PNG libraries

[Stewart Gordon]

"Lutger" <lutger.blijdestijn at gmail.com> wrote in message 
news:fc711f$ocl$1 at digitalmars.com...
> Lodepng was designed not to do everything the PNG format is capable of 
> since that makes it easier to do what png is most used for: image loading 
> / saving. However, the way the recent iteration is coded will make it 
> easy, with a few minor changes, to implement an extensible api. It does 
> have the benefit of supporting the full range of color formats and 
> generally being spec compliant already.
>
> If you are interested in making use of lodepng or extending it to an 
> editor, I'm open to discussion and willing to help.

Now I think the question is how much can be done without making your library 
too complex for its purpose.

Preserving unknown chunks should be fairly simple to implement - we 
basically just need a data structure or two to hold them and the order of 
all chunks in the file.  (Obviously, this behaviour should be optional.) 
Given this, it would also be straightforward to allow the library user to 
add private chunks.

But to allow the user to manipulate the range of public ancillary chunks 
available, there's the added complication of chunk ordering rules to 
consider, at least if we want to protect the user against inadvertently 
creating a PNG file that's invalid because the chunks are in the wrong 
order.

On this basis, what do you reckon?

Stewart.