) { 981 while (ok && VP8LReadBits(br, 1)) { 982 ok = ReadTransform(&transform_xsize, &transform_ysize, dec); 983 } 984 } 985 986 // Color cache 987 if (ok && VP8LReadBits(br, 1)) { 988 color_cache_bits = VP8LReadBits(br, 4); 989 ok = (color_cache_bits >= 1 && color_cache_bits <= MAX_CACHE_BITS); 990 if (!ok) { 991 dec->status_ = VP8_STATUS_BITSTREAM_ERROR; 992 goto End; 993 } 994 } 995 996 // Read the Huffman codes (may recurse). 997 ok = ok && ReadHuffmanCodes(dec, transform_xsize, transform_ysize, 998 color_cache_bits, is_level0); 999 if (!ok) { 1000 dec->status_ = VP8_STATUS_BITSTREAM_ERROR; 1001 goto End; 1002 } 1003 1004 // Finish setting up the color-cache 1005 if (color_cache_bits > 0) { 1006 hdr->color_cache_size_ = 1 << color_cache_bits; 1007 if (!VP8LColorCacheInit(&hdr->color_cache_, color_cache_bits)) { 1008 dec->status_ = VP8_STATUS_OUT_OF_MEMORY; 1009 ok = 0; 1010 goto End; 1011 } 1012 } else { 1013 hdr->color_cache_size_ = 0; 1014 } 1015 UpdateDecoder(dec, transform_xsize, transform_ysize); 1016 1017 if (is_level0) { // level 0 complete 1018 dec->state_ = READ_HDR; 1019 goto End; 1020 } 1021 1022 { 1023 const uint64_t total_size = (uint64_t)transform_xsize * transform_ysize; 1024 data = (uint32_t*)WebPSafeMalloc(total_size, sizeof(*data)); 1025 if (data == NULL) { 1026 dec->status_ = VP8_STATUS_OUT_OF_MEMORY; 1027 ok = 0; 1028 goto End; 1029 } 1030 } 1031 1032 // Use the Huffman trees to decode the LZ77 encoded data. 1033 ok = DecodeImageData(dec, data, transform_xsize, transform_ysize, NULL); 1034 ok = ok && !br->error_; 1035 1036 End: 1037 1038 if (!ok) { 1039 free(data); 1040 ClearMetadata(hdr); 1041 // If not enough data (br.eos_) resulted in BIT_STREAM_ERROR, update the 1042 // status appropriately. 1043 if (dec->status_ == VP8_STATUS_BITSTREAM_ERROR && dec->br_.eos_) { 1044 dec->status_ = VP8_STATUS_SUSPENDED; 1045 } 1046 } else { 1047 if (decoded_data != NULL) { 1048 *decoded_data = data; 1049 } else { 1050 // We allocate image data in this function only for transforms. At level 0 1051 // (that is: not the transforms), we shouldn't have allocated anything. 1052 assert(data == NULL); 1053 assert(is_level0); 1054 } 1055 if (!is_level0) ClearMetadata(hdr); // Clean up temporary data behind. 1056 } 1057 return ok; 1058 } 1059 1060 //------------------------------------------------------------------------------ 1061 // Allocate internal buffers dec->pixels_ and dec->argb_cache_. 1062 static int AllocateInternalBuffers(VP8LDecoder* const dec, int final_width, 1063 size_t bytes_per_pixel) { 1064 const int argb_cache_needed = (bytes_per_pixel == sizeof(uint32_t)); 1065 const uint64_t num_pixels = (uint64_t)dec->width_ * dec->height_; 1066 // Scratch buffer corresponding to top-prediction row for transforming the 1067 // first row in the row-blocks. Not needed for paletted alpha. 1068 const uint64_t cache_top_pixels = 1069 argb_cache_needed ? (uint16_t)final_width : 0ULL; 1070 // Scratch buffer for temporary BGRA storage. Not needed for paletted alpha. 1071 const uint64_t cache_pixels = 1072 argb_cache_needed ? (uint64_t)final_width * NUM_ARGB_CACHE_ROWS : 0ULL; 1073 const uint64_t total_num_pixels = 1074 num_pixels + cache_top_pixels + cache_pixels; 1075 1076 assert(dec->width_ <= final_width); 1077 dec->pixels_ = (uint32_t*)WebPSafeMalloc(total_num_pixels, bytes_per_pixel); 1078 if (dec->pixels_ == NULL) { 1079 dec->argb_cache_ = NULL; // for sanity check 1080 dec->status_ = VP8_STATUS_OUT_OF_MEMORY; 1081 return 0; 1082 } 1083 dec->argb_cache_ = 1084 argb_cache_needed ? dec->pixels_ + num_pixels + cache_top_pixels : NULL; 1085 return 1; 1086 } 1087 1088 //------------------------------------------------------------------------------ 1089 1090 // Special row-processing that only stores the alpha data. 1091 static void ExtractAlphaRows(VP8LDecoder* const dec, int row) { 1092 const int num_rows = row - dec->last_row_; 1093 const uint32_t* const in = dec->pixels_ + dec->width_ * dec->last_row_; 1094 1095 if (num_rows <= 0) return; // Nothing to be done. 1096 ApplyInverseTransforms(dec, num_rows, in); 1097 1098 // Extract alpha (which is stored in the green plane). 1099 { 1100 const int width = dec->io_->width; // the final width (!= dec->width_) 1101 const int cache_pixs = width * num_rows; 1102 uint8_t* const dst = (uint8_t*)dec->io_->opaque + width * dec->last_row_; 1103 const uint32_t* const src = dec->argb_cache_; 1104 int i; 1105 for (i = 0; i < cache_pixs; ++i) dst[i] = (src[i] >> 8) & 0xff; 1106 } 1107 dec->last_row_ = dec->last_out_row_ = row; 1108 } 1109 1110 // Row-processing for the special case when alpha data contains only one 1111 // transform: color indexing. 1112 static void ExtractPalettedAlphaRows(VP8LDecoder* const dec, int row) { 1113 const int num_rows = row - dec->last_row_; 1114 const uint8_t* const in = 1115 (uint8_t*)dec->pixels_ + dec->width_ * dec->last_row_; 1116 if (num_rows <= 0) return; // Nothing to be done. 1117 ApplyInverseTransformsAlpha(dec, num_rows, in); 1118 dec->last_row_ = dec->last_out_row_ = row; 1119 } 1120 1121 int VP8LDecodeAlphaImageStream(int width, int height, const uint8_t* const data, 1122 size_t data_size, uint8_t* const output) { 1123 VP8Io io; 1124 int ok = 0; 1125 VP8LDecoder* const dec = VP8LNew(); 1126 size_t bytes_per_pixel = sizeof(uint32_t); // Default: BGRA mode. 1127 if (dec == NULL) return 0; 1128 1129 dec->width_ = width; 1130 dec->height_ = height; 1131 dec->io_ = &io; 1132 1133 VP8InitIo(&io); 1134 WebPInitCustomIo(NULL, &io); // Just a sanity Init. io won't be used. 1135 io.opaque = output; 1136 io.width = width; 1137 io.height = height; 1138 1139 dec->status_ = VP8_STATUS_OK; 1140 VP8LInitBitReader(&dec->br_, data, data_size); 1141 1142 dec->action_ = READ_HDR; 1143 if (!DecodeImageStream(width, height, 1, dec, NULL)) goto Err; 1144 1145 // Special case: if alpha data uses only the color indexing transform and 1146 // doesn't use color cache (a frequent case), we will use DecodeAlphaData() 1147 // method that only needs allocation of 1 byte per pixel (alpha channel). 1148 if (dec->next_transform_ == 1 && 1149 dec->transforms_[0].type_ == COLOR_INDEXING_TRANSFORM && 1150 dec->hdr_.color_cache_size_ == 0) { 1151 bytes_per_pixel = sizeof(uint8_t); 1152 } 1153 1154 // Allocate internal buffers (note that dec->width_ may have changed here). 1155 if (!AllocateInternalBuffers(dec, width, bytes_per_pixel)) goto Err; 1156 1157 // Decode (with special row processing). 1158 dec->action_ = READ_DATA; 1159 ok = (bytes_per_pixel == sizeof(uint8_t)) ? 1160 DecodeAlphaData(dec, (uint8_t*)dec->pixels_, dec->width_, dec->height_, 1161 ExtractPalettedAlphaRows) : 1162 DecodeImageData(dec, dec->pixels_, dec->width_, dec->height_, 1163 ExtractAlphaRows); 1164 1165 Err: 1166 VP8LDelete(dec); 1167 return ok; 1168 } 1169 1170 //------------------------------------------------------------------------------ 1171 1172 int VP8LDecodeHeader(VP8LDecoder* const dec, VP8Io* const io) { 1173 int width, height, has_alpha; 1174 1175 if (dec == NULL) return 0; 1176 if (io == NULL) { 1177 dec->status_ = VP8_STATUS_INVALID_PARAM; 1178 return 0; 1179 } 1180 1181 dec->io_ = io; 1182 dec->status_ = VP8_STATUS_OK; 1183 VP8LInitBitReader(&dec->br_, io->data, io->data_size); 1184 if (!ReadImageInfo(&dec->br_, &width, &height, &has_alpha)) { 1185 dec->status_ = VP8_STATUS_BITSTREAM_ERROR; 1186 goto Error; 1187 } 1188 dec->state_ = READ_DIM; 1189 io->width = width; 1190 io->height = height; 1191 1192 dec->action_ = READ_HDR; 1193 if (!DecodeImageStream(width, height, 1, dec, NULL)) goto Error; 1194 return 1; 1195 1196 Error: 1197 VP8LClear(dec); 1198 assert(dec->status_ != VP8_STATUS_OK); 1199 return 0; 1200 } 1201 1202 int VP8LDecodeImage(VP8LDecoder* const dec) { 1203 const size_t bytes_per_pixel = sizeof(uint32_t); 1204 VP8Io* io = NULL; 1205 WebPDecParams* params = NULL; 1206 1207 // Sanity checks. 1208 if (dec == NULL) return 0; 1209 1210 io = dec->io_; 1211 assert(io != NULL); 1212 params = (WebPDecParams*)io->opaque; 1213 assert(params != NULL); 1214 dec->output_ = params->output; 1215 assert(dec->output_ != NULL); 1216 1217 // Initialization. 1218 if (!WebPIoInitFromOptions(params->options, io, MODE_BGRA)) { 1219 dec->status_ = VP8_STATUS_INVALID_PARAM; 1220 goto Err; 1221 } 1222 1223 if (!AllocateInternalBuffers(dec, io->width, bytes_per_pixel)) goto Err; 1224 1225 if (io->use_scaling && !AllocateAndInitRescaler(dec, io)) goto Err; 1226 1227 // Decode. 1228 dec->action_ = READ_DATA; 1229 if (!DecodeImageData(dec, dec->pixels_, dec->width_, dec->height_, 1230 ProcessRows)) { 1231 goto Err; 1232 } 1233 1234 // Cleanup. 1235 params->last_y = dec->last_out_row_; 1236 VP8LClear(dec); 1237 return 1; 1238 1239 Err: 1240 VP8LClear(dec); 1241 assert(dec->status_ != VP8_STATUS_OK); 1242 return 0; 1243 } 1244 1245 //------------------------------------------------------------------------------ 1246 1247 #if defined(__cplusplus) || defined(c_plusplus) 1248 } // extern "C" 1249 #endif 1250
