From 1ee7646cfceb07354fb0a805737dd576e0aad944 Mon Sep 17 00:00:00 2001
From: Chris Dodge <cdodge@edx.org>
Date: Fri, 28 Sep 2012 10:20:57 -0400
Subject: [PATCH] per feedback, use reverse() when generating callback urls.
 Also generate thumbnails when ingesting static images. We'll need these handy
 for the CMS UI.

---
 cms/djangoapps/contentstore/views.py          | 61 +++++++++++++++++--
 common/djangoapps/contentserver/middleware.py |  4 +-
 2 files changed, 59 insertions(+), 6 deletions(-)

diff --git a/cms/djangoapps/contentstore/views.py b/cms/djangoapps/contentstore/views.py
index d8cbe0c7a9..3223bfda29 100644
--- a/cms/djangoapps/contentstore/views.py
+++ b/cms/djangoapps/contentstore/views.py
@@ -1,10 +1,15 @@
 from util.json_request import expect_json
 import json
+import os
 import logging
 import sys
 import mimetypes
+import StringIO
 from collections import defaultdict
 
+# to install PIL on MacOSX: 'easy_install http://dist.repoze.org/PIL-1.1.6.tar.gz'
+from PIL import Image
+
 from django.http import HttpResponse, Http404, HttpResponseBadRequest, HttpResponseForbidden
 from django.contrib.auth.decorators import login_required
 from django.core.context_processors import csrf
@@ -101,11 +106,18 @@ def course_index(request, org, course, name):
     _course = modulestore().get_item(location)
     weeks = _course.get_children()
 
-    upload_asset_callback_url = "/{org}/{course}/course/{name}/upload_asset".format(
-        org = org, 
-        course = course,
-        name = name
-        )
+    #upload_asset_callback_url = "/{org}/{course}/course/{name}/upload_asset".format(
+    #    org = org, 
+    #    course = course,
+    #    name = name
+    #    )
+
+    upload_asset_callback_url = reverse('upload_asset', kwargs = {
+            'org' : org,
+            'course' : course,
+            'coursename' : name
+            })
+    logging.debug(upload_asset_callback_url)
 
     return render_to_response('course_index.html', {
             'weeks': weeks, 
@@ -460,5 +472,44 @@ def upload_asset(request, org, course, coursename):
     # to re-populate the cache.
     del_cached_content(file_location)
 
+    # if we're uploading an image, then let's generate a thumbnail so that we can
+    # serve it up when needed without having to rescale on the fly
+    if mime_type.split('/')[0] == 'image':
+        try:
+            # not sure if this is necessary, but let's rewind the stream just in case
+            request.FILES['file'].seek(0)
+
+            # use PIL to do the thumbnail generation (http://www.pythonware.com/products/pil/)
+            # My understanding is that PIL will maintain aspect ratios while restricting
+            # the max-height/width to be whatever you pass in as 'size'
+            # @todo: move the thumbnail size to a configuration setting?!?
+            im = Image.open(request.FILES['file'])
+
+            # I've seen some exceptions from the PIL library when trying to save palletted 
+            # PNG files to JPEG. Per the google-universe, they suggest converting to RGB first.
+            im = im.convert('RGB')
+            size = 128, 128
+            im.thumbnail(size, Image.ANTIALIAS)
+            thumbnail_file = StringIO.StringIO()
+            im.save(thumbnail_file, 'JPEG')
+            thumbnail_file.seek(0)
+        
+            # use a naming convention to associate originals with the thumbnail
+            #   <name_without_extention>.thumbnail.jpg
+            thumbnail_name = os.path.splitext(name)[0] + '.thumbnail.jpg'
+            # then just store this thumbnail as any other piece of content
+            thumbnail_file_location = StaticContent.compute_location_filename(org, course, 
+                                                                              thumbnail_name)
+            thumbnail_content = StaticContent(thumbnail_file_location, thumbnail_name, 
+                                              'image/jpeg', thumbnail_file)
+            contentstore().save(thumbnail_content)
+
+            # remove any cached content at this location, as thumbnails are treated just like any
+            # other bit of static content
+            del_cached_content(thumbnail_file_location)
+        except:
+            # catch, log, and continue as thumbnails are not a hard requirement
+            logging.error('Failed to generate thumbnail for {0}. Continuing...'.format(name))
+
     return HttpResponse('Upload completed')
 
diff --git a/common/djangoapps/contentserver/middleware.py b/common/djangoapps/contentserver/middleware.py
index 1f0cdbba2a..56d4ed8d1c 100644
--- a/common/djangoapps/contentserver/middleware.py
+++ b/common/djangoapps/contentserver/middleware.py
@@ -26,7 +26,9 @@ class StaticContentServer(object):
                 # since we fetched it from DB, let's cache it going forward
                 set_cached_content(content)
             else:
-                logging.debug('cache hit on {0}'.format(content.filename))
+                # @todo: we probably want to have 'cache hit' counters so we can
+                # measure the efficacy of our caches
+                pass
 
             # see if the last-modified at hasn't changed, if not return a 302 (Not Modified)