gecko-dev/gfx/thebes/public/gfxColor.h

206 строки
7.2 KiB
C

/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 4 -*-
* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is Oracle Corporation code.
*
* The Initial Developer of the Original Code is Oracle Corporation.
* Portions created by the Initial Developer are Copyright (C) 2005
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
* Stuart Parmenter <pavlov@pavlov.net>
*
* Alternatively, the contents of this file may be used under the terms of
* either the GNU General Public License Version 2 or later (the "GPL"), or
* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK ***** */
#ifndef GFX_COLOR_H
#define GFX_COLOR_H
#include "nsPrintfCString.h"
#include "gfxTypes.h"
/**
* Fast approximate division by 255. It has the property that
* for all 0 <= n <= 255*255, FAST_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 macro
*
* equivalent to (((c)*(a))/255)
*/
#define GFX_PREMULTIPLY(c,a) GFX_DIVIDE_BY_255((c)*(a))
/**
* Macro to pack the 4 8-bit channels (A,R,G,B)
* into a 32-bit packed premultiplied pixel.
*
* The checks for 0 alpha or max alpha ensure that the
* compiler selects the quicked calculation when alpha is constant.
*/
#define GFX_PACKED_PIXEL(a,r,g,b) \
((a) == 0x00) ? 0x00000000 : \
((a) == 0xFF) ? ((0xFF << 24) | ((r) << 16) | ((g) << 8) | (b)) \
: ((a) << 24) | \
(GFX_PREMULTIPLY(r,a) << 16) | \
(GFX_PREMULTIPLY(g,a) << 8) | \
(GFX_PREMULTIPLY(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 THEBES_API gfxRGBA {
gfxFloat r, g, b, a;
enum PackedColorType {
PACKED_ABGR,
PACKED_ABGR_PREMULTIPLIED,
PACKED_ARGB,
PACKED_ARGB_PREMULTIPLIED,
PACKED_XBGR,
PACKED_XRGB
};
gfxRGBA() { }
gfxRGBA(const gfxRGBA& c) : r(c.r), g(c.g), b(c.b), a(c.a) {}
/**
* Intialize this color using explicit red, green, blue and alpha
* values.
*/
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.
*
* @see gfxRGBA::Packed
*/
gfxRGBA(PRUint32 c, PackedColorType colorType = PACKED_ABGR) {
if (colorType == PACKED_ABGR ||
colorType == PACKED_XBGR ||
colorType == PACKED_ABGR_PREMULTIPLIED)
{
r = ((c >> 0) & 0xff) / 255.0;
g = ((c >> 8) & 0xff) / 255.0;
b = ((c >> 16) & 0xff) / 255.0;
a = ((c >> 24) & 0xff) / 255.0;
} else if (colorType == PACKED_ARGB ||
colorType == PACKED_XRGB ||
colorType == PACKED_ARGB_PREMULTIPLIED)
{
b = ((c >> 0) & 0xff) / 255.0;
g = ((c >> 8) & 0xff) / 255.0;
r = ((c >> 16) & 0xff) / 255.0;
a = ((c >> 24) & 0xff) / 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_XBGR ||
colorType == PACKED_XRGB)
{
a = 1.0;
}
}
/**
* Initialize this color by parsing the given string.
* XXX implement me!
*/
#if 0
gfxRGBA(const char* str) {
a = 1.0;
// if aString[0] is a #, parse it as hex
// if aString[0] is a letter, parse it as a color name
// if aString[0] is a number, parse it loosely as hex
}
#endif
/**
* Returns this color value as a packed 32-bit integer. This reconstructs
* the int32 based on the given colorType, always in the native byte order.
*/
PRUint32 Packed(PackedColorType colorType = PACKED_ABGR) const {
if (colorType == PACKED_ABGR || colorType == PACKED_XBGR) {
return (((PRUint8)(a * 255.0) << 24) |
((PRUint8)(b * 255.0) << 16) |
((PRUint8)(g * 255.0) << 8) |
((PRUint8)(r * 255.0)));
} else if (colorType == PACKED_ARGB || colorType == PACKED_XRGB) {
return (((PRUint8)(a * 255.0) << 24) |
((PRUint8)(r * 255.0) << 16) |
((PRUint8)(g * 255.0) << 8) |
((PRUint8)(b * 255.0)));
} else if (colorType == PACKED_ABGR_PREMULTIPLIED) {
return (((PRUint8)(a * 255.0) << 24) |
((PRUint8)((b*a) * 255.0) << 16) |
((PRUint8)((g*a) * 255.0) << 8) |
((PRUint8)((r*a) * 255.0)));
} else if (colorType == PACKED_ARGB_PREMULTIPLIED) {
return (((PRUint8)(a * 255.0) << 24) |
((PRUint8)((r*a) * 255.0) << 16) |
((PRUint8)((g*a) * 255.0) << 8) |
((PRUint8)((b*a) * 255.0)));
} else {
return 0;
}
}
/**
* Convert this color to a hex value. For example, for rgb(255,0,0),
* this will return FF0000.
*/
// XXX I'd really prefer to just have this return an nsACString
// Does this function even make sense, since we're just ignoring the alpha value?
void Hex(nsACString& result) const {
nsPrintfCString hex(8, "%02x%02x%02x", PRUint8(r*255.0), PRUint8(g*255.0), PRUint8(b*255.0));
result.Assign(hex);
}
};
#endif /* _GFX_COLOR_H */