Question

I would like to send dynamically created images to my users, such as charts, graphs etc. These images are “throw-away” images, they will be only sent to one user and then destroyed, hence the “no files involved”.

I would like to send the image directly to the user, without saving it on the file system first. With PHP this could be achieved by linking an image in your HTML files to a PHP script such as:

edit: SO swallowed my image tag:

<img src="someScript.php?param1=xyz">

The script then sent the correct headers (filetype=>jpeg etc) to the browser and directly wrote the image back to the client, without temporarily saving it to the file system.

How could I do something like this with a WSGI application. Currently I am using Python’s internal SimpleWSGI Server. I am aware that this server was mainly meant for demonstration purposes and not for actual use, as it lacks multi threading capabilities, so please don’t point this out to me, I am aware of that, and for now it fulfills my requirements 🙂

Is it really as simple as putting the URL into the image tags and handling the request with WSGI, or is there a better practise?

Has anyone had any experience with this and could give me a few pointers (no 32Bit ones please)

Thanks,

Tom

Answer 1

It is not related to WSGI or php or any other specific web technology. consider

<img src="someScript.php?param1=xyz">

in general for url someScript.php?param1=xyz server should return data of image type and it would work

Consider this example:

from wsgiref.simple_server import make_server

def serveImage(environ, start_response):
    status = '200 OK'
    headers = [('Content-type', 'image/png')]
    start_response(status, headers)

    return open("about.png", "rb").read()

httpd = make_server('', 8000, serveImage)
httpd.serve_forever()

here any url pointing to serveImage will return a valid image and you can use it in any img tag or any other tag place where a image can be used e.g. css or background images

Image data can be generated on the fly using many third party libraries e.g. PIL etc
e.g see examples of generating images dynamically using python imaging library
http://lost-theory.org/python/dynamicimg.html