Re: studio.h -> gamma_magick

On Wed, 19 Feb 2020, Pro Turm wrote:

> I coudnt define the reason for the following line of code:
>
> studio.h -> #define gamma gamma_magick
>
> What is gamma_magick supposed to be about?

This sort of thing is done to avoid conflicts with a symbol called 
'gamma' which might be provided by the compiler or operating system.

It appears that on some systems, there is a pre-processor symbol 
called 'gamma' and it conflicts with or redefines the 'gamma' member 
in the Image struct.  Gamma is the name of a C'99 math function often 
declared in math.h.  The compilers sometimes get confused if there is 
both a function and a structure member with the same name.

Indeed, the similar re-declarations in studio.h are to avoid 
conflicts with standard symbols.

Achieving broad portability requires dealing with such things.

Bob
-- 
Bob Friesenhahn
[email protected], http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/
Public Key,     http://www.simplesystems.org/users/bfriesen/public-key.txt