Re: PNG libraries on Mac OS (was Re: [XaraXtreme-dev] Problems with ranlib while compiling XaraLX)

["Ben Fowler" <ben.the.mole@xxxxxxxxx>]

On 24/04/06, Alex Bligh <alex@xxxxxxxxxxx> wrote:
> Ben Fowler wrote:
> > On 24/04/06, Ben Fowler <ben.the.mole@xxxxxxxxx> wrote:
> >> [ snip ]
> >>
> >> This may not be the end of the story. Since wx makes use of PNG only as
> >> backing for its wxBitmap class, there is an over-arching question of why
> >> Camelot needs PNG at all. Whilst I haven't looked at every file, ...
>
> ... I've also found several
> wxBitmap bugs. The main one is that you can't create arbitrary BPP
> bitmaps in BPP different from your current screenmode (though you can
> always generate full colour ones).

We have the option of passing bug fixes upstream, there will be a wxWidgets
2.6.4 one day!

> Camelot needs PNG because it is a supported file format! It's also
> used in preview headers etc. If you really want to use wxWidgets
> to serialize and unserialize PNG (which is I think what you are
> advocating) then the answer is simply to convert the PNG in memory
> to a wxImage (rather than wxBitmap) and serialize it. However, wxImage
> is always 24bpp - if PNG's have lower bpp options (I can't remember)
> you will lose palette options.

If we know that we need arbitrary PNG routines ( '... supported file
format' ), then
using any abstraction is a trade off; but as you say this is not part of the
present problem. At the moment, I am merely advocating finding a short term
strategy to get independant devs up and running. If we also identify pointers
for the future, such as not relying on wxBitmap, then that is all to the good.

> I don't really think there is a good reason to muck around with
> program functionality ...

My mistake, I was thinking of implementaion, not functionality. I haven't yet
seen Xara LX working, but there is a hint on Talkgraphics that export to PNG is
planned but not yet in.

> just because there is a difficulty linking to
> the library. If it's that difficult to find a "correct" version
> of pnglib, then let's just distribute a known good version of
> pnglib with the program.

That looks to be the most attractive option. It would be nice to know
what Safari
does, it is a puzzle that there is no pnglib for Mac OS, and if it is
a licensing
concern, again to get that out into the open

It is not really my call.

Ben