zeroinstall/gtkui/icon.py

   1 """Loading icons."""
   2 # Copyright (C) 2009, Thomas Leonard
   3 # See the README file for details, or visit http://0install.net.
   4
   5 from zeroinstall import _
   6 import gtk
   7 from logging import warn
   8 import math
   9
  10 def load_icon(icon_path, icon_width=None, icon_height=None):
  11         """Load icon from path. Icon MUST be in PNG format.
  12         @param icon_path: pathname of icon, or None to load nothing
  13         @return: a GdkPixbuf, or None on failure"""
  14         if not icon_path:
  15                 return None
  16
  17         def size_prepared_cb(loader, width, height):
  18                 dest_width = icon_width or width
  19                 dest_height = icon_height or height
  20
  21                 if dest_width == width and dest_height == height:
  22                         return
  23
  24                 ratio_width = float(dest_width) / width
  25                 ratio_height = float(dest_height) / height
  26                 ratio = min(ratio_width, ratio_height)
  27
  28                 # preserve original ration
  29                 if ratio_width != ratio:
  30                         dest_width = int(math.ceil(width * ratio))
  31                 elif ratio_height != ratio:
  32                         dest_height = int(math.ceil(height * ratio))
  33
  34                 loader.set_size(int(dest_width), int(dest_height))
  35
  36         # Restrict icon formats to avoid attacks
  37         try:
  38                 loader = gtk.gdk.PixbufLoader('png')
  39                 if icon_width or icon_height:
  40                         loader.connect('size-prepared', size_prepared_cb)
  41                 try:
  42                         with open(icon_path, 'rb') as stream:
  43                                 loader.write(stream.read())
  44                 finally:
  45                         loader.close()
  46                 return loader.get_pixbuf()
  47         except Exception as ex:
  48                 warn(_("Failed to load cached PNG icon: %s") % ex)
  49                 return None