Re: [AD] native image loaders

[Matthew Leverton <meffer@xxxxxxxxxx>]

On Fri, Apr 9, 2010 at 9:16 PM, Peter Wang <novalazy@xxxxxxxxxx> wrote:
> On 2010-04-09, Matthew Leverton <meffer@xxxxxxxxxx> wrote:
> The current plan is not fully consistent, but I think it's simple:
>
> - link with allegro_image => you get PNG/JPEG/BMP/TGA/PCX [*]
> - link with allegro_flac => you get FLAC support
> - link with allegro_vorbis => you get Ogg Vorbis support
> - link with allegro_modaudio => you get XM/IT/S3M/etc support
> - link with allegro_jp2k (hypothetical) => you get JPEG2000 support
>
> [*] on all platforms these are essentially "free"
>
Then you'd need to make PNG and JPEG absolute requirements for
building Allegro image, even on Windows. Otherwise, you have the same
problem: your program may or may not be able to load the images. And
if you don't want to make them requirements, then they have to be in
their own add-ons to ensure that everything works.

GDI+ should help for Windows, but currently it is buggy on Vista. Even
assuming that can be fixed, MinGW doesn't have native support for it,
so those people would still most likely have to get libpng and
libjpeg.

I'm not particularly opposed to what you've detailed above, but I
think it lends itself to arbitrary inclusions and exclusions based on
what we think is popular today. Your concerns are valid, but I'm not
sure they have any significance in the common-use sense.

Basically, you won't ever be able to guarantee that anything works
unless you provide a complete binary package, core Allegro and all.

On Linux, people would have no reason to disable libpng, etc. But even
if they did, on the first program they got that said, "Sorry, you need
to add PNG support," they would recompile Allegro with PNG. Never more
a problem. Say it happened with MOD files, which is something less
likely to be installed. Regardless of modular vs monolithic, you'd
have to recompile/compile *something* to add support. It's no less
trivial to go back and build modaudio as a stand alone add-on. It
might be of some concern if a package maintainer decided to not
include support for something, but dynamic loading of dependencies
could help with that.

On Windows, people are going to distribute their own DLLs. If you want
your program to work, don't do something foolish by relying on system
DLLs.

For what it's worth, SDL does not guarantee that any non-trivial
format is available in SDL_Mixer and Image. But they also allow you to
dynamically load formats at run time.

What are your thoughts regarding the usefulness of explicit loader
functions (e.g. al_load_bmp)?

--
Matthew Leverton