/*

     File: AppController.m

 Abstract: Continuously animate a gradient layer

  Version: 1.1

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*/

#import "AppController.h"

@implementation AppController

-(void)awakeFromNib {

    //Create the root layer

    rootLayer = [CALayer layer];

    //Set the root layer's attributes

    rootLayer.bounds = CGRectMake(0, 0, [view bounds].size.width, [view bounds].size.height);

    CGColorRef black = CGColorCreateGenericRGB(0.0, 0.0, 0.0, 1);

    rootLayer.backgroundColor = black;

    CGColorRelease(black);

    //Create a 3D perspective transform

    CATransform3D t = CATransform3DIdentity;

    t.m34 = 1.0 / -900.0;

    rootLayer.sublayerTransform = t;

    //Create the gradient layer

    gradientLayer = [CAGradientLayer layer];

    //Create 2 colors for the gradient

    CGColorRef green = CGColorCreateGenericRGB(0.0, 1.0, 0.0, 1);

    CGColorRef blue = CGColorCreateGenericRGB(0.0, 0.0, 1.0, 1);

    //Package the colors in a NSArray and add it to the layer

    NSArray *colors = [NSArray arrayWithObjects:(id) green, (id) blue, nil];

    gradientLayer.colors = colors;

    //Release the colors

    CGColorRelease(green);

    CGColorRelease(blue);

    //Set the size and position of the gradient layer

    gradientLayer.bounds = CGRectMake(0, 0, 250, 300);

    gradientLayer.position = CGPointMake([view bounds].size.width / 2.0, [view bounds].size.height / 2.0);

    //Rotate the gradient layer by adding a rotation matrix

    gradientLayer.transform = CATransform3DMakeRotation(0.5, 1, -1, 0);

    //Build the layer heirarchy and turn on CoreAnimation for the view

    [rootLayer addSublayer:gradientLayer];

    [view setLayer:rootLayer];

    [view setWantsLayer:YES];

    //Start a timer to automaticly call animate

    autoTimer = [NSTimer scheduledTimerWithTimeInterval:1.5 target:self selector:@selector(animate) userInfo:NULL repeats:YES];

}   

//Animate to a new set of random colors

-(void)animate {

    //Generate 2 new random colors

    CGColorRef color1 = CGColorCreateGenericRGB(randFloat(), randFloat(), randFloat(), 1);

    CGColorRef color2 = CGColorCreateGenericRGB(randFloat(), randFloat(), randFloat(), 1);

    //Package the new color pair in an array (the format required for CAGradientLayer)

    NSArray *colors = [NSArray arrayWithObjects:(id) color1, color2, nil];

    //Set the duration for implicit animations to 1.5 sec

    [CATransaction setAnimationDuration:1.5];

    //implicitly animate the gradient colors

    [gradientLayer setColors:colors];

    //Release the colors

    CGColorRelease(color1);

    CGColorRelease(color2);

}

//Resize the gradient layer to match the new window size

-(void)windowDidResize:(NSNotification*)aNotification {

    //Querey the view's size

    float viewHeight = [view bounds].size.height;

    float viewWidth = [view bounds].size.width;

    //Disable implict animations for the resize

    [CATransaction setDisableActions:YES];

    //Resize the gradient layer and place it in the center

    gradientLayer.bounds = CGRectMake(0, 0, viewWidth / 2.5f, viewHeight / 1.6f);

    gradientLayer.position = CGPointMake(viewWidth / 2.0f, viewHeight / 2.0f);

    //Re-enable implict animations

    [CATransaction setDisableActions:NO];

}

// Generate a random floating point value  in [0, 1]

float randFloat() {

    return (random() % 1001) / 1000.0f;

}

@end