Many improvements to smart cropping

wagtail/wagtailimages/backends/base.py

@@ -44,17 +44,31 @@ class BaseImageBackend(object):
 
     def crop_to_point(self, image, size, focal_point):
         crop_box = crop.crop_to_point(image.size, size, focal_point)
+
+        # Don't crop if we don't need to
         if crop_box.size != image.size:
-            return self.crop(image, crop_box)
-        else:
-            return image
+            image = self.crop(image, crop_box)
+
+        # If the focal points are too large, the cropping system may not
+        # crop it fully, resize the image if this has happened:
+        if crop_box.size != size:
+            image = self.resize_to_fill(image, size)
+
+        return image
 
     def crop_to_points(self, image, size, focal_points):
         crop_box = crop.crop_to_points(image.size, size, focal_points)
+
+        # Don't crop if we don't need to
         if crop_box.size != image.size:
-            return self.crop(image, crop_box)
-        else:
-            return image
+            image = self.crop(image, crop_box)
+
+        # If the focal points are too large, the cropping system may not
+        # crop it fully, resize the image if this has happened:
+        if crop_box.size != size:
+            image = self.resize_to_fill(image, size)
+
+        return image
 
     def smart_crop(self, image, size):
         image_mode, image_data = self.image_data_as_rgb(image)
@@ -161,7 +175,6 @@ class BaseImageBackend(object):
         resized_image = self.resize_to_min(image, size)
         return self.crop_to_centre(resized_image, size)
 
-
     def no_operation(self, image, param):
         """Return the image unchanged"""
         return image

wagtail/wagtailimages/utils/crop.py

@@ -45,15 +45,49 @@ def crop_to_point(image_size, crop_size, focal_point):
     if not focal_point:
         focal_point = FocalPoint(original_width / 2, original_height / 2)
 
+    # Get size of focal point, add 15% extra to give some room around the edge
+    focal_point_width = focal_point.width * 1.15
+    focal_point_height = focal_point.height * 1.15
+
+    # Make sure that the crop size is no smaller than the focal point
+    crop_width = max(crop_width, focal_point_width)
+    crop_height = max(crop_height, focal_point_height)
+
     # Make sure final dimensions do not exceed original dimensions
     final_width = min(original_width, crop_width)
     final_height = min(original_height, crop_height)
 
+    # Get UV for focal point
+    focal_point_u = focal_point.x / original_width
+    focal_point_v = focal_point.y / original_height
+
     # Get crop box
-    left = focal_point.x - final_width / 2
-    top = focal_point.y - final_height / 2
-    right = focal_point.x + final_width / 2
-    bottom = focal_point.y + final_height / 2
+    left = focal_point.x - focal_point_u * final_width
+    top = focal_point.y - focal_point_v * final_height
+    right = focal_point.x - focal_point_u * final_width + final_width
+    bottom = focal_point.y - focal_point_v * final_height  + final_height
+
+    # Make sure the entire focal point is in the crop box
+    focal_point_left = focal_point.x - focal_point.width / 2
+    focal_point_top = focal_point.y - focal_point.height / 2
+    focal_point_right = focal_point.x + focal_point.width / 2
+    focal_point_bottom = focal_point.y + focal_point.height / 2
+
+    if left > focal_point_left:
+        right -= left - focal_point_left
+        left = focal_point_left
+
+    if top > focal_point_top:
+        bottom -= top - focal_point_top
+        top = focal_point_top
+
+    if right < focal_point_right:
+        left += focal_point_right - right;
+        right = focal_point_right
+
+    if bottom < focal_point_bottom:
+        top += focal_point_bottom - bottom;
+        bottom = focal_point_bottom
 
     # Don't allow the crop box to go over the image boundary
     if left < 0:
@@ -76,5 +110,9 @@ def crop_to_point(image_size, crop_size, focal_point):
 
 
 def crop_to_points(image_size, crop_size, focal_points):
-    focal_point = combine_focal_points(focal_points)
+    if len(focal_points) == 1:
+        focal_point = focal_points[0]
+    else:
+        focal_point = combine_focal_points(focal_points)
+
     return crop_to_point(image_size, crop_size, focal_point)

wagtail/wagtailimages/utils/feature_detection.py

@@ -45,7 +45,7 @@ def detect_features(image_size, image_mode, image_data):
 
 def detect_faces(image_size, image_mode, image_data):
     if opencv_available:
-        cascade_filename = os.path.join(os.path.dirname(__file__), 'face_detection', 'haarcascade_frontalface_alt.xml')
+        cascade_filename = os.path.join(os.path.dirname(__file__), 'face_detection', 'haarcascade_frontalface_alt2.xml')
         cascade = cv.Load(cascade_filename)
         image = get_cv_gray_image(image_size, image_mode, image_data)
 

wagtail/wagtailimages/utils/focal_point.py

@@ -84,4 +84,16 @@ def combine_focal_points(focal_points):
     x = total_x / total_weight
     y = total_y / total_weight
 
-    return FocalPoint(x, y, weight=total_weight)
+    min_x = min([point.x - point.width / 2 for point in focal_points])
+    min_y = min([point.y - point.height / 2 for point in focal_points])
+    max_x = max([point.x + point.width / 2 for point in focal_points])
+    max_y = max([point.y + point.height / 2 for point in focal_points])
+
+    width = max_x - min_x
+    height = max_y - min_y
+
+    return FocalPoint(x, y, width=width, height=height, weight=total_weight)
+
+
+def largest_point(focal_points):
+    return sorted(focal_points, key=lambda point: point.weight, reverse=True)[0]