Added AdminThumbnailView field.

You're no longer restricted to just one, special-case admin thumbnail. Make as
many as you want by adding AdminThumbnailView properties to your model and
including them in your admin class's `list_display` tuple. You can also provide
a custom template. Note that (because this change introduces templates to
imagekit), imagekit is now required in INSTALLED_APPS.

Ideally we could get this stuff out of the model, but we'll have to look into
whether that's possible without making things really complicated.

imagekit/fields.py

@@ -0,0 +1,44 @@
+from django.utils.translation import ugettext_lazy as _
+from django.template.loader import render_to_string
+
+
+class BoundAdminThumbnailView(object):
+    short_description = _('Thumbnail')
+    allow_tags = True
+
+    def __init__(self, model_instance, image_field, template=None):
+        self.model_instance = model_instance
+        self.image_field = image_field
+        self.template = template
+
+    def __unicode__(self):
+        thumbnail = getattr(self.model_instance, self.image_field, None)
+        
+        if not thumbnail:
+            raise Exception('The property {0} is not defined on {1}.'.format(
+                    self.model_instance, self.image_field))
+
+        original_image = getattr(thumbnail, '_imgfield', None) or thumbnail
+        template = self.template or 'imagekit/admin/thumbnail.html'
+
+        return render_to_string(template, {
+            'model': self.model_instance,
+            'thumbnail': thumbnail,
+            'original_image': original_image,
+        })
+
+
+class AdminThumbnailView(object):
+    def __init__(self, image_field, template=None):
+        """
+        Keyword arguments:
+        image_field -- the name of the ImageField or ImageSpec on the model to
+                use for the thumbnail.
+        template -- the template with which to render the thumbnail
+
+        """
+        self.image_field = image_field
+        self.template = template
+
+    def __get__(self, obj, type=None):
+        return BoundAdminThumbnailView(obj, self.image_field, self.template)

imagekit/models.py

@@ -67,28 +67,9 @@ class ImageModel(models.Model):
     """
     __metaclass__ = ImageModelBase
 
-    admin_thumbnail = defaults.DjangoAdminThumbnail()
-
     class Meta:
         abstract = True
 
-    def admin_thumbnail_view(self):
-        if not self._imgfields:
-            return None
-        prop = getattr(self, self._ik.admin_thumbnail_property, None)
-        if prop is None:
-            return 'The property "%s" has not been defined.' % \
-              self._ik.admin_thumbnail_property
-        else:
-            if hasattr(self, 'get_absolute_url'):
-                return u'<a href="%s"><img src="%s"></a>' % \
-                    (escape(self.get_absolute_url()), escape(prop.url))
-            else:
-                return u'<a href="%s"><img src="%s"></a>' % \
-                    (escape(self._get_imgfield(self).url), escape(prop.url))
-    admin_thumbnail_view.short_description = _('Thumbnail')
-    admin_thumbnail_view.allow_tags = True
-
     class IKOptions:
         pass
 

imagekit/options.py

@@ -10,9 +10,6 @@ class Options(object):
 
     """
 
-    admin_thumbnail_property = 'admin_thumbnail'
-    """The name of the spec to be used by the admin_thumbnail_view"""
-
     default_image_field = None
     """The name of the image field property on the model.
     Can be overridden on a per-spec basis by setting the image_field property on

imagekit/templates/imagekit/admin/thumbnail.html

@@ -0,0 +1,3 @@
+<a href="{{ model.get_absolute_url|default:original_image.url }}">
+	<img src="{{ thumbnail.url }}">
+</a>