Also -- this feedback is really helpful when writing some comments in the wrappers as to why certain things are the way they are... I'll make sure to include rationales for raw file fast path and the need to open the files on the Python side.
Mike On 12/04/2012 08:45 AM, Michael Droettboom wrote: > On 12/03/2012 08:01 PM, Chris Barker - NOAA Federal wrote: >> On Mon, Dec 3, 2012 at 4:16 PM, Nathaniel Smith <n...@pobox.com> wrote: >> >>> Yeah, this is a general problem with the Python file API, trying to >>> hook it up to stdio is not at all an easy thing. A better version of >>> this code would skip that altogether like: >>> >>> cdef void write_to_pyfile(png_structp s, png_bytep data, png_size_t count): >>> fobj = <object>png_get_io_ptr(s) >>> pydata = PyString_FromStringAndSize(data, count) >>> fobj.write(pydata) >> Good point -- not at all Cython-specific, but do you need libpng (or >> whatever) to write to the file? can you just get a buffer with the >> encoded data and write it on the Python side? Particularly if the user >> wants to pass in an open file object. This might be a better API for >> folks that might want stream an image right through a web app, too. > You need to support both: raw C FILE objects for speed, and writing to a > Python file-like object for flexibility. The code in master already > does this (albeit with PyCXX), and the code on my "No CXX" branch does > this as well with Cython. >> As a lot of Python APIs take either a file name or a file-like object, >> perhaps it would make sense to push that distinction down to the >> Cython level: >> -- if it's a filename, open it with raw C > Unfortunately, as stated in detail in my last e-mail, that doesn't work > with Unicode paths. > >> -- if it's a file-like object, have libpng write to a buffer (bytes >> object) , and pass that to the file-like object in Python > libpng does one better and allows us to stream directly to a callback > which can then write to a Python object. This prevents double > allocation of memory. > >> anyway, not really a Cython issue, but that second object sure would >> be easy on Cython.... >> > Yeah -- once I figured out how to make a real C callback function from > Cython, the contents of the callback function itself is pretty easy to > write. > > Mike > > ------------------------------------------------------------------------------ > LogMeIn Rescue: Anywhere, Anytime Remote support for IT. Free Trial > Remotely access PCs and mobile devices and provide instant support > Improve your efficiency, and focus on delivering more value-add services > Discover what IT Professionals Know. Rescue delivers > http://p.sf.net/sfu/logmein_12329d2d > _______________________________________________ > Matplotlib-devel mailing list > Matplotlib-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/matplotlib-devel ------------------------------------------------------------------------------ LogMeIn Rescue: Anywhere, Anytime Remote support for IT. Free Trial Remotely access PCs and mobile devices and provide instant support Improve your efficiency, and focus on delivering more value-add services Discover what IT Professionals Know. Rescue delivers http://p.sf.net/sfu/logmein_12329d2d _______________________________________________ Matplotlib-devel mailing list Matplotlib-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-devel
