| /* |
| * Copyright 2015 Google Inc. |
| * |
| * Use of this source code is governed by a BSD-style license that can be |
| * found in the LICENSE file. |
| */ |
| #include "src/codec/SkMasks.h" |
| |
| #include "src/codec/SkCodecPriv.h" |
| |
| /* |
| * |
| * Used to convert 1-7 bit color components into 8-bit color components |
| * |
| */ |
| static constexpr uint8_t n_bit_to_8_bit_lookup_table[] = { |
| // 1 bit |
| 0, 255, |
| // 2 bits |
| 0, 85, 170, 255, |
| // 3 bits |
| 0, 36, 73, 109, 146, 182, 219, 255, |
| // 4 bits |
| 0, 17, 34, 51, 68, 85, 102, 119, 136, 153, 170, 187, 204, 221, 238, 255, |
| // 5 bits |
| 0, 8, 16, 25, 33, 41, 49, 58, 66, 74, 82, 90, 99, 107, 115, 123, 132, 140, |
| 148, 156, 165, 173, 181, 189, 197, 206, 214, 222, 230, 239, 247, 255, |
| // 6 bits |
| 0, 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 45, 49, 53, 57, 61, 65, 69, 73, |
| 77, 81, 85, 89, 93, 97, 101, 105, 109, 113, 117, 121, 125, 130, 134, 138, |
| 142, 146, 150, 154, 158, 162, 166, 170, 174, 178, 182, 186, 190, 194, 198, |
| 202, 206, 210, 215, 219, 223, 227, 231, 235, 239, 243, 247, 251, 255, |
| // 7 bits |
| 0, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, |
| 40, 42, 44, 46, 48, 50, 52, 54, 56, 58, 60, 62, 64, 66, 68, 70, 72, 74, 76, |
| 78, 80, 82, 84, 86, 88, 90, 92, 94, 96, 98, 100, 102, 104, 106, 108, 110, |
| 112, 114, 116, 118, 120, 122, 124, 126, 129, 131, 133, 135, 137, 139, 141, |
| 143, 145, 147, 149, 151, 153, 155, 157, 159, 161, 163, 165, 167, 169, 171, |
| 173, 175, 177, 179, 181, 183, 185, 187, 189, 191, 193, 195, 197, 199, 201, |
| 203, 205, 207, 209, 211, 213, 215, 217, 219, 221, 223, 225, 227, 229, 231, |
| 233, 235, 237, 239, 241, 243, 245, 247, 249, 251, 253, 255 |
| }; |
| |
| /* |
| * |
| * Convert an n bit component to an 8-bit component |
| * |
| */ |
| static uint8_t convert_to_8(uint8_t component, uint32_t n) { |
| if (0 == n) { |
| return 0; |
| } else if (8 > n) { |
| return n_bit_to_8_bit_lookup_table[(1 << n) - 2 + component]; |
| } else { |
| SkASSERT(8 == n); |
| return component; |
| } |
| } |
| |
| static uint8_t get_comp(uint32_t pixel, uint32_t mask, uint32_t shift, |
| uint32_t size) { |
| return convert_to_8((pixel & mask) >> shift, size); |
| } |
| |
| /* |
| * |
| * Get a color component |
| * |
| */ |
| uint8_t SkMasks::getRed(uint32_t pixel) const { |
| return get_comp(pixel, fRed.mask, fRed.shift, fRed.size); |
| } |
| uint8_t SkMasks::getGreen(uint32_t pixel) const { |
| return get_comp(pixel, fGreen.mask, fGreen.shift, fGreen.size); |
| } |
| uint8_t SkMasks::getBlue(uint32_t pixel) const { |
| return get_comp(pixel, fBlue.mask, fBlue.shift, fBlue.size); |
| } |
| uint8_t SkMasks::getAlpha(uint32_t pixel) const { |
| return get_comp(pixel, fAlpha.mask, fAlpha.shift, fAlpha.size); |
| } |
| |
| /* |
| * |
| * Process an input mask to obtain the necessary information |
| * |
| */ |
| static SkMasks::MaskInfo process_mask(uint32_t mask) { |
| // Determine properties of the mask |
| uint32_t tempMask = mask; |
| uint32_t shift = 0; |
| uint32_t size = 0; |
| if (tempMask != 0) { |
| // Count trailing zeros on masks |
| for (; (tempMask & 1) == 0; tempMask >>= 1) { |
| shift++; |
| } |
| // Count the size of the mask |
| for (; tempMask & 1; tempMask >>= 1) { |
| size++; |
| } |
| // Verify that the mask is continuous |
| if (tempMask) { |
| SkCodecPrintf("Warning: Bit mask is not continuous.\n"); |
| // Finish processing the mask |
| for (; tempMask; tempMask >>= 1) { |
| size++; |
| } |
| } |
| // Truncate masks greater than 8 bits |
| if (size > 8) { |
| shift += size - 8; |
| size = 8; |
| mask &= 0xFF << shift; |
| } |
| } |
| |
| return { mask, shift, size }; |
| } |
| |
| /* |
| * |
| * Create the masks object |
| * |
| */ |
| SkMasks* SkMasks::CreateMasks(InputMasks masks, int bytesPerPixel) { |
| SkASSERT(0 < bytesPerPixel && bytesPerPixel <= 4); |
| |
| // Trim the input masks to match bytesPerPixel. |
| if (bytesPerPixel < 4) { |
| int bitsPerPixel = 8*bytesPerPixel; |
| masks.red &= (1 << bitsPerPixel) - 1; |
| masks.green &= (1 << bitsPerPixel) - 1; |
| masks.blue &= (1 << bitsPerPixel) - 1; |
| masks.alpha &= (1 << bitsPerPixel) - 1; |
| } |
| |
| // Check that masks do not overlap. |
| if (((masks.red & masks.green) | |
| (masks.red & masks.blue ) | |
| (masks.red & masks.alpha) | |
| (masks.green & masks.blue ) | |
| (masks.green & masks.alpha) | |
| (masks.blue & masks.alpha) ) != 0) { |
| return nullptr; |
| } |
| |
| return new SkMasks(process_mask(masks.red ), |
| process_mask(masks.green), |
| process_mask(masks.blue ), |
| process_mask(masks.alpha)); |
| } |
| |