Basic ColorAt example.

C4WorkSpace.m

#import "C4WorkSpace.h"

@implementation C4WorkSpace {
    C4Image *image;
    NSInteger count;
    C4Timer *timer;
}

-(void)setup {
    image = [C4Image imageNamed:@"C4Sky"];
    image.center = self.canvas.center;
    [image loadPixelData];
    [self listenFor:@"pixelDataWasLoaded" andRunMethod:@"grabColors"];

}

-(void)grabColors {
    timer = [C4Timer timerWithInterval:0.05f target:self method:@"test" repeats:YES];
    [timer start];
}

-(void)test {
    CGPoint randomPoint = CGPointMake([C4Math randomInt:(int)image.width],[C4Math randomInt:(int)image.height]);
    UIColor *c = [image colorAt:randomPoint];

    randomPoint.x += image.origin.x;
    randomPoint.y += image.origin.y;
    
    C4Shape *s = [C4Shape ellipse:CGRectMake(randomPoint.x-10, randomPoint.y-10, 20, 20)];
    s.fillColor = c;
    s.lineWidth = 0.0f;
    [self.canvas addShape:s];
    count++;
}

@end