Fix translate() which panics on negative x offset (image-rs#390)

dan-jfisher · Oct 19, 2019 · e025cac · e025cac
1 parent 3d20e5a
commit e025cac
Showing 1 changed file with 17 additions and 1 deletion.
diff --git a/src/geometric_transformations.rs b/src/geometric_transformations.rs
@@ -354,7 +354,7 @@ where
             }
 
             if w + tx > 0 {
-                let in_base = (y_in as usize * width as usize - (tx as usize)) * num_channels;
+                let in_base = (y_in as usize * width as usize + (tx.abs() as usize)) * num_channels;
                 let out_base = (y as usize * width as usize) * num_channels;
                 let len = (w + tx) as usize * num_channels;
                 (*out)[out_base..][..len].copy_from_slice(&(**image)[in_base..][..len]);
@@ -856,6 +856,22 @@ mod tests {
         assert_pixels_eq!(translated, expected);
     }
 
+    #[test]
+    fn test_translate_negative_x() {
+        let image = gray_image!(
+            00, 01, 02;
+            10, 11, 12;
+            20, 21, 22);
+
+        let expected = gray_image!(
+            01, 02, 02;
+            11, 12, 12;
+            21, 22, 22);
+
+        let translated = translate(&image, (-1, 0));
+        assert_pixels_eq!(translated, expected);
+    }
+
     #[test]
     fn test_translate_large_x_large_y() {
         let image = gray_image!(