Image scaling and Basic C

Discussion in 'iOS Programming' started by nashyo, Jul 14, 2012.

  1. nashyo, Jul 14, 2012
    Last edited: Jul 14, 2012

    nashyo macrumors 6502


    Oct 1, 2010
    Can anyone help me with this please.

        CGFloat horizontalRatio = bounds.width / self.size.width;
        CGFloat verticalRatio = bounds.height / self.size.height;
        CGFloat ratio = MIN(horizontalRatio, verticalRatio);
        CGSize newSize = CGSizeMake(self.size.width * ratio, self.size.height * ratio);
        UIGraphicsBeginImageContextWithOptions(newSize, YES, 0);
        [self drawInRect:CGRectMake(0, 0, newSize.width, newSize.height)];
        UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
        return newImage;
    What does MIN() do?
  2. ArtOfWarfare macrumors G3


    Nov 26, 2007
    I tried using it in my app and it wasn't recognized, so it doesn't seem to be part of a standard library/framework.

    It appears to be a macro, based on the decision to name it in all capitals. (I'll be honest, Xcode suggested it to me. I already suspected it was a macro, but it didn't even occur to me that there might be a naming convention... I've always just used whatever names I feel like for macros.)

    If I had to guess, I'd say that somewhere in a header you import (or possibly you import a header that imports it... or possibly so on) you'll probably find something like

    #define MIN(A,B) (A<B)?A:B
    That's just a guess though. The macro I just typed would replace every instance of MIN(A,B) with a ternary operator that first checks if A is less than B, and if it is, return A, and if it isn't, return B. In effect, it returns the lesser of A and B, or finds the MINimum (my guess for what MIN is short for) value of A and B.
  3. nashyo thread starter macrumors 6502


    Oct 1, 2010
    Thanks. Its difficult to search for an answer to this.
  4. chown33 macrumors 604

    Aug 9, 2009
    Sailing beyond the sunset
    Where did the code come from?
  5. PhoneyDeveloper macrumors 68040


    Sep 2, 2008
    MIN and MAX are a part of standard Objective-C. A quick check shows that they are macros defined in NSObjeCRuntime.h, which is almost certainly #imported in every .m file.

    MIN returns the minimum value of the two parameters and MAX returns the maximum value of the two parameters.

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