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/*
* ColourUtils.h
*
* Copyright 2012 Stewart Hamilton-Arrandale.
* http://creativewax.co.uk
*
* Modified by Yannick Loriot.
* http://yannickloriot.com
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*
*/
#import <Foundation/Foundation.h>
typedef struct
{
double r; // percent
double g; // percent
double b; // percent
double a; // percent
} RGBA;
typedef struct
{
double h; // angle in degrees
double s; // percent
double v; // percent
} HSV;
@interface CCColourUtils : NSObject
#pragma mark - Constuctors - Initializers
#pragma mark - Public Methods
+ (HSV)HSVfromRGB:(RGBA)value;
+ (RGBA)RGBfromHSV:(HSV)value;
@end
/**
* ColourUtils.m
*
* Copyright 2012 Stewart Hamilton-Arrandale.
* http://creativewax.co.uk
*
* Modified by Yannick Loriot.
* http://yannickloriot.com
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*
*/
#import "CCColourUtils.h"
@implementation CCColourUtils
#pragma mark - Initialization
#pragma mark -
#pragma mark ColourUtils Public Methods
+ (HSV)HSVfromRGB:(RGBA)value
{
HSV out;
double min, max, delta;
min = value.r < value.g ? value.r : value.g;
min = min < value.b ? min : value.b;
max = value.r > value.g ? value.r : value.g;
max = max > value.b ? max : value.b;
out.v = max; // v
delta = max - min;
if( max > 0.0 )
{
out.s = (delta / max); // s
} else
{
// r = g = b = 0 // s = 0, v is undefined
out.s = 0.0;
out.h = NAN; // its now undefined
return out;
}
if( value.r >= max ) // > is bogus, just keeps compilor happy
{
out.h = ( value.g - value.b ) / delta; // between yellow & magenta
} else
{
if( value.g >= max )
out.h = 2.0 + ( value.b - value.r ) / delta; // between cyan & yellow
else
out.h = 4.0 + ( value.r - value.g ) / delta; // between magenta & cyan
}
out.h *= 60.0; // degrees
if( out.h < 0.0 )
out.h += 360.0;
return out;
}
+ (RGBA)RGBfromHSV:(HSV)value
{
double hh, p, q, t, ff;
long i;
RGBA out;
out.a = 1;
if (value.s <= 0.0) // < is bogus, just shuts up warnings
{
if (isnan(value.h)) // value.h == NAN
{
out.r = value.v;
out.g = value.v;
out.b = value.v;
return out;
}
// error - should never happen
out.r = 0.0;
out.g = 0.0;
out.b = 0.0;
return out;
}
hh = value.h;
if(hh >= 360.0) hh = 0.0;
hh /= 60.0;
i = (long)hh;
ff = hh - i;
p = value.v * (1.0 - value.s);
q = value.v * (1.0 - (value.s * ff));
t = value.v * (1.0 - (value.s * (1.0 - ff)));
switch(i)
{
case 0:
out.r = value.v;
out.g = t;
out.b = p;
break;
case 1:
out.r = q;
out.g = value.v;
out.b = p;
break;
case 2:
out.r = p;
out.g = value.v;
out.b = t;
break;
case 3:
out.r = p;
out.g = q;
out.b = value.v;
break;
case 4:
out.r = t;
out.g = p;
out.b = value.v;
break;
case 5:
default:
out.r = value.v;
out.g = p;
out.b = q;
break;
}
return out;
}
@end
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