iOS 图片取色器

#import "ViewController.h"
@interface ViewController ()
@property(nonatomic,strong)UIImageView *imageView;
@end

@implementation ViewController

- (void)viewDidLoad
{
[super viewDidLoad];
self.view.backgroundColor=[UIColor whiteColor];

UIImageView *imageView=[[UIImageView alloc]init];

if (fabs(([[UIScreen mainScreen] bounds].size.height - 568)) < 1)
{
// 5 & 5s & 5c
imageView.image=[UIImage imageNamed:@"RGBCircle_5"];
imageView.frame=CGRectMake(54, 44, imageView.image.size.width, imageView.image.size.height);

}
else if (fabs(([[UIScreen mainScreen] bounds].size.height - 667)) < 1)
{
// 6 & 6s
imageView.image=[UIImage imageNamed:@"RGBCircle_6"];
imageView.frame=CGRectMake(57, 44, imageView.image.size.width, imageView.image.size.height);
}
else if (fabs(([[UIScreen mainScreen] bounds].size.height - 736)) < 1)
{
// 6p & 6sp
imageView.image=[UIImage imageNamed:@"RGBCircle_6p"];
imageView.frame=CGRectMake(62, 44, imageView.image.size.width, imageView.image.size.height);

}

NSLog(@"ooooo %f %f",imageView.image.size.width,imageView.image.size.height);
imageView.userInteractionEnabled=YES;
self.imageView=imageView;
[self.view addSubview:imageView];

}

-(void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event
{
//触点对象
UITouch *touch=touches.anyObject;
//触点位置
CGPoint touchLocation=[touch locationInView:self.imageView];
//触点颜色
UIColor *positionColor=[self getPixelColorAtLocation:touchLocation];

const CGFloat *components=CGColorGetComponents(positionColor.CGColor);

NSString *rValue=[NSString stringWithFormat:@"%d",(int)(components[0]*255)];
NSString *gValue=[NSString stringWithFormat:@"%d",(int)(components[1]*255)];
NSString *bValue=[NSString stringWithFormat:@"%d",(int)(components[2]*255)];
NSLog(@"我看看结果:%@ %@ %@",rValue,gValue,bValue);
}

- (UIColor*) getPixelColorAtLocation:(CGPoint)point
{
UIColor* color = nil;
UIImageView *colorImageView=self.imageView;
CGImageRef inImage = colorImageView.image.CGImage;
// Create off screen bitmap context to draw the image into. Format ARGB is 4 bytes for each pixel: Alpa, Red, Green, Blue
CGContextRef cgctx = [self createARGBBitmapContextFromImage:inImage];
if (cgctx == NULL)
{
return nil;
}
size_t w = CGImageGetWidth(inImage);
size_t h = CGImageGetHeight(inImage);
CGRect rect = {{0,0},{w,h}};

// Draw the image to the bitmap context. Once we draw, the memory
// allocated for the context for rendering will then contain the
// raw image data in the specified color space.
CGContextDrawImage(cgctx, rect, inImage);

// Now we can get a pointer to the image data associated with the bitmap
// context.
unsigned char* data = CGBitmapContextGetData (cgctx);
if (data != NULL)
{
//offset locates the pixel in the data from x,y.
//4 for 4 bytes of data per pixel, w is width of one row of data.
@try
{
int offset = 4*((w*round(point.y))+round(point.x));
//NSLog(@"offset: %d", offset);
int alpha =  data[offset];
int red = data[offset+1];
int green = data[offset+2];
int blue = data[offset+3];
//            NSLog(@"offset: %i colors: RGB A %i %i %i  %i",offset,red,green,blue,alpha);
color = [UIColor colorWithRed:(red/255.0f) green:(green/255.0f) blue:(blue/255.0f) alpha:(alpha/255.0f)];
}
@catch (NSException * e)
{
NSLog(@"%@",[e reason]);
}
@finally
{

}

}

// When finished, release the context
CGContextRelease(cgctx);
// Free image data memory for the context
if (data)
{
free(data);
}

return color;
}

- (CGContextRef) createARGBBitmapContextFromImage:(CGImageRef) inImage
{

CGContextRef    context = NULL;
CGColorSpaceRef colorSpace;
void *          bitmapData;
int             bitmapByteCount;
int             bitmapBytesPerRow;

// Get image width, height. We'll use the entire image.
size_t pixelsWide = CGImageGetWidth(inImage);
size_t pixelsHigh = CGImageGetHeight(inImage);

// Declare the number of bytes per row. Each pixel in the bitmap in this
// example is represented by 4 bytes; 8 bits each of red, green, blue, and
// alpha.
bitmapBytesPerRow   = (int)(pixelsWide * 4);
bitmapByteCount     =(int)(bitmapBytesPerRow * pixelsHigh);

// Use the generic RGB color space.
colorSpace = CGColorSpaceCreateDeviceRGB();

if (colorSpace == NULL)
{
fprintf(stderr, "Error allocating color space\n");
return NULL;
}

// Allocate memory for image data. This is the destination in memory
// where any drawing to the bitmap context will be rendered.
bitmapData = malloc( bitmapByteCount );
if (bitmapData == NULL)
{
fprintf (stderr, "Memory not allocated!");
CGColorSpaceRelease( colorSpace );
return NULL;
}

// Create the bitmap context. We want pre-multiplied ARGB, 8-bits
// per component. Regardless of what the source image format is
// (CMYK, Grayscale, and so on) it will be converted over to the format
// specified here by CGBitmapContextCreate.
context = CGBitmapContextCreate (bitmapData,
pixelsWide,
pixelsHigh,
8,      // bits per component
bitmapBytesPerRow,
colorSpace,
kCGImageAlphaPremultipliedFirst);
if (context == NULL)
{
free (bitmapData);
fprintf (stderr, "Context not created!");
}

// Make sure and release colorspace before returning
CGColorSpaceRelease( colorSpace );

return context;
}@end