Image method

creates a subimage and draws it enlarged

myImageArea = CGRectMake (rooster_head_x_origin, rooster_head_y_origin,

myWidth, myHeight);

mySubimage = CGImageCreateWithImageInRect (myRoosterImage, myImageArea);

myRect = CGRectMake(0, 0, myWidth*2, myHeight*2);

CGContextDrawImage(context, myRect, mySubimage);

Mask image

+ (UIImage*) maskImage:(UIImage*)image withMask:(UIImage*)mask {

    

    CGImageRef imgRef = [image CGImage];CGImageRef maskRef = [mask CGImage];

    CGImageRef actualMask =CGImageMaskCreate(CGImageGetWidth(maskRef),CGImageGetHeight(maskRef),

                                              CGImageGetBitsPerComponent(maskRef),

                                              CGImageGetBitsPerPixel(maskRef),

                                              CGImageGetBytesPerRow(maskRef),

                                              CGImageGetDataProvider(maskRef),

                                              NULL,false);

    CGImageRef masked = CGImageCreateWithMask(imgRef,actualMask);

    return [UIImageimageWithCGImage:masked];

}

// 颜色mask

    const CGFloat myMaskingColors[6] = {124,255,  68, 222,0, 165};

    CGImageRef newImage = CGImageCreateWithMaskingColors(image.CGImage, myMaskingColors);

// 将屏幕的内容翻转

  //  CGContextTranslateCTM(context,self.bounds.size.width, self.bounds.size.height);

   // CGContextRotateCTM(context,M_PI);

    CGContextTranslateCTM(context,0,  self.bounds.size.height);

    CGContextScaleCTM(context, 1.0, -1.0);