iOS截取正方形的图片

//截取正方形的图片 centerBool为YES  表示从中心开始截取
&＃43;(UIImage*)getSubImage:(UIImage *)image mCGRect:(CGRect)mCGRect centerBool:(BOOL)centerBool{
 /*如若centerBool为Yes则是由中心点取mCGRect范围的图片*/
 
 float imgWidth &＃61; image.size.width;
 float imgHeight &＃61; image.size.height;
 float viewWidth &＃61; mCGRect.size.width;
 float viewHidth &＃61; mCGRect.size.height;
 CGRect rect;
 if(centerBool)
     rect &＃61; CGRectMake((imgWidth-viewWidth)/2,(imgHeight-viewHidth)/2,viewWidth,viewHidth);
 else{
     if(viewHidth      {
         if(imgWidth<&＃61; imgHeight)
         {
             rect&＃61;CGRectMake(0, 0,imgWidth, imgWidth*viewHidth/viewWidth);
         }else
         {
             float width &＃61; viewWidth*imgHeight/viewHidth;
             float x &＃61; (imgWidth  - width)/2;
             if(x>0)
             {
                 rect &＃61; CGRectMake(x,0,  width, imgHeight);
             }else
             {
                 rect &＃61;  CGRectMake(0,  0,  imgWidth, imgWidth*viewHidth/viewWidth);
             }
         }
     }else
     {
         if(imgWidth <&＃61; imgHeight)
         {
             float height &＃61; viewHidth*imgWidth/viewWidth;
             if(height              {
                 rect &＃61;CGRectMake(0,  0, imgWidth, height);
             }else
             {
                 rect &＃61; CGRectMake(0,  0,viewWidth*imgHeight/viewHidth, imgHeight);
             }
         }else
         {
             float width &＃61; viewWidth*imgHeight/viewHidth;
             if(width              {
                 float x &＃61;  (imgWidth - width)/2;
                 rect &＃61;CGRectMake(x,  0,width, imgHeight);
             }else
             {
                 rect &＃61;CGRectMake(0,  0,imgWidth, imgHeight);
             }
         }
     }
 }
 
 CGImageRef subImageRef &＃61; CGImageCreateWithImageInRect(image.CGImage,rect);
 CGRect smallBounds &＃61;CGRectMake(0, 0,CGImageGetWidth(subImageRef),CGImageGetHeight(subImageRef));
 
 UIGraphicsBeginImageContext(smallBounds.size); CGContextRef context &＃61;UIGraphicsGetCurrentContext();CGContextDrawImage(context, smallBounds, subImageRef);
 UIImage *smallImage &＃61;[UIImage imageWithCGImage:subImageRef];
 UIGraphicsEndImageContext();
 
 return smallImage;
}