nodes: add feathering to to ImagePadForOutpaint

nodes.py

@@ -919,6 +919,7 @@ class ImagePadForOutpaint:
                 "top": ("INT", {"default": 0, "min": 0, "max": 4096, "step": 64}),
                 "right": ("INT", {"default": 0, "min": 0, "max": 4096, "step": 64}),
                 "bottom": ("INT", {"default": 0, "min": 0, "max": 4096, "step": 64}),
+                "feathering": ("INT", {"default": 0, "min": 0, "max": 4096, "step": 1}),
             }
         }
 
@@ -927,7 +928,7 @@ class ImagePadForOutpaint:
 
     CATEGORY = "image"
 
-    def expand_image(self, image, left, top, right, bottom):
+    def expand_image(self, image, left, top, right, bottom, feathering):
         d1, d2, d3, d4 = image.size()
 
         new_image = torch.zeros(
@@ -940,10 +941,30 @@ class ImagePadForOutpaint:
             (d2 + top + bottom, d3 + left + right),
             dtype=torch.float32,
         )
-        mask[top:top + d2, left:left + d3] = torch.zeros(
-            (d2, d3),
-            dtype=torch.float32,
-        )
+
+        if feathering > 0 and feathering * 2 < d2 and feathering * 2 < d3:
+            # distances to border
+            mi, mj = torch.meshgrid(
+                torch.arange(d2, dtype=torch.float32),
+                torch.arange(d3, dtype=torch.float32),
+                indexing='ij',
+            )
+            distances = torch.minimum(
+                torch.minimum(mi, mj),
+                torch.minimum(d2 - 1 - mi, d3 - 1 - mj),
+            )
+            # convert distances to square falloff from 1 to 0
+            t = (feathering - distances) / feathering
+            t.clamp_(min=0)
+            t.square_()
+
+            mask[top:top + d2, left:left + d3] = t
+        else:
+            mask[top:top + d2, left:left + d3] = torch.zeros(
+                (d2, d3),
+                dtype=torch.float32,
+            )
+
         return (new_image, mask)