Make it possible to load image from a buffer

[inikolaev]

Right now it's only possible to load image from a file. I have a use case where I would like to load image from a buffer, specifically the the response contents returned by requests library, e.g.:

import lycon
import requests

response = requests.get("https://example.com/image.jpeg")
image = lycon.load(response.content)

[l3robot]

you could use the io python standard library to "fake" a file stream.

import io
import lycon
image = lycon.load(io.BytesIO(buffer))

[nieksand]

Using a io.BytesIO() didn't work for me:

    return lycon.load(io.BytesIO(png_dat))

_lycon.PyconError: Assertion Failure: `str` evaluated to false in `string_from_pyobject` (/tmp/pip-install-nv5q896g/lycon/src/lycon/python/interop.cc:322)

A gross work around is to write to a temp file and then read from that:

    (fdesc, fname) = tempfile.mkstemp(prefix='tmp-lycon-hack-')
    os.write(fdesc, png_dat)
    os.close(fdesc)

    dat = lycon.load(fname)
    os.remove(fname)
    return dat

[nurpax]

It looks from reading the source that Lycon really only supports passing a file name argument to lycon.load(). This makes it impossible to load images from container formats such as a zipfile using lycon and various other uses. I was excited to learn about a faster library than PIL.Image, but the API is a dealbreaker for me.