PFColorPicker.m

//
//  ColorPicker.m
//  ColorPicker
//
//  Created by Bailey Seymour on 3/16/14.
//  Copyright (c) 2011 Bailey Seymour All rights reserved.
//

#import <QuartzCore/QuartzCore.h>
#import "PFColorPicker.h"
#import "UIColor+PFColor.h"

#if TARGET_OS_IPHONE
@implementation PFColorPicker

- (id)initWithFrame:(CGRect)frame {
    self = [super initWithFrame:frame];
    if (self)
        [self setBackgroundColor:UIColor.clearColor];
    return self;
}

+ (NSString *)cacheImageNameWithFrame:(CGRect)frame {
    return [NSString stringWithFormat:@"/tmp/_PFColorPickerImage_%gx%g.png", frame.size.width, frame.size.height];
}

+ (UIColor *)colorWithHueForLocation:(CGFloat)location {
    return [UIColor colorWithHue:location saturation:1 brightness:1 alpha:1];
}

- (UIImage *)captureView {
    CGRect rect = [self frame];

    UIGraphicsBeginImageContextWithOptions(rect.size, NO, [UIScreen mainScreen].scale);
    CGContextRef context = UIGraphicsGetCurrentContext();
    [self.layer renderInContext:context];   
    UIImage *img = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    
    return img;
}

- (void)drawRect:(CGRect)rect {
    float widthX = rect.size.width;
    float widthY = rect.size.height;

    CGContextRef context = UIGraphicsGetCurrentContext();

    BOOL imageExists = [[NSFileManager defaultManager] fileExistsAtPath:[PFColorPicker cacheImageNameWithFrame:rect]];

    UIImage *image = imageExists ? [[UIImage alloc] initWithContentsOfFile:[PFColorPicker cacheImageNameWithFrame:rect]] : nil;

    if (!image || !CGSizeEqualToSize(image.size, rect.size)) {
        int size = 1;
    
        for (float posY = 0; posY <= widthY; posY += size) {
            for (float posX = 0; posX <= widthX; posX += size) {
                float h = posY / widthY;
                float w = posX / widthX;
                float s = (w <= 0.5 ? 1 : 1 - w) * 2;
                float b = (w <= 0.5 ? w : 1) * 2;
            
                [[UIColor colorWithHue:h saturation:s brightness:b alpha:1] setFill];
                CGContextFillRect(context, CGRectMake(posX, posY, size, size));
            }
        }
        shouldSaveNewCache = YES;
    } else if (image) {
        [image drawInRect:rect];
    }
}

- (void)saveCache {
    if (shouldSaveNewCache) {
        NSData *imageData = UIImagePNGRepresentation([self captureView]);
        [imageData writeToFile:[PFColorPicker cacheImageNameWithFrame:self.frame] atomically:YES];
        shouldSaveNewCache = NO;
    }
}

- (void)makeReadyForDisplay {
    UIPanGestureRecognizer *drag = [[UIPanGestureRecognizer alloc]initWithTarget:self action:@selector(selectColor:)];
    [self addGestureRecognizer:drag];
    [self setUserInteractionEnabled:YES];
}

- (UIColor *)colorAtPoint:(CGPoint)point {
    unsigned char pixel[4] = {0};
    
    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
    
    CGContextRef context = CGBitmapContextCreate(pixel, 1, 1, 8, 4, colorSpace, kCGBitmapAlphaInfoMask & kCGImageAlphaPremultipliedLast);
    
    CGContextTranslateCTM(context, -point.x, -point.y);
    
    [self.layer renderInContext:context];
    
    CGContextRelease(context);
    CGColorSpaceRelease(colorSpace);
    
    //NSLog(@"pixel: %d %d %d %d", pixel[0], pixel[1], pixel[2], pixel[3]);
    
    UIColor *color = [UIColor colorWithRed:pixel[0] / 255.0
                                     green:pixel[1] / 255.0
                                      blue:pixel[2] / 255.0
                                     alpha:pixel[3] / 255.0];
    
    if (!color)
        color = [self lastSelectedColor];

    return color;
}

- (void)selectColor:(UIPanGestureRecognizer *)gest {
	CGPoint point = [gest locationInView:self]; //where user stopped dragging on image
    [self useColorAtPoint:point];
}

- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
    UITouch *touch = [touches anyObject];
    CGPoint point = [touch locationInView:self]; //where image was tapped
    [self useColorAtPoint:point];
}

- (void)useColorAtPoint:(CGPoint)point {
    CGRect r = self.frame;
    r.origin = CGPointZero;
    
    if (CGRectContainsPoint(r, point)) {
        UIColor *color = [self colorAtPoint:point];
        if (!color)
            return;
    }
    
    if ([_delegate respondsToSelector:@selector(pickedColor:)])
        [_delegate performSelector:@selector(pickedColor:) withObject:_lastSelectedColor];
}

@end
#endif