Add JPEGField (#211)

Author: codingjoe

README.md

@@ -30,20 +30,23 @@ and add `'stdimage'` to `INSTALLED_APP`s in your settings.py, that's it!
 
 ## Usage
 
-
-``StdImageField`` works just like Django's own
+`StdImageField` works just like Django's own
 [ImageField](https://docs.djangoproject.com/en/dev/ref/models/fields/#imagefield)
 except that you can specify different sized variations.
 
+The `JPEGField` works similar to the `StdImageField` but all size variations are
+converted to JPEGs, no matter what type the original file is.
+
 ### Variations
+
 Variations are specified within a dictionary. The key will be the attribute referencing the resized image.
 A variation can be defined both as a tuple or a dictionary.
 
 Example:
 
 ```python
 from django.db import models
-from stdimage.models import StdImageField
+from stdimage import StdImageField, JPEGField
 
 
 class MyModel(models.Model):
@@ -56,6 +59,12 @@ class MyModel(models.Model):
 
     # is the same as dictionary-style call
     image = StdImageField(upload_to='path/to/img', variations={'thumbnail': (100, 75)})
+    
+    # variations are converted to JPEGs
+    jpeg = JPEGField(
+        upload_to='path/to/img',
+        variations={'full': (float('inf'), float('inf')), 'thumbnail': (100, 75)},
+    )
 
     # creates a thumbnail resized to 100x100 croping if necessary
     image = StdImageField(upload_to='path/to/img', variations={
@@ -67,11 +76,10 @@ class MyModel(models.Model):
         'large': (600, 400),
         'thumbnail': (100, 100, True),
         'medium': (300, 200),
-        delete_orphans=True,
-    })
+    }, delete_orphans=True)
 ```
 
- For using generated variations in templates use `myimagefield.variation_name`.
+For using generated variations in templates use `myimagefield.variation_name`.
 
 Example:
 

stdimage/__init__.py

@@ -1 +1 @@
-from .models import StdImageField  # NOQA
+from .models import JPEGField, StdImageField  # NOQA

stdimage/models.py

@@ -18,7 +18,7 @@ class StdImageFileDescriptor(ImageFileDescriptor):
     """The variation property of the field is accessible in instance cases."""
 
     def __set__(self, instance, value):
-        super(StdImageFileDescriptor, self).__set__(instance, value)
+        super().__set__(instance, value)
         self.field.set_variations(instance)
 
 
@@ -170,7 +170,7 @@ class StdImageField(ImageField):
         'width': float('inf'),
         'height': float('inf'),
         'crop': False,
-        'resample': Image.ANTIALIAS
+        'resample': Image.ANTIALIAS,
     }
 
     def __init__(self, verbose_name=None, name=None, variations=None,
@@ -236,8 +236,9 @@ def __init__(self, verbose_name=None, name=None, variations=None,
 
     def add_variation(self, name, params):
         variation = self.def_variation.copy()
+        variation["kwargs"] = {}
         if isinstance(params, (list, tuple)):
-            variation.update(dict(zip(("width", "height", "crop"), params)))
+            variation.update(dict(zip(("width", "height", "crop", "kwargs"), params)))
         else:
             variation.update(params)
         variation["name"] = name
@@ -287,3 +288,65 @@ def save_form_data(self, instance, data):
             if file and file._committed and file != data:
                 file.delete(save=False)
         super().save_form_data(instance, data)
+
+
+class JPEGFieldFile(StdImageFieldFile):
+
+    @classmethod
+    def get_variation_name(cls, file_name, variation_name):
+        path = super().get_variation_name(file_name, variation_name)
+        path, ext = os.path.splitext(path)
+        return '%s.jpeg' % path
+
+    @classmethod
+    def process_variation(cls, variation, image):
+        """Process variation before actual saving."""
+        save_kargs = {}
+        file_format = 'JPEG'
+        save_kargs['format'] = file_format
+
+        resample = variation['resample']
+
+        factor = 1
+        while image.size[0] / factor \
+                > 2 * variation['width'] \
+                and image.size[1] * 2 / factor \
+                > 2 * variation['height']:
+            factor *= 2
+        if factor > 1:
+            image.thumbnail(
+                (int(image.size[0] / factor),
+                 int(image.size[1] / factor)),
+                resample=resample
+            )
+
+        size = variation['width'], variation['height']
+        size = tuple(int(i) if i != float('inf') else i
+                     for i in size)
+
+        # http://stackoverflow.com/a/21669827
+        image = image.convert('RGB')
+        save_kargs['optimize'] = True
+        save_kargs['quality'] = 'web_high'
+        if size[0] * size[1] > 10000:  # roughly <10kb
+            save_kargs['progressive'] = True
+
+        if variation['crop']:
+            image = ImageOps.fit(
+                image,
+                size,
+                method=resample
+            )
+        else:
+            image.thumbnail(
+                size,
+                resample=resample
+            )
+
+        save_kargs.update(variation['kwargs'])
+
+        return image, save_kargs
+
+
+class JPEGField(StdImageField):
+    attr_class = JPEGFieldFile

tests/models.py

@@ -5,7 +5,7 @@
 from django.db import models
 from PIL import Image
 
-from stdimage import StdImageField
+from stdimage import JPEGField, StdImageField
 from stdimage.models import StdImageFieldFile
 from stdimage.utils import render_variations
 from stdimage.validators import MaxSizeValidator, MinSizeValidator
@@ -59,6 +59,19 @@ class ThumbnailModel(models.Model):
     )
 
 
+class JPEGModel(models.Model):
+    """creates a thumbnail resized to maximum size to fit a 100x75 area"""
+    image = JPEGField(
+        upload_to=upload_to,
+        blank=True,
+        variations={
+            'full': (float('inf'), float('inf')),
+            'thumbnail': (100, 75, True),
+         },
+        delete_orphans=True,
+    )
+
+
 class MaxSizeModel(models.Model):
     image = StdImageField(
         upload_to=upload_to,

tests/test_models.py

@@ -7,6 +7,7 @@
 from django.core.files.uploadedfile import SimpleUploadedFile
 from PIL import Image
 
+from . import models
 from .models import (AdminDeleteModel, CustomRenderVariationsModel, ResizeCropModel,
                      ResizeModel, SimpleModel, ThumbnailModel,
                      ThumbnailWithoutDirectoryModel, UtilVariationsModel,)
@@ -222,3 +223,11 @@ def test_min_size_validator(self, admin_client):
             'image': self.fixtures['100.gif'],
         })
         assert not os.path.exists(os.path.join(IMG_DIR, '100.gif'))
+
+
+class TestJPEGField(TestStdImage):
+    def test_convert(self, db):
+        obj = models.JPEGModel.objects.create(image=self.fixtures['100.gif'])
+        assert obj.image.thumbnail.path.endswith('img/100.thumbnail.jpeg')
+        assert obj.image.full.width == 100
+        assert obj.image.full.height == 100