mygpo/web/logo.py

   1 #
   2 # This file is part of my.gpodder.org.
   3 #
   4 # my.gpodder.org is free software: you can redistribute it and/or modify it
   5 # under the terms of the GNU Affero General Public License as published by
   6 # the Free Software Foundation, either version 3 of the License, or (at your
   7 # option) any later version.
   8 #
   9 # my.gpodder.org is distributed in the hope that it will be useful, but
  10 # WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  11 # or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Affero General Public
  12 # License for more details.
  13 #
  14 # You should have received a copy of the GNU Affero General Public License
  15 # along with my.gpodder.org. If not, see <http://www.gnu.org/licenses/>.
  16 #
  17
  18 import os.path
  19 import io
  20 from datetime import datetime
  21 from glob import glob
  22 import errno
  23 import hashlib
  24
  25 from PIL import Image, ImageDraw
  26
  27 from django.core.urlresolvers import reverse
  28 from django.conf import settings
  29 from django.http import Http404, HttpResponse, HttpResponseNotFound
  30 from django.views.generic.base import View
  31 from django.utils.decorators import method_decorator
  32 from django.views.decorators.http import last_modified
  33
  34 import logging
  35 logger = logging.getLogger(__name__)
  36
  37 LOGO_DIR = os.path.join(settings.BASE_DIR, '..', 'htdocs', 'media', 'logo')
  38
  39
  40 def _last_modified(request, size, prefix, filename):
  41
  42     target = os.path.join(LOGO_DIR, size, prefix, filename)
  43
  44     try:
  45         return datetime.fromtimestamp(os.path.getmtime(target))
  46
  47     except OSError:
  48         return None
  49
  50
  51 class CoverArt(View):
  52
  53     @method_decorator(last_modified(_last_modified))
  54     def get(self, request, size, prefix, filename):
  55
  56         size = int(size)
  57
  58         target = self.get_thumbnail(size, prefix, filename)
  59         original = self.get_original(prefix, filename)
  60
  61         if os.path.exists(target):
  62             return self.send_file(target)
  63
  64         if not os.path.exists(original):
  65             raise Http404('Cover Art not available' + original)
  66
  67         target_dir = self.get_dir(target)
  68
  69         try:
  70             im = Image.open(original)
  71             if im.mode not in ('RGB', 'RGBA'):
  72                 im = im.convert('RGB')
  73         except IOError:
  74             raise Http404('Cannot open cover file')
  75
  76         try:
  77             im.thumbnail((size, size), Image.ANTIALIAS)
  78             resized = im
  79         except (IOError, IndexError) as ex:
  80             # raised when trying to read an interlaced PNG;
  81             logger.warn('Could not create thumbnail: %s', str(ex))
  82
  83             # we use the original instead
  84             return self.send_file(original)
  85
  86         # If it's a RGBA image, composite it onto a white background for JPEG
  87         if resized.mode == 'RGBA':
  88             background = Image.new('RGB', resized.size)
  89             draw = ImageDraw.Draw(background)
  90             draw.rectangle((-1, -1, resized.size[0]+1, resized.size[1]+1),
  91                            fill=(255, 255, 255))
  92             del draw
  93             resized = Image.composite(resized, background, resized)
  94
  95         sio = io.StringIO()
  96
  97         try:
  98             resized.save(sio, 'JPEG', optimize=True, progression=True,
  99                          quality=80)
 100         except IOError as ex:
 101             return self.send_file(original)
 102
 103         s = sio.getvalue()
 104
 105         fp = open(target, 'wb')
 106         fp.write(s)
 107         fp.close()
 108
 109         return self.send_file(target)
 110
 111     # the length of the prefix is defined here and in web/urls.py
 112     @staticmethod
 113     def get_prefix(filename):
 114         return filename[:3]
 115
 116     @staticmethod
 117     def get_thumbnail(size, prefix, filename):
 118         return os.path.join(LOGO_DIR, str(size), prefix, filename)
 119
 120     @staticmethod
 121     def get_existing_thumbnails(prefix, filename):
 122         files = glob(os.path.join(LOGO_DIR, '*', prefix, filename))
 123         return [f for f in files if 'original' not in f]
 124
 125     @staticmethod
 126     def get_original(prefix, filename):
 127         return os.path.join(LOGO_DIR, 'original', prefix, filename)
 128
 129     @staticmethod
 130     def get_dir(filename):
 131         path = os.path.dirname(filename)
 132         try:
 133             os.makedirs(path)
 134
 135         except OSError as ose:
 136             if ose.errno != errno.EEXIST:
 137                 raise
 138
 139         return path
 140
 141     def send_file(self, filename):
 142         try:
 143             f = open(filename)
 144         except IOError:
 145             return HttpResponseNotFound()
 146
 147         resp = HttpResponse(content_type='image/jpeg')
 148         resp.status_code = 200
 149         resp.write(f.read())
 150         return resp
 151
 152
 153 def get_logo_url(podcast, size):
 154     """ Return the logo URL for the podcast """
 155
 156     if podcast.logo_url:
 157         filename = hashlib.sha1(podcast.logo_url.encode('utf-8')).hexdigest()
 158     else:
 159         filename = 'podcast-%d.png' % (hash(podcast.title) % 5, )
 160
 161     prefix = CoverArt.get_prefix(filename)
 162
 163     return reverse('logo', args=[size, prefix, filename])