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