[IOS]调色板

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[IOS]调色板

Demo:http://download.csdn.net/detail/u012881779/9408857

功能：使用用户在UIImageView上的触摸点从UIImage获取该点的UIColor(RGB)

先使用Category方式拓展UIImage

#import "UIImage+ColorSelect.h"@implementation UIImage (ColorSelect)- (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;    }        NSInteger pointX = trunc(point.x);    NSInteger pointY = trunc(point.y);    CGImageRef cgImage = self.CGImage;    NSUInteger width = self.size.width;    NSUInteger height = self.size.height;    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-(CGFloat)height);    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

再创建控制器从UIImagView获取CGPoint

#import "SelectColorViewController.h"#import "UIImage+ColorSelect.h"@interface SelectColorViewController ()//素材图片不要拉伸去适配分辨率，那样获取的颜色会不准确@property (weak, nonatomic) IBOutlet UIImageView    *sourceImgView;@property (weak, nonatomic) IBOutlet UIImageView    *resultImagView;@end@implementation SelectColorViewController- (void)viewDidLoad {    [super viewDidLoad];    }//完成选择-(void)finishedAction:(CGPoint)point{    UIColor *tempColor = [_sourceImgView.image colorAtPixel:point];    [_resultImagView setBackgroundColor:tempColor];    NSLog(@"\n_x=%f,y=%f",point.x,point.y);}//Touch- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event{    }- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event{    UITouch *touch = [touches anyObject];    CGPoint tempPoint = [touch locationInView:_sourceImgView];    [self finishedAction:tempPoint];}- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event{  }@end

示意图：

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