A few minor updates for image exporter

- use `image_type` to avoid shadowing built-in `type`
- if condition: pass else: action -> if not condition: action
- remove unused vars and imporve style

Author: cslzchen

mfr/extensions/image/export.py

@@ -18,15 +18,12 @@ def __init__(self, *args, **kwargs):
 
     def export(self):
         parts = self.format.split('.')
-        type = parts[-1].lower()
-        max_size = {
-            'w': None,
-            'h': None
-        }
+        image_type = parts[-1].lower()
+        max_size = {'w': None, 'h': None}
         if len(parts) == 2:
             max_size['w'], max_size['h'] = [int(size) for size in parts[0].split('x')]
         self.metrics.merge({
-            'type': type,
+            'type': image_type,
             'max_size_w': max_size['w'],
             'max_size_h': max_size['h'],
         })
@@ -41,18 +38,14 @@ def export(self):
             else:
                 image = Image.open(self.source_file_path)
 
-            if not (max_size.get('w') or max_size.get('h')):
-                # If any of the dimensions for the resize aren't defined:
-                pass
-            else:
+            # Only resize when both dimensions are available
+            if max_size.get('w') and max_size.get('h'):
                 # resize the image to the w/h maximum specified
                 ratio = min(max_size['w'] / image.size[0], max_size['h'] / image.size[1])
                 self.metrics.add('ratio', ratio)
                 if ratio < 1:
-                    image = image.resize(
-                        (round(image.size[0] * ratio), round(image.size[1] * ratio)),
-                        Image.ANTIALIAS
-                    )
+                    size_tuple = (round(image.size[0] * ratio), round(image.size[1] * ratio))
+                    image = image.resize(size_tuple, Image.ANTIALIAS)
 
             # Mode 'P' is for paletted images. They must be converted to RGB before exporting to
             # jpeg, otherwise Pillow will throw an error.  This is a temporary workaround, as the
@@ -63,22 +56,22 @@ def export(self):
 
             # handle transparency
             # from https://github.com/python-pillow/Pillow/issues/2609
-            if image.mode in ('RGBA', 'RGBa', 'LA') and type in ['jpeg', 'jpg']:
+            if image.mode in ('RGBA', 'RGBa', 'LA') and image_type in ['jpeg', 'jpg']:
                 # JPEG has no transparency, so anything that was transparent gets changed to
                 # EXPORT_BACKGROUND_COLOR. Default is white.
                 background = Image.new(image.mode[:-1], image.size, EXPORT_BACKGROUND_COLOR)
                 background.paste(image, image.split()[-1])
                 image = background
 
-            image.save(self.output_file_path, type)
+            image.save(self.output_file_path, image_type)
             image.close()
 
         except (UnicodeDecodeError, IOError, FileNotFoundError, OSError) as err:
-            name, extension = os.path.splitext(os.path.split(self.source_file_path)[-1])
+            os.path.splitext(os.path.split(self.source_file_path)[-1])
             raise exceptions.PillowImageError(
                 'Unable to export the file as a {}, please check that the '
-                'file is a valid image.'.format(type),
-                export_format=type,
+                'file is a valid image.'.format(image_type),
+                export_format=image_type,
                 detected_format=imghdr.what(self.source_file_path),
                 original_exception=err,
                 code=400,