From ffe56b55bcf00ec9b10a6262643b73e8ed0d3830 Mon Sep 17 00:00:00 2001
From: Jumar Macato <hikari.netto23@gmail.com>
Date: Tue, 14 May 2019 16:44:38 +0800
Subject: [PATCH] Fix #2490

---
 src/Avalonia.Animation/TransitionInstance.cs | 17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/src/Avalonia.Animation/TransitionInstance.cs b/src/Avalonia.Animation/TransitionInstance.cs
index eff2c4e9f3..fe8103adb2 100644
--- a/src/Avalonia.Animation/TransitionInstance.cs
+++ b/src/Avalonia.Animation/TransitionInstance.cs
@@ -30,13 +30,22 @@ namespace Avalonia.Animation
         {
             var interpVal = (double)t.Ticks / _duration.Ticks;
 
-            if (interpVal > 1d || interpVal < 0d)
+            // Clamp interpolation value.
+            if (interpVal >= 1d)
             {
+                PublishNext(1d);
                 PublishCompleted();
-                return;
             }
-
-            PublishNext(interpVal);
+            // Cut-off when interpolation value is negative.
+            else if (interpVal < 0d)
+            {
+                PublishNext(0d);
+                PublishCompleted();
+            }
+            else
+            {
+                PublishNext(interpVal);
+            }
         }
 
         protected override void Unsubscribed()