Unfortunately, there’s one small trick you need to work around. If your applet is so simple that it just needs a single, static icon, then sub-classing awn.AppletSimple, followed by a call to set_icon, works great. It gets more difficult if you need to draw dynamic content in the area usually occupied by the icon.

The problem is that set_icon (as well as its misunderstood cousin, set_temp_icon) takes a Pixbuf as its input parameter. However, the drawing framework for doing just about anything, especially loading PNGs, is cairo. Cairo has no native support for converting a surface to a Pixbuf. I discovered a trick for doing this by looking at the source code for the PyClock and BlingSwitcher applets. Let’s say you have a Cairo image surface that you’ve created from an existing PNG, thusly:

cs = cairo.ImageSurface.create_from_png(iconName)
ct = cairo.Context(cs)
ct.set_source_surface(cs)
ct.paint()

…and you want to get a Pixbuf from that image. The following function takes the surface, writes it to a PNG that is stored in a string, then uses the Pixbuf loader to load it from that PNG string:

# Stolen from diogodivision's "BlingSwitcher"
def get_pixbuf_from_surface(self, surface):
  sio = StringIO()
  surface.write_to_png(sio)
  sio.seek(0)
  loader = gtk.gdk.PixbufLoader()
  loader.write(sio.getvalue())
  loader.close()
  return loader.get_pixbuf()

Neat, huh? This is how I manage to display the temperature on the weather applet. I load up the icon into an ImageSurface, write the text on top of it by calling show_text, call the function above to convert the ImageSurface to a PixBuf, then call set_temp_icon using the new PixBuf.

You can see it in action by downloading the weather applet, and looking in weather.py. The relevant code is in the draw_current_conditions function.