/*

File: QuartzDrawing.c

Abstract: Implements basic Quartz Drawing helpers used by the

    ShadingView, GradientView and PreviewView

Version: 1.0

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*/

#include "QuartzDrawing.h"

#define kRadialSize 1.0

#define kSquareBounds CGRectMake(-kRadialSize, -kRadialSize, kRadialSize * 2.0, kRadialSize * 2.0)

// Creates a square path that encompases the unit coordinate area.

CGPathRef GetSquarePath()

{

    static CGMutablePathRef square = NULL;

    if(square == NULL)

    {

        square = CGPathCreateMutable();

        CGPathAddRect(square, NULL, kSquareBounds);

    }

    return square;

}

// Creates a circular path that encompases the unit coordinate area.

CGPathRef GetCirclePath()

{

    static CGMutablePathRef circle = NULL;

    if(circle == NULL)

    {

        circle = CGPathCreateMutable();

        CGPathAddEllipseInRect(circle, NULL, kSquareBounds);

    }

    return circle;

}

// Creates a star-shaped path that encompases the unit coordinate area.

CGPathRef GetStarPath()

{

    static CGMutablePathRef star = NULL;

    if(star == NULL)

    {

        CGAffineTransform starPoints[5];

        int i;

        for(i = 0; i < 5; ++i)

        {

            starPoints[i] = CGAffineTransformMakeRotation(M_PI * 2.0 * i / 5.0);

        }

        star = CGPathCreateMutable();

        CGPathMoveToPoint(star, &starPoints[0], 0.0, kRadialSize);

        for(i = 2; i < 10; i += 2)

        {

            CGPathAddLineToPoint(star, &starPoints[i%5], 0.0, kRadialSize);

        }

        CGPathCloseSubpath(star);

    }

    return star;

}

typedef struct

{

    // the start value is where in the domain this

    // color should be at full intensity.

    CGFloat start;

    // the color to present at the start point and to

    // interpolate with.

    CGFloat components[4];

} LinearColorSpec;

static void LinearColorEvaluator(

    void *inInfo,

    const CGFloat *inInputs,

    CGFloat *outOutputs)

{

    // We assume 3 LinearColorSpecs, as that is what CreateShadingFunction creates.

    LinearColorSpec *colorInfo = (LinearColorSpec*)inInfo;

    CGFloat progression = inInputs[0];

    if(progression <= colorInfo[0].start)

    {

        memcpy(outOutputs, colorInfo[0].components, 4 * sizeof(CGFloat));

    }

    else if(progression <= colorInfo[1].start)

    {

        // progression is in the range of [color1Start, color2Start]. So we can calculate the correct

        // color we want a value between [0,1], so we convert the value of progression from the former domain

        // to the latter domain here.

        CGFloat value = (progression - colorInfo[0].start) / (colorInfo[1].start - colorInfo[0].start);

        int i;

        for(i = 0; i < 4; ++i)

        {

            // transition smoothly from color1 => color2

            outOutputs[i] = colorInfo[0].components[i] + value * (colorInfo[1].components[i] - colorInfo[0].components[i]);

        }

    }

    else if(progression <= colorInfo[2].start)

    {

        // progression is in the range of [color2Start, color3Start]. So we can calculate the correct

        // color we want a value between [0,1], so we convert the value of progression from the former domain

        // to the latter domain here.

        CGFloat value = (progression - colorInfo[1].start) / (colorInfo[2].start - colorInfo[1].start);

        int i;

        for(i = 0; i < 4; ++i)

        {

            // transition smoothly from color2 => color3

            outOutputs[i] = colorInfo[1].components[i] + value * (colorInfo[2].components[i] - colorInfo[1].components[i]);

        }

    }

    else

    {

        memcpy(outOutputs, colorInfo[2].components, 4 * sizeof(CGFloat));

    }

}

static void LinearColorReleaser(

    void *inInfo)

{

    free(inInfo);

}

// This is basically a bubble sort implemented in our tiny tiny domain of 3 color specs.

// A more sophisticated sort wasn't used for various sundry reasons

// including that they are all overkill for sorting 3 numbers.

void Sort(LinearColorSpec * specs)

{

    LinearColorSpec temp;

    if(specs[0].start > specs[1].start)

    {

        temp = specs[0]; specs[0] = specs[1]; specs[1] = temp;

    }

    if(specs[1].start > specs[2].start)

    {

        temp = specs[1]; specs[1] = specs[2]; specs[2] = temp;

    }

    // spec[2] is definately largest at this point...

    if(specs[0].start > specs[1].start)

    {

        temp = specs[0]; specs[0] = specs[1]; specs[1] = temp;

    }

    // spec[1] is definately larger than spec[0], thus we are sorted.

}

CGFunctionRef CreateShadingFunction(

    CGColorRef inColor1,

    CGFloat inColor1Start,

    CGColorRef inColor2,

    CGFloat inColor2Start,

    CGColorRef inColor3,

    CGFloat inColor3Start)

{

    // Version 0, use LinearColorEvaluator to derive values, and LinearColorReleaser to clean up.

    static CGFunctionCallbacks callbacks = {0, &LinearColorEvaluator, &LinearColorReleaser};

    // Our domain (input) consists of 1 parameter whose values range from 0.0 to 1.0 inclusive.

    CGFloat domain[2] = {0.0, 1.0};

    // Our range (output) consists of 4 parameters whose values range from 0.0 to 1.0 inclusive.

    CGFloat range[8] = {0.0, 1.0, 0.0, 1.0, 0.0, 1.0, 0.0, 1.0};

    // Allocate enough space for 3 color specs.

    LinearColorSpec * info = malloc(sizeof(LinearColorSpec) * 3);

    // Fill them out

    info[0].start = inColor1Start;

    info[1].start = inColor2Start;

    info[2].start = inColor3Start;

    memcpy(info[0].components, CGColorGetComponents(inColor1), sizeof(info[0].components));

    memcpy(info[1].components, CGColorGetComponents(inColor2), sizeof(info[1].components));

    memcpy(info[2].components, CGColorGetComponents(inColor3), sizeof(info[2].components));

    // Sort the specs - this mimics what CGGradientCreateWithColors does.

    Sort(info);

    // Create the function

    CGFunctionRef function = CGFunctionCreate(info, 1, domain, 4, range, &callbacks);

    if(function == NULL)

    {

        // if we have a failure, then clean up now, since our callback will not be called.

        LinearColorReleaser(info);

    }

    return function;

}

CGGradientRef CreateGradient(

    CGColorRef inColor1,

    CGFloat inColor1Start,

    CGColorRef inColor2,

    CGFloat inColor2Start,

    CGColorRef inColor3,

    CGFloat inColor3Start)

{

    // Setup a CFArray with our CGColorRefs

    const void *colorRefs[3] = {inColor1, inColor2, inColor3};

    CFArrayRef colorArray = CFArrayCreate(kCFAllocatorDefault, colorRefs, 3, &kCFTypeArrayCallBacks);

    // Setup a parallel array that contains the start locations of those colors

    CGFloat locations[3] = {inColor1Start, inColor2Start, inColor3Start};

    // Create the gradient

    CGGradientRef gradient = CGGradientCreateWithColors(NULL, colorArray, locations);

    // clean up the color array (the gradient will retain it if necessary)

    CFRelease(colorArray);

    return gradient;

}

// A simple utility function to return a Generic RGB colorspace that we don't have to release.

CGColorSpaceRef GetGenericRGBColorspace()

{

    static CGColorSpaceRef rgb = NULL;

    if(rgb == NULL)

    {

        rgb = CGColorSpaceCreateWithName(kCGColorSpaceGenericRGB);

    }

    return rgb;

}

void DrawEmbellishments(CGContextRef context, CGSize size, CGPoint startPoint, CGFloat startRadius, CGPoint endPoint, CGFloat endRadius, bool drawRadii)

{

    CGFloat startX = startPoint.x * size.width / 2.0;

    CGFloat startY = startPoint.y * size.height / 2.0;

    CGFloat endX = endPoint.x * size.width / 2.0;

    CGFloat endY = endPoint.y * size.height / 2.0;

    CGContextSaveGState(context);

    CGContextSetBlendMode(context, kCGBlendModeDifference);

    CGContextSetRGBStrokeColor(context, 1.0, 1.0, 1.0, 1.0);

    // Line joining crosshairs

    CGContextMoveToPoint(context, startX, startY);

    CGContextAddLineToPoint(context, endX, endY);

    CGContextStrokePath(context);

    // Crosshairs

    CGContextMoveToPoint(context, startX, startY - 5.0);

    CGContextAddLineToPoint(context, startX, startY + 5.0);

    CGContextStrokePath(context);

    CGContextMoveToPoint(context, startX - 5.0, startY);

    CGContextAddLineToPoint(context, startX + 5.0, startY);

    CGContextStrokePath(context);

    CGContextMoveToPoint(context, endX, endY - 5.0);

    CGContextAddLineToPoint(context, endX, endY + 5.0);

    CGContextStrokePath(context);

    CGContextMoveToPoint(context, endX - 5.0, endY);

    CGContextAddLineToPoint(context, endX + 5.0, endY);

    CGContextStrokePath(context);

    // Radii if requested

    if(drawRadii)

    {

        CGFloat startRX = startRadius * size.width / 2.0;

        CGFloat startRY = startRadius * size.height / 2.0;

        CGFloat endRX = endRadius * size.width / 2.0;

        CGFloat endRY = endRadius * size.height / 2.0;

        CGContextStrokeEllipseInRect(context, CGRectMake(startX - startRX, startY - startRY, startRX * 2.0, startRY * 2.0));

        CGContextStrokeEllipseInRect(context, CGRectMake(endX - endRX, endY - endRY, endRX * 2.0, endRY * 2.0));

    }

    CGContextRestoreGState(context);

}