Hi,
I'm trying to write a program which uses threads to load large images and scale
them down to a medium size (maybe 640x480) in the background. The idea is to
keep maybe 5 images at a time loaded and show the next one quickly without
having to wait.
The problem is that in my thread, during the call to
gtk.gdk.pixbuf_new_from_file() and in gtk.gdk.Pixbuf.scale_simple() the UI is
blocked. So I downloaded the pygtk source, edit gtk/gdk.c, and changed the code
to release and reacquire the GIL (for example, in
_wrap_gdk_pixbuf_new_from_file):
pyg_begin_allow_threads;
ret = gdk_pixbuf_new_from_file(filename, &error);
pyg_end_allow_threads;
I ran my script again and it worked perfectly! So my questions are:
* is there a reason why this is not in pygtk now? Do we really need to keep
the GIL? pixbuf_new_from_file only reads from a file and produces no data, so I
would think other threads couldn't harm it. (Unless, of course, they modify the
filename, but that could be strdup'd). Would it be OK for scale_simple too, or
could another thread modify the pixbuf?
* is there a better way to accomplish what I am trying to do -- load large
images in the background without freezing the UI? It seems like this must be a
common problem (don't programs have to load thumbnails in the background?!)
Anyway, if you need me to provide a diff (presumably for gtk/gdk.override)
and/or an example I'd be happy to.
Thanks,
Evan
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