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| 1 // Copyright 2009 Google Inc. | |
| 2 // | |
| 3 // Licensed under the Apache License, Version 2.0 (the "License"); | |
| 4 // you may not use this file except in compliance with the License. | |
| 5 // You may obtain a copy of the License at | |
| 6 // | |
| 7 // http://www.apache.org/licenses/LICENSE-2.0 | |
| 8 // | |
| 9 // Unless required by applicable law or agreed to in writing, software | |
| 10 // distributed under the License is distributed on an "AS IS" BASIS, | |
| 11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | |
| 12 // See the License for the specific language governing permissions and | |
| 13 // limitations under the License. | |
| 14 | |
| 15 ////////////////////////////////////////////////////////////////////////////////
////////// | |
| 16 | |
| 17 // This is a fork of the AOSP project ETC1 codec. The original code can be found | |
| 18 // at the following web site: | |
| 19 // https://android.googlesource.com/platform/frameworks/native/+/master/opengl/i
nclude/ETC1/ | |
| 20 | |
| 21 ////////////////////////////////////////////////////////////////////////////////
////////// | |
| 22 | |
| 23 #include "etc1.h" | |
| 24 | |
| 25 #include <cstring> | |
| 26 | |
| 27 /* From http://www.khronos.org/registry/gles/extensions/OES/OES_compressed_ETC1_
RGB8_texture.txt | |
| 28 | |
| 29 The number of bits that represent a 4x4 texel block is 64 bits if | |
| 30 <internalformat> is given by ETC1_RGB8_OES. | |
| 31 | |
| 32 The data for a block is a number of bytes, | |
| 33 | |
| 34 {q0, q1, q2, q3, q4, q5, q6, q7} | |
| 35 | |
| 36 where byte q0 is located at the lowest memory address and q7 at | |
| 37 the highest. The 64 bits specifying the block is then represented | |
| 38 by the following 64 bit integer: | |
| 39 | |
| 40 int64bit = 256*(256*(256*(256*(256*(256*(256*q0+q1)+q2)+q3)+q4)+q5)+q6)+q7; | |
| 41 | |
| 42 ETC1_RGB8_OES: | |
| 43 | |
| 44 a) bit layout in bits 63 through 32 if diffbit = 0 | |
| 45 | |
| 46 63 62 61 60 59 58 57 56 55 54 53 52 51 50 49 48 | |
| 47 ----------------------------------------------- | |
| 48 | base col1 | base col2 | base col1 | base col2 | | |
| 49 | R1 (4bits)| R2 (4bits)| G1 (4bits)| G2 (4bits)| | |
| 50 ----------------------------------------------- | |
| 51 | |
| 52 47 46 45 44 43 42 41 40 39 38 37 36 35 34 33 32 | |
| 53 --------------------------------------------------- | |
| 54 | base col1 | base col2 | table | table |diff|flip| | |
| 55 | B1 (4bits)| B2 (4bits)| cw 1 | cw 2 |bit |bit | | |
| 56 --------------------------------------------------- | |
| 57 | |
| 58 | |
| 59 b) bit layout in bits 63 through 32 if diffbit = 1 | |
| 60 | |
| 61 63 62 61 60 59 58 57 56 55 54 53 52 51 50 49 48 | |
| 62 ----------------------------------------------- | |
| 63 | base col1 | dcol 2 | base col1 | dcol 2 | | |
| 64 | R1' (5 bits) | dR2 | G1' (5 bits) | dG2 | | |
| 65 ----------------------------------------------- | |
| 66 | |
| 67 47 46 45 44 43 42 41 40 39 38 37 36 35 34 33 32 | |
| 68 --------------------------------------------------- | |
| 69 | base col 1 | dcol 2 | table | table |diff|flip| | |
| 70 | B1' (5 bits) | dB2 | cw 1 | cw 2 |bit |bit | | |
| 71 --------------------------------------------------- | |
| 72 | |
| 73 | |
| 74 c) bit layout in bits 31 through 0 (in both cases) | |
| 75 | |
| 76 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 | |
| 77 ----------------------------------------------- | |
| 78 | most significant pixel index bits | | |
| 79 | p| o| n| m| l| k| j| i| h| g| f| e| d| c| b| a| | |
| 80 ----------------------------------------------- | |
| 81 | |
| 82 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 | |
| 83 -------------------------------------------------- | |
| 84 | least significant pixel index bits | | |
| 85 | p| o| n| m| l| k| j| i| h| g| f| e| d| c | b | a | | |
| 86 -------------------------------------------------- | |
| 87 | |
| 88 | |
| 89 Add table 3.17.2: Intensity modifier sets for ETC1 compressed textures: | |
| 90 | |
| 91 table codeword modifier table | |
| 92 ------------------ ---------------------- | |
| 93 0 -8 -2 2 8 | |
| 94 1 -17 -5 5 17 | |
| 95 2 -29 -9 9 29 | |
| 96 3 -42 -13 13 42 | |
| 97 4 -60 -18 18 60 | |
| 98 5 -80 -24 24 80 | |
| 99 6 -106 -33 33 106 | |
| 100 7 -183 -47 47 183 | |
| 101 | |
| 102 | |
| 103 Add table 3.17.3 Mapping from pixel index values to modifier values for | |
| 104 ETC1 compressed textures: | |
| 105 | |
| 106 pixel index value | |
| 107 --------------- | |
| 108 msb lsb resulting modifier value | |
| 109 ----- ----- ------------------------- | |
| 110 1 1 -b (large negative value) | |
| 111 1 0 -a (small negative value) | |
| 112 0 0 a (small positive value) | |
| 113 0 1 b (large positive value) | |
| 114 | |
| 115 | |
| 116 */ | |
| 117 | |
| 118 static const int kModifierTable[] = { | |
| 119 /* 0 */2, 8, -2, -8, | |
| 120 /* 1 */5, 17, -5, -17, | |
| 121 /* 2 */9, 29, -9, -29, | |
| 122 /* 3 */13, 42, -13, -42, | |
| 123 /* 4 */18, 60, -18, -60, | |
| 124 /* 5 */24, 80, -24, -80, | |
| 125 /* 6 */33, 106, -33, -106, | |
| 126 /* 7 */47, 183, -47, -183 }; | |
| 127 | |
| 128 static const int kLookup[8] = { 0, 1, 2, 3, -4, -3, -2, -1 }; | |
| 129 | |
| 130 static inline etc1_byte clamp(int x) { | |
| 131 return (etc1_byte) (x >= 0 ? (x < 255 ? x : 255) : 0); | |
| 132 } | |
| 133 | |
| 134 static | |
| 135 inline int convert4To8(int b) { | |
| 136 int c = b & 0xf; | |
| 137 return (c << 4) | c; | |
| 138 } | |
| 139 | |
| 140 static | |
| 141 inline int convert5To8(int b) { | |
| 142 int c = b & 0x1f; | |
| 143 return (c << 3) | (c >> 2); | |
| 144 } | |
| 145 | |
| 146 static | |
| 147 inline int convert6To8(int b) { | |
| 148 int c = b & 0x3f; | |
| 149 return (c << 2) | (c >> 4); | |
| 150 } | |
| 151 | |
| 152 static | |
| 153 inline int divideBy255(int d) { | |
| 154 return (d + 128 + (d >> 8)) >> 8; | |
| 155 } | |
| 156 | |
| 157 static | |
| 158 inline int convert8To4(int b) { | |
| 159 int c = b & 0xff; | |
| 160 return divideBy255(c * 15); | |
| 161 } | |
| 162 | |
| 163 static | |
| 164 inline int convert8To5(int b) { | |
| 165 int c = b & 0xff; | |
| 166 return divideBy255(c * 31); | |
| 167 } | |
| 168 | |
| 169 static | |
| 170 inline int convertDiff(int base, int diff) { | |
| 171 return convert5To8((0x1f & base) + kLookup[0x7 & diff]); | |
| 172 } | |
| 173 | |
| 174 static | |
| 175 void decode_subblock(etc1_byte* pOut, int r, int g, int b, const int* table, | |
| 176 etc1_uint32 low, bool second, bool flipped) { | |
| 177 int baseX = 0; | |
| 178 int baseY = 0; | |
| 179 if (second) { | |
| 180 if (flipped) { | |
| 181 baseY = 2; | |
| 182 } else { | |
| 183 baseX = 2; | |
| 184 } | |
| 185 } | |
| 186 for (int i = 0; i < 8; i++) { | |
| 187 int x, y; | |
| 188 if (flipped) { | |
| 189 x = baseX + (i >> 1); | |
| 190 y = baseY + (i & 1); | |
| 191 } else { | |
| 192 x = baseX + (i >> 2); | |
| 193 y = baseY + (i & 3); | |
| 194 } | |
| 195 int k = y + (x * 4); | |
| 196 int offset = ((low >> k) & 1) | ((low >> (k + 15)) & 2); | |
| 197 int delta = table[offset]; | |
| 198 etc1_byte* q = pOut + 3 * (x + 4 * y); | |
| 199 *q++ = clamp(r + delta); | |
| 200 *q++ = clamp(g + delta); | |
| 201 *q++ = clamp(b + delta); | |
| 202 } | |
| 203 } | |
| 204 | |
| 205 // Input is an ETC1 compressed version of the data. | |
| 206 // Output is a 4 x 4 square of 3-byte pixels in form R, G, B | |
| 207 | |
| 208 void etc1_decode_block(const etc1_byte* pIn, etc1_byte* pOut) { | |
| 209 etc1_uint32 high = (pIn[0] << 24) | (pIn[1] << 16) | (pIn[2] << 8) | pIn[3]; | |
| 210 etc1_uint32 low = (pIn[4] << 24) | (pIn[5] << 16) | (pIn[6] << 8) | pIn[7]; | |
| 211 int r1, r2, g1, g2, b1, b2; | |
| 212 if (high & 2) { | |
| 213 // differential | |
| 214 int rBase = high >> 27; | |
| 215 int gBase = high >> 19; | |
| 216 int bBase = high >> 11; | |
| 217 r1 = convert5To8(rBase); | |
| 218 r2 = convertDiff(rBase, high >> 24); | |
| 219 g1 = convert5To8(gBase); | |
| 220 g2 = convertDiff(gBase, high >> 16); | |
| 221 b1 = convert5To8(bBase); | |
| 222 b2 = convertDiff(bBase, high >> 8); | |
| 223 } else { | |
| 224 // not differential | |
| 225 r1 = convert4To8(high >> 28); | |
| 226 r2 = convert4To8(high >> 24); | |
| 227 g1 = convert4To8(high >> 20); | |
| 228 g2 = convert4To8(high >> 16); | |
| 229 b1 = convert4To8(high >> 12); | |
| 230 b2 = convert4To8(high >> 8); | |
| 231 } | |
| 232 int tableIndexA = 7 & (high >> 5); | |
| 233 int tableIndexB = 7 & (high >> 2); | |
| 234 const int* tableA = kModifierTable + tableIndexA * 4; | |
| 235 const int* tableB = kModifierTable + tableIndexB * 4; | |
| 236 bool flipped = (high & 1) != 0; | |
| 237 decode_subblock(pOut, r1, g1, b1, tableA, low, false, flipped); | |
| 238 decode_subblock(pOut, r2, g2, b2, tableB, low, true, flipped); | |
| 239 } | |
| 240 | |
| 241 typedef struct { | |
| 242 etc1_uint32 high; | |
| 243 etc1_uint32 low; | |
| 244 etc1_uint32 score; // Lower is more accurate | |
| 245 } etc_compressed; | |
| 246 | |
| 247 static | |
| 248 inline void take_best(etc_compressed* a, const etc_compressed* b) { | |
| 249 if (a->score > b->score) { | |
| 250 *a = *b; | |
| 251 } | |
| 252 } | |
| 253 | |
| 254 static | |
| 255 void etc_average_colors_subblock(const etc1_byte* pIn, etc1_uint32 inMask, | |
| 256 etc1_byte* pColors, bool flipped, bool second) { | |
| 257 int r = 0; | |
| 258 int g = 0; | |
| 259 int b = 0; | |
| 260 | |
| 261 if (flipped) { | |
| 262 int by = 0; | |
| 263 if (second) { | |
| 264 by = 2; | |
| 265 } | |
| 266 for (int y = 0; y < 2; y++) { | |
| 267 int yy = by + y; | |
| 268 for (int x = 0; x < 4; x++) { | |
| 269 int i = x + 4 * yy; | |
| 270 if (inMask & (1 << i)) { | |
| 271 const etc1_byte* p = pIn + i * 3; | |
| 272 r += *(p++); | |
| 273 g += *(p++); | |
| 274 b += *(p++); | |
| 275 } | |
| 276 } | |
| 277 } | |
| 278 } else { | |
| 279 int bx = 0; | |
| 280 if (second) { | |
| 281 bx = 2; | |
| 282 } | |
| 283 for (int y = 0; y < 4; y++) { | |
| 284 for (int x = 0; x < 2; x++) { | |
| 285 int xx = bx + x; | |
| 286 int i = xx + 4 * y; | |
| 287 if (inMask & (1 << i)) { | |
| 288 const etc1_byte* p = pIn + i * 3; | |
| 289 r += *(p++); | |
| 290 g += *(p++); | |
| 291 b += *(p++); | |
| 292 } | |
| 293 } | |
| 294 } | |
| 295 } | |
| 296 pColors[0] = (etc1_byte)((r + 4) >> 3); | |
| 297 pColors[1] = (etc1_byte)((g + 4) >> 3); | |
| 298 pColors[2] = (etc1_byte)((b + 4) >> 3); | |
| 299 } | |
| 300 | |
| 301 static | |
| 302 inline int square(int x) { | |
| 303 return x * x; | |
| 304 } | |
| 305 | |
| 306 static etc1_uint32 chooseModifier(const etc1_byte* pBaseColors, | |
| 307 const etc1_byte* pIn, etc1_uint32 *pLow, int bitIndex, | |
| 308 const int* pModifierTable) { | |
| 309 etc1_uint32 bestScore = ~0; | |
| 310 int bestIndex = 0; | |
| 311 int pixelR = pIn[0]; | |
| 312 int pixelG = pIn[1]; | |
| 313 int pixelB = pIn[2]; | |
| 314 int r = pBaseColors[0]; | |
| 315 int g = pBaseColors[1]; | |
| 316 int b = pBaseColors[2]; | |
| 317 for (int i = 0; i < 4; i++) { | |
| 318 int modifier = pModifierTable[i]; | |
| 319 int decodedG = clamp(g + modifier); | |
| 320 etc1_uint32 score = (etc1_uint32) (6 * square(decodedG - pixelG)); | |
| 321 if (score >= bestScore) { | |
| 322 continue; | |
| 323 } | |
| 324 int decodedR = clamp(r + modifier); | |
| 325 score += (etc1_uint32) (3 * square(decodedR - pixelR)); | |
| 326 if (score >= bestScore) { | |
| 327 continue; | |
| 328 } | |
| 329 int decodedB = clamp(b + modifier); | |
| 330 score += (etc1_uint32) square(decodedB - pixelB); | |
| 331 if (score < bestScore) { | |
| 332 bestScore = score; | |
| 333 bestIndex = i; | |
| 334 } | |
| 335 } | |
| 336 etc1_uint32 lowMask = (((bestIndex >> 1) << 16) | (bestIndex & 1)) | |
| 337 << bitIndex; | |
| 338 *pLow |= lowMask; | |
| 339 return bestScore; | |
| 340 } | |
| 341 | |
| 342 static | |
| 343 void etc_encode_subblock_helper(const etc1_byte* pIn, etc1_uint32 inMask, | |
| 344 etc_compressed* pCompressed, bool flipped, bool second, | |
| 345 const etc1_byte* pBaseColors, const int* pModifierTable) { | |
| 346 int score = pCompressed->score; | |
| 347 if (flipped) { | |
| 348 int by = 0; | |
| 349 if (second) { | |
| 350 by = 2; | |
| 351 } | |
| 352 for (int y = 0; y < 2; y++) { | |
| 353 int yy = by + y; | |
| 354 for (int x = 0; x < 4; x++) { | |
| 355 int i = x + 4 * yy; | |
| 356 if (inMask & (1 << i)) { | |
| 357 score += chooseModifier(pBaseColors, pIn + i * 3, | |
| 358 &pCompressed->low, yy + x * 4, pModifierTable); | |
| 359 } | |
| 360 } | |
| 361 } | |
| 362 } else { | |
| 363 int bx = 0; | |
| 364 if (second) { | |
| 365 bx = 2; | |
| 366 } | |
| 367 for (int y = 0; y < 4; y++) { | |
| 368 for (int x = 0; x < 2; x++) { | |
| 369 int xx = bx + x; | |
| 370 int i = xx + 4 * y; | |
| 371 if (inMask & (1 << i)) { | |
| 372 score += chooseModifier(pBaseColors, pIn + i * 3, | |
| 373 &pCompressed->low, y + xx * 4, pModifierTable); | |
| 374 } | |
| 375 } | |
| 376 } | |
| 377 } | |
| 378 pCompressed->score = score; | |
| 379 } | |
| 380 | |
| 381 static bool inRange4bitSigned(int color) { | |
| 382 return color >= -4 && color <= 3; | |
| 383 } | |
| 384 | |
| 385 static void etc_encodeBaseColors(etc1_byte* pBaseColors, | |
| 386 const etc1_byte* pColors, etc_compressed* pCompressed) { | |
| 387 int r1, g1, b1, r2, g2, b2; // 8 bit base colors for sub-blocks | |
| 388 bool differential; | |
| 389 { | |
| 390 int r51 = convert8To5(pColors[0]); | |
| 391 int g51 = convert8To5(pColors[1]); | |
| 392 int b51 = convert8To5(pColors[2]); | |
| 393 int r52 = convert8To5(pColors[3]); | |
| 394 int g52 = convert8To5(pColors[4]); | |
| 395 int b52 = convert8To5(pColors[5]); | |
| 396 | |
| 397 r1 = convert5To8(r51); | |
| 398 g1 = convert5To8(g51); | |
| 399 b1 = convert5To8(b51); | |
| 400 | |
| 401 int dr = r52 - r51; | |
| 402 int dg = g52 - g51; | |
| 403 int db = b52 - b51; | |
| 404 | |
| 405 differential = inRange4bitSigned(dr) && inRange4bitSigned(dg) | |
| 406 && inRange4bitSigned(db); | |
| 407 if (differential) { | |
| 408 r2 = convert5To8(r51 + dr); | |
| 409 g2 = convert5To8(g51 + dg); | |
| 410 b2 = convert5To8(b51 + db); | |
| 411 pCompressed->high |= (r51 << 27) | ((7 & dr) << 24) | (g51 << 19) | |
| 412 | ((7 & dg) << 16) | (b51 << 11) | ((7 & db) << 8) | 2; | |
| 413 } | |
| 414 } | |
| 415 | |
| 416 if (!differential) { | |
| 417 int r41 = convert8To4(pColors[0]); | |
| 418 int g41 = convert8To4(pColors[1]); | |
| 419 int b41 = convert8To4(pColors[2]); | |
| 420 int r42 = convert8To4(pColors[3]); | |
| 421 int g42 = convert8To4(pColors[4]); | |
| 422 int b42 = convert8To4(pColors[5]); | |
| 423 r1 = convert4To8(r41); | |
| 424 g1 = convert4To8(g41); | |
| 425 b1 = convert4To8(b41); | |
| 426 r2 = convert4To8(r42); | |
| 427 g2 = convert4To8(g42); | |
| 428 b2 = convert4To8(b42); | |
| 429 pCompressed->high |= (r41 << 28) | (r42 << 24) | (g41 << 20) | (g42 | |
| 430 << 16) | (b41 << 12) | (b42 << 8); | |
| 431 } | |
| 432 pBaseColors[0] = r1; | |
| 433 pBaseColors[1] = g1; | |
| 434 pBaseColors[2] = b1; | |
| 435 pBaseColors[3] = r2; | |
| 436 pBaseColors[4] = g2; | |
| 437 pBaseColors[5] = b2; | |
| 438 } | |
| 439 | |
| 440 static | |
| 441 void etc_encode_block_helper(const etc1_byte* pIn, etc1_uint32 inMask, | |
| 442 const etc1_byte* pColors, etc_compressed* pCompressed, bool flipped) { | |
| 443 pCompressed->score = ~0; | |
| 444 pCompressed->high = (flipped ? 1 : 0); | |
| 445 pCompressed->low = 0; | |
| 446 | |
| 447 etc1_byte pBaseColors[6]; | |
| 448 | |
| 449 etc_encodeBaseColors(pBaseColors, pColors, pCompressed); | |
| 450 | |
| 451 int originalHigh = pCompressed->high; | |
| 452 | |
| 453 const int* pModifierTable = kModifierTable; | |
| 454 for (int i = 0; i < 8; i++, pModifierTable += 4) { | |
| 455 etc_compressed temp; | |
| 456 temp.score = 0; | |
| 457 temp.high = originalHigh | (i << 5); | |
| 458 temp.low = 0; | |
| 459 etc_encode_subblock_helper(pIn, inMask, &temp, flipped, false, | |
| 460 pBaseColors, pModifierTable); | |
| 461 take_best(pCompressed, &temp); | |
| 462 } | |
| 463 pModifierTable = kModifierTable; | |
| 464 etc_compressed firstHalf = *pCompressed; | |
| 465 for (int i = 0; i < 8; i++, pModifierTable += 4) { | |
| 466 etc_compressed temp; | |
| 467 temp.score = firstHalf.score; | |
| 468 temp.high = firstHalf.high | (i << 2); | |
| 469 temp.low = firstHalf.low; | |
| 470 etc_encode_subblock_helper(pIn, inMask, &temp, flipped, true, | |
| 471 pBaseColors + 3, pModifierTable); | |
| 472 if (i == 0) { | |
| 473 *pCompressed = temp; | |
| 474 } else { | |
| 475 take_best(pCompressed, &temp); | |
| 476 } | |
| 477 } | |
| 478 } | |
| 479 | |
| 480 static void writeBigEndian(etc1_byte* pOut, etc1_uint32 d) { | |
| 481 pOut[0] = (etc1_byte)(d >> 24); | |
| 482 pOut[1] = (etc1_byte)(d >> 16); | |
| 483 pOut[2] = (etc1_byte)(d >> 8); | |
| 484 pOut[3] = (etc1_byte) d; | |
| 485 } | |
| 486 | |
| 487 // Input is a 4 x 4 square of 3-byte pixels in form R, G, B | |
| 488 // inmask is a 16-bit mask where bit (1 << (x + y * 4)) tells whether the corres
ponding (x,y) | |
| 489 // pixel is valid or not. Invalid pixel color values are ignored when compressin
g. | |
| 490 // Output is an ETC1 compressed version of the data. | |
| 491 | |
| 492 void etc1_encode_block(const etc1_byte* pIn, etc1_uint32 inMask, | |
| 493 etc1_byte* pOut) { | |
| 494 etc1_byte colors[6]; | |
| 495 etc1_byte flippedColors[6]; | |
| 496 etc_average_colors_subblock(pIn, inMask, colors, false, false); | |
| 497 etc_average_colors_subblock(pIn, inMask, colors + 3, false, true); | |
| 498 etc_average_colors_subblock(pIn, inMask, flippedColors, true, false); | |
| 499 etc_average_colors_subblock(pIn, inMask, flippedColors + 3, true, true); | |
| 500 | |
| 501 etc_compressed a, b; | |
| 502 etc_encode_block_helper(pIn, inMask, colors, &a, false); | |
| 503 etc_encode_block_helper(pIn, inMask, flippedColors, &b, true); | |
| 504 take_best(&a, &b); | |
| 505 writeBigEndian(pOut, a.high); | |
| 506 writeBigEndian(pOut + 4, a.low); | |
| 507 } | |
| 508 | |
| 509 // Return the size of the encoded image data (does not include size of PKM heade
r). | |
| 510 | |
| 511 etc1_uint32 etc1_get_encoded_data_size(etc1_uint32 width, etc1_uint32 height) { | |
| 512 return (((width + 3) & ~3) * ((height + 3) & ~3)) >> 1; | |
| 513 } | |
| 514 | |
| 515 // Encode an entire image. | |
| 516 // pIn - pointer to the image data. Formatted such that the Red component of | |
| 517 // pixel (x,y) is at pIn + pixelSize * x + stride * y + redOffset; | |
| 518 // pOut - pointer to encoded data. Must be large enough to store entire encoded
image. | |
| 519 | |
| 520 int etc1_encode_image(const etc1_byte* pIn, etc1_uint32 width, etc1_uint32 heigh
t, | |
| 521 etc1_uint32 pixelSize, etc1_uint32 stride, etc1_byte* pOut) { | |
| 522 if (pixelSize < 2 || pixelSize > 3) { | |
| 523 return -1; | |
| 524 } | |
| 525 static const unsigned short kYMask[] = { 0x0, 0xf, 0xff, 0xfff, 0xffff }; | |
| 526 static const unsigned short kXMask[] = { 0x0, 0x1111, 0x3333, 0x7777, | |
| 527 0xffff }; | |
| 528 etc1_byte block[ETC1_DECODED_BLOCK_SIZE]; | |
| 529 etc1_byte encoded[ETC1_ENCODED_BLOCK_SIZE]; | |
| 530 | |
| 531 etc1_uint32 encodedWidth = (width + 3) & ~3; | |
| 532 etc1_uint32 encodedHeight = (height + 3) & ~3; | |
| 533 | |
| 534 for (etc1_uint32 y = 0; y < encodedHeight; y += 4) { | |
| 535 etc1_uint32 yEnd = height - y; | |
| 536 if (yEnd > 4) { | |
| 537 yEnd = 4; | |
| 538 } | |
| 539 int ymask = kYMask[yEnd]; | |
| 540 for (etc1_uint32 x = 0; x < encodedWidth; x += 4) { | |
| 541 etc1_uint32 xEnd = width - x; | |
| 542 if (xEnd > 4) { | |
| 543 xEnd = 4; | |
| 544 } | |
| 545 int mask = ymask & kXMask[xEnd]; | |
| 546 for (etc1_uint32 cy = 0; cy < yEnd; cy++) { | |
| 547 etc1_byte* q = block + (cy * 4) * 3; | |
| 548 const etc1_byte* p = pIn + pixelSize * x + stride * (y + cy); | |
| 549 if (pixelSize == 3) { | |
| 550 memcpy(q, p, xEnd * 3); | |
| 551 } else { | |
| 552 for (etc1_uint32 cx = 0; cx < xEnd; cx++) { | |
| 553 int pixel = (p[1] << 8) | p[0]; | |
| 554 *q++ = convert5To8(pixel >> 11); | |
| 555 *q++ = convert6To8(pixel >> 5); | |
| 556 *q++ = convert5To8(pixel); | |
| 557 p += pixelSize; | |
| 558 } | |
| 559 } | |
| 560 } | |
| 561 etc1_encode_block(block, mask, encoded); | |
| 562 memcpy(pOut, encoded, sizeof(encoded)); | |
| 563 pOut += sizeof(encoded); | |
| 564 } | |
| 565 } | |
| 566 return 0; | |
| 567 } | |
| 568 | |
| 569 // Decode an entire image. | |
| 570 // pIn - pointer to encoded data. | |
| 571 // pOut - pointer to the image data. Will be written such that the Red component
of | |
| 572 // pixel (x,y) is at pIn + pixelSize * x + stride * y + redOffset. Must be | |
| 573 // large enough to store entire image. | |
| 574 | |
| 575 | |
| 576 int etc1_decode_image(const etc1_byte* pIn, etc1_byte* pOut, | |
| 577 etc1_uint32 width, etc1_uint32 height, | |
| 578 etc1_uint32 pixelSize, etc1_uint32 stride) { | |
| 579 if (pixelSize < 2 || pixelSize > 3) { | |
| 580 return -1; | |
| 581 } | |
| 582 etc1_byte block[ETC1_DECODED_BLOCK_SIZE]; | |
| 583 | |
| 584 etc1_uint32 encodedWidth = (width + 3) & ~3; | |
| 585 etc1_uint32 encodedHeight = (height + 3) & ~3; | |
| 586 | |
| 587 for (etc1_uint32 y = 0; y < encodedHeight; y += 4) { | |
| 588 etc1_uint32 yEnd = height - y; | |
| 589 if (yEnd > 4) { | |
| 590 yEnd = 4; | |
| 591 } | |
| 592 for (etc1_uint32 x = 0; x < encodedWidth; x += 4) { | |
| 593 etc1_uint32 xEnd = width - x; | |
| 594 if (xEnd > 4) { | |
| 595 xEnd = 4; | |
| 596 } | |
| 597 etc1_decode_block(pIn, block); | |
| 598 pIn += ETC1_ENCODED_BLOCK_SIZE; | |
| 599 for (etc1_uint32 cy = 0; cy < yEnd; cy++) { | |
| 600 const etc1_byte* q = block + (cy * 4) * 3; | |
| 601 etc1_byte* p = pOut + pixelSize * x + stride * (y + cy); | |
| 602 if (pixelSize == 3) { | |
| 603 memcpy(p, q, xEnd * 3); | |
| 604 } else { | |
| 605 for (etc1_uint32 cx = 0; cx < xEnd; cx++) { | |
| 606 etc1_byte r = *q++; | |
| 607 etc1_byte g = *q++; | |
| 608 etc1_byte b = *q++; | |
| 609 etc1_uint32 pixel = ((r >> 3) << 11) | ((g >> 2) << 5) |
(b >> 3); | |
| 610 *p++ = (etc1_byte) pixel; | |
| 611 *p++ = (etc1_byte) (pixel >> 8); | |
| 612 } | |
| 613 } | |
| 614 } | |
| 615 } | |
| 616 } | |
| 617 return 0; | |
| 618 } | |
| 619 | |
| 620 static const char kMagic[] = { 'P', 'K', 'M', ' ', '1', '0' }; | |
| 621 | |
| 622 static const etc1_uint32 ETC1_PKM_FORMAT_OFFSET = 6; | |
| 623 static const etc1_uint32 ETC1_PKM_ENCODED_WIDTH_OFFSET = 8; | |
| 624 static const etc1_uint32 ETC1_PKM_ENCODED_HEIGHT_OFFSET = 10; | |
| 625 static const etc1_uint32 ETC1_PKM_WIDTH_OFFSET = 12; | |
| 626 static const etc1_uint32 ETC1_PKM_HEIGHT_OFFSET = 14; | |
| 627 | |
| 628 static const etc1_uint32 ETC1_RGB_NO_MIPMAPS = 0; | |
| 629 | |
| 630 static void writeBEUint16(etc1_byte* pOut, etc1_uint32 data) { | |
| 631 pOut[0] = (etc1_byte) (data >> 8); | |
| 632 pOut[1] = (etc1_byte) data; | |
| 633 } | |
| 634 | |
| 635 static etc1_uint32 readBEUint16(const etc1_byte* pIn) { | |
| 636 return (pIn[0] << 8) | pIn[1]; | |
| 637 } | |
| 638 | |
| 639 // Format a PKM header | |
| 640 | |
| 641 void etc1_pkm_format_header(etc1_byte* pHeader, etc1_uint32 width, etc1_uint32 h
eight) { | |
| 642 memcpy(pHeader, kMagic, sizeof(kMagic)); | |
| 643 etc1_uint32 encodedWidth = (width + 3) & ~3; | |
| 644 etc1_uint32 encodedHeight = (height + 3) & ~3; | |
| 645 writeBEUint16(pHeader + ETC1_PKM_FORMAT_OFFSET, ETC1_RGB_NO_MIPMAPS); | |
| 646 writeBEUint16(pHeader + ETC1_PKM_ENCODED_WIDTH_OFFSET, encodedWidth); | |
| 647 writeBEUint16(pHeader + ETC1_PKM_ENCODED_HEIGHT_OFFSET, encodedHeight); | |
| 648 writeBEUint16(pHeader + ETC1_PKM_WIDTH_OFFSET, width); | |
| 649 writeBEUint16(pHeader + ETC1_PKM_HEIGHT_OFFSET, height); | |
| 650 } | |
| 651 | |
| 652 // Check if a PKM header is correctly formatted. | |
| 653 | |
| 654 etc1_bool etc1_pkm_is_valid(const etc1_byte* pHeader) { | |
| 655 if (memcmp(pHeader, kMagic, sizeof(kMagic))) { | |
| 656 return false; | |
| 657 } | |
| 658 etc1_uint32 format = readBEUint16(pHeader + ETC1_PKM_FORMAT_OFFSET); | |
| 659 etc1_uint32 encodedWidth = readBEUint16(pHeader + ETC1_PKM_ENCODED_WIDTH_OFF
SET); | |
| 660 etc1_uint32 encodedHeight = readBEUint16(pHeader + ETC1_PKM_ENCODED_HEIGHT_O
FFSET); | |
| 661 etc1_uint32 width = readBEUint16(pHeader + ETC1_PKM_WIDTH_OFFSET); | |
| 662 etc1_uint32 height = readBEUint16(pHeader + ETC1_PKM_HEIGHT_OFFSET); | |
| 663 return format == ETC1_RGB_NO_MIPMAPS && | |
| 664 encodedWidth >= width && encodedWidth - width < 4 && | |
| 665 encodedHeight >= height && encodedHeight - height < 4; | |
| 666 } | |
| 667 | |
| 668 // Read the image width from a PKM header | |
| 669 | |
| 670 etc1_uint32 etc1_pkm_get_width(const etc1_byte* pHeader) { | |
| 671 return readBEUint16(pHeader + ETC1_PKM_WIDTH_OFFSET); | |
| 672 } | |
| 673 | |
| 674 // Read the image height from a PKM header | |
| 675 | |
| 676 etc1_uint32 etc1_pkm_get_height(const etc1_byte* pHeader){ | |
| 677 return readBEUint16(pHeader + ETC1_PKM_HEIGHT_OFFSET); | |
| 678 } | |
| OLD | NEW |
|---|
Chromium Code Reviews
Issue 1296253003:
Depend on ETC1 via DEPS instead of a direct third_party checkin. (Closed)
Base URL: https://skia.googlesource.com/skia.git@master