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fstream and libpng

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How do I do it? The damn libpng uses a FILE *. Is there any way to get a compatible file pointer from an ifstream? [Edited by - Prune on October 27, 2008 11:54:00 AM]

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You have to write a new input source. It's all in the libpng docs.

Alternatively, I have a C++ wrapper that makes this incredibly easy. You can get the source code from here:

pngxx. You'll need this support library, too.

EDIT: you'll need Mercurial to get the code, at least until I release some zip files.

I haven't put together any docs yet (hopefully soon, though) but here's the basic idea:

std::vector<unsigned char> raster;
std::ifstream source("lalala.png"); // could be any istream

imagexx::raster_details d = pngxx::read_image(source, back_inserter(raster));

// Now query the details of the raster by looking at d

It also supports reading from an arbitrary input iterator pair, or you could give the filename directly. There are a bunch of iterator adaptors too, to allow you to read it in to any pre-existing image containers. Just ask if you want to know more.

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