gecko-dev/gfx/public/nsColor.h

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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* ***** 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 mozilla.org code.
*
* The Initial Developer of the Original Code is
* Netscape Communications Corporation.
* Portions created by the Initial Developer are Copyright (C) 1998
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
*
* Alternatively, the contents of this file may be used under the terms of
* either of 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
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* the provisions above, a recipient may use your version of this file under
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* ***** END LICENSE BLOCK ***** */
#ifndef nsColor_h___
#define nsColor_h___
#include "gfxCore.h"
#include "nscore.h"
class nsAString;
class nsString;
class nsCString;
// A color is a 32 bit unsigned integer with four components: R, G, B
// and A.
typedef PRUint32 nscolor;
// Make a color out of r,g,b values. This assumes that the r,g,b values are
// properly constrained to 0-255. This also assumes that a is 255.
#define NS_RGB(_r,_g,_b) \
((nscolor) ((255 << 24) | ((_b)<<16) | ((_g)<<8) | (_r)))
// Make a color out of r,g,b,a values. This assumes that the r,g,b,a
// values are properly constrained to 0-255.
#define NS_RGBA(_r,_g,_b,_a) \
((nscolor) (((_a) << 24) | ((_b)<<16) | ((_g)<<8) | (_r)))
// Extract color components from nscolor
#define NS_GET_R(_rgba) ((PRUint8) ((_rgba) & 0xff))
#define NS_GET_G(_rgba) ((PRUint8) (((_rgba) >> 8) & 0xff))
#define NS_GET_B(_rgba) ((PRUint8) (((_rgba) >> 16) & 0xff))
#define NS_GET_A(_rgba) ((PRUint8) (((_rgba) >> 24) & 0xff))
// 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 target=v/255
#define FAST_DIVIDE_BY_255(target,v) \
PR_BEGIN_MACRO \
unsigned tmp_ = v; \
target = ((tmp_ << 8) + tmp_ + 255) >> 16; \
PR_END_MACRO
// Blending macro
//
// equivalent to target=(bg*(255-alpha)+fg*alpha)/255
#define MOZ_BLEND(target, bg, fg, alpha) \
FAST_DIVIDE_BY_255(target, (bg)*(255-(alpha)) + (fg)*(alpha))
// Translate a hex string to a color. Return true if it parses ok,
// otherwise return false.
// This accepts only 3 or 6 digits
NS_GFX_(PRBool) NS_HexToRGB(const nsString& aBuf, nscolor* aResult);
// Compose one NS_RGB color onto another. The result is what you get
// if you draw aBG onto RGBA(0,0,0,0) and then aFG on top of that,
// with operator OVER.
NS_GFX_(nscolor) NS_ComposeColors(nscolor aBG, nscolor aFG);
// Translate a hex string to a color. Return true if it parses ok,
// otherwise return false.
// This version accepts 1 to 9 digits (missing digits are 0)
NS_GFX_(PRBool) NS_LooseHexToRGB(const nsString& aBuf, nscolor* aResult);
// Translate a color to a hex string and prepend a '#'.
// The returned string is always 7 characters including a '#' character.
NS_GFX_(void) NS_RGBToHex(nscolor aColor, nsAString& aResult);
// Translate a color name to a color. Return true if it parses ok,
// otherwise return false.
NS_GFX_(PRBool) NS_ColorNameToRGB(const nsAString& aBuf, nscolor* aResult);
// function to convert from HSL color space to RGB color space
// the float parameters are all expected to be in the range 0-1
NS_GFX_(nscolor) NS_HSL2RGB(float h, float s, float l);
#endif /* nsColor_h___ */