1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/gfx/skia/trunk/src/core/SkDither.cpp Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,55 @@
1.4 +
1.5 +/*
1.6 + * Copyright 2011 Google Inc.
1.7 + *
1.8 + * Use of this source code is governed by a BSD-style license that can be
1.9 + * found in the LICENSE file.
1.10 + */
1.11 +#include "SkDither.h"
1.12 +
1.13 +/* The base dither matrix we use to derive optimized ones for 565 and 4444
1.14 +
1.15 + { 0, 32, 8, 40, 2, 34, 10, 42 },
1.16 + { 48, 16, 56, 24, 50, 18, 58, 26 },
1.17 + { 12, 44, 4, 36, 14, 46, 6, 38 },
1.18 + { 60, 28, 52, 20, 62, 30, 54, 22 },
1.19 + { 3, 35, 11, 43, 1, 33, 9, 41 },
1.20 + { 51, 19, 59, 27, 49, 17, 57, 25 },
1.21 + { 15, 47, 7, 39, 13, 45, 5, 37 },
1.22 + { 63, 31, 55, 23, 61, 29, 53, 21 }
1.23 +
1.24 + The 4444 version only needs 4 bits, and given that we can reduce its size
1.25 + since the other 4x4 sub pieces all look the same once we truncate the bits.
1.26 +
1.27 + The 565 version only needs 3 bits for red/blue, and only 2 bits for green.
1.28 + For simplicity, we store 3 bits, and have the dither macros for green know
1.29 + this, and they shift the dither value down by 1 to make it 2 bits.
1.30 + */
1.31 +
1.32 +#ifdef ENABLE_DITHER_MATRIX_4X4
1.33 +
1.34 +const uint8_t gDitherMatrix_4Bit_4X4[4][4] = {
1.35 + { 0, 8, 2, 10 },
1.36 + { 12, 4, 14, 6 },
1.37 + { 3, 11, 1, 9 },
1.38 + { 15, 7, 13, 5 }
1.39 +};
1.40 +
1.41 +const uint8_t gDitherMatrix_3Bit_4X4[4][4] = {
1.42 + { 0, 4, 1, 5 },
1.43 + { 6, 2, 7, 3 },
1.44 + { 1, 5, 0, 4 },
1.45 + { 7, 3, 6, 2 }
1.46 +};
1.47 +
1.48 +#else // used packed shorts for a scanlines worth of dither values
1.49 +
1.50 +const uint16_t gDitherMatrix_4Bit_16[4] = {
1.51 + 0xA280, 0x6E4C, 0x91B3, 0x5D7F
1.52 +};
1.53 +
1.54 +const uint16_t gDitherMatrix_3Bit_16[4] = {
1.55 + 0x5140, 0x3726, 0x4051, 0x2637
1.56 +};
1.57 +
1.58 +#endif
