Re: [pygame] Displaying real time streaming images

[Pete Shinners <pete@shinners.org>]

Arthur Elsenaar wrote:
> newbie question; how do I go about displaying arbitrary images coming in 
> over a socket as they arrive. I see PIL has some functions to read from 
> a buffer and has a parser to convert different formats, but I am at a 
> loss how to fit it all together as I am still learning. Also I suspect 
> it can be done solely in pygame?
>
> Can someone help me out on this, so I can understand what's needed? 
> Maybe there's an example somewhere that I haven't found?
Pygame can load an image from any Python "file-like" object. This works 
for most Python streams. Unfortunately, SDL's image loaders require the 
stream to support seeking, so you'll need to create a temporary buffer.

>>> import pygame, urllib2, StringIO
>>> stream = urllib2.urlopen('http://pygame.org/docs/pygame_tiny.gif')
>>> pygame.image.load(stream)
Traceback (most recent call last):
  File "<stdin>", line 1, in ?
pygame.error: Can't seek in this data source
>>> stream = urllib2.urlopen('http://pygame.org/docs/pygame_tiny.gif')
>>> buffer = StringIO.StringIO(stream.read())
>>> pygame.image.load(buffer)
<Surface(200x60x8 SW)>

This technique will work for loading images from Zip archives and more. 
Also, don't mistake this for "progressive" image loading, where you can 
start to preview an image downloading over a slow link. Dropping the 
source into a StringIO buffer will wait until the entire stream has been 
read before continuing.

If you are sending raw image data over a socket, you should use calls 
like pygame.image.tostring() and pygame.image.fromstring(). These 
transfer the image to a large binary string, which can be sent over the 
socket, or even exchanged with PIL's or PyopenGL's matching functions.