Merge pull request #15 from ansman/fix/14

Fix a crash when comparing differently sized images
dropbox · Feb 2, 2024 · 807cccc · 807cccc
2 parents 957ada7 + e575a28
commit 807cccc
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Showing 2 changed files with 11 additions and 1 deletion.
diff --git a/differ/src/commonMain/kotlin/com/dropbox/differ/ImageComparator.kt b/differ/src/commonMain/kotlin/com/dropbox/differ/ImageComparator.kt
@@ -48,7 +48,7 @@ class SimpleImageComparator(
         (b..t).forEach { offsetY ->
           if (offsetX != x || offsetY != y) {
             // If we're out of bounds for either of the images, return false
-            if (x >= minOf(left.width, right.width) || y >= minOf(left.height, right.height)) return false
+            if (offsetX >= minOf(left.width, right.width) || offsetY >= minOf(left.height, right.height)) return false
 
             val c1 = left.getPixel(offsetX, offsetY)
             val localDeltaThreshold = color.distance(c1)

diff --git a/differ/src/commonTest/kotlin/com/dropbox/differ/ShiftComparisonTest.kt b/differ/src/commonTest/kotlin/com/dropbox/differ/ShiftComparisonTest.kt
@@ -61,4 +61,14 @@ class ShiftComparisonTest {
     assertEquals(comparator.hShift, 0)
     assertEquals(comparator.vShift, 10)
   }
+
+  @Test fun `returns DIFFERENT for different sized images`() {
+    val first = TestImage(width = 1080, height = 1080)
+    val second = TestImage(width = 1080, height = 540)
+    second.setPixel(second.width - 1, second.height - 1, Color(0f, 0f, 0f, 0f))
+
+    val comparator = SimpleImageComparator(hShift = 1, vShift = 1)
+    assertEquals(540 * 1080 + 1, comparator.compare(first, second).pixelDifferences)
+    assertEquals(540 * 1080, comparator.compare(second, first).pixelDifferences)
+  }
 }