| /* |
| * Copyright 2011 Google Inc. |
| * |
| * Use of this source code is governed by a BSD-style license that can be |
| * found in the LICENSE file. |
| */ |
| #include "SkDither.h" |
| |
| /* The base dither matrix we use to derive optimized ones for 565 and 4444 |
| |
| { 0, 32, 8, 40, 2, 34, 10, 42 }, |
| { 48, 16, 56, 24, 50, 18, 58, 26 }, |
| { 12, 44, 4, 36, 14, 46, 6, 38 }, |
| { 60, 28, 52, 20, 62, 30, 54, 22 }, |
| { 3, 35, 11, 43, 1, 33, 9, 41 }, |
| { 51, 19, 59, 27, 49, 17, 57, 25 }, |
| { 15, 47, 7, 39, 13, 45, 5, 37 }, |
| { 63, 31, 55, 23, 61, 29, 53, 21 } |
| |
| The 4444 version only needs 4 bits, and given that we can reduce its size |
| since the other 4x4 sub pieces all look the same once we truncate the bits. |
| |
| The 565 version only needs 3 bits for red/blue, and only 2 bits for green. |
| For simplicity, we store 3 bits, and have the dither macros for green know |
| this, and they shift the dither value down by 1 to make it 2 bits. |
| */ |
| |
| #ifdef ENABLE_DITHER_MATRIX_4X4 |
| |
| const uint8_t gDitherMatrix_4Bit_4X4[4][4] = { |
| { 0, 8, 2, 10 }, |
| { 12, 4, 14, 6 }, |
| { 3, 11, 1, 9 }, |
| { 15, 7, 13, 5 } |
| }; |
| |
| const uint8_t gDitherMatrix_3Bit_4X4[4][4] = { |
| { 0, 4, 1, 5 }, |
| { 6, 2, 7, 3 }, |
| { 1, 5, 0, 4 }, |
| { 7, 3, 6, 2 } |
| }; |
| |
| #else // used packed shorts for a scanlines worth of dither values |
| |
| const uint16_t gDitherMatrix_4Bit_16[4] = { |
| 0xA280, 0x6E4C, 0x91B3, 0x5D7F |
| }; |
| |
| const uint16_t gDitherMatrix_3Bit_16[4] = { |
| 0x5140, 0x3726, 0x4051, 0x2637 |
| }; |
| |
| #endif |