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Diffstat (limited to 'src/core/SkDither.h')
-rw-r--r-- | src/core/SkDither.h | 198 |
1 files changed, 198 insertions, 0 deletions
diff --git a/src/core/SkDither.h b/src/core/SkDither.h new file mode 100644 index 0000000000..d82b4167b5 --- /dev/null +++ b/src/core/SkDither.h @@ -0,0 +1,198 @@ + +/* + * Copyright 2008 The Android Open Source Project + * + * Use of this source code is governed by a BSD-style license that can be + * found in the LICENSE file. + */ + + +#ifndef SkDither_DEFINED +#define SkDither_DEFINED + +#include "SkColorPriv.h" + +#define SK_DitherValueMax4444 15 +#define SK_DitherValueMax565 7 + +/* need to use macros for bit-counts for each component, and then + move these into SkColorPriv.h +*/ + +#define SkDITHER_R32_FOR_565_MACRO(r, d) (r + d - (r >> 5)) +#define SkDITHER_G32_FOR_565_MACRO(g, d) (g + (d >> 1) - (g >> 6)) +#define SkDITHER_B32_FOR_565_MACRO(b, d) (b + d - (b >> 5)) + +#define SkDITHER_A32_FOR_4444_MACRO(a, d) (a + 15 - (a >> 4)) +#define SkDITHER_R32_FOR_4444_MACRO(r, d) (r + d - (r >> 4)) +#define SkDITHER_G32_FOR_4444_MACRO(g, d) (g + d - (g >> 4)) +#define SkDITHER_B32_FOR_4444_MACRO(b, d) (b + d - (b >> 4)) + +#ifdef SK_DEBUG + inline unsigned SkDITHER_R32_FOR_565(unsigned r, unsigned d) + { + SkASSERT(d <= SK_DitherValueMax565); + SkA32Assert(r); + r = SkDITHER_R32_FOR_565_MACRO(r, d); + SkA32Assert(r); + return r; + } + inline unsigned SkDITHER_G32_FOR_565(unsigned g, unsigned d) + { + SkASSERT(d <= SK_DitherValueMax565); + SkG32Assert(g); + g = SkDITHER_G32_FOR_565_MACRO(g, d); + SkG32Assert(g); + return g; + } + inline unsigned SkDITHER_B32_FOR_565(unsigned b, unsigned d) + { + SkASSERT(d <= SK_DitherValueMax565); + SkB32Assert(b); + b = SkDITHER_B32_FOR_565_MACRO(b, d); + SkB32Assert(b); + return b; + } +#else + #define SkDITHER_R32_FOR_565(r, d) SkDITHER_R32_FOR_565_MACRO(r, d) + #define SkDITHER_G32_FOR_565(g, d) SkDITHER_G32_FOR_565_MACRO(g, d) + #define SkDITHER_B32_FOR_565(b, d) SkDITHER_B32_FOR_565_MACRO(b, d) +#endif + +#define SkDITHER_R32To565(r, d) SkR32ToR16(SkDITHER_R32_FOR_565(r, d)) +#define SkDITHER_G32To565(g, d) SkG32ToG16(SkDITHER_G32_FOR_565(g, d)) +#define SkDITHER_B32To565(b, d) SkB32ToB16(SkDITHER_B32_FOR_565(b, d)) + +#define SkDITHER_A32To4444(a, d) SkA32To4444(SkDITHER_A32_FOR_4444_MACRO(a, d)) +#define SkDITHER_R32To4444(r, d) SkR32To4444(SkDITHER_R32_FOR_4444_MACRO(r, d)) +#define SkDITHER_G32To4444(g, d) SkG32To4444(SkDITHER_G32_FOR_4444_MACRO(g, d)) +#define SkDITHER_B32To4444(b, d) SkB32To4444(SkDITHER_B32_FOR_4444_MACRO(b, d)) + +static inline SkPMColor SkDitherARGB32For565(SkPMColor c, unsigned dither) +{ + SkASSERT(dither <= SK_DitherValueMax565); + + unsigned sa = SkGetPackedA32(c); + dither = SkAlphaMul(dither, SkAlpha255To256(sa)); + + unsigned sr = SkGetPackedR32(c); + unsigned sg = SkGetPackedG32(c); + unsigned sb = SkGetPackedB32(c); + sr = SkDITHER_R32_FOR_565(sr, dither); + sg = SkDITHER_G32_FOR_565(sg, dither); + sb = SkDITHER_B32_FOR_565(sb, dither); + + return SkPackARGB32(sa, sr, sg, sb); +} + +static inline SkPMColor SkDitherRGB32For565(SkPMColor c, unsigned dither) +{ + SkASSERT(dither <= SK_DitherValueMax565); + + unsigned sr = SkGetPackedR32(c); + unsigned sg = SkGetPackedG32(c); + unsigned sb = SkGetPackedB32(c); + sr = SkDITHER_R32_FOR_565(sr, dither); + sg = SkDITHER_G32_FOR_565(sg, dither); + sb = SkDITHER_B32_FOR_565(sb, dither); + + return SkPackARGB32(0xFF, sr, sg, sb); +} + +static inline uint16_t SkDitherRGBTo565(U8CPU r, U8CPU g, U8CPU b, + unsigned dither) +{ + SkASSERT(dither <= SK_DitherValueMax565); + r = SkDITHER_R32To565(r, dither); + g = SkDITHER_G32To565(g, dither); + b = SkDITHER_B32To565(b, dither); + return SkPackRGB16(r, g, b); +} + +static inline uint16_t SkDitherRGB32To565(SkPMColor c, unsigned dither) +{ + SkASSERT(dither <= SK_DitherValueMax565); + + unsigned sr = SkGetPackedR32(c); + unsigned sg = SkGetPackedG32(c); + unsigned sb = SkGetPackedB32(c); + sr = SkDITHER_R32To565(sr, dither); + sg = SkDITHER_G32To565(sg, dither); + sb = SkDITHER_B32To565(sb, dither); + + return SkPackRGB16(sr, sg, sb); +} + +static inline uint16_t SkDitherARGB32To565(U8CPU sa, SkPMColor c, unsigned dither) +{ + SkASSERT(dither <= SK_DitherValueMax565); + dither = SkAlphaMul(dither, SkAlpha255To256(sa)); + + unsigned sr = SkGetPackedR32(c); + unsigned sg = SkGetPackedG32(c); + unsigned sb = SkGetPackedB32(c); + sr = SkDITHER_R32To565(sr, dither); + sg = SkDITHER_G32To565(sg, dither); + sb = SkDITHER_B32To565(sb, dither); + + return SkPackRGB16(sr, sg, sb); +} + +///////////////////////// 4444 + +static inline SkPMColor16 SkDitherARGB32To4444(U8CPU a, U8CPU r, U8CPU g, + U8CPU b, unsigned dither) +{ + dither = SkAlphaMul(dither, SkAlpha255To256(a)); + + a = SkDITHER_A32To4444(a, dither); + r = SkDITHER_R32To4444(r, dither); + g = SkDITHER_G32To4444(g, dither); + b = SkDITHER_B32To4444(b, dither); + + return SkPackARGB4444(a, r, g, b); +} + +static inline SkPMColor16 SkDitherARGB32To4444(SkPMColor c, unsigned dither) +{ + unsigned a = SkGetPackedA32(c); + unsigned r = SkGetPackedR32(c); + unsigned g = SkGetPackedG32(c); + unsigned b = SkGetPackedB32(c); + + dither = SkAlphaMul(dither, SkAlpha255To256(a)); + + a = SkDITHER_A32To4444(a, dither); + r = SkDITHER_R32To4444(r, dither); + g = SkDITHER_G32To4444(g, dither); + b = SkDITHER_B32To4444(b, dither); + + return SkPackARGB4444(a, r, g, b); +} + +// TODO: need dither routines for 565 -> 4444 + +// this toggles between a 4x4 and a 1x4 array +//#define ENABLE_DITHER_MATRIX_4X4 + +#ifdef ENABLE_DITHER_MATRIX_4X4 + extern const uint8_t gDitherMatrix_4Bit_4X4[4][4]; + extern const uint8_t gDitherMatrix_3Bit_4X4[4][4]; + + #define DITHER_4444_SCAN(y) const uint8_t* dither_scan = gDitherMatrix_4Bit_4X4[(y) & 3] + #define DITHER_565_SCAN(y) const uint8_t* dither_scan = gDitherMatrix_3Bit_4X4[(y) & 3] + + #define DITHER_VALUE(x) dither_scan[(x) & 3] +#else + extern const uint16_t gDitherMatrix_4Bit_16[4]; + extern const uint16_t gDitherMatrix_3Bit_16[4]; + + #define DITHER_4444_SCAN(y) const uint16_t dither_scan = gDitherMatrix_4Bit_16[(y) & 3] + #define DITHER_565_SCAN(y) const uint16_t dither_scan = gDitherMatrix_3Bit_16[(y) & 3] + + #define DITHER_VALUE(x) ((dither_scan >> (((x) & 3) << 2)) & 0xF) +#endif + +#define DITHER_INC_X(x) ++(x) + +#endif |