UIImage+CKUITools.m

//
//  UIImage+CKUITools.m
//
//  Created by Constantine Karlis on 03/30/2013.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

#import "UIImage+CKUITools.h"

@implementation UIImage (CKUITools)

+(UIImage*)imageWithCALayer:(CALayer*)layer
{
    UIGraphicsBeginImageContextWithOptions(layer.frame.size, NO, [[UIScreen mainScreen] scale]);
    
    [layer renderInContext:UIGraphicsGetCurrentContext()];
    UIImage* out = UIGraphicsGetImageFromCurrentImageContext();
    
    UIGraphicsEndImageContext();
    
    return out;
}

+ (UIImage *)imageWithUIView:(UIView *)view
{
    return [UIImage imageWithCALayer:view.layer];
}

+ (UIImage *)imageNamed:(NSString *)name tint:(UIColor *)tint;
{
  return [[self imageNamed:name] tint:tint];
}

- (UIImage *)tint:(UIColor *)tint;
{
  NSAssert(tint != nil, @"tint must not be nil");
  
  UIGraphicsBeginImageContextWithOptions([self size], NO, 0.0);
  CGRect bounds = CGRectMake(0, 0, self.size.width, self.size.height);
  
  [tint setFill];
  
  UIRectFill(bounds);
  [self drawInRect:bounds blendMode:kCGBlendModeDestinationIn alpha:1.0];
  
  UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
  UIGraphicsEndImageContext();
  
  return image;
}

- (UIColor *)colorAtPixel:(CGPoint)point
{
    // Cancel if point is outside image coordinates
    if (!CGRectContainsPoint(CGRectMake(0.0f, 0.0f, self.size.width, self.size.height), point)) {
        return nil;
    }
    
    
    // Create a 1x1 pixel byte array and bitmap context to draw the pixel into.
    // Reference: http://stackoverflow.com/questions/1042830/retrieving-a-pixel-alpha-value-for-a-uiimage
    NSInteger pointX = trunc(point.x);
    // flip it larry
    NSInteger pointY = trunc(self.size.height - point.y);
    CGImageRef cgImage = self.CGImage;
    NSUInteger width = CGImageGetWidth(cgImage);
    NSUInteger height = CGImageGetHeight(cgImage);
    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
    int bytesPerPixel = 4;
    int bytesPerRow = bytesPerPixel * 1;
    NSUInteger bitsPerComponent = 8;
    unsigned char pixelData[4] = { 0, 0, 0, 0 };
    CGContextRef context = CGBitmapContextCreate(pixelData,
                                                 1,
                                                 1,
                                                 bitsPerComponent,
                                                 bytesPerRow,
                                                 colorSpace,
                                                 kCGImageAlphaPremultipliedLast | kCGBitmapByteOrder32Big);
    CGColorSpaceRelease(colorSpace);
    CGContextSetBlendMode(context, kCGBlendModeCopy);
    
    // Draw the pixel we are interested in onto the bitmap context
    CGContextTranslateCTM(context, -pointX, -pointY);
    CGContextDrawImage(context, CGRectMake(0.0f, 0.0f, (CGFloat)width, (CGFloat)height), cgImage);
    CGContextRelease(context);
    
    // Convert color values [0..255] to floats [0.0..1.0]
    CGFloat red   = (CGFloat)pixelData[0] / 255.0f;
    CGFloat green = (CGFloat)pixelData[1] / 255.0f;
    CGFloat blue  = (CGFloat)pixelData[2] / 255.0f;
    CGFloat alpha = (CGFloat)pixelData[3] / 255.0f;
    return [UIColor colorWithRed:red green:green blue:blue alpha:alpha];
}

@end