Merge pull request #4908 from radarhere/effect_spread

Fixed effect_spread bug for zero distance
python-pillow · Sep 9, 2020 · 6a630fd · 6a630fd
2 parents 9e6dabf + 272f519
commit 6a630fd
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Showing 2 changed files with 28 additions and 9 deletions.
diff --git a/Tests/test_image.py b/Tests/test_image.py
@@ -454,6 +454,17 @@ def test_effect_spread(self):
         with Image.open("Tests/images/effect_spread.png") as im3:
             assert_image_similar(im2, im3, 110)
 
+    def test_effect_spread_zero(self):
+        # Arrange
+        im = hopper()
+        distance = 0
+
+        # Act
+        im2 = im.effect_spread(distance)
+
+        # Assert
+        assert_image_equal(im, im2)
+
     def test_check_size(self):
         # Checking that the _check_size function throws value errors when we want it to
         with pytest.raises(ValueError):

diff --git a/src/libImaging/Effects.c b/src/libImaging/Effects.c
@@ -131,15 +131,23 @@ ImagingEffectSpread(Imaging imIn, int distance)
     }
 
 #define SPREAD(type, image)\
-    for (y = 0; y < imOut->ysize; y++) {\
-        for (x = 0; x < imOut->xsize; x++) {\
-            int xx = x + (rand() % distance) - distance/2;\
-            int yy = y + (rand() % distance) - distance/2;\
-            if (xx >= 0 && xx < imIn->xsize && yy >= 0 && yy < imIn->ysize) {\
-                imOut->image[yy][xx] = imIn->image[y][x];\
-                imOut->image[y][x]   = imIn->image[yy][xx];\
-            } else {\
-                imOut->image[y][x]   = imIn->image[y][x];\
+    if (distance == 0) {\
+        for (y = 0; y < imOut->ysize; y++) {\
+            for (x = 0; x < imOut->xsize; x++) {\
+                imOut->image[y][x] = imIn->image[y][x];\
+            }\
+        }\
+    } else {\
+        for (y = 0; y < imOut->ysize; y++) {\
+            for (x = 0; x < imOut->xsize; x++) {\
+                int xx = x + (rand() % distance) - distance/2;\
+                int yy = y + (rand() % distance) - distance/2;\
+                if (xx >= 0 && xx < imIn->xsize && yy >= 0 && yy < imIn->ysize) {\
+                    imOut->image[yy][xx] = imIn->image[y][x];\
+                    imOut->image[y][x]   = imIn->image[yy][xx];\
+                } else {\
+                    imOut->image[y][x]   = imIn->image[y][x];\
+                }\
             }\
         }\
     }