Re: [gentoo-user] Re: libpng slot usage

[Fox <halfsocialfox@gmail.com>]

On 02/24/2014 02:06 AM, eroen wrote:
> On Sun, 23 Feb 2014 17:54:07 +0100, Fox <halfsocialfox@gmail.com> wrote:
>> Hello,
>> I am trying to compile fltk-1.1.10 both using an ebuild from [1] and
>> with just the downloaded source. I think this version needs libpng
>> 1.2 which is installed in one of the slots.
>>
>> Using the source code and cmake with FLTK_USE_SYSTEM_PNG off it
>> complies fine. I can see that it automatically points the libs to
>> /usr/lib64/libpng12.so.0.
>>
>> The ebuild does not use cmake, it uses autoconf/automake which is
>> also suported. I tried to build the code this way with
>> --disable/enable-localpng with no luck.
>>
>> The problem is the used png.h file. Which is /usr/include/png.h which
>> points to /usr/include/libpng16/png.h but I need the one from version
>> 1.2.
>>
>> I thought slots would allow to have both versions of the library and
>> use them but only one include file is present:
>> $ equery f libpng:1.2
>>    * Searching for libpng:1.2 ...
>>    * Contents of media-libs/libpng-1.2.50-r1:
>> /usr
>> /usr/lib64
>> /usr/lib64/libpng12.so.0
>> /usr/share
>> /usr/share/doc
>> /usr/share/doc/libpng-1.2.50-r1
>> /usr/share/doc/libpng-1.2.50-r1/CHANGES.bz2
>> /usr/share/doc/libpng-1.2.50-r1/README.bz2
>> /usr/share/doc/libpng-1.2.50-r1/TODO.bz2
>>
>> Any idea on how to solve this problem? Some how it should be possible
>> maybe not using the system lib like I did with cmake but I can't
>> figure it out how to do it with autoconf/automake.
>>
>> Thank you,
>> Quim
>>
>>
>> [1]
>> http://sources.gentoo.org/cgi-bin/viewvc.cgi/gentoo-x86/x11-libs/fltk/fltk-1.1.10.ebuild?view=log
>>
> The libpng slots, apart from "0", only install the shared library files,
> not the headers. They are intended for compatibility with old binaries
> for which no source code is available, not for building new software.
>
> Afaik the common opinion is that different libpng versions are mostly
> source compatible, and minor patching to other things is preferable to
> inventing a non-standard way to make the libpng implementation
> switchable at build-time.
>
> Is there a reason you can not use fltk-1.1.10-r2.ebuild [1] in stead,
> which incorporates a patch [2] for libpng-1.5 (which probably still
> works with 1.6), as well as various other fixes?
>
> 1:
> http://sources.gentoo.org/cgi-bin/viewvc.cgi/gentoo-x86/x11-libs/fltk/fltk-1.1.10-r2.ebuild
> 2:
> http://sources.gentoo.org/cgi-bin/viewvc.cgi/gentoo-x86/x11-libs/fltk/files/fltk-1.1.10-libpng15.patch
>
I didn't know about this patch, this should make the job.