gecko/layout/base/nsCSSColorUtils.cpp

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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
2012-05-21 04:12:37 -07:00
/* 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/. */
/* functions that manipulate colors */
#include "nsCSSColorUtils.h"
#include "nsDebug.h"
#include <math.h>
// Weird color computing code stolen from winfe which was stolen
// from the xfe which was written originally by Eric Bina. So there.
#define RED_LUMINOSITY 299
#define GREEN_LUMINOSITY 587
#define BLUE_LUMINOSITY 114
#define INTENSITY_FACTOR 25
#define LIGHT_FACTOR 0
#define LUMINOSITY_FACTOR 75
#define MAX_COLOR 255
#define COLOR_DARK_THRESHOLD 51
#define COLOR_LIGHT_THRESHOLD 204
#define COLOR_LITE_BS_FACTOR 45
#define COLOR_LITE_TS_FACTOR 70
#define COLOR_DARK_BS_FACTOR 30
#define COLOR_DARK_TS_FACTOR 50
#define LIGHT_GRAY NS_RGB(192, 192, 192)
#define DARK_GRAY NS_RGB(96, 96, 96)
#define WHITE NS_RGB(255, 255, 255)
#define BLACK NS_RGB(0, 0, 0)
#define MAX_BRIGHTNESS 254
#define MAX_DARKNESS 0
void NS_GetSpecial3DColors(nscolor aResult[2],
nscolor aBackgroundColor,
nscolor aBorderColor)
{
PRUint8 f0, f1;
PRUint8 r, g, b;
PRUint8 rb = NS_GET_R(aBorderColor);
PRUint8 gb = NS_GET_G(aBorderColor);
PRUint8 bb = NS_GET_B(aBorderColor);
PRUint8 a = NS_GET_A(aBorderColor);
// This needs to be optimized.
// Calculating background brightness again and again is
// a waste of time!!!. Just calculate it only once.
// .....somehow!!!
PRUint8 red = NS_GET_R(aBackgroundColor);
PRUint8 green = NS_GET_G(aBackgroundColor);
PRUint8 blue = NS_GET_B(aBackgroundColor);
PRUint8 elementBrightness = NS_GetBrightness(rb,gb,bb);
PRUint8 backgroundBrightness = NS_GetBrightness(red, green, blue);
if (backgroundBrightness < COLOR_DARK_THRESHOLD) {
f0 = COLOR_DARK_BS_FACTOR;
f1 = COLOR_DARK_TS_FACTOR;
if(elementBrightness == MAX_DARKNESS)
{
rb = NS_GET_R(DARK_GRAY);
gb = NS_GET_G(DARK_GRAY);
bb = NS_GET_B(DARK_GRAY);
}
}else if (backgroundBrightness > COLOR_LIGHT_THRESHOLD) {
f0 = COLOR_LITE_BS_FACTOR;
f1 = COLOR_LITE_TS_FACTOR;
if(elementBrightness == MAX_BRIGHTNESS)
{
rb = NS_GET_R(LIGHT_GRAY);
gb = NS_GET_G(LIGHT_GRAY);
bb = NS_GET_B(LIGHT_GRAY);
}
}else {
f0 = COLOR_DARK_BS_FACTOR +
(backgroundBrightness *
(COLOR_LITE_BS_FACTOR - COLOR_DARK_BS_FACTOR) / MAX_COLOR);
f1 = COLOR_DARK_TS_FACTOR +
(backgroundBrightness *
(COLOR_LITE_TS_FACTOR - COLOR_DARK_TS_FACTOR) / MAX_COLOR);
}
r = rb - (f0 * rb / 100);
g = gb - (f0 * gb / 100);
b = bb - (f0 * bb / 100);
aResult[0] = NS_RGBA(r, g, b, a);
r = rb + (f1 * (MAX_COLOR - rb) / 100);
g = gb + (f1 * (MAX_COLOR - gb) / 100);
b = bb + (f1 * (MAX_COLOR - bb) / 100);
aResult[1] = NS_RGBA(r, g, b, a);
}
int NS_GetBrightness(PRUint8 aRed, PRUint8 aGreen, PRUint8 aBlue)
{
PRUint8 intensity = (aRed + aGreen + aBlue) / 3;
PRUint8 luminosity = NS_GetLuminosity(NS_RGB(aRed, aGreen, aBlue)) / 1000;
return ((intensity * INTENSITY_FACTOR) +
(luminosity * LUMINOSITY_FACTOR)) / 100;
}
PRInt32 NS_GetLuminosity(nscolor aColor)
{
// When aColor is not opaque, the perceived luminosity will depend
// on what color(s) aColor is ultimately drawn on top of, which we
// do not know.
NS_ASSERTION(NS_GET_A(aColor) == 255,
"impossible to compute luminosity of a non-opaque color");
return (NS_GET_R(aColor) * RED_LUMINOSITY +
NS_GET_G(aColor) * GREEN_LUMINOSITY +
NS_GET_B(aColor) * BLUE_LUMINOSITY);
}
// Function to convert RGB color space into the HSV colorspace
// Hue is the primary color defined from 0 to 359 degrees
// Saturation is defined from 0 to 255. The higher the number.. the deeper
// the color Value is the brightness of the color. 0 is black, 255 is white.
void NS_RGB2HSV(nscolor aColor, PRUint16 &aHue, PRUint16 &aSat,
PRUint16 &aValue, PRUint8 &aAlpha)
{
PRUint8 r, g, b;
PRInt16 delta, min, max, r1, b1, g1;
float hue;
r = NS_GET_R(aColor);
g = NS_GET_G(aColor);
b = NS_GET_B(aColor);
if (r>g) {
max = r;
min = g;
} else {
max = g;
min = r;
}
if (b>max) {
max = b;
}
if (b<min) {
min = b;
}
// value or brightness will always be the max of all the colors(RGB)
aValue = max;
delta = max-min;
aSat = (max!=0)?((delta*255)/max):0;
r1 = r;
b1 = b;
g1 = g;
if (aSat==0) {
hue = 1000;
} else {
if(r==max){
hue=(float)(g1-b1)/(float)delta;
} else if (g1==max) {
hue= 2.0f+(float)(b1-r1)/(float)delta;
} else {
hue = 4.0f+(float)(r1-g1)/(float)delta;
}
}
if(hue<999) {
hue*=60;
if(hue<0){
hue+=360;
}
} else {
hue=0;
}
aHue = (PRUint16)hue;
aAlpha = NS_GET_A(aColor);
}
// Function to convert HSV color space into the RGB colorspace
// Hue is the primary color defined from 0 to 359 degrees
// Saturation is defined from 0 to 255. The higher the number.. the deeper
// the color Value is the brightness of the color. 0 is black, 255 is white.
void NS_HSV2RGB(nscolor &aColor, PRUint16 aHue, PRUint16 aSat, PRUint16 aValue,
PRUint8 aAlpha)
{
PRUint16 r = 0, g = 0, b = 0;
PRUint16 i, p, q, t;
double h, f, percent;
if ( aSat == 0 ){
// achromatic color, no hue is defined
r = aValue;
g = aValue;
b = aValue;
} else {
// hue in in degrees around the color wheel defined from
// 0 to 360 degrees.
if (aHue >= 360) {
aHue = 0;
}
// we break the color wheel into 6 areas.. these
// areas define how the saturation and value define the color.
// reds behave differently than the blues
h = (double)aHue / 60.0;
i = (PRUint16) floor(h);
f = h-(double)i;
percent = ((double)aValue/255.0); // this needs to be a value from 0 to 1, so a percentage
// can be calculated of the saturation.
p = (PRUint16)(percent*(255-aSat));
q = (PRUint16)(percent*(255-(aSat*f)));
t = (PRUint16)(percent*(255-(aSat*(1.0-f))));
// i is guaranteed to never be larger than 5.
switch(i){
case 0: r = aValue; g = t; b = p;break;
case 1: r = q; g = aValue; b = p;break;
case 2: r = p; g = aValue; b = t;break;
case 3: r = p; g = q; b = aValue;break;
case 4: r = t; g = p; b = aValue;break;
case 5: r = aValue; g = p; b = q;break;
}
}
aColor = NS_RGBA(r, g, b, aAlpha);
}