[Scummvm-devel] png support

Filippos Karapetis bluegr at gmail.com
Fri Apr 29 13:20:00 CEST 2011


Hello

I'm the one who wrote the PNG decoder. The situation is as follows:
Broken Sword 2.5 requires both a PNG decoder (for its images) and a PNG
encoder (for the thumbnails in its saved games).
Right now, the thumbnails in the saved games are broken (they always were
broken), it's something I haven't looked into yet.

The PNG decoder works almost flawlessly.
I haven't written a PNG encoder, which is where libpng is still needed.

The original plan was to remove compatibility with the saved games that the
original engine creates (as they are version
specific anyway), starting with the thumbnail support. If you don't mind
dropping savegame compatibility with the original
engine, we can remove the libpng dependency.

So... the available options are:
- Keep savegame compatibility with game version 1.0, keep libpng, remove our
own PNG decoder (which works, as I said) and
attempt to find the problem with the savegame thumbnails
- Drop savegame compatibility, use our own thumbnail code, remove libpng and
use our own PNG decoder

What should we do?

Regards
Filippos


On Fri, Apr 29, 2011 at 1:49 PM, Max Horn <max at quendi.de> wrote:

> Just did a configure run with a cross compiler for which I had no libpng,
> and got this:
>
> Checking for PNG >= 1.2.8... no
> ...disabling Broken Sword 2.5 engine. PNG is required
>
> Now I am confused: I thought folks added a custom png decoder to graphics/
> so that we don't need libpng anymore. So, do we really still need to disable
> BS2.5 just because libpng is present? And if libpng is present, do we
> disable graphics/png.* ?
>
> It would be nice if somebody could clarify this. My take is this:
> If graphics/png.* cannot substitute libpng good enough to be used as a
> replacement in BS2.5, I don't see why we have it at all (unless somebody is
> actively working on fixing it).
>
> If it can act as a substitute for libpng, then
> 1) we should not disable BS2.5 in configure just because libpng is missing,
> 2) maybe we should compiler *either* with libpng, *or* with our custom png
> decoder. Having both present simultaneously seems like wasting binary size
> for nothing.
>
> But maybe I am missing something here. So once  more, I'd appreciate if
> somebody (the people who added the png decoder in the first place, maybe?)
> could take a look at this and clarify this / fix it as appropriate :).
>
> Thanks & Cheers,
> Max
>
>
>
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