mygpo/web/logo.py

   1 import os.path
   2 import io
   3 from datetime import datetime
   4 from glob import glob
   5 import errno
   6 import hashlib
   7 import struct
   8
   9 from PIL import Image, ImageDraw
  10
  11 from django.core.urlresolvers import reverse
  12 from django.conf import settings
  13 from django.http import Http404, HttpResponse, HttpResponseNotFound
  14 from django.views.generic.base import View
  15 from django.utils.decorators import method_decorator
  16 from django.views.decorators.http import last_modified
  17
  18 import logging
  19 logger = logging.getLogger(__name__)
  20
  21 LOGO_DIR = os.path.join(settings.BASE_DIR, '..', 'htdocs', 'media', 'logo')
  22
  23
  24 def _last_modified(request, size, prefix, filename):
  25
  26     target = os.path.join(LOGO_DIR, size, prefix, filename)
  27
  28     try:
  29         return datetime.fromtimestamp(os.path.getmtime(target))
  30
  31     except OSError:
  32         return None
  33
  34
  35 class CoverArt(View):
  36
  37     @method_decorator(last_modified(_last_modified))
  38     def get(self, request, size, prefix, filename):
  39
  40         size = int(size)
  41
  42         target = self.get_thumbnail(size, prefix, filename)
  43         original = self.get_original(prefix, filename)
  44
  45         if os.path.exists(target):
  46             return self.send_file(target)
  47
  48         if not os.path.exists(original):
  49             raise Http404('Cover Art not available' + original)
  50
  51         target_dir = self.get_dir(target)
  52
  53         try:
  54             im = Image.open(original)
  55             if im.mode not in ('RGB', 'RGBA'):
  56                 im = im.convert('RGB')
  57         except IOError:
  58             raise Http404('Cannot open cover file')
  59
  60         try:
  61             im.thumbnail((size, size), Image.ANTIALIAS)
  62             resized = im
  63         except (struct.error, IOError, IndexError) as ex:
  64             # raised when trying to read an interlaced PNG;
  65             logger.warn('Could not create thumbnail: %s', str(ex))
  66
  67             # we use the original instead
  68             return self.send_file(original)
  69
  70         # If it's a RGBA image, composite it onto a white background for JPEG
  71         if resized.mode == 'RGBA':
  72             background = Image.new('RGB', resized.size)
  73             draw = ImageDraw.Draw(background)
  74             draw.rectangle((-1, -1, resized.size[0]+1, resized.size[1]+1),
  75                            fill=(255, 255, 255))
  76             del draw
  77             resized = Image.composite(resized, background, resized)
  78
  79         sio = io.BytesIO()
  80
  81         try:
  82             resized.save(sio, 'JPEG', optimize=True, progression=True,
  83                          quality=80)
  84         except IOError as ex:
  85             return self.send_file(original)
  86
  87         s = sio.getvalue()
  88
  89         fp = open(target, 'wb')
  90         fp.write(s)
  91         fp.close()
  92
  93         return self.send_file(target)
  94
  95     # the length of the prefix is defined here and in web/urls.py
  96     @staticmethod
  97     def get_prefix(filename):
  98         return filename[:3]
  99
 100     @staticmethod
 101     def get_thumbnail(size, prefix, filename):
 102         return os.path.join(LOGO_DIR, str(size), prefix, filename)
 103
 104     @staticmethod
 105     def get_existing_thumbnails(prefix, filename):
 106         files = glob(os.path.join(LOGO_DIR, '*', prefix, filename))
 107         return [f for f in files if 'original' not in f]
 108
 109     @staticmethod
 110     def get_original(prefix, filename):
 111         return os.path.join(LOGO_DIR, 'original', prefix, filename)
 112
 113     @staticmethod
 114     def get_dir(filename):
 115         path = os.path.dirname(filename)
 116         try:
 117             os.makedirs(path)
 118
 119         except OSError as ose:
 120             if ose.errno != errno.EEXIST:
 121                 raise
 122
 123         return path
 124
 125     def send_file(self, filename):
 126         try:
 127             f = open(filename, 'rb')
 128         except IOError:
 129             return HttpResponseNotFound()
 130
 131         resp = HttpResponse(content_type='image/jpeg')
 132         resp.status_code = 200
 133         resp.write(f.read())
 134         return resp
 135
 136
 137 def get_logo_url(podcast, size):
 138     """ Return the logo URL for the podcast """
 139
 140     if podcast.logo_url:
 141         filename = hashlib.sha1(podcast.logo_url.encode('utf-8')).hexdigest()
 142     else:
 143         filename = 'podcast-%d.png' % (hash(podcast.title) % 5, )
 144
 145     prefix = CoverArt.get_prefix(filename)
 146
 147     return reverse('logo', args=[size, prefix, filename])