From f0818c5d2dd49219c9254fa0359a6d40a0b6b483 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jan=20Ku=C4=8Dera?=
 <10546952+miloush@users.noreply.github.com>
Date: Wed, 1 Oct 2025 20:22:31 +0100
Subject: [PATCH] Do not recapture already captured element (#19740)
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Content-Type: text/plain; charset=UTF-8
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* Do not recapture already captured element

* Recapture tests

---------

Co-authored-by: Jan Kučera <miloush@users.noreply.github.com>
---
 src/Avalonia.Base/Input/Pointer.cs              |  7 +++++--
 .../Input/PointerTests.cs                       | 17 +++++++++++++++++
 .../Input/PointerTestsBase.cs                   | 12 ++++++++++++
 3 files changed, 34 insertions(+), 2 deletions(-)

diff --git a/src/Avalonia.Base/Input/Pointer.cs b/src/Avalonia.Base/Input/Pointer.cs
index 7b98d6e3df..1f6741a09e 100644
--- a/src/Avalonia.Base/Input/Pointer.cs
+++ b/src/Avalonia.Base/Input/Pointer.cs
@@ -46,9 +46,12 @@ namespace Avalonia.Input
 
         private void Capture(IInputElement? control, bool platformInitiated)
         {
-            if (Captured is Visual v1)
-                v1.DetachedFromVisualTree -= OnCaptureDetached;
             var oldCapture = Captured;
+            if (oldCapture == control)
+                return;
+
+            if (oldCapture is Visual v1)
+                v1.DetachedFromVisualTree -= OnCaptureDetached;
             Captured = control;
             
             if (!platformInitiated)
diff --git a/tests/Avalonia.Base.UnitTests/Input/PointerTests.cs b/tests/Avalonia.Base.UnitTests/Input/PointerTests.cs
index 0bd23d64a9..912ce5b6a6 100644
--- a/tests/Avalonia.Base.UnitTests/Input/PointerTests.cs
+++ b/tests/Avalonia.Base.UnitTests/Input/PointerTests.cs
@@ -36,5 +36,22 @@ namespace Avalonia.Base.UnitTests.Input
             pointer.Capture(null);
             Assert.True(receivers.SequenceEqual(new object[] { newCapture, newParent, el, root }));
         }
+
+        [Fact]
+        public void Capture_Captured_ShouldNot_Call_Platform()
+        {
+            var pointer = new TestPointer(Pointer.GetNextFreeId(), PointerType.Mouse, true);
+
+            Border capture = new Border();
+            pointer.Capture(capture);
+            pointer.Capture(capture);
+
+            Assert.Equal(1, pointer.PlatformCaptureCalled);
+
+            pointer.Capture(null);
+            pointer.Capture(null);
+
+            Assert.Equal(2, pointer.PlatformCaptureCalled);
+        }
     }
 }
diff --git a/tests/Avalonia.Base.UnitTests/Input/PointerTestsBase.cs b/tests/Avalonia.Base.UnitTests/Input/PointerTestsBase.cs
index 95091be5f6..659ed1aaf1 100644
--- a/tests/Avalonia.Base.UnitTests/Input/PointerTestsBase.cs
+++ b/tests/Avalonia.Base.UnitTests/Input/PointerTestsBase.cs
@@ -16,6 +16,18 @@ namespace Avalonia.Base.UnitTests.Input;
 
 public abstract class PointerTestsBase : ScopedTestBase
 {
+    protected class TestPointer : Pointer
+    {
+        internal int PlatformCaptureCalled = 0;
+
+        internal TestPointer(int id, PointerType type, bool isPrimary) : base(id, type, isPrimary) { }
+
+        protected override void PlatformCapture(IInputElement? element)
+        {
+            PlatformCaptureCalled++;
+        }
+    }
+
     private protected static void SetHit(Mock<IHitTester> renderer, Control? hit)
     {
         renderer.Setup(x => x.HitTest(It.IsAny<Point>(), It.IsAny<Visual>(), It.IsAny<Func<Visual, bool>>()))