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diff --git a/info/libgamma.texinfo b/info/libgamma.texinfo index bcc3cd4..5c5afdd 100644 --- a/info/libgamma.texinfo +++ b/info/libgamma.texinfo @@ -54,6 +54,7 @@ Texts. A copy of the license is included in the section entitled * Overview:: Brief overview of @command{libgamma}. * Compiling:: Configuring, compiling and installing @command{libgamma}. * Linking:: Linking your software to @command{libgamma}. +* API:: @command{libgamma}'s advanced programming interface. * GNU Free Documentation License:: Copying and sharing this manual. @end menu @@ -378,6 +379,57 @@ and for the freedom of all. +@node API +@chapter API + +To use @command{libgamma} add ``@code{#include <libgamma.h>}'' +to and C file or C header file that requires anything +from @command{libgamma}. @file{libgamma.h} is the only +header file from @command{libgamma} which should be +included directly. + +Once @file{libgamma.h} is included your program will +have access the @command{libgamma}'s API which includes +functions, data structures, error codes, and adjustment +method identifers. + +It is highly recommened to add a check for new error +codes if your program will be using error codes from +@command{libgamma}. This allows you to get a notification +if you program is not up to date with new error codes +in @command{libgamma}. To do this, @file{libgamma.h} +provides the C preprocessor definition @code{LIBGAMMA_ERROR_MIN}; +this is the lowest value of that any error code has, +all error codes are negative, a new error code is added +it will have a lower value that the ones added before it. +The first step in adding this check is to figure out +what the value of @code{LIBGAMMA_ERROR_MIN} is on your +system. To do this, use the @command{cpp} program, it +should be included with your C compiler. + +@example +cpp <<EOF | tail --lines 1 +#include <libgamma.h> +LIBGAMMA_ERROR_MIN +EOF +@end example + +The next step is to add some C preprocessor directives +to one of your C files that includes @file{libgamma.h}. + +@example +#if LIBGAMMA_ERROR_MIN < -10 +# warning New error codes have been added to libgamma. +#endif +@end example + +In this example, we assume that output of the first +step was `-10', which it really was not. So if you +use this in your program you should receive a warning +until you update the value. + + + @node GNU Free Documentation License @appendix GNU Free Documentation License @include fdl.texinfo |