gecko-dev/gfx/thebes/gfxColor.h

228 lines
7.1 KiB
C

/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 4 -*-
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifndef GFX_COLOR_H
#define GFX_COLOR_H
#include "gfxTypes.h"
#include "mozilla/Attributes.h" // for MOZ_ALWAYS_INLINE
#include "mozilla/Endian.h" // for mozilla::NativeEndian::swapToBigEndian
#define GFX_UINT32_FROM_BPTR(pbptr,i) (((uint32_t*)(pbptr))[i])
/**
* GFX_0XFF_PPIXEL_FROM_BPTR(x)
*
* Avoid tortured construction of 32-bit ARGB pixel from 3 individual bytes
* of memory plus constant 0xFF. RGB bytes are already contiguous!
* Equivalent to: GFX_PACKED_PIXEL(0xff,r,g,b)
*
* Attempt to use fast byte-swapping instruction(s), e.g. bswap on x86, in
* preference to a sequence of shift/or operations.
*/
#define GFX_0XFF_PPIXEL_FROM_UINT32(x) \
( (mozilla::NativeEndian::swapToBigEndian(uint32_t(x)) >> 8) | (0xFFU << 24) )
#define GFX_0XFF_PPIXEL_FROM_BPTR(x) \
( GFX_0XFF_PPIXEL_FROM_UINT32(GFX_UINT32_FROM_BPTR((x),0)) )
/**
* GFX_BLOCK_RGB_TO_FRGB(from,to)
* sizeof(*from) == sizeof(char)
* sizeof(*to) == sizeof(uint32_t)
*
* Copy 4 pixels at a time, reading blocks of 12 bytes (RGB x4)
* and writing blocks of 16 bytes (FRGB x4)
*/
#define GFX_BLOCK_RGB_TO_FRGB(from,to) \
PR_BEGIN_MACRO \
uint32_t m0 = GFX_UINT32_FROM_BPTR(from,0), \
m1 = GFX_UINT32_FROM_BPTR(from,1), \
m2 = GFX_UINT32_FROM_BPTR(from,2), \
rgbr = mozilla::NativeEndian::swapToBigEndian(m0), \
gbrg = mozilla::NativeEndian::swapToBigEndian(m1), \
brgb = mozilla::NativeEndian::swapToBigEndian(m2), \
p0, p1, p2, p3; \
p0 = 0xFF000000 | ((rgbr) >> 8); \
p1 = 0xFF000000 | ((rgbr) << 16) | ((gbrg) >> 16); \
p2 = 0xFF000000 | ((gbrg) << 8) | ((brgb) >> 24); \
p3 = 0xFF000000 | (brgb); \
to[0] = p0; to[1] = p1; to[2] = p2; to[3] = p3; \
PR_END_MACRO
/**
* Fast approximate division by 255. It has the property that
* for all 0 <= n <= 255*255, GFX_DIVIDE_BY_255(n) == n/255.
* But it only uses two adds and two shifts instead of an
* integer division (which is expensive on many processors).
*
* equivalent to ((v)/255)
*/
#define GFX_DIVIDE_BY_255(v) \
(((((unsigned)(v)) << 8) + ((unsigned)(v)) + 255) >> 16)
/**
* Fast premultiply
*
* equivalent to (((c)*(a))/255)
*/
uint8_t MOZ_ALWAYS_INLINE gfxPreMultiply(uint8_t c, uint8_t a) {
return GFX_DIVIDE_BY_255((c)*(a));
}
/**
* Pack the 4 8-bit channels (A,R,G,B)
* into a 32-bit packed NON-premultiplied pixel.
*/
uint32_t MOZ_ALWAYS_INLINE
gfxPackedPixelNoPreMultiply(uint8_t a, uint8_t r, uint8_t g, uint8_t b) {
return (((a) << 24) | ((r) << 16) | ((g) << 8) | (b));
}
/**
* Pack the 4 8-bit channels (A,R,G,B)
* into a 32-bit packed premultiplied pixel.
*/
uint32_t MOZ_ALWAYS_INLINE
gfxPackedPixel(uint8_t a, uint8_t r, uint8_t g, uint8_t b) {
if (a == 0x00)
return 0x00000000;
else if (a == 0xFF) {
return gfxPackedPixelNoPreMultiply(a, r, g, b);
} else {
return ((a) << 24) |
(gfxPreMultiply(r,a) << 16) |
(gfxPreMultiply(g,a) << 8) |
(gfxPreMultiply(b,a));
}
}
/**
* A color value, storing red, green, blue and alpha components.
* This class does not use premultiplied alpha.
*
* XXX should this use doubles (instead of gfxFloat), for consistency with
* cairo?
*/
struct gfxRGBA {
gfxFloat r, g, b, a;
enum PackedColorType {
PACKED_ABGR,
PACKED_ABGR_PREMULTIPLIED,
PACKED_ARGB,
PACKED_ARGB_PREMULTIPLIED,
PACKED_XRGB
};
gfxRGBA() { }
/**
* Intialize this color using explicit red, green, blue and alpha
* values.
*/
MOZ_CONSTEXPR gfxRGBA(gfxFloat _r, gfxFloat _g, gfxFloat _b, gfxFloat _a=1.0) : r(_r), g(_g), b(_b), a(_a) {}
/**
* Initialize this color from a packed 32-bit color.
* The color value is interpreted based on colorType;
* all values use the native platform endianness.
*
* Resulting gfxRGBA stores non-premultiplied data.
*
* @see gfxRGBA::Packed
*/
gfxRGBA(uint32_t c, PackedColorType colorType = PACKED_ABGR) {
if (colorType == PACKED_ABGR ||
colorType == PACKED_ABGR_PREMULTIPLIED)
{
r = ((c >> 0) & 0xff) * (1.0 / 255.0);
g = ((c >> 8) & 0xff) * (1.0 / 255.0);
b = ((c >> 16) & 0xff) * (1.0 / 255.0);
a = ((c >> 24) & 0xff) * (1.0 / 255.0);
} else if (colorType == PACKED_ARGB ||
colorType == PACKED_XRGB ||
colorType == PACKED_ARGB_PREMULTIPLIED)
{
b = ((c >> 0) & 0xff) * (1.0 / 255.0);
g = ((c >> 8) & 0xff) * (1.0 / 255.0);
r = ((c >> 16) & 0xff) * (1.0 / 255.0);
a = ((c >> 24) & 0xff) * (1.0 / 255.0);
}
if (colorType == PACKED_ABGR_PREMULTIPLIED ||
colorType == PACKED_ARGB_PREMULTIPLIED)
{
if (a > 0.0) {
r /= a;
g /= a;
b /= a;
}
} else if (colorType == PACKED_XRGB) {
a = 1.0;
}
}
bool operator==(const gfxRGBA& other) const
{
return r == other.r && g == other.g && b == other.b && a == other.a;
}
bool operator!=(const gfxRGBA& other) const
{
return !(*this == other);
}
/**
* Returns this color value as a packed 32-bit integer. This reconstructs
* the int32_t based on the given colorType, always in the native byte order.
*
* Note: gcc 4.2.3 on at least Ubuntu (x86) does something strange with
* (uint8_t)(c * 255.0) << x, where the result is different than
* double d = c * 255.0; v = ((uint8_t) d) << x.
*/
uint32_t Packed(PackedColorType colorType = PACKED_ABGR) const {
gfxFloat rb = (r * 255.0);
gfxFloat gb = (g * 255.0);
gfxFloat bb = (b * 255.0);
gfxFloat ab = (a * 255.0);
if (colorType == PACKED_ABGR) {
return (uint8_t(ab) << 24) |
(uint8_t(bb) << 16) |
(uint8_t(gb) << 8) |
(uint8_t(rb) << 0);
}
if (colorType == PACKED_ARGB || colorType == PACKED_XRGB) {
return (uint8_t(ab) << 24) |
(uint8_t(rb) << 16) |
(uint8_t(gb) << 8) |
(uint8_t(bb) << 0);
}
rb *= a;
gb *= a;
bb *= a;
if (colorType == PACKED_ABGR_PREMULTIPLIED) {
return (((uint8_t)(ab) << 24) |
((uint8_t)(bb) << 16) |
((uint8_t)(gb) << 8) |
((uint8_t)(rb) << 0));
}
if (colorType == PACKED_ARGB_PREMULTIPLIED) {
return (((uint8_t)(ab) << 24) |
((uint8_t)(rb) << 16) |
((uint8_t)(gb) << 8) |
((uint8_t)(bb) << 0));
}
return 0;
}
};
#endif /* _GFX_COLOR_H */