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Subject: Re: [boost] Formal Review of IO and Toolbox extensions to Boost.GIL starts TOMORROW
From: Domagoj Saric (domagoj.saric_at_[hidden])
Date: 2010-12-09 07:31:21

"Andreas Pokorny" <andreas.pokorny_at_[hidden]> wrote in message
> I think we should get rid of those backends entirely. Phil stated
> interesting use cases in a different thread, that might not be
> accomplished with these libraries. Additionally to that I made bad
> experiences with libpng and non broken but somehow not conformant png
> images.
> There are alternatives to using libpng and libjpeg:
> * LodePNG:
> * STB_Image
> I havent used the stb jpeg loader, but I switched to lodepng for the
> non-gil code.

IMO GIL.IO should not make the decision on the backends used (as io and
io_new currently do), instead it should provide wrappers around different
backends that provide a unified interface and let the user decide which
backend to use (as io2 does)...
For the same reason a decision to simply switch from LibPNG to LodePNG would
be equally 'wrong' there are many factors that influence the choice of
the backend that a particular user might want (or need to use)...e.g. a GUI
library might force/prefer the use of a particular backend...

But the whole xjmp issue is a bit overblown IMO as there are two solutions
that are easily implementable, one is the
'always-safe-albeit-less-efficient-one', to wrap all LibXXX calls that can
call longjmp and convert the call in setjmp to a C++ exception and the other
is to simply throw from the error callbacks for platforms/compilers/build
setups that can throw through the LibXXX code...

Furthermore, if no unwindable objects are used during the decoding of an
image (as is the case with io2 when the target is a raw/non-virtual GIL
image) the solution is even simpler (no need for constant setjmp calls in

"What Huxley teaches is that in the age of advanced technology, spiritual
devastation is more likely to come from an enemy with a smiling face than
from one whose countenance exudes suspicion and hate."
Neil Postman 

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