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