Extract suggest_extension util from generator

imagekit/generators.py

@@ -7,9 +7,8 @@ from django.core.files.base import ContentFile
 from django.utils.encoding import smart_str, smart_unicode
 
 from .processors import ProcessorPipeline, AutoConvert
-from .utils import img_to_fobj, open_image, \
-        format_to_extension, extension_to_format, UnknownFormatError, \
-        UnknownExtensionError
+from .utils import (img_to_fobj, open_image, extension_to_format,
+        UnknownExtensionError)
 
 
 class SpecFile(ContentFile):
@@ -76,28 +75,6 @@ class SpecFileGenerator(object):
         content = SpecFile(filename, imgfile.read())
         return img, content
 
-    def suggest_extension(self, name):
-        original_extension = os.path.splitext(name)[1]
-        try:
-            suggested_extension = format_to_extension(self.format)
-        except UnknownFormatError:
-            extension = original_extension
-        else:
-            if suggested_extension.lower() == original_extension.lower():
-                extension = original_extension
-            else:
-                try:
-                    original_format = extension_to_format(original_extension)
-                except UnknownExtensionError:
-                    extension = suggested_extension
-                else:
-                    # If the formats match, give precedence to the original extension.
-                    if self.format.lower() == original_format.lower():
-                        extension = original_extension
-                    else:
-                        extension = suggested_extension
-        return extension
-
     def generate_file(self, filename, source_file, save=True):
         """
         Generates a new image file by processing the source file and returns

imagekit/models/fields/__init__.py

@@ -7,6 +7,7 @@ from ...imagecache import get_default_image_cache_backend
 from ...generators import SpecFileGenerator
 from .files import ImageSpecFieldFile, ProcessedImageFieldFile
 from .utils import ImageSpecFileDescriptor, ImageKitMeta, BoundImageKitMeta
+from ...utils import suggest_extension
 
 
 class ImageSpecField(object):
@@ -169,7 +170,7 @@ class ProcessedImageField(models.ImageField):
         filename = os.path.normpath(self.storage.get_valid_name(
                 os.path.basename(filename)))
         name, ext = os.path.splitext(filename)
-        ext = self.generator.suggest_extension(filename)
+        ext = suggest_extension(filename, self.generator.format)
         return u'%s%s' % (name, ext)
 
 

imagekit/models/fields/files.py

@@ -4,6 +4,8 @@ import datetime
 from django.db.models.fields.files import ImageField, ImageFieldFile
 from django.utils.encoding import force_unicode, smart_str
 
+from ...utils import suggest_extension
+
 
 class ImageSpecFieldFile(ImageFieldFile):
     def __init__(self, instance, field, attname):
@@ -118,9 +120,8 @@ class ImageSpecFieldFile(ImageFieldFile):
                     raise Exception('No cache_to or default_cache_to value'
                             ' specified')
                 if callable(cache_to):
-                    suggested_extension = \
-                            self.field.generator.suggest_extension(
-                            self.source_file.name)
+                    suggested_extension = suggest_extension(
+                            self.source_file.name, self.field.generator.format)
                     new_filename = force_unicode(
                             datetime.datetime.now().strftime(
                             smart_str(cache_to(self.instance,

imagekit/utils.py

@@ -1,3 +1,4 @@
+import os
 import tempfile
 import types
 
@@ -165,3 +166,26 @@ def validate_app_cache(apps, force_revalidation=False):
                 if force_revalidation:
                     f.invalidate()
                 f.validate()
+
+
+def suggest_extension(name, format):
+    original_extension = os.path.splitext(name)[1]
+    try:
+        suggested_extension = format_to_extension(format)
+    except UnknownFormatError:
+        extension = original_extension
+    else:
+        if suggested_extension.lower() == original_extension.lower():
+            extension = original_extension
+        else:
+            try:
+                original_format = extension_to_format(original_extension)
+            except UnknownExtensionError:
+                extension = suggested_extension
+            else:
+                # If the formats match, give precedence to the original extension.
+                if format.lower() == original_format.lower():
+                    extension = original_extension
+                else:
+                    extension = suggested_extension
+    return extension