reed@android.com | 8a1c16f | 2008-12-17 15:59:43 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright (C) 2006 The Android Open Source Project |
| 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | * |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | |
| 17 | #ifndef SkColorPriv_DEFINED |
| 18 | #define SkColorPriv_DEFINED |
| 19 | |
| 20 | // turn this own for extra debug checking when blending onto 565 |
| 21 | #ifdef SK_DEBUG |
| 22 | #define CHECK_FOR_565_OVERFLOW |
| 23 | #endif |
| 24 | |
| 25 | #include "SkColor.h" |
| 26 | #include "SkMath.h" |
| 27 | |
| 28 | /** Turn 0..255 into 0..256 by adding 1 at the half-way point. Used to turn a |
| 29 | byte into a scale value, so that we can say scale * value >> 8 instead of |
| 30 | alpha * value / 255. |
| 31 | |
| 32 | In debugging, asserts that alpha is 0..255 |
| 33 | */ |
| 34 | static inline unsigned SkAlpha255To256(U8CPU alpha) { |
| 35 | SkASSERT(SkToU8(alpha) == alpha); |
| 36 | return alpha + (alpha >> 7); |
| 37 | } |
| 38 | |
| 39 | /** Multiplify value by 0..256, and shift the result down 8 |
| 40 | (i.e. return (value * alpha256) >> 8) |
| 41 | */ |
| 42 | #define SkAlphaMul(value, alpha256) (SkMulS16(value, alpha256) >> 8) |
| 43 | |
| 44 | // The caller may want negative values, so keep all params signed (int) |
| 45 | // so we don't accidentally slip into unsigned math and lose the sign |
| 46 | // extension when we shift (in SkAlphaMul) |
| 47 | inline int SkAlphaBlend(int src, int dst, int scale256) { |
| 48 | SkASSERT((unsigned)scale256 <= 256); |
| 49 | return dst + SkAlphaMul(src - dst, scale256); |
| 50 | } |
| 51 | |
| 52 | #define SK_R16_BITS 5 |
| 53 | #define SK_G16_BITS 6 |
| 54 | #define SK_B16_BITS 5 |
| 55 | |
| 56 | #define SK_R16_SHIFT (SK_B16_BITS + SK_G16_BITS) |
| 57 | #define SK_G16_SHIFT (SK_B16_BITS) |
| 58 | #define SK_B16_SHIFT 0 |
| 59 | |
| 60 | #define SK_R16_MASK ((1 << SK_R16_BITS) - 1) |
| 61 | #define SK_G16_MASK ((1 << SK_G16_BITS) - 1) |
| 62 | #define SK_B16_MASK ((1 << SK_B16_BITS) - 1) |
| 63 | |
| 64 | #define SkGetPackedR16(color) (((unsigned)(color) >> SK_R16_SHIFT) & SK_R16_MASK) |
| 65 | #define SkGetPackedG16(color) (((unsigned)(color) >> SK_G16_SHIFT) & SK_G16_MASK) |
| 66 | #define SkGetPackedB16(color) (((unsigned)(color) >> SK_B16_SHIFT) & SK_B16_MASK) |
| 67 | |
| 68 | #define SkR16Assert(r) SkASSERT((unsigned)(r) <= SK_R16_MASK) |
| 69 | #define SkG16Assert(g) SkASSERT((unsigned)(g) <= SK_G16_MASK) |
| 70 | #define SkB16Assert(b) SkASSERT((unsigned)(b) <= SK_B16_MASK) |
| 71 | |
| 72 | static inline uint16_t SkPackRGB16(unsigned r, unsigned g, unsigned b) { |
| 73 | SkASSERT(r <= SK_R16_MASK); |
| 74 | SkASSERT(g <= SK_G16_MASK); |
| 75 | SkASSERT(b <= SK_B16_MASK); |
| 76 | |
| 77 | return SkToU16((r << SK_R16_SHIFT) | (g << SK_G16_SHIFT) | (b << SK_B16_SHIFT)); |
| 78 | } |
| 79 | |
| 80 | #define SK_R16_MASK_IN_PLACE (SK_R16_MASK << SK_R16_SHIFT) |
| 81 | #define SK_G16_MASK_IN_PLACE (SK_G16_MASK << SK_G16_SHIFT) |
| 82 | #define SK_B16_MASK_IN_PLACE (SK_B16_MASK << SK_B16_SHIFT) |
| 83 | |
| 84 | /** Expand the 16bit color into a 32bit value that can be scaled all at once |
| 85 | by a value up to 32. Used in conjunction with SkCompact_rgb_16. |
| 86 | */ |
| 87 | static inline uint32_t SkExpand_rgb_16(U16CPU c) { |
| 88 | SkASSERT(c == (uint16_t)c); |
| 89 | |
| 90 | return ((c & SK_G16_MASK_IN_PLACE) << 16) | (c & ~SK_G16_MASK_IN_PLACE); |
| 91 | } |
| 92 | |
| 93 | /** Compress an expanded value (from SkExpand_rgb_16) back down to a 16bit |
| 94 | color value. The computation yields only 16bits of valid data, but we claim |
| 95 | to return 32bits, so that the compiler won't generate extra instructions to |
| 96 | "clean" the top 16bits. However, the top 16 can contain garbage, so it is |
| 97 | up to the caller to safely ignore them. |
| 98 | */ |
| 99 | static inline U16CPU SkCompact_rgb_16(uint32_t c) { |
| 100 | return ((c >> 16) & SK_G16_MASK_IN_PLACE) | (c & ~SK_G16_MASK_IN_PLACE); |
| 101 | } |
| 102 | |
| 103 | /** Scale the 16bit color value by the 0..256 scale parameter. |
| 104 | The computation yields only 16bits of valid data, but we claim |
| 105 | to return 32bits, so that the compiler won't generate extra instructions to |
| 106 | "clean" the top 16bits. |
| 107 | */ |
| 108 | static inline U16CPU SkAlphaMulRGB16(U16CPU c, unsigned scale) { |
| 109 | return SkCompact_rgb_16(SkExpand_rgb_16(c) * (scale >> 3) >> 5); |
| 110 | } |
| 111 | |
| 112 | // this helper explicitly returns a clean 16bit value (but slower) |
| 113 | #define SkAlphaMulRGB16_ToU16(c, s) (uint16_t)SkAlphaMulRGB16(c, s) |
| 114 | |
| 115 | /** Blend src and dst 16bit colors by the 0..256 scale parameter. |
| 116 | The computation yields only 16bits of valid data, but we claim |
| 117 | to return 32bits, so that the compiler won't generate extra instructions to |
| 118 | "clean" the top 16bits. |
| 119 | */ |
| 120 | static inline U16CPU SkBlendRGB16(U16CPU src, U16CPU dst, int srcScale) { |
| 121 | SkASSERT((unsigned)srcScale <= 256); |
| 122 | |
| 123 | srcScale >>= 3; |
| 124 | |
| 125 | uint32_t src32 = SkExpand_rgb_16(src); |
| 126 | uint32_t dst32 = SkExpand_rgb_16(dst); |
| 127 | return SkCompact_rgb_16(dst32 + ((src32 - dst32) * srcScale >> 5)); |
| 128 | } |
| 129 | |
| 130 | static inline void SkBlendRGB16(const uint16_t src[], uint16_t dst[], |
| 131 | int srcScale, int count) { |
| 132 | SkASSERT(count > 0); |
| 133 | SkASSERT((unsigned)srcScale <= 256); |
| 134 | |
| 135 | srcScale >>= 3; |
| 136 | |
| 137 | do { |
| 138 | uint32_t src32 = SkExpand_rgb_16(*src++); |
| 139 | uint32_t dst32 = SkExpand_rgb_16(*dst); |
| 140 | *dst++ = SkCompact_rgb_16(dst32 + ((src32 - dst32) * srcScale >> 5)); |
| 141 | } while (--count > 0); |
| 142 | } |
| 143 | |
| 144 | #ifdef SK_DEBUG |
| 145 | static U16CPU SkRGB16Add(U16CPU a, U16CPU b) { |
| 146 | SkASSERT(SkGetPackedR16(a) + SkGetPackedR16(b) <= SK_R16_MASK); |
| 147 | SkASSERT(SkGetPackedG16(a) + SkGetPackedG16(b) <= SK_G16_MASK); |
| 148 | SkASSERT(SkGetPackedB16(a) + SkGetPackedB16(b) <= SK_B16_MASK); |
| 149 | |
| 150 | return a + b; |
| 151 | } |
| 152 | #else |
| 153 | #define SkRGB16Add(a, b) ((a) + (b)) |
| 154 | #endif |
| 155 | |
| 156 | ///////////////////////////////////////////////////////////////////////////////////////////// |
| 157 | |
| 158 | #define SK_A32_BITS 8 |
| 159 | #define SK_R32_BITS 8 |
| 160 | #define SK_G32_BITS 8 |
| 161 | #define SK_B32_BITS 8 |
| 162 | |
| 163 | /* we check to see if the SHIFT value has already been defined (SkUserConfig.h) |
| 164 | if not, we define it ourself to some default values. We default to OpenGL |
| 165 | order (in memory: r,g,b,a) |
| 166 | */ |
| 167 | #ifndef SK_A32_SHIFT |
| 168 | #ifdef SK_CPU_BENDIAN |
| 169 | #define SK_R32_SHIFT 24 |
| 170 | #define SK_G32_SHIFT 16 |
| 171 | #define SK_B32_SHIFT 8 |
| 172 | #define SK_A32_SHIFT 0 |
| 173 | #else |
| 174 | #define SK_R32_SHIFT 0 |
| 175 | #define SK_G32_SHIFT 8 |
| 176 | #define SK_B32_SHIFT 16 |
| 177 | #define SK_A32_SHIFT 24 |
| 178 | #endif |
| 179 | #endif |
| 180 | |
| 181 | #define SK_A32_MASK ((1 << SK_A32_BITS) - 1) |
| 182 | #define SK_R32_MASK ((1 << SK_R32_BITS) - 1) |
| 183 | #define SK_G32_MASK ((1 << SK_G32_BITS) - 1) |
| 184 | #define SK_B32_MASK ((1 << SK_B32_BITS) - 1) |
| 185 | |
| 186 | #define SkGetPackedA32(packed) ((uint32_t)((packed) << (24 - SK_A32_SHIFT)) >> 24) |
| 187 | #define SkGetPackedR32(packed) ((uint32_t)((packed) << (24 - SK_R32_SHIFT)) >> 24) |
| 188 | #define SkGetPackedG32(packed) ((uint32_t)((packed) << (24 - SK_G32_SHIFT)) >> 24) |
| 189 | #define SkGetPackedB32(packed) ((uint32_t)((packed) << (24 - SK_B32_SHIFT)) >> 24) |
| 190 | |
| 191 | #define SkA32Assert(a) SkASSERT((unsigned)(a) <= SK_A32_MASK) |
| 192 | #define SkR32Assert(r) SkASSERT((unsigned)(r) <= SK_R32_MASK) |
| 193 | #define SkG32Assert(g) SkASSERT((unsigned)(g) <= SK_G32_MASK) |
| 194 | #define SkB32Assert(b) SkASSERT((unsigned)(b) <= SK_B32_MASK) |
| 195 | |
| 196 | #ifdef SK_DEBUG |
| 197 | inline void SkPMColorAssert(SkPMColor c) { |
| 198 | unsigned a = SkGetPackedA32(c); |
| 199 | unsigned r = SkGetPackedR32(c); |
| 200 | unsigned g = SkGetPackedG32(c); |
| 201 | unsigned b = SkGetPackedB32(c); |
| 202 | |
| 203 | SkA32Assert(a); |
| 204 | SkASSERT(r <= a); |
| 205 | SkASSERT(g <= a); |
| 206 | SkASSERT(b <= a); |
| 207 | } |
| 208 | #else |
| 209 | #define SkPMColorAssert(c) |
| 210 | #endif |
| 211 | |
| 212 | inline SkPMColor SkPackARGB32(U8CPU a, U8CPU r, U8CPU g, U8CPU b) { |
| 213 | SkA32Assert(a); |
| 214 | SkASSERT(r <= a); |
| 215 | SkASSERT(g <= a); |
| 216 | SkASSERT(b <= a); |
| 217 | |
| 218 | return (a << SK_A32_SHIFT) | (r << SK_R32_SHIFT) | |
| 219 | (g << SK_G32_SHIFT) | (b << SK_B32_SHIFT); |
| 220 | } |
| 221 | |
| 222 | extern const uint32_t gMask_00FF00FF; |
| 223 | |
| 224 | inline uint32_t SkAlphaMulQ(uint32_t c, unsigned scale) { |
| 225 | uint32_t mask = gMask_00FF00FF; |
| 226 | // uint32_t mask = 0xFF00FF; |
| 227 | |
| 228 | uint32_t rb = ((c & mask) * scale) >> 8; |
| 229 | uint32_t ag = ((c >> 8) & mask) * scale; |
| 230 | return (rb & mask) | (ag & ~mask); |
| 231 | } |
| 232 | |
| 233 | inline SkPMColor SkPMSrcOver(SkPMColor src, SkPMColor dst) { |
| 234 | return src + SkAlphaMulQ(dst, SkAlpha255To256(255 - SkGetPackedA32(src))); |
| 235 | } |
| 236 | |
| 237 | inline SkPMColor SkBlendARGB32(SkPMColor src, SkPMColor dst, U8CPU aa) { |
| 238 | SkASSERT((unsigned)aa <= 255); |
| 239 | |
| 240 | unsigned src_scale = SkAlpha255To256(aa); |
| 241 | unsigned dst_scale = SkAlpha255To256(255 - SkAlphaMul(SkGetPackedA32(src), src_scale)); |
| 242 | |
| 243 | return SkAlphaMulQ(src, src_scale) + SkAlphaMulQ(dst, dst_scale); |
| 244 | } |
| 245 | |
| 246 | //////////////////////////////////////////////////////////////////////////////////////////// |
| 247 | // Convert a 32bit pixel to a 16bit pixel (no dither) |
| 248 | |
| 249 | #define SkR32ToR16_MACRO(r) ((unsigned)(r) >> (SK_R32_BITS - SK_R16_BITS)) |
| 250 | #define SkG32ToG16_MACRO(g) ((unsigned)(g) >> (SK_G32_BITS - SK_G16_BITS)) |
| 251 | #define SkB32ToB16_MACRO(b) ((unsigned)(b) >> (SK_B32_BITS - SK_B16_BITS)) |
| 252 | |
| 253 | #ifdef SK_DEBUG |
| 254 | inline unsigned SkR32ToR16(unsigned r) |
| 255 | { |
| 256 | SkR32Assert(r); |
| 257 | return SkR32ToR16_MACRO(r); |
| 258 | } |
| 259 | inline unsigned SkG32ToG16(unsigned g) |
| 260 | { |
| 261 | SkG32Assert(g); |
| 262 | return SkG32ToG16_MACRO(g); |
| 263 | } |
| 264 | inline unsigned SkB32ToB16(unsigned b) |
| 265 | { |
| 266 | SkB32Assert(b); |
| 267 | return SkB32ToB16_MACRO(b); |
| 268 | } |
| 269 | #else |
| 270 | #define SkR32ToR16(r) SkR32ToR16_MACRO(r) |
| 271 | #define SkG32ToG16(g) SkG32ToG16_MACRO(g) |
| 272 | #define SkB32ToB16(b) SkB32ToB16_MACRO(b) |
| 273 | #endif |
| 274 | |
| 275 | #define SkPacked32ToR16(c) (((unsigned)(c) >> (SK_R32_SHIFT + SK_R32_BITS - SK_R16_BITS)) & SK_R16_MASK) |
| 276 | #define SkPacked32ToG16(c) (((unsigned)(c) >> (SK_G32_SHIFT + SK_G32_BITS - SK_G16_BITS)) & SK_G16_MASK) |
| 277 | #define SkPacked32ToB16(c) (((unsigned)(c) >> (SK_B32_SHIFT + SK_B32_BITS - SK_B16_BITS)) & SK_B16_MASK) |
| 278 | |
| 279 | inline U16CPU SkPixel32ToPixel16(SkPMColor c) |
| 280 | { |
| 281 | unsigned r = ((c >> (SK_R32_SHIFT + (8 - SK_R16_BITS))) & SK_R16_MASK) << SK_R16_SHIFT; |
| 282 | unsigned g = ((c >> (SK_G32_SHIFT + (8 - SK_G16_BITS))) & SK_G16_MASK) << SK_G16_SHIFT; |
| 283 | unsigned b = ((c >> (SK_B32_SHIFT + (8 - SK_B16_BITS))) & SK_B16_MASK) << SK_B16_SHIFT; |
| 284 | return r | g | b; |
| 285 | } |
| 286 | |
| 287 | inline U16CPU SkPack888ToRGB16(U8CPU r, U8CPU g, U8CPU b) |
| 288 | { |
| 289 | return (SkR32ToR16(r) << SK_R16_SHIFT) | |
| 290 | (SkG32ToG16(g) << SK_G16_SHIFT) | |
| 291 | (SkB32ToB16(b) << SK_B16_SHIFT); |
| 292 | } |
| 293 | |
| 294 | #define SkPixel32ToPixel16_ToU16(src) SkToU16(SkPixel32ToPixel16(src)) |
| 295 | |
| 296 | ///////////////////////////////////////////////////////////////////////////////////////// |
| 297 | // Fast dither from 32->16 |
| 298 | |
| 299 | #define SkShouldDitherXY(x, y) (((x) ^ (y)) & 1) |
| 300 | |
| 301 | inline uint16_t SkDitherPack888ToRGB16(U8CPU r, U8CPU g, U8CPU b) |
| 302 | { |
| 303 | r = ((r << 1) - ((r >> (8 - SK_R16_BITS) << (8 - SK_R16_BITS)) | (r >> SK_R16_BITS))) >> (8 - SK_R16_BITS); |
| 304 | g = ((g << 1) - ((g >> (8 - SK_G16_BITS) << (8 - SK_G16_BITS)) | (g >> SK_G16_BITS))) >> (8 - SK_G16_BITS); |
| 305 | b = ((b << 1) - ((b >> (8 - SK_B16_BITS) << (8 - SK_B16_BITS)) | (b >> SK_B16_BITS))) >> (8 - SK_B16_BITS); |
| 306 | |
| 307 | return SkPackRGB16(r, g, b); |
| 308 | } |
| 309 | |
| 310 | inline uint16_t SkDitherPixel32ToPixel16(SkPMColor c) |
| 311 | { |
| 312 | return SkDitherPack888ToRGB16(SkGetPackedR32(c), SkGetPackedG32(c), SkGetPackedB32(c)); |
| 313 | } |
| 314 | |
| 315 | /* Return c in expanded_rgb_16 format, but also scaled up by 32 (5 bits) |
| 316 | It is now suitable for combining with a scaled expanded_rgb_16 color |
| 317 | as in SkSrcOver32To16(). |
| 318 | We must do this 565 high-bit replication, in order for the subsequent add |
| 319 | to saturate properly (and not overflow). If we take the 8 bits as is, it is |
| 320 | possible to overflow. |
| 321 | */ |
| 322 | static inline uint32_t SkPMColorToExpanded16x5(SkPMColor c) |
| 323 | { |
| 324 | unsigned sr = SkPacked32ToR16(c); |
| 325 | unsigned sg = SkPacked32ToG16(c); |
| 326 | unsigned sb = SkPacked32ToB16(c); |
| 327 | |
| 328 | sr = (sr << 5) | sr; |
| 329 | sg = (sg << 5) | (sg >> 1); |
| 330 | sb = (sb << 5) | sb; |
| 331 | return (sr << 11) | (sg << 21) | (sb << 0); |
| 332 | } |
| 333 | |
| 334 | /* SrcOver the 32bit src color with the 16bit dst, returning a 16bit value |
| 335 | (with dirt in the high 16bits, so caller beware). |
| 336 | */ |
| 337 | static inline U16CPU SkSrcOver32To16(SkPMColor src, uint16_t dst) { |
| 338 | unsigned sr = SkGetPackedR32(src); |
| 339 | unsigned sg = SkGetPackedG32(src); |
| 340 | unsigned sb = SkGetPackedB32(src); |
| 341 | |
| 342 | unsigned dr = SkGetPackedR16(dst); |
| 343 | unsigned dg = SkGetPackedG16(dst); |
| 344 | unsigned db = SkGetPackedB16(dst); |
| 345 | |
| 346 | unsigned isa = 255 - SkGetPackedA32(src); |
| 347 | |
| 348 | dr = (sr + SkMul16ShiftRound(dr, isa, SK_R16_BITS)) >> (8 - SK_R16_BITS); |
| 349 | dg = (sg + SkMul16ShiftRound(dg, isa, SK_G16_BITS)) >> (8 - SK_G16_BITS); |
| 350 | db = (sb + SkMul16ShiftRound(db, isa, SK_B16_BITS)) >> (8 - SK_B16_BITS); |
| 351 | |
| 352 | return SkPackRGB16(dr, dg, db); |
| 353 | } |
| 354 | |
| 355 | //////////////////////////////////////////////////////////////////////////////////////////// |
| 356 | // Convert a 16bit pixel to a 32bit pixel |
| 357 | |
| 358 | inline unsigned SkR16ToR32(unsigned r) |
| 359 | { |
| 360 | return (r << (8 - SK_R16_BITS)) | (r >> (2 * SK_R16_BITS - 8)); |
| 361 | } |
| 362 | inline unsigned SkG16ToG32(unsigned g) |
| 363 | { |
| 364 | return (g << (8 - SK_G16_BITS)) | (g >> (2 * SK_G16_BITS - 8)); |
| 365 | } |
| 366 | inline unsigned SkB16ToB32(unsigned b) |
| 367 | { |
| 368 | return (b << (8 - SK_B16_BITS)) | (b >> (2 * SK_B16_BITS - 8)); |
| 369 | } |
| 370 | |
| 371 | #define SkPacked16ToR32(c) SkR16ToR32(SkGetPackedR16(c)) |
| 372 | #define SkPacked16ToG32(c) SkG16ToG32(SkGetPackedG16(c)) |
| 373 | #define SkPacked16ToB32(c) SkB16ToB32(SkGetPackedB16(c)) |
| 374 | |
| 375 | inline SkPMColor SkPixel16ToPixel32(U16CPU src) |
| 376 | { |
| 377 | SkASSERT(src == SkToU16(src)); |
| 378 | |
| 379 | unsigned r = SkPacked16ToR32(src); |
| 380 | unsigned g = SkPacked16ToG32(src); |
| 381 | unsigned b = SkPacked16ToB32(src); |
| 382 | |
| 383 | SkASSERT((r >> (8 - SK_R16_BITS)) == SkGetPackedR16(src)); |
| 384 | SkASSERT((g >> (8 - SK_G16_BITS)) == SkGetPackedG16(src)); |
| 385 | SkASSERT((b >> (8 - SK_B16_BITS)) == SkGetPackedB16(src)); |
| 386 | |
| 387 | return SkPackARGB32(0xFF, r, g, b); |
| 388 | } |
| 389 | |
| 390 | /////////////////////////////////////////////////////////////////////////////// |
| 391 | |
| 392 | typedef uint16_t SkPMColor16; |
| 393 | |
| 394 | // Put in OpenGL order (r g b a) |
| 395 | #define SK_A4444_SHIFT 0 |
| 396 | #define SK_R4444_SHIFT 12 |
| 397 | #define SK_G4444_SHIFT 8 |
| 398 | #define SK_B4444_SHIFT 4 |
| 399 | |
| 400 | #define SkA32To4444(a) ((unsigned)(a) >> 4) |
| 401 | #define SkR32To4444(r) ((unsigned)(r) >> 4) |
| 402 | #define SkG32To4444(g) ((unsigned)(g) >> 4) |
| 403 | #define SkB32To4444(b) ((unsigned)(b) >> 4) |
| 404 | |
| 405 | static U8CPU SkReplicateNibble(unsigned nib) |
| 406 | { |
| 407 | SkASSERT(nib <= 0xF); |
| 408 | return (nib << 4) | nib; |
| 409 | } |
| 410 | |
| 411 | #define SkA4444ToA32(a) SkReplicateNibble(a) |
| 412 | #define SkR4444ToR32(r) SkReplicateNibble(r) |
| 413 | #define SkG4444ToG32(g) SkReplicateNibble(g) |
| 414 | #define SkB4444ToB32(b) SkReplicateNibble(b) |
| 415 | |
| 416 | #define SkGetPackedA4444(c) (((unsigned)(c) >> SK_A4444_SHIFT) & 0xF) |
| 417 | #define SkGetPackedR4444(c) (((unsigned)(c) >> SK_R4444_SHIFT) & 0xF) |
| 418 | #define SkGetPackedG4444(c) (((unsigned)(c) >> SK_G4444_SHIFT) & 0xF) |
| 419 | #define SkGetPackedB4444(c) (((unsigned)(c) >> SK_B4444_SHIFT) & 0xF) |
| 420 | |
| 421 | #define SkPacked4444ToA32(c) SkReplicateNibble(SkGetPackedA4444(c)) |
| 422 | #define SkPacked4444ToR32(c) SkReplicateNibble(SkGetPackedR4444(c)) |
| 423 | #define SkPacked4444ToG32(c) SkReplicateNibble(SkGetPackedG4444(c)) |
| 424 | #define SkPacked4444ToB32(c) SkReplicateNibble(SkGetPackedB4444(c)) |
| 425 | |
| 426 | #ifdef SK_DEBUG |
| 427 | static inline void SkPMColor16Assert(U16CPU c) |
| 428 | { |
| 429 | unsigned a = SkGetPackedA4444(c); |
| 430 | unsigned r = SkGetPackedR4444(c); |
| 431 | unsigned g = SkGetPackedG4444(c); |
| 432 | unsigned b = SkGetPackedB4444(c); |
| 433 | |
| 434 | SkASSERT(a <= 0xF); |
| 435 | SkASSERT(r <= a); |
| 436 | SkASSERT(g <= a); |
| 437 | SkASSERT(b <= a); |
| 438 | } |
| 439 | #else |
| 440 | #define SkPMColor16Assert(c) |
| 441 | #endif |
| 442 | |
| 443 | static inline unsigned SkAlpha15To16(unsigned a) |
| 444 | { |
| 445 | SkASSERT(a <= 0xF); |
| 446 | return a + (a >> 3); |
| 447 | } |
| 448 | |
| 449 | #ifdef SK_DEBUG |
| 450 | static inline int SkAlphaMul4(int value, int scale) |
| 451 | { |
| 452 | SkASSERT((unsigned)scale <= 0x10); |
| 453 | return value * scale >> 4; |
| 454 | } |
| 455 | #else |
| 456 | #define SkAlphaMul4(value, scale) ((value) * (scale) >> 4) |
| 457 | #endif |
| 458 | |
| 459 | static inline unsigned SkR4444ToR565(unsigned r) |
| 460 | { |
| 461 | SkASSERT(r <= 0xF); |
| 462 | return (r << (SK_R16_BITS - 4)) | (r >> (8 - SK_R16_BITS)); |
| 463 | } |
| 464 | |
| 465 | static inline unsigned SkG4444ToG565(unsigned g) |
| 466 | { |
| 467 | SkASSERT(g <= 0xF); |
| 468 | return (g << (SK_G16_BITS - 4)) | (g >> (8 - SK_G16_BITS)); |
| 469 | } |
| 470 | |
| 471 | static inline unsigned SkB4444ToB565(unsigned b) |
| 472 | { |
| 473 | SkASSERT(b <= 0xF); |
| 474 | return (b << (SK_B16_BITS - 4)) | (b >> (8 - SK_B16_BITS)); |
| 475 | } |
| 476 | |
| 477 | static inline SkPMColor16 SkPackARGB4444(unsigned a, unsigned r, |
| 478 | unsigned g, unsigned b) |
| 479 | { |
| 480 | SkASSERT(a <= 0xF); |
| 481 | SkASSERT(r <= a); |
| 482 | SkASSERT(g <= a); |
| 483 | SkASSERT(b <= a); |
| 484 | |
| 485 | return (SkPMColor16)((a << SK_A4444_SHIFT) | (r << SK_R4444_SHIFT) | |
| 486 | (g << SK_G4444_SHIFT) | (b << SK_B4444_SHIFT)); |
| 487 | } |
| 488 | |
| 489 | extern const uint16_t gMask_0F0F; |
| 490 | |
| 491 | inline U16CPU SkAlphaMulQ4(U16CPU c, unsigned scale) |
| 492 | { |
| 493 | SkASSERT(scale <= 16); |
| 494 | |
| 495 | const unsigned mask = 0xF0F; //gMask_0F0F; |
| 496 | |
| 497 | #if 0 |
| 498 | unsigned rb = ((c & mask) * scale) >> 4; |
| 499 | unsigned ag = ((c >> 4) & mask) * scale; |
| 500 | return (rb & mask) | (ag & ~mask); |
| 501 | #else |
| 502 | c = (c & mask) | ((c & (mask << 4)) << 12); |
| 503 | c = c * scale >> 4; |
| 504 | return (c & mask) | ((c >> 12) & (mask << 4)); |
| 505 | #endif |
| 506 | } |
| 507 | |
| 508 | /** Expand the SkPMColor16 color into a 32bit value that can be scaled all at |
| 509 | once by a value up to 16. Used in conjunction with SkCompact_4444. |
| 510 | */ |
| 511 | inline uint32_t SkExpand_4444(U16CPU c) |
| 512 | { |
| 513 | SkASSERT(c == (uint16_t)c); |
| 514 | |
| 515 | const unsigned mask = 0xF0F; //gMask_0F0F; |
| 516 | return (c & mask) | ((c & ~mask) << 12); |
| 517 | } |
| 518 | |
| 519 | /** Compress an expanded value (from SkExpand_4444) back down to a SkPMColor16. |
| 520 | NOTE: this explicitly does not clean the top 16 bits (which may be garbage). |
| 521 | It does this for speed, since if it is being written directly to 16bits of |
| 522 | memory, the top 16bits will be ignored. Casting the result to uint16_t here |
| 523 | would add 2 more instructions, slow us down. It is up to the caller to |
| 524 | perform the cast if needed. |
| 525 | */ |
| 526 | static inline U16CPU SkCompact_4444(uint32_t c) |
| 527 | { |
| 528 | const unsigned mask = 0xF0F; //gMask_0F0F; |
| 529 | return (c & mask) | ((c >> 12) & ~mask); |
| 530 | } |
| 531 | |
| 532 | static inline uint16_t SkSrcOver4444To16(SkPMColor16 s, uint16_t d) |
| 533 | { |
| 534 | unsigned sa = SkGetPackedA4444(s); |
| 535 | unsigned sr = SkR4444ToR565(SkGetPackedR4444(s)); |
| 536 | unsigned sg = SkG4444ToG565(SkGetPackedG4444(s)); |
| 537 | unsigned sb = SkB4444ToB565(SkGetPackedB4444(s)); |
| 538 | |
| 539 | // To avoid overflow, we have to clear the low bit of the synthetic sg |
| 540 | // if the src alpha is <= 7. |
| 541 | // to see why, try blending 0x4444 on top of 565-white and watch green |
| 542 | // overflow (sum == 64) |
| 543 | sg &= ~(~(sa >> 3) & 1); |
| 544 | |
| 545 | unsigned scale = SkAlpha15To16(15 - sa); |
| 546 | unsigned dr = SkAlphaMul4(SkGetPackedR16(d), scale); |
| 547 | unsigned dg = SkAlphaMul4(SkGetPackedG16(d), scale); |
| 548 | unsigned db = SkAlphaMul4(SkGetPackedB16(d), scale); |
| 549 | |
| 550 | #if 0 |
| 551 | if (sg + dg > 63) { |
| 552 | SkDebugf("---- SkSrcOver4444To16 src=%x dst=%x scale=%d, sg=%d dg=%d\n", s, d, scale, sg, dg); |
| 553 | } |
| 554 | #endif |
| 555 | return SkPackRGB16(sr + dr, sg + dg, sb + db); |
| 556 | } |
| 557 | |
| 558 | static inline uint16_t SkBlend4444To16(SkPMColor16 src, uint16_t dst, int scale16) |
| 559 | { |
| 560 | SkASSERT((unsigned)scale16 <= 16); |
| 561 | |
| 562 | return SkSrcOver4444To16(SkAlphaMulQ4(src, scale16), dst); |
| 563 | } |
| 564 | |
| 565 | static inline uint16_t SkBlend4444(SkPMColor16 src, SkPMColor16 dst, int scale16) |
| 566 | { |
| 567 | SkASSERT((unsigned)scale16 <= 16); |
| 568 | |
| 569 | uint32_t src32 = SkExpand_4444(src) * scale16; |
| 570 | // the scaled srcAlpha is the bottom byte |
| 571 | #ifdef SK_DEBUG |
| 572 | { |
| 573 | unsigned srcA = SkGetPackedA4444(src) * scale16; |
| 574 | SkASSERT(srcA == (src32 & 0xFF)); |
| 575 | } |
| 576 | #endif |
| 577 | unsigned dstScale = SkAlpha255To256(255 - (src32 & 0xFF)) >> 4; |
| 578 | uint32_t dst32 = SkExpand_4444(dst) * dstScale; |
| 579 | return SkCompact_4444((src32 + dst32) >> 4); |
| 580 | } |
| 581 | |
| 582 | static inline SkPMColor SkPixel4444ToPixel32(U16CPU c) |
| 583 | { |
| 584 | uint32_t d = (SkGetPackedA4444(c) << SK_A32_SHIFT) | |
| 585 | (SkGetPackedR4444(c) << SK_R32_SHIFT) | |
| 586 | (SkGetPackedG4444(c) << SK_G32_SHIFT) | |
| 587 | (SkGetPackedB4444(c) << SK_B32_SHIFT); |
| 588 | return d | (d << 4); |
| 589 | } |
| 590 | |
| 591 | static inline SkPMColor16 SkPixel32ToPixel4444(SkPMColor c) |
| 592 | { |
| 593 | return (((c >> (SK_A32_SHIFT + 4)) & 0xF) << SK_A4444_SHIFT) | |
| 594 | (((c >> (SK_R32_SHIFT + 4)) & 0xF) << SK_R4444_SHIFT) | |
| 595 | (((c >> (SK_G32_SHIFT + 4)) & 0xF) << SK_G4444_SHIFT) | |
| 596 | (((c >> (SK_B32_SHIFT + 4)) & 0xF) << SK_B4444_SHIFT); |
| 597 | } |
| 598 | |
| 599 | // cheap 2x2 dither |
| 600 | static inline SkPMColor16 SkDitherARGB32To4444(U8CPU a, U8CPU r, |
| 601 | U8CPU g, U8CPU b) |
| 602 | { |
| 603 | a = ((a << 1) - ((a >> 4 << 4) | (a >> 4))) >> 4; |
| 604 | r = ((r << 1) - ((r >> 4 << 4) | (r >> 4))) >> 4; |
| 605 | g = ((g << 1) - ((g >> 4 << 4) | (g >> 4))) >> 4; |
| 606 | b = ((b << 1) - ((b >> 4 << 4) | (b >> 4))) >> 4; |
| 607 | |
| 608 | return SkPackARGB4444(a, r, g, b); |
| 609 | } |
| 610 | |
| 611 | static inline SkPMColor16 SkDitherPixel32To4444(SkPMColor c) |
| 612 | { |
| 613 | return SkDitherARGB32To4444(SkGetPackedA32(c), SkGetPackedR32(c), |
| 614 | SkGetPackedG32(c), SkGetPackedB32(c)); |
| 615 | } |
| 616 | |
| 617 | /* Assumes 16bit is in standard RGBA order. |
| 618 | Transforms a normal ARGB_8888 into the same byte order as |
| 619 | expanded ARGB_4444, but keeps each component 8bits |
| 620 | */ |
| 621 | static uint32_t SkExpand_8888(SkPMColor c) |
| 622 | { |
| 623 | return (((c >> SK_R32_SHIFT) & 0xFF) << 24) | |
| 624 | (((c >> SK_G32_SHIFT) & 0xFF) << 8) | |
| 625 | (((c >> SK_B32_SHIFT) & 0xFF) << 16) | |
| 626 | (((c >> SK_A32_SHIFT) & 0xFF) << 0); |
| 627 | } |
| 628 | |
| 629 | /* Undo the operation of SkExpand_8888, turning the argument back into |
| 630 | a SkPMColor. |
| 631 | */ |
| 632 | static SkPMColor SkCompact_8888(uint32_t c) |
| 633 | { |
| 634 | return (((c >> 24) & 0xFF) << SK_R32_SHIFT) | |
| 635 | (((c >> 8) & 0xFF) << SK_G32_SHIFT) | |
| 636 | (((c >> 16) & 0xFF) << SK_B32_SHIFT) | |
| 637 | (((c >> 0) & 0xFF) << SK_A32_SHIFT); |
| 638 | } |
| 639 | |
| 640 | /* Like SkExpand_8888, this transforms a pmcolor into the expanded 4444 format, |
| 641 | but this routine just keeps the high 4bits of each component in the low |
| 642 | 4bits of the result (just like a newly expanded PMColor16). |
| 643 | */ |
| 644 | static uint32_t SkExpand32_4444(SkPMColor c) |
| 645 | { |
| 646 | return (((c >> (SK_R32_SHIFT + 4)) & 0xF) << 24) | |
| 647 | (((c >> (SK_G32_SHIFT + 4)) & 0xF) << 8) | |
| 648 | (((c >> (SK_B32_SHIFT + 4)) & 0xF) << 16) | |
| 649 | (((c >> (SK_A32_SHIFT + 4)) & 0xF) << 0); |
| 650 | } |
| 651 | |
| 652 | // takes two values and alternamtes them as part of a memset16 |
| 653 | // used for cheap 2x2 dithering when the colors are opaque |
| 654 | void sk_dither_memset16(uint16_t dst[], uint16_t value, uint16_t other, int n); |
| 655 | |
| 656 | #endif |
| 657 | |