Michael Marcin wrote:
Hello,
I have the need to load a PNG from a generic input stream that has a similar interface (i.e. has a read, operator ! and fail with the same signature/semantics as std::istream). The png reading extensions don't appear to be able to load from anything other than a FILE*. In a library as modern as GIL I'm sort of suprised there is apparently no way to load from a generic stream.
Indeed the I/O extension has not received as much development attention as the core library. There are lots of ways to improve it - using streams is just one of them. In fact I proposed at some point in the past the possibility of keeping the I/O extension out of Boost. The disadvantage is that I/O support is one of the most useful functionalities. It is hard to use GIL without some way of reading/writing to file. If anyone has the bandwidth to rewrite the I/O library we would greatly appreciate it. As for using streams, GIL's I/O is simply a translation layer to the underlying low level I/O library. In this case libpng takes FILE, so we take FILE. But if Stefan has an adaptor that would be a helpful first step. Of course, we would need such an adaptor for the other I/O formats too. Lubomir