diff options
author | msarett <msarett@google.com> | 2015-03-16 08:27:53 -0700 |
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committer | Commit bot <commit-bot@chromium.org> | 2015-03-16 08:27:53 -0700 |
commit | 3675874468de7228944ce21922e6ec863f5f2310 (patch) | |
tree | 0cee05f6f1703fecf3ba6850a7dcac029ef26407 /src/codec/SkMasks.cpp | |
parent | dedc2d8e8dc635ff43e6b314b280e3efe85ce8a7 (diff) |
Implementation of image decoding for bmp files, in accordance with the new API.
Currently decodes to opaque and unpremul.
Tested on local test suite.
BUG=skia:3257
Review URL: https://codereview.chromium.org/947283002
Diffstat (limited to 'src/codec/SkMasks.cpp')
-rw-r--r-- | src/codec/SkMasks.cpp | 160 |
1 files changed, 160 insertions, 0 deletions
diff --git a/src/codec/SkMasks.cpp b/src/codec/SkMasks.cpp new file mode 100644 index 0000000000..1c542ceab2 --- /dev/null +++ b/src/codec/SkMasks.cpp @@ -0,0 +1,160 @@ +/* + * 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 "SkMasks.h" +#include "SkTypes.h" + +/* + * + * Used to convert 1-7 bit color components into 8-bit color components + * + */ +const static 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(uint32_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) { + return get_comp(pixel, fRed.mask, fRed.shift, fRed.size); +} +uint8_t SkMasks::getGreen(uint32_t pixel) { + return get_comp(pixel, fGreen.mask, fGreen.shift, fGreen.size); +} +uint8_t SkMasks::getBlue(uint32_t pixel) { + return get_comp(pixel, fBlue.mask, fBlue.shift, fBlue.size); +} +uint8_t SkMasks::getAlpha(uint32_t pixel) { + return get_comp(pixel, fAlpha.mask, fAlpha.shift, fAlpha.size); +} + +/* + * + * Process an input mask to obtain the necessary information + * + */ +const SkMasks::MaskInfo process_mask(uint32_t mask, uint32_t bpp) { + // Trim the masks to the allowed number of bits + if (bpp < 32) { + mask &= (1 << bpp) - 1; + } + + // 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++; + } + // Check that the mask is continuous + if (tempMask != 0) { + SkDebugf("Warning: Bit masks is not continuous.\n"); + } + // Truncate masks greater than 8 bits + if (size > 8) { + shift += size - 8; + size = 8; + } + } + + // Save the calculated values + const SkMasks::MaskInfo info = { mask, shift, size }; + return info; +} + +/* + * + * Create the masks object + * + */ +SkMasks* SkMasks::CreateMasks(InputMasks masks, uint32_t bitsPerPixel) { + // Trim the input masks according to bitsPerPixel + if (bitsPerPixel < 32) { + 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 NULL; + } + + // Collect information about the masks + const MaskInfo red = process_mask(masks.red, bitsPerPixel); + const MaskInfo green = process_mask(masks.green, bitsPerPixel); + const MaskInfo blue = process_mask(masks.blue, bitsPerPixel); + const MaskInfo alpha = process_mask(masks.alpha, bitsPerPixel); + + return SkNEW_ARGS(SkMasks, (red, green, blue, alpha)); +} + + +SkMasks::SkMasks(const MaskInfo red, const MaskInfo green, + const MaskInfo blue, const MaskInfo alpha) + : fRed(red) + , fGreen(green) + , fBlue(blue) + , fAlpha(alpha) +{} |