How do I serve an image from a python script?

[gbreed at cix.compulink.co.uk]

In article <3B2039DB.8884C4B4 at yahoo.com>, haaserd at yahoo.com (haaserd) 
wrote:

> Hi,
> 
> I am trying to serve an image from a Python script using Apache under
> Windows.  My simple HTML statement:
> 
>     <img src="ShowPict.py?fn=xxx"  alt="a picture">
> 
> ...and my simple script:
> 
> #!c:/Python20/python.exe
> import sys
> 
> def pix():
>     n = 'c:/My Pictures/Sample.jpg'
>     p = open(n,'rb')
>     apix = p.read()
>     p.close()
>     sys.stdout.write("content-type: image/jpeg\n\n")
>     sys.stdout.write(apix)
>     sys.stdout.flush()
> 
> if __name__ == '__main__':
>     pix()

I've found this script to work on IIS:

import cgi
import sys, os
input = open(r'absolute.filename.gif','rb')
output = os.fdopen(sys.stdout.fileno(), 'wb')
output.write('Content-Type: image/gif\r\n\r\n')
output.write(input.read())
input.close()
# don't close stdout!


The only important difference with yours is that I'm using \r\n instead of 
\n.  I think that os.fdopen stuff is wank, but worth a try if all else 
fails.


> As you can see I am ignoring the CGI fields for the moment and am just 
> trying
> to serve up an image.  Through debugging statements that I have 
> removed, I
> know the program crashes on the statement
>     sys.stdout.write(apix)
> if the picture is over 200,000 bytes.

That's above what I was testing with, hope it isn't too big a problem.  
Perhaps writing out the file in chunks will fix it.

> On small images (10k), the script runs to completion, but no image 
> appears.
> What am I doing wrong?

When you say no image appears, does that mean nothing's being sent from 
the server?  You can test this by changing the MIME type to text/plain 
(and perhaps not using IE) so you'll see some garbage appear if it's 
working.

Anyway, I expect what you're doing wrong is not setting binary output.  
That would correlate with your not using the correct line termination 
characters.  So add a -u to the command line, however that's specified.  
If it's that magic line at the top of the file, make it

#!c:/Python20/python.exe -u


                         Graham