iOS颜色摄合器，获取图片某点的颜色值

iOS颜色摄合器，获取图片某点的颜色值

版权声明：本文为博主原创文章

1.新建一个继承于UIImageView的类-YWColorByImageView
2.重写set方法，并通过上下图文创建实际对应像素的image

/**
 重设image
 
 @param image image
 */
- (void)setImage:(UIImage *)image {
    
    UIImage *temp = [self imageForResizeWithImage:image resize:CGSizeMake(self.frame.size.width, self.frame.size.width)];
    [super setImage:temp];
    
}

/**
 通过上下图文创建self对应像素的image
 
 @param picture 要加载的图片
 @param resize 实际self的大小
 @return 返回self对应像素的大小的image
 */
- (UIImage *)imageForResizeWithImage:(UIImage *)picture resize:(CGSize)resize {
    
    CGSize imageSize = resize; //CGSizeMake(25, 25)
    
    /**
     UIGraphicsBeginImageContextWithOptions(CGSize size, BOOL opaque, CGFloat scale);
     1.参数size为新创建的位图上下文的大小
     2.opaque—透明开关，如果图形完全不用透明，设置为YES以优化位图的存储
     3.scale—–缩放因子 iPhone 4是2.0，其他是1.0;实际上设为0后，系统就会自动设置正确的比例了。
     */
    
    UIGraphicsBeginImageContextWithOptions(imageSize, NO,0.0);
    CGRect imageRect = CGRectMake(0.0, 0.0, imageSize.width, imageSize.height);
    [picture drawInRect:imageRect];
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    return image;
}

3. 通过触摸点，判断该点是否在范围内，然后获取某点的颜色值

- (void)touchesBegan:(NSSet *)touches withEvent:(nullable UIEvent *)event {
    
    UITouch *touch = [touches anyObject];
    
    CGPoint location_point = [touch locationInView:self];
    
    
    if ([YWDistanceTool getlayer:location_point withRadius:self.bounds.size.width/2]) {
        
        UIColor *color = [UIColor colorAtPixel:location_point withImage:self.image];
        
        if (self.pointColorBlock) {
            self.pointColorBlock(color);
        }
        if ([self.delegate respondsToSelector:@selector(getCurrentColor:)]) {
            [self.delegate getCurrentColor:color];
        }
        
        
    }
    
    
}

- (void)touchesMoved:(NSSet *)touches withEvent:(nullable UIEvent *)event {
    
    UITouch *touch = [touches anyObject];
    
    CGPoint location_point = [touch locationInView:self];
    
    if ([YWDistanceTool getlayer:location_point withRadius:self.bounds.size.width/2]) {
        
        UIColor *color = [UIColor colorAtPixel:location_point withImage:self.image];
        
        if (self.pointColorBlock) {
            self.pointColorBlock(color);
        }
        if ([self.delegate respondsToSelector:@selector(getCurrentColor:)]) {
            [self.delegate getCurrentColor:color];
        }
    }
    
}


- (void)touchesEnded:(NSSet *)touches withEvent:(nullable UIEvent *)event {
    
    UITouch *touch = [touches anyObject];
    CGPoint location_point = [touch locationInView:self];
    
    if ([YWDistanceTool getlayer:location_point withRadius:self.bounds.size.width/2]) {
        
        UIColor *color = [UIColor colorAtPixel:location_point withImage:self.image];
        
        if (self.pointColorBlock) {
            self.pointColorBlock(color);
        }
        if ([self.delegate respondsToSelector:@selector(getCurrentColor:)]) {
            [self.delegate getCurrentColor:color];
        }
    }
    
}
/**
 获取图片某一点的颜色

 @param point 点击图片的某一点
 @param image 图片
 @return 图片某点的颜色值
 */
+ (UIColor *)colorAtPixel:(CGPoint)point withImage:(UIImage *)image {
    
    //    判断给定的点是否被一个CGRect包含
    
    if (!CGRectContainsPoint(CGRectMake(0.0f, 0.0f, image.size.width, image.size.height), point)) {
        return nil;
    }
    
    //    trunc（n1,n2），n1表示被截断的数字，n2表示要截断到那一位。n2可以是负数，表示截断小数点前。注意，TRUNC截断不是四舍五入。
    //    TRUNC(15.79)---15
    //    trunc(15.79,1)--15.7
    
    NSInteger pointX = trunc(point.x);
    
    NSInteger pointY = trunc(point.y);
    
    CGImageRef cgImage = image.CGImage;
    
    NSUInteger width = image.size.width;
    NSUInteger height = image.size.height;
    //    创建色彩标准
    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);
    
    CGContextTranslateCTM(context, -pointX, pointY-(CGFloat)height);
    CGContextDrawImage(context, CGRectMake(0.0f, 0.0f, (CGFloat)width, (CGFloat)height), cgImage);
    CGContextRelease(context);
    
    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];
    
}

源码请转：https://github.com/flyOfYW/YWDemo.git