124 lines
4.3 KiB
C++
124 lines
4.3 KiB
C++
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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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 nsColor_h___
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#define nsColor_h___
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#include <stddef.h> // for size_t
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#include <stdint.h> // for uint8_t, uint32_t
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#include "nscore.h" // for nsAString
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#include "nsCoord.h" // for NSToIntRound
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class nsAString;
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class nsString;
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// A color is a 32 bit unsigned integer with four components: R, G, B
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// and A.
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typedef uint32_t nscolor;
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// Make a color out of r,g,b values. This assumes that the r,g,b values are
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// properly constrained to 0-255. This also assumes that a is 255.
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#define NS_RGB(_r,_g,_b) \
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((nscolor) ((255 << 24) | ((_b)<<16) | ((_g)<<8) | (_r)))
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// Make a color out of r,g,b,a values. This assumes that the r,g,b,a
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// values are properly constrained to 0-255.
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#define NS_RGBA(_r,_g,_b,_a) \
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((nscolor) (((_a) << 24) | ((_b)<<16) | ((_g)<<8) | (_r)))
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// Extract color components from nscolor
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#define NS_GET_R(_rgba) ((uint8_t) ((_rgba) & 0xff))
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#define NS_GET_G(_rgba) ((uint8_t) (((_rgba) >> 8) & 0xff))
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#define NS_GET_B(_rgba) ((uint8_t) (((_rgba) >> 16) & 0xff))
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#define NS_GET_A(_rgba) ((uint8_t) (((_rgba) >> 24) & 0xff))
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namespace mozilla {
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template<typename T>
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inline uint8_t ClampColor(T aColor)
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{
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if (aColor >= 255) {
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return 255;
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}
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if (aColor <= 0) {
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return 0;
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}
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return NSToIntRound(aColor);
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}
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} // namespace mozilla
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// Fast approximate division by 255. It has the property that
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// for all 0 <= n <= 255*255, FAST_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 target=v/255
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#define FAST_DIVIDE_BY_255(target,v) \
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PR_BEGIN_MACRO \
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unsigned tmp_ = v; \
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target = ((tmp_ << 8) + tmp_ + 255) >> 16; \
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PR_END_MACRO
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enum class nsHexColorType : uint8_t {
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NoAlpha, // 3 or 6 digit hex colors only
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AllowAlpha, // 3, 4, 6, or 8 digit hex colors
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};
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// Translate a hex string to a color. Return true if it parses ok,
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// otherwise return false.
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// This accepts the number of digits specified by aType.
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bool
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NS_HexToRGBA(const nsAString& aBuf, nsHexColorType aType, nscolor* aResult);
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// Compose one NS_RGB color onto another. The result is what
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// you get if you draw aFG on top of aBG with operator OVER.
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nscolor NS_ComposeColors(nscolor aBG, nscolor aFG);
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namespace mozilla {
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inline uint32_t RoundingDivideBy255(uint32_t n)
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{
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// There is an approximate alternative: ((n << 8) + n + 32896) >> 16
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// But that is actually slower than this simple expression on a modern
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// machine with a modern compiler.
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return (n + 127) / 255;
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}
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// Blend one RGBA color with another based on a given ratio.
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// It is a linear interpolation on each channel with alpha premultipled.
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nscolor LinearBlendColors(nscolor aBg, nscolor aFg, uint_fast8_t aFgRatio);
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} // namespace mozilla
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// Translate a hex string to a color. Return true if it parses ok,
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// otherwise return false.
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// This version accepts 1 to 9 digits (missing digits are 0)
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bool NS_LooseHexToRGB(const nsString& aBuf, nscolor* aResult);
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// There is no function to translate a color to a hex string, because
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// the hex-string syntax does not support transparency.
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// Translate a color name to a color. Return true if it parses ok,
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// otherwise return false.
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bool NS_ColorNameToRGB(const nsAString& aBuf, nscolor* aResult);
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// Returns an array of all possible color names, and sets
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// *aSizeArray to the size of that array. Do NOT call |free()| on this array.
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const char * const * NS_AllColorNames(size_t *aSizeArray);
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// function to convert from HSL color space to RGB color space
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// the float parameters are all expected to be in the range 0-1
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nscolor NS_HSL2RGB(float h, float s, float l);
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// Return a color name for the given nscolor. If there is no color
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// name for it, returns null. If there are multiple possible color
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// names for the given color, the first one in nsColorNameList.h
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// (which is generally the first one in alphabetical order) will be
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// returned.
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const char* NS_RGBToColorName(nscolor aColor);
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#endif /* nsColor_h___ */
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