相关疑难解决方法(0)

我有一个UIImage(Cocoa Touch).从那以后,我很高兴得到一个CGImage或其他你想要的东西.我想写这个函数:

- (int)getRGBAFromImage:(UIImage *)image atX:(int)xx andY:(int)yy {
  // [...]
  // What do I want to read about to help
  // me fill in this bit, here?
  // [...]

  int result = (red << 24) | (green << 16) | (blue << 8) | alpha;
  return result;
}

谢谢!

UIImage有一个只读属性CGImage.我必须将其像素读取到内存块并编辑它们,然后创建一个新的UIImage来替换旧的UIImage.我想知道是否有办法绕过只读属性并直接编辑这些像素.

谢谢.

谢谢大家.我找到了一种方法.用这些方法写一个类:

-(void)preProcess:(UIImage*)srcImage {
    m_Context = ...// Created by calling CGBitmapContextCreate(...)
    ...
    CGContextDrawImage(m_Context, rect, srcImage.CGImage);
    m_Bits = (unsigned char*)CGBitmapContextGetData (mContext);
}

-(void)postProcess {
    CGContextRelease(m_Context);
    free(m_Bits);
}

-(UIImage*)doProcess:(CGPoint)pt {// just a example 
    unsigned char* ppxl = m_Bits + ...
    // do something...
    CGImageRef imRef = CGBitmapContextCreateImage(mContext);
    return [UIImage imageWithCGImage:imRef];
}

preProcess和postProcess只调用一次.

只是想知道如何将径向渐变(点>圆)渲染到新的UIImage(iphone)上.我看到以下内容:

http://developer.apple.com/library/ios/#documentation/GraphicsImaging/Conceptual/drawingwithquartz2d/dq_shadings/dq_shadings.html

它让我觉得我需要使用CGShadingRef或CGGradientRef,并使用UIImage的'imageWithCGImage'构造函数从CG*转到UIImage ...但我无法弄清楚如何.

任何建议都非常感谢!