Re: [ft-devel] Question about default SVG library integration in FreeType build system

[Werner LEMBERG]

> 1. The `rules.mk' of the `svg' module compiles the port files.  That
>    should only be compiled only if a default SVG port is needed,
>    otherwise not.  So, my question was how do I access this
>    information (whether `yes'/`auto' was selected or `no-default')
>    in my `rules.mk'.  The solution I am using temporarily is, I
>    create the placeholder for a new variable in `unix-cc.in' called
>    `COMPILE_SVG_PORT', this placeholder gets filled by the script
>    `configure.raw' and I can access this variable from `rules.mk'.
>    Let me know if there's a better solution here.

This looks like the right solution.  There should be other, similar
use-cases already in the code.

> 2. A concern I have is that at the moment, the `includes' for
>    `librsvg' (my temporary default for experimentation) gets
>    appended to the variable `CFLAGS' in `configure.raw', the same is
>    the case for `harfbuzz' and `libpng' as well.  However, in the
>    case of an SVG library, these `includes' are only needed in the
>    compilation of the default port, and nowhere else.  Would it be a
>    good idea to create a separate variable called `LIBRSVG_CFLAGS'
>    in `unix-cc.in'?  This way, we can only use the flags where they
>    are actually required.  Or would that be an overkill and isn't
>    really important?

Theoretically, this is a good idea, since it avoids potential name
clashes and makes compilation faster.  On the other hand, I think it
is overkill since virtually all Unix programs accumulate include file
directories in the way you are describing.

FreeType is a small library with a very limited set of necessary
libraries.  I think we thus don't need a better solution.

> 3. I want the `svg' module to not get compiled if `--with-svg' was
>    set to `no'.  I could use a similar trick as in (1) but
>    `modules.cfg' gets included far before `unix-cc.mk' is.

Simply protect the whole code in the SVG module file(s) with

  #ifdef FT_CONFIG_OPTION_SVG
  ...
  #endif

Compare this to, say, the `bzip2' module code.


    Werner