Re: [gentoo-amd64] New Jpeg-7 -- was Re: kdelibs insanity

[Frank Peters]

On Fri, 31 Jul 2009 10:20:45 +0000 (UTC)
Duncan <1i5t5.duncan@×××.net> wrote:

>
> > Many new packages that have been released
> > seem to break everything that depends on them.  For example, a new jpeg
> > library, version 7, was released recently (which has not yet made it
> > into Gentoo) that will require a rebuild of every program that processes
> > images, and this includes the extensive GTK package as it uses libjpeg
> > for its pixbuffer loader.
>
> Thanks for the warning!  I hadn't read anything about that one yet.
>

FWIW, I need to continue this comment.

Since I process a lot of images, libjpeg is very important to me.  The new
jpeg-7 now includes arithmetic encoding which can produce smaller compressed
file sizes and there are also some changes to the scaling and quality features.
Unlike most Open Source packages, which are updated quite frequently (too
frequently?), jpeg-7 is the first new release since 1998.

Rather than wait for Gentoo to create the ebuilds for the new jpeg-7, I decided
to compile it myself and then list it in packages.provided.  In addition,
the old jpeg-6 shared objects were kept, but all the include files and
static libraries for linking would refer to the new jpeg-7.  In this way,
any update of a package that depends on libjpeg would be linked with the
new libraries, but any existing package that still needs jpeg-6 could be
left untouched.  I don't like to have to re-compile everything at once.  When
the time comes to update a package the new libraries will be available but until
then the old libraries will suffice.  (Gentoo is flexible enough to nicely
accomodate this.)

However, after emerging a new GTK+, which automatically then became linked
to the new jpeg-7 libraries, I noticed a severe problem.  Jpeg images viewed
using programs that depend on GTK+ -- and there are a lot of them -- were
strangely blurred and out of focus.  Doing some searching, I found this
thread that explains the problem:

http://bbs.archlinux.org/viewtopic.php?id=75529

The issue is with the new scaling methods in jpeg-7.  Programs such as firefox
and many others process images through GTK+ facilities, and GTK+ needs to be
patched before it can utilize the new jpeg-7.  AFAIK, the GTK+ people do not
even yet know about this issue.  Also, unless I am mistaken, any patch that
accommodates jpeg-7 will no longer function with jpeg-6.

So there ends my nice, neat plan to have both jpeg-7 and jpeg-6 together
serving my system.  The situation also illustrates how unanticipated problems
can easily be injected into this loose but wonderful conglomeration known
as Open Source software.

Frank Peters