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84 lines
2.6 KiB
C
84 lines
2.6 KiB
C
/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 4 -*-
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef GFX_COLOR_H
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#define GFX_COLOR_H
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#include "mozilla/Attributes.h" // for MOZ_ALWAYS_INLINE
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#include "mozilla/Endian.h" // for mozilla::NativeEndian::swapToBigEndian
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/**
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* GFX_BLOCK_RGB_TO_FRGB(from,to)
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* sizeof(*from) == sizeof(char)
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* sizeof(*to) == sizeof(uint32_t)
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*
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* Copy 4 pixels at a time, reading blocks of 12 bytes (RGB x4)
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* and writing blocks of 16 bytes (FRGB x4)
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*/
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#define GFX_BLOCK_RGB_TO_FRGB(from,to) \
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PR_BEGIN_MACRO \
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uint32_t m0 = ((uint32_t*)from)[0], \
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m1 = ((uint32_t*)from)[1], \
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m2 = ((uint32_t*)from)[2], \
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rgbr = mozilla::NativeEndian::swapToBigEndian(m0), \
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gbrg = mozilla::NativeEndian::swapToBigEndian(m1), \
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brgb = mozilla::NativeEndian::swapToBigEndian(m2), \
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p0, p1, p2, p3; \
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p0 = 0xFF000000 | ((rgbr) >> 8); \
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p1 = 0xFF000000 | ((rgbr) << 16) | ((gbrg) >> 16); \
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p2 = 0xFF000000 | ((gbrg) << 8) | ((brgb) >> 24); \
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p3 = 0xFF000000 | (brgb); \
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to[0] = p0; to[1] = p1; to[2] = p2; to[3] = p3; \
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PR_END_MACRO
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/**
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* Fast approximate division by 255. It has the property that
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* for all 0 <= n <= 255*255, GFX_DIVIDE_BY_255(n) == n/255.
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* But it only uses two adds and two shifts instead of an
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* integer division (which is expensive on many processors).
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*
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* equivalent to ((v)/255)
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*/
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#define GFX_DIVIDE_BY_255(v) \
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(((((unsigned)(v)) << 8) + ((unsigned)(v)) + 255) >> 16)
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/**
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* Fast premultiply
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*
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* equivalent to (((c)*(a))/255)
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*/
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uint8_t MOZ_ALWAYS_INLINE gfxPreMultiply(uint8_t c, uint8_t a) {
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return GFX_DIVIDE_BY_255((c)*(a));
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}
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/**
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* Pack the 4 8-bit channels (A,R,G,B)
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* into a 32-bit packed NON-premultiplied pixel.
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*/
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uint32_t MOZ_ALWAYS_INLINE
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gfxPackedPixelNoPreMultiply(uint8_t a, uint8_t r, uint8_t g, uint8_t b) {
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return (((a) << 24) | ((r) << 16) | ((g) << 8) | (b));
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}
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/**
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* Pack the 4 8-bit channels (A,R,G,B)
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* into a 32-bit packed premultiplied pixel.
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*/
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uint32_t MOZ_ALWAYS_INLINE
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gfxPackedPixel(uint8_t a, uint8_t r, uint8_t g, uint8_t b) {
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if (a == 0x00)
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return 0x00000000;
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else if (a == 0xFF) {
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return gfxPackedPixelNoPreMultiply(a, r, g, b);
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} else {
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return ((a) << 24) |
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(gfxPreMultiply(r,a) << 16) |
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(gfxPreMultiply(g,a) << 8) |
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(gfxPreMultiply(b,a));
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}
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}
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#endif /* _GFX_COLOR_H */
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