Move generation of thumbnail to image path instead of templatetag

website/thaliawebsite/urls.py

@@ -33,7 +33,7 @@ from events.feeds import DeprecationFeed
 from members.sitemaps import sitemap as members_sitemap
 from partners.sitemaps import sitemap as partners_sitemap
 from thabloid.sitemaps import sitemap as thabloid_sitemap
-from utils.views import private_thumbnails
+from utils.views import private_thumbnails, generate_thumbnail
 
 from . import views
 from .sitemaps import StaticViewSitemap
@@ -79,6 +79,7 @@ urlpatterns = [
     url(r'^career/', include('partners.urls', namespace='partners')),
     url(r'^contact$', TemplateView.as_view(template_name='singlepages/contact.html'), name='contact'),
     url(r'^private-thumbnails/(?P<size_fit>\d+x\d+_[01])/(?P<path>.*)', private_thumbnails, name='private-thumbnails'),
+    url(r'^generate-thumbnail/(?P<size_fit>\d+x\d+_[01])/(?P<path>[^/]+)/(?P<thumbpath>[^/]+)', generate_thumbnail, name='generate-thumbnail'),
     url(r'^api/', include([
         url(r'^', include('events.api.urls')),
         url(r'^', include('members.api.urls')),

website/utils/templatetags/thumbnail.py

@@ -4,7 +4,7 @@ from django import template
 from django.conf import settings
 from django.db.models.fields.files import ImageFieldFile
 from django.urls import reverse
-from PIL import Image, ImageOps
+from django.utils.http import urlquote
 
 register = template.Library()
 
@@ -15,33 +15,30 @@ def thumbnail(path, size, fit=True):
         path = path.name
 
     size_fit = '{}_{}'.format(size, int(fit))
-
     parts = path.split('/')
-    # If we're dealing with an image in media/public/..
+
     if parts[0] == 'public':
-        # We actually want it to end up in media/public/thumbnails/..
-        # since those files can be accessed without passing through a view.
         thumbpath = os.path.join(parts[0], 'thumbnails', size_fit, *parts[1:])
     else:
-        # Otherwise simply place it in media/thumbnails.
         thumbpath = os.path.join('thumbnails', size_fit, path)
 
     full_thumbpath = os.path.join(settings.MEDIA_ROOT, thumbpath)
     full_path = os.path.join(settings.MEDIA_ROOT, path)
 
-    os.makedirs(os.path.dirname(full_thumbpath), exist_ok=True)
-
+    # Check if we need to generate, then redirect to the generating route,
+    # otherwise just return the file path
     if (not os.path.isfile(full_thumbpath) or
             os.path.getmtime(full_path) > os.path.getmtime(full_thumbpath)):
-        image = Image.open(full_path)
-        size = tuple(int(dim) for dim in size.split('x'))
-        if not fit:
-            ratio = min([a / b for a, b in zip(size, image.size)])
-            size = tuple(int(ratio * x) for x in image.size)
-        thumb = ImageOps.fit(image, size, Image.ANTIALIAS)
-        thumb.save(full_thumbpath)
+        pathuri = urlquote(path, safe=[''])
+        thumburi = urlquote(thumbpath, safe=[''])
+        return reverse('generate-thumbnail',
+                       args=[size_fit, pathuri, thumburi])
 
+    # If we're dealing with an image in media/public/..
     if parts[0] == 'public':
+        # We actually want it to end up in media/public/thumbnails/..
+        # since those files can be accessed without passing through a view.
         return settings.MEDIA_URL + thumbpath
-    else:
-        return reverse('private-thumbnails', args=[size_fit, path])
+
+    # Otherwise simply place it in media/thumbnails.
+    return reverse('private-thumbnails', args=[size_fit, path])

website/utils/views.py

 import os
 
+from PIL import Image, ImageOps
 from django.conf import settings
 from django.contrib.auth.decorators import login_required
 from django.http import Http404
+from django.shortcuts import redirect
+from django.urls import reverse
+from django.utils.http import urlunquote
 from sendfile import sendfile
 
 from .snippets import sanitize_path
@@ -22,3 +26,37 @@ def _private_thumbnails_unauthed(request, size_fit, path):
 @login_required
 def private_thumbnails(request, size_fit, path):
     return _private_thumbnails_unauthed(request, size_fit, path)
+
+
+def generate_thumbnail(request, size_fit, path, thumbpath):
+    """The thumbnails are generated with this route. Because the
+    thumbnails will be generated in parallel, it will not block
+    page load when many thumbnails need to be generated.
+    After it is done, the user is redirected to the new location
+    of the thumbnail."""
+    thumbpath = urlunquote(thumbpath)
+    path = urlunquote(path)
+    full_thumbpath = os.path.join(settings.MEDIA_ROOT, thumbpath)
+    full_path = os.path.join(settings.MEDIA_ROOT, path)
+    size, fit = size_fit.split('_')
+
+    os.makedirs(os.path.dirname(full_thumbpath), exist_ok=True)
+    if (not os.path.isfile(full_thumbpath) or
+            os.path.getmtime(full_path) > os.path.getmtime(full_thumbpath)):
+        image = Image.open(full_path)
+        size = tuple(int(dim) for dim in size.split('x'))
+        if not fit:
+            ratio = min([a / b for a, b in zip(size, image.size)])
+            size = tuple(int(ratio * x) for x in image.size)
+        thumb = ImageOps.fit(image, size, Image.ANTIALIAS)
+        thumb.save(full_thumbpath)
+
+    # We can instantly redirect to the new correct image url
+    if path.split('/')[0] == 'public':
+        return redirect(settings.MEDIA_URL + thumbpath, permanent=True)
+
+    # Otherwise redirect to the route with an auth check
+    return redirect(
+        reverse('private-thumbnails', args=[size_fit, path]),
+        permanent=True
+    )