locale start

[wolnelektury.git] / apps / picture / engine.py

diff --git a/apps/picture/engine.py b/apps/picture/engine.py
new file mode 100644 (file)
index 0000000..a4435ae
--- /dev/null
+++ b/apps/picture/engine.py
@@ -0,0 +1,57 @@
+from sorl.thumbnail.engines import pil_engine
+from sorl.thumbnail import parsers
+
+#
+# Class developed by 
+# http://timmyomahony.com/blog/custom-cropping-engine-sorl-thumbnail/
+#
+class CustomCroppingEngine(pil_engine.Engine):
+    """
+    A custom sorl.thumbnail engine (using PIL) that first crops an image
+    according to 4 pixel/percentage values in the source image, then scales
+    that crop down to the size specified in the geometry. This is in contrast
+    to sorl.thumbnails default engine which first scales the image down to the
+    specified geometry and applies the crop afterward.
+    """
+    def create(self, image, geometry, options):
+        image = self.orientation(image, geometry, options)
+    image = self.colorspace(image, geometry, options)
+    image = self.crop(image, geometry, options)
+    image = self.scale(image, geometry, options)
+    return image
+
+    def _crop_parse(self, crop, xy_image, xy_window):
+        """
+        Conver the crop string passed by the user to accurate cropping values
+        (This is adapter from the default sorl.thumbnail.parsers.parse_crop)
+        """
+        crops = crop.split(' ')
+        if len(crops) != 4:
+            raise parsers.ThumbnailParseError('Unrecognized crop option: %s' % crop)
+        x1, y1, x2, y2 = crops
+
+        def get_offset(crop, epsilon):
+            m = parsers.bgpos_pat.match(crop)
+            if not m:
+                raise parsers.ThumbnailParseError('Unrecognized crop option: %s' % crop)
+            value = int(m.group('value')) # we only take ints in the regexp
+            unit = m.group('unit')
+            if unit == '%':
+                value = epsilon * value / 100.0
+                return int(max(0, min(value, epsilon)))
+        x1 = get_offset(x1, xy_image[0])
+        y1 = get_offset(y1, xy_image[0])
+        x2 = get_offset(x2, xy_image[1])
+        y2 = get_offset(y2, xy_image[1])
+        return x1, y1, x2, y2
+
+    def crop(self, image, geometry, options):
+        crop = options['crop']
+        if not crop or crop == 'noop':
+            return image
+        x_image, y_image = self.get_image_size(image)
+        x1,y1,x2,y2 = self._crop_parse(crop, (x_image, y_image), geometry)
+        return self._crop(image, x1, y1, x2, y2)
+
+    def _crop(self, image, x1, y1, x2, y2):
+        return image.crop((x1, y1, x2, y2))