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transmission/macosx/CTGradient/CTGradient.m

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//
// CTGradient.m
//
// Created by Chad Weider on 2/14/07.
// Writtin by Chad Weider.
//
// Released into public domain on 4/10/08.
//
// Version: 1.8
#import "CTGradient.h"
@interface CTGradient (Private)
- (void)_commonInit;
- (void)setBlendingMode:(CTGradientBlendingMode)mode;
- (void)addElement:(CTGradientElement*)newElement;
- (CTGradientElement *)elementAtIndex:(unsigned)index;
- (CTGradientElement)removeElementAtIndex:(unsigned)index;
- (CTGradientElement)removeElementAtPosition:(float)position;
@end
//C Fuctions for color blending
static void linearEvaluation (void *info, const float *in, float *out);
static void chromaticEvaluation(void *info, const float *in, float *out);
static void inverseChromaticEvaluation(void *info, const float *in, float *out);
static void transformRGB_HSV(float *components);
static void transformHSV_RGB(float *components);
static void resolveHSV(float *color1, float *color2);
@implementation CTGradient
/////////////////////////////////////Initialization Type Stuff
- (id)init
{
self = [super init];
if (self != nil)
{
[self _commonInit];
[self setBlendingMode:CTLinearBlendingMode];
}
return self;
}
- (void)_commonInit
{
elementList = nil;
}
- (void)dealloc
{
CGFunctionRelease(gradientFunction);
CTGradientElement *elementToRemove = elementList;
while(elementList != nil)
{
elementToRemove = elementList;
elementList = elementList->nextElement;
free(elementToRemove);
}
[super dealloc];
}
- (id)copyWithZone:(NSZone *)zone
{
CTGradient *copy = [[[self class] allocWithZone:zone] init];
//now just copy my elementlist
CTGradientElement *currentElement = elementList;
while(currentElement != nil)
{
[copy addElement:currentElement];
currentElement = currentElement->nextElement;
}
[copy setBlendingMode:blendingMode];
return copy;
}
- (void)encodeWithCoder:(NSCoder *)coder
{
if([coder allowsKeyedCoding])
{
unsigned count = 0;
CTGradientElement *currentElement = elementList;
while(currentElement != nil)
{
[coder encodeValueOfObjCType:@encode(float) at:&(currentElement->red)];
[coder encodeValueOfObjCType:@encode(float) at:&(currentElement->green)];
[coder encodeValueOfObjCType:@encode(float) at:&(currentElement->blue)];
[coder encodeValueOfObjCType:@encode(float) at:&(currentElement->alpha)];
[coder encodeValueOfObjCType:@encode(float) at:&(currentElement->position)];
count++;
currentElement = currentElement->nextElement;
}
[coder encodeInt:count forKey:@"CTGradientElementCount"];
[coder encodeInt:blendingMode forKey:@"CTGradientBlendingMode"];
}
else
[NSException raise:NSInvalidArchiveOperationException format:@"Only supports NSKeyedArchiver coders"];
}
- (id)initWithCoder:(NSCoder *)coder
{
[self _commonInit];
[self setBlendingMode:[coder decodeIntForKey:@"CTGradientBlendingMode"]];
unsigned count = [coder decodeIntForKey:@"CTGradientElementCount"];
while(count != 0)
{
CTGradientElement newElement;
[coder decodeValueOfObjCType:@encode(float) at:&(newElement.red)];
[coder decodeValueOfObjCType:@encode(float) at:&(newElement.green)];
[coder decodeValueOfObjCType:@encode(float) at:&(newElement.blue)];
[coder decodeValueOfObjCType:@encode(float) at:&(newElement.alpha)];
[coder decodeValueOfObjCType:@encode(float) at:&(newElement.position)];
count--;
[self addElement:&newElement];
}
return self;
}
#pragma mark -
#pragma mark Creation
+ (id)gradientWithBeginningColor:(NSColor *)begin endingColor:(NSColor *)end
{
id newInstance = [[[self class] alloc] init];
CTGradientElement color1;
CTGradientElement color2;
[[begin colorUsingColorSpaceName:NSCalibratedRGBColorSpace] getRed:&color1.red
green:&color1.green
blue:&color1.blue
alpha:&color1.alpha];
[[end colorUsingColorSpaceName:NSCalibratedRGBColorSpace] getRed:&color2.red
green:&color2.green
blue:&color2.blue
alpha:&color2.alpha];
color1.position = 0;
color2.position = 1;
[newInstance addElement:&color1];
[newInstance addElement:&color2];
return [newInstance autorelease];
}
+ (id)aquaSelectedGradient
{
id newInstance = [[[self class] alloc] init];
CTGradientElement color1;
color1.red = 0.58;
color1.green = 0.86;
color1.blue = 0.98;
color1.alpha = 1.00;
color1.position = 0;
CTGradientElement color2;
color2.red = 0.42;
color2.green = 0.68;
color2.blue = 0.90;
color2.alpha = 1.00;
color2.position = 11.5/23;
CTGradientElement color3;
color3.red = 0.64;
color3.green = 0.80;
color3.blue = 0.94;
color3.alpha = 1.00;
color3.position = 11.5/23;
CTGradientElement color4;
color4.red = 0.56;
color4.green = 0.70;
color4.blue = 0.90;
color4.alpha = 1.00;
color4.position = 1;
[newInstance addElement:&color1];
[newInstance addElement:&color2];
[newInstance addElement:&color3];
[newInstance addElement:&color4];
return [newInstance autorelease];
}
+ (id)aquaNormalGradient
{
id newInstance = [[[self class] alloc] init];
CTGradientElement color1;
color1.red = color1.green = color1.blue = 0.95;
color1.alpha = 1.00;
color1.position = 0;
CTGradientElement color2;
color2.red = color2.green = color2.blue = 0.83;
color2.alpha = 1.00;
color2.position = 11.5/23;
CTGradientElement color3;
color3.red = color3.green = color3.blue = 0.95;
color3.alpha = 1.00;
color3.position = 11.5/23;
CTGradientElement color4;
color4.red = color4.green = color4.blue = 0.92;
color4.alpha = 1.00;
color4.position = 1;
[newInstance addElement:&color1];
[newInstance addElement:&color2];
[newInstance addElement:&color3];
[newInstance addElement:&color4];
return [newInstance autorelease];
}
+ (id)aquaPressedGradient
{
id newInstance = [[[self class] alloc] init];
CTGradientElement color1;
color1.red = color1.green = color1.blue = 0.80;
color1.alpha = 1.00;
color1.position = 0;
CTGradientElement color2;
color2.red = color2.green = color2.blue = 0.64;
color2.alpha = 1.00;
color2.position = 11.5/23;
CTGradientElement color3;
color3.red = color3.green = color3.blue = 0.80;
color3.alpha = 1.00;
color3.position = 11.5/23;
CTGradientElement color4;
color4.red = color4.green = color4.blue = 0.77;
color4.alpha = 1.00;
color4.position = 1;
[newInstance addElement:&color1];
[newInstance addElement:&color2];
[newInstance addElement:&color3];
[newInstance addElement:&color4];
return [newInstance autorelease];
}
+ (id)unifiedSelectedGradient
{
id newInstance = [[[self class] alloc] init];
CTGradientElement color1;
color1.red = color1.green = color1.blue = 0.85;
color1.alpha = 1.00;
color1.position = 0;
CTGradientElement color2;
color2.red = color2.green = color2.blue = 0.95;
color2.alpha = 1.00;
color2.position = 1;
[newInstance addElement:&color1];
[newInstance addElement:&color2];
return [newInstance autorelease];
}
+ (id)unifiedNormalGradient
{
id newInstance = [[[self class] alloc] init];
CTGradientElement color1;
color1.red = color1.green = color1.blue = 0.75;
color1.alpha = 1.00;
color1.position = 0;
CTGradientElement color2;
color2.red = color2.green = color2.blue = 0.90;
color2.alpha = 1.00;
color2.position = 1;
[newInstance addElement:&color1];
[newInstance addElement:&color2];
return [newInstance autorelease];
}
+ (id)unifiedPressedGradient
{
id newInstance = [[[self class] alloc] init];
CTGradientElement color1;
color1.red = color1.green = color1.blue = 0.60;
color1.alpha = 1.00;
color1.position = 0;
CTGradientElement color2;
color2.red = color2.green = color2.blue = 0.75;
color2.alpha = 1.00;
color2.position = 1;
[newInstance addElement:&color1];
[newInstance addElement:&color2];
return [newInstance autorelease];
}
+ (id)unifiedDarkGradient
{
id newInstance = [[[self class] alloc] init];
CTGradientElement color1;
color1.red = color1.green = color1.blue = 0.68;
color1.alpha = 1.00;
color1.position = 0;
CTGradientElement color2;
color2.red = color2.green = color2.blue = 0.83;
color2.alpha = 1.00;
color2.position = 1;
[newInstance addElement:&color1];
[newInstance addElement:&color2];
return [newInstance autorelease];
}
+ (id)sourceListSelectedGradient
{
id newInstance = [[[self class] alloc] init];
CTGradientElement color1;
color1.red = 0.06;
color1.green = 0.37;
color1.blue = 0.85;
color1.alpha = 1.00;
color1.position = 0;
CTGradientElement color2;
color2.red = 0.30;
color2.green = 0.60;
color2.blue = 0.92;
color2.alpha = 1.00;
color2.position = 1;
[newInstance addElement:&color1];
[newInstance addElement:&color2];
return [newInstance autorelease];
}
+ (id)sourceListUnselectedGradient
{
id newInstance = [[[self class] alloc] init];
CTGradientElement color1;
color1.red = 0.43;
color1.green = 0.43;
color1.blue = 0.43;
color1.alpha = 1.00;
color1.position = 0;
CTGradientElement color2;
color2.red = 0.60;
color2.green = 0.60;
color2.blue = 0.60;
color2.alpha = 1.00;
color2.position = 1;
[newInstance addElement:&color1];
[newInstance addElement:&color2];
return [newInstance autorelease];
}
+ (id)rainbowGradient
{
id newInstance = [[[self class] alloc] init];
CTGradientElement color1;
color1.red = 1.00;
color1.green = 0.00;
color1.blue = 0.00;
color1.alpha = 1.00;
color1.position = 0.0;
CTGradientElement color2;
color2.red = 0.54;
color2.green = 0.00;
color2.blue = 1.00;
color2.alpha = 1.00;
color2.position = 1.0;
[newInstance addElement:&color1];
[newInstance addElement:&color2];
[newInstance setBlendingMode:CTChromaticBlendingMode];
return [newInstance autorelease];
}
+ (id)hydrogenSpectrumGradient
{
id newInstance = [[[self class] alloc] init];
struct {float hue; float position; float width;} colorBands[4];
colorBands[0].hue = 22;
colorBands[0].position = .145;
colorBands[0].width = .01;
colorBands[1].hue = 200;
colorBands[1].position = .71;
colorBands[1].width = .008;
colorBands[2].hue = 253;
colorBands[2].position = .885;
colorBands[2].width = .005;
colorBands[3].hue = 275;
colorBands[3].position = .965;
colorBands[3].width = .003;
int i;
/////////////////////////////
for(i = 0; i < 4; i++)
{
float color[4];
color[0] = colorBands[i].hue - 180*colorBands[i].width;
color[1] = 1;
color[2] = 0.001;
color[3] = 1;
transformHSV_RGB(color);
CTGradientElement fadeIn;
fadeIn.red = color[0];
fadeIn.green = color[1];
fadeIn.blue = color[2];
fadeIn.alpha = color[3];
fadeIn.position = colorBands[i].position - colorBands[i].width;
color[0] = colorBands[i].hue;
color[1] = 1;
color[2] = 1;
color[3] = 1;
transformHSV_RGB(color);
CTGradientElement band;
band.red = color[0];
band.green = color[1];
band.blue = color[2];
band.alpha = color[3];
band.position = colorBands[i].position;
color[0] = colorBands[i].hue + 180*colorBands[i].width;
color[1] = 1;
color[2] = 0.001;
color[3] = 1;
transformHSV_RGB(color);
CTGradientElement fadeOut;
fadeOut.red = color[0];
fadeOut.green = color[1];
fadeOut.blue = color[2];
fadeOut.alpha = color[3];
fadeOut.position = colorBands[i].position + colorBands[i].width;
[newInstance addElement:&fadeIn];
[newInstance addElement:&band];
[newInstance addElement:&fadeOut];
}
[newInstance setBlendingMode:CTChromaticBlendingMode];
return [newInstance autorelease];
}
#pragma mark -
#pragma mark Modification
- (CTGradient *)gradientWithAlphaComponent:(float)alpha
{
id newInstance = [[[self class] alloc] init];
CTGradientElement *curElement = elementList;
CTGradientElement tempElement;
while(curElement != nil)
{
tempElement = *curElement;
tempElement.alpha = alpha;
[newInstance addElement:&tempElement];
curElement = curElement->nextElement;
}
return [newInstance autorelease];
}
- (CTGradient *)gradientWithBlendingMode:(CTGradientBlendingMode)mode
{
CTGradient *newGradient = [self copy];
[newGradient setBlendingMode:mode];
return [newGradient autorelease];
}
//Adds a color stop with <color> at <position> in elementList
//(if two elements are at the same position then added imediatly after the one that was there already)
- (CTGradient *)addColorStop:(NSColor *)color atPosition:(float)position
{
CTGradient *newGradient = [self copy];
CTGradientElement newGradientElement;
//put the components of color into the newGradientElement - must make sure it is a RGB color (not Gray or CMYK)
[[color colorUsingColorSpaceName:NSCalibratedRGBColorSpace] getRed:&newGradientElement.red
green:&newGradientElement.green
blue:&newGradientElement.blue
alpha:&newGradientElement.alpha];
newGradientElement.position = position;
//Pass it off to addElement to take care of adding it to the elementList
[newGradient addElement:&newGradientElement];
return [newGradient autorelease];
}
//Removes the color stop at <position> from elementList
- (CTGradient *)removeColorStopAtPosition:(float)position
{
CTGradient *newGradient = [self copy];
CTGradientElement removedElement = [newGradient removeElementAtPosition:position];
if(isnan(removedElement.position))
[NSException raise:NSRangeException format:@"-[%@ removeColorStopAtPosition:]: no such colorStop at position (%f)", [self class], position];
return [newGradient autorelease];
}
- (CTGradient *)removeColorStopAtIndex:(unsigned)index
{
CTGradient *newGradient = [self copy];
CTGradientElement removedElement = [newGradient removeElementAtIndex:index];
if(isnan(removedElement.position))
[NSException raise:NSRangeException format:@"-[%@ removeColorStopAtIndex:]: index (%i) beyond bounds", [self class], index];
return [newGradient autorelease];
}
#pragma mark -
#pragma mark Information
- (CTGradientBlendingMode)blendingMode
{
return blendingMode;
}
//Returns color at <position> in gradient
- (NSColor *)colorStopAtIndex:(unsigned)index
{
CTGradientElement *element = [self elementAtIndex:index];
if(element != nil)
return [NSColor colorWithCalibratedRed:element->red
green:element->green
blue:element->blue
alpha:element->alpha];
[NSException raise:NSRangeException format:@"-[%@ removeColorStopAtIndex:]: index (%i) beyond bounds", [self class], index];
return nil;
}
- (NSColor *)colorAtPosition:(float)position
{
float components[4];
switch(blendingMode)
{
case CTLinearBlendingMode:
linearEvaluation(&elementList, &position, components); break;
case CTChromaticBlendingMode:
chromaticEvaluation(&elementList, &position, components); break;
case CTInverseChromaticBlendingMode:
inverseChromaticEvaluation(&elementList, &position, components); break;
}
return [NSColor colorWithCalibratedRed:components[0]/components[3] //undo premultiplication that CG requires
green:components[1]/components[3]
blue:components[2]/components[3]
alpha:components[3]];
}
#pragma mark -
#pragma mark Drawing
- (void)drawSwatchInRect:(NSRect)rect
{
[self fillRect:rect angle:45];
}
- (void)fillRect:(NSRect)rect angle:(float)angle
{
//First Calculate where the beginning and ending points should be
CGPoint startPoint;
CGPoint endPoint;
if(angle == 0) //screw the calculations - we know the answer
{
startPoint = CGPointMake(NSMinX(rect), NSMinY(rect)); //right of rect
endPoint = CGPointMake(NSMaxX(rect), NSMinY(rect)); //left of rect
}
else if(angle == 90) //same as above
{
startPoint = CGPointMake(NSMinX(rect), NSMinY(rect)); //bottom of rect
endPoint = CGPointMake(NSMinX(rect), NSMaxY(rect)); //top of rect
}
else //ok, we'll do the calculations now
{
float x,y;
float sina, cosa, tana;
float length;
float deltax,
deltay;
float rangle = angle * pi/180; //convert the angle to radians
if(fabsf(tan(rangle))<=1) //for range [-45,45], [135,225]
{
x = NSWidth(rect);
y = NSHeight(rect);
sina = sin(rangle);
cosa = cos(rangle);
tana = tan(rangle);
length = x/fabsf(cosa)+(y-x*fabsf(tana))*fabsf(sina);
deltax = length*cosa/2;
deltay = length*sina/2;
}
else //for range [45,135], [225,315]
{
x = NSHeight(rect);
y = NSWidth(rect);
sina = sin(rangle - 90*pi/180);
cosa = cos(rangle - 90*pi/180);
tana = tan(rangle - 90*pi/180);
length = x/fabsf(cosa)+(y-x*fabsf(tana))*fabsf(sina);
deltax =-length*sina/2;
deltay = length*cosa/2;
}
startPoint = CGPointMake(NSMidX(rect)-deltax, NSMidY(rect)-deltay);
endPoint = CGPointMake(NSMidX(rect)+deltax, NSMidY(rect)+deltay);
}
//Calls to CoreGraphics
CGContextRef currentContext = (CGContextRef)[[NSGraphicsContext currentContext] graphicsPort];
CGContextSaveGState(currentContext);
#if MAC_OS_X_VERSION_MIN_REQUIRED >= MAC_OS_X_VERSION_10_4
CGColorSpaceRef colorspace = CGColorSpaceCreateWithName(kCGColorSpaceGenericRGB);
#else
CGColorSpaceRef colorspace = CGColorSpaceCreateDeviceRGB();
#endif
CGShadingRef myCGShading = CGShadingCreateAxial(colorspace, startPoint, endPoint, gradientFunction, false, false);
CGContextClipToRect (currentContext, *(CGRect *)&rect); //This is where the action happens
CGContextDrawShading(currentContext, myCGShading);
CGShadingRelease(myCGShading);
CGColorSpaceRelease(colorspace );
CGContextRestoreGState(currentContext);
}
- (void)radialFillRect:(NSRect)rect
{
CGPoint startPoint, endPoint;
float startRadius, endRadius;
float scalex, scaley, transx, transy;
startPoint = endPoint = CGPointMake(NSMidX(rect), NSMidY(rect));
startRadius = -1;
if(NSHeight(rect)>NSWidth(rect))
{
scalex = NSWidth(rect)/NSHeight(rect);
transx = (NSHeight(rect)-NSWidth(rect))/2;
scaley = 1;
transy = 1;
endRadius = NSHeight(rect)/2;
}
else
{
scalex = 1;
transx = 1;
scaley = NSHeight(rect)/NSWidth(rect);
transy = (NSWidth(rect)-NSHeight(rect))/2;
endRadius = NSWidth(rect)/2;
}
//Calls to CoreGraphics
CGContextRef currentContext = (CGContextRef)[[NSGraphicsContext currentContext] graphicsPort];
CGContextSaveGState(currentContext);
#if MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_X_VERSION_10_4
CGColorSpaceRef colorspace = CGColorSpaceCreateWithName(kCGColorSpaceGenericRGB);
#else
CGColorSpaceRef colorspace = CGColorSpaceCreateDeviceRGB();
#endif
CGShadingRef myCGShading = CGShadingCreateRadial(colorspace, startPoint, startRadius, endPoint, endRadius, gradientFunction, true, true);
CGContextClipToRect (currentContext, *(CGRect *)&rect);
CGContextScaleCTM (currentContext, scalex, scaley);
CGContextTranslateCTM(currentContext, transx, transy);
CGContextDrawShading (currentContext, myCGShading); //This is where the action happens
CGShadingRelease(myCGShading);
CGColorSpaceRelease(colorspace);
CGContextRestoreGState(currentContext);
}
- (void)fillBezierPath:(NSBezierPath *)path angle:(float)angle
{
NSGraphicsContext *currentContext = [NSGraphicsContext currentContext];
[currentContext saveGraphicsState];
NSAffineTransform *transform = [[NSAffineTransform alloc] init];
[transform rotateByDegrees:-angle];
[path transformUsingAffineTransform:transform];
[transform invert];
[transform concat];
[path addClip];
[self fillRect:[path bounds] angle:0];
[path transformUsingAffineTransform:transform];
[transform release];
[currentContext restoreGraphicsState];
}
- (void)radialFillBezierPath:(NSBezierPath *)path
{
NSGraphicsContext *currentContext = [NSGraphicsContext currentContext];
[currentContext saveGraphicsState];
[path addClip];
[self radialFillRect:[path bounds]];
[currentContext restoreGraphicsState];
}
#pragma mark -
#pragma mark Private Methods
- (void)setBlendingMode:(CTGradientBlendingMode)mode;
{
blendingMode = mode;
//Choose what blending function to use
void *evaluationFunction;
switch(blendingMode)
{
case CTLinearBlendingMode:
evaluationFunction = &linearEvaluation; break;
case CTChromaticBlendingMode:
evaluationFunction = &chromaticEvaluation; break;
case CTInverseChromaticBlendingMode:
evaluationFunction = &inverseChromaticEvaluation; break;
}
//replace the current CoreGraphics Function with new one
if(gradientFunction != NULL)
CGFunctionRelease(gradientFunction);
CGFunctionCallbacks evaluationCallbackInfo = {0 , evaluationFunction, NULL}; //Version, evaluator function, cleanup function
static const float input_value_range [2] = { 0, 1 }; //range for the evaluator input
static const float output_value_ranges [8] = { 0, 1, 0, 1, 0, 1, 0, 1 }; //ranges for the evaluator output (4 returned values)
gradientFunction = CGFunctionCreate(&elementList, //the two transition colors
1, input_value_range , //number of inputs (just fraction of progression)
4, output_value_ranges, //number of outputs (4 - RGBa)
&evaluationCallbackInfo); //info for using the evaluator function
}
- (void)addElement:(CTGradientElement *)newElement
{
if(elementList == nil || newElement->position < elementList->position) //inserting at beginning of list
{
CTGradientElement *tmpNext = elementList;
elementList = malloc(sizeof(CTGradientElement));
*elementList = *newElement;
elementList->nextElement = tmpNext;
}
else //inserting somewhere inside list
{
CTGradientElement *curElement = elementList;
while(curElement->nextElement != nil && !((curElement->position <= newElement->position) && (newElement->position < curElement->nextElement->position)))
{
curElement = curElement->nextElement;
}
CTGradientElement *tmpNext = curElement->nextElement;
curElement->nextElement = malloc(sizeof(CTGradientElement));
*(curElement->nextElement) = *newElement;
curElement->nextElement->nextElement = tmpNext;
}
}
- (CTGradientElement)removeElementAtIndex:(unsigned)index
{
CTGradientElement removedElement;
if(elementList != nil)
{
if(index == 0)
{
CTGradientElement *tmpNext = elementList;
elementList = elementList->nextElement;
removedElement = *tmpNext;
free(tmpNext);
return removedElement;
}
unsigned count = 1; //we want to start one ahead
CTGradientElement *currentElement = elementList;
while(currentElement->nextElement != nil)
{
if(count == index)
{
CTGradientElement *tmpNext = currentElement->nextElement;
currentElement->nextElement = currentElement->nextElement->nextElement;
removedElement = *tmpNext;
free(tmpNext);
return removedElement;
}
count++;
currentElement = currentElement->nextElement;
}
}
//element is not found, return empty element
removedElement.red = 0.0;
removedElement.green = 0.0;
removedElement.blue = 0.0;
removedElement.alpha = 0.0;
removedElement.position = NAN;
removedElement.nextElement = nil;
return removedElement;
}
- (CTGradientElement)removeElementAtPosition:(float)position
{
CTGradientElement removedElement;
if(elementList != nil)
{
if(elementList->position == position)
{
CTGradientElement *tmpNext = elementList;
elementList = elementList->nextElement;
removedElement = *tmpNext;
free(tmpNext);
return removedElement;
}
else
{
CTGradientElement *curElement = elementList;
while(curElement->nextElement != nil)
{
if(curElement->nextElement->position == position)
{
CTGradientElement *tmpNext = curElement->nextElement;
curElement->nextElement = curElement->nextElement->nextElement;
removedElement = *tmpNext;
free(tmpNext);
return removedElement;
}
}
}
}
//element is not found, return empty element
removedElement.red = 0.0;
removedElement.green = 0.0;
removedElement.blue = 0.0;
removedElement.alpha = 0.0;
removedElement.position = NAN;
removedElement.nextElement = nil;
return removedElement;
}
- (CTGradientElement *)elementAtIndex:(unsigned)index;
{
unsigned count = 0;
CTGradientElement *currentElement = elementList;
while(currentElement != nil)
{
if(count == index)
return currentElement;
count++;
currentElement = currentElement->nextElement;
}
return nil;
}
#pragma mark -
#pragma mark Core Graphics
//////////////////////////////////////Blending Functions/////////////////////////////////////
void linearEvaluation (void *info, const float *in, float *out)
{
float position = *in;
if(*(CTGradientElement **)info == nil) //if elementList is empty return clear color
{
out[0] = out[1] = out[2] = out[3] = 1;
return;
}
//This grabs the first two colors in the sequence
CTGradientElement *color1 = *(CTGradientElement **)info;
CTGradientElement *color2 = color1->nextElement;
//make sure first color and second color are on other sides of position
while(color2 != nil && color2->position < position)
{
color1 = color2;
color2 = color1->nextElement;
}
//if we don't have another color then make next color the same color
if(color2 == nil)
{
color2 = color1;
}
//----------FailSafe settings----------
//color1->red = 1; color2->red = 0;
//color1->green = 1; color2->green = 0;
//color1->blue = 1; color2->blue = 0;
//color1->alpha = 1; color2->alpha = 1;
//color1->position = .5;
//color2->position = .5;
//-------------------------------------
if(position <= color1->position) //Make all below color color1's position equal to color1
{
out[0] = color1->red;
out[1] = color1->green;
out[2] = color1->blue;
out[3] = color1->alpha;
}
else if (position >= color2->position) //Make all above color color2's position equal to color2
{
out[0] = color2->red;
out[1] = color2->green;
out[2] = color2->blue;
out[3] = color2->alpha;
}
else //Interpolate color at postions between color1 and color1
{
//adjust position so that it goes from 0 to 1 in the range from color 1 & 2's position
position = (position-color1->position)/(color2->position - color1->position);
out[0] = (color2->red - color1->red )*position + color1->red;
out[1] = (color2->green - color1->green)*position + color1->green;
out[2] = (color2->blue - color1->blue )*position + color1->blue;
out[3] = (color2->alpha - color1->alpha)*position + color1->alpha;
}
//Premultiply the color by the alpha.
out[0] *= out[3];
out[1] *= out[3];
out[2] *= out[3];
}
//Chromatic Evaluation -
// This blends colors by their Hue, Saturation, and Value(Brightness) right now I just
// transform the RGB values stored in the CTGradientElements to HSB, in the future I may
// streamline it to avoid transforming in and out of HSB colorspace *for later*
//
// For the chromatic blend we shift the hue of color1 to meet the hue of color2. To do
// this we will add to the hue's angle (if we subtract we'll be doing the inverse
// chromatic...scroll down more for that). All we need to do is keep adding to the hue
// until we wrap around the colorwheel and get to color2.
void chromaticEvaluation(void *info, const float *in, float *out)
{
float position = *in;
if(*(CTGradientElement **)info == nil) //if elementList is empty return clear color
{
out[0] = out[1] = out[2] = out[3] = 1;
return;
}
//This grabs the first two colors in the sequence
CTGradientElement *color1 = *(CTGradientElement **)info;
CTGradientElement *color2 = color1->nextElement;
float c1[4];
float c2[4];
//make sure first color and second color are on other sides of position
while(color2 != nil && color2->position < position)
{
color1 = color2;
color2 = color1->nextElement;
}
//if we don't have another color then make next color the same color
if(color2 == nil)
{
color2 = color1;
}
c1[0] = color1->red;
c1[1] = color1->green;
c1[2] = color1->blue;
c1[3] = color1->alpha;
c2[0] = color2->red;
c2[1] = color2->green;
c2[2] = color2->blue;
c2[3] = color2->alpha;
transformRGB_HSV(c1);
transformRGB_HSV(c2);
resolveHSV(c1,c2);
if(c1[0] > c2[0]) //if color1's hue is higher than color2's hue then
c2[0] += 360; // we need to move c2 one revolution around the wheel
if(position <= color1->position) //Make all below color color1's position equal to color1
{
out[0] = c1[0];
out[1] = c1[1];
out[2] = c1[2];
out[3] = c1[3];
}
else if (position >= color2->position) //Make all above color color2's position equal to color2
{
out[0] = c2[0];
out[1] = c2[1];
out[2] = c2[2];
out[3] = c2[3];
}
else //Interpolate color at postions between color1 and color1
{
//adjust position so that it goes from 0 to 1 in the range from color 1 & 2's position
position = (position-color1->position)/(color2->position - color1->position);
out[0] = (c2[0] - c1[0])*position + c1[0];
out[1] = (c2[1] - c1[1])*position + c1[1];
out[2] = (c2[2] - c1[2])*position + c1[2];
out[3] = (c2[3] - c1[3])*position + c1[3];
}
transformHSV_RGB(out);
//Premultiply the color by the alpha.
out[0] *= out[3];
out[1] *= out[3];
out[2] *= out[3];
}
//Inverse Chromatic Evaluation -
// Inverse Chromatic is about the same story as Chromatic Blend, but here the Hue
// is strictly decreasing, that is we need to get from color1 to color2 by decreasing
// the 'angle' (i.e. 90<39> -> 180<38> would be done by subtracting 270<37> and getting -180<38>...
// which is equivalent to 180<38> mod 360<36>
void inverseChromaticEvaluation(void *info, const float *in, float *out)
{
float position = *in;
if(*(CTGradientElement **)info == nil) //if elementList is empty return clear color
{
out[0] = out[1] = out[2] = out[3] = 1;
return;
}
//This grabs the first two colors in the sequence
CTGradientElement *color1 = *(CTGradientElement **)info;
CTGradientElement *color2 = color1->nextElement;
float c1[4];
float c2[4];
//make sure first color and second color are on other sides of position
while(color2 != nil && color2->position < position)
{
color1 = color2;
color2 = color1->nextElement;
}
//if we don't have another color then make next color the same color
if(color2 == nil)
{
color2 = color1;
}
c1[0] = color1->red;
c1[1] = color1->green;
c1[2] = color1->blue;
c1[3] = color1->alpha;
c2[0] = color2->red;
c2[1] = color2->green;
c2[2] = color2->blue;
c2[3] = color2->alpha;
transformRGB_HSV(c1);
transformRGB_HSV(c2);
resolveHSV(c1,c2);
if(c1[0] < c2[0]) //if color1's hue is higher than color2's hue then
c1[0] += 360; // we need to move c2 one revolution back on the wheel
if(position <= color1->position) //Make all below color color1's position equal to color1
{
out[0] = c1[0];
out[1] = c1[1];
out[2] = c1[2];
out[3] = c1[3];
}
else if (position >= color2->position) //Make all above color color2's position equal to color2
{
out[0] = c2[0];
out[1] = c2[1];
out[2] = c2[2];
out[3] = c2[3];
}
else //Interpolate color at postions between color1 and color1
{
//adjust position so that it goes from 0 to 1 in the range from color 1 & 2's position
position = (position-color1->position)/(color2->position - color1->position);
out[0] = (c2[0] - c1[0])*position + c1[0];
out[1] = (c2[1] - c1[1])*position + c1[1];
out[2] = (c2[2] - c1[2])*position + c1[2];
out[3] = (c2[3] - c1[3])*position + c1[3];
}
transformHSV_RGB(out);
//Premultiply the color by the alpha.
out[0] *= out[3];
out[1] *= out[3];
out[2] *= out[3];
}
void transformRGB_HSV(float *components) //H,S,B -> R,G,B
{
float H, S, V;
float R = components[0],
G = components[1],
B = components[2];
float MAX = R > G ? (R > B ? R : B) : (G > B ? G : B),
MIN = R < G ? (R < B ? R : B) : (G < B ? G : B);
if(MAX == MIN)
H = NAN;
else if(MAX == R)
if(G >= B)
H = 60*(G-B)/(MAX-MIN)+0;
else
H = 60*(G-B)/(MAX-MIN)+360;
else if(MAX == G)
H = 60*(B-R)/(MAX-MIN)+120;
else if(MAX == B)
H = 60*(R-G)/(MAX-MIN)+240;
S = MAX == 0 ? 0 : 1 - MIN/MAX;
V = MAX;
components[0] = H;
components[1] = S;
components[2] = V;
}
void transformHSV_RGB(float *components) //H,S,B -> R,G,B
{
float R, G, B;
float H = fmodf(components[0],359), //map to [0,360)
S = components[1],
V = components[2];
int Hi = (int)floorf(H/60.) % 6;
float f = H/60-Hi,
p = V*(1-S),
q = V*(1-f*S),
t = V*(1-(1-f)*S);
switch (Hi)
{
case 0: R=V;G=t;B=p; break;
case 1: R=q;G=V;B=p; break;
case 2: R=p;G=V;B=t; break;
case 3: R=p;G=q;B=V; break;
case 4: R=t;G=p;B=V; break;
case 5: R=V;G=p;B=q; break;
}
components[0] = R;
components[1] = G;
components[2] = B;
}
void resolveHSV(float *color1, float *color2) //H value may be undefined (i.e. graycale color)
{ // we want to fill it with a sensible value
if(isnan(color1[0]) && isnan(color2[0]))
color1[0] = color2[0] = 0;
else if(isnan(color1[0]))
color1[0] = color2[0];
else if(isnan(color2[0]))
color2[0] = color1[0];
}
@end
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