From f07f2c8c5a1b2b7c63129e400aed8c500b6e8eac Mon Sep 17 00:00:00 2001
From: Dan Walmsley <dan@walms.co.uk>
Date: Thu, 15 Jul 2021 14:25:01 +0100
Subject: [PATCH] Merge pull request #6213 from
 AvaloniaUI/fixes/textbox-crash-when-focused-but-not-visible

Fixes/textbox crash when focused but not visible
---
 src/Avalonia.Controls/TextBox.cs              | 21 +++++++++++---
 .../TextBoxTests.cs                           | 29 +++++++++++++++++++
 2 files changed, 46 insertions(+), 4 deletions(-)

diff --git a/src/Avalonia.Controls/TextBox.cs b/src/Avalonia.Controls/TextBox.cs
index c1516613b3..3aef2abac5 100644
--- a/src/Avalonia.Controls/TextBox.cs
+++ b/src/Avalonia.Controls/TextBox.cs
@@ -1098,6 +1098,11 @@ namespace Avalonia.Controls
 
         private bool MoveVertical(int count)
         {
+            if (_presenter is null)
+            {
+                return false;
+            }
+
             var formattedText = _presenter.FormattedText;
             var lines = formattedText.GetLines().ToList();
             var caretIndex = CaretIndex;
@@ -1113,14 +1118,17 @@ namespace Avalonia.Controls
                 CaretIndex = hit.TextPosition + (hit.IsTrailing ? 1 : 0);
                 return true;
             }
-            else
-            {
-                return false;
-            }
+
+            return false;
         }
 
         private void MoveHome(bool document)
         {
+            if (_presenter is null)
+            {
+                return;
+            }
+            
             var text = Text ?? string.Empty;
             var caretIndex = CaretIndex;
 
@@ -1151,6 +1159,11 @@ namespace Avalonia.Controls
 
         private void MoveEnd(bool document)
         {
+            if (_presenter is null)
+            {
+                return;
+            }
+            
             var text = Text ?? string.Empty;
             var caretIndex = CaretIndex;
 
diff --git a/tests/Avalonia.Controls.UnitTests/TextBoxTests.cs b/tests/Avalonia.Controls.UnitTests/TextBoxTests.cs
index 64c0020f92..cb20071860 100644
--- a/tests/Avalonia.Controls.UnitTests/TextBoxTests.cs
+++ b/tests/Avalonia.Controls.UnitTests/TextBoxTests.cs
@@ -8,6 +8,7 @@ using Avalonia.Controls.Templates;
 using Avalonia.Data;
 using Avalonia.Input;
 using Avalonia.Input.Platform;
+using Avalonia.Layout;
 using Avalonia.Media;
 using Avalonia.Platform;
 using Avalonia.UnitTests;
@@ -556,6 +557,31 @@ namespace Avalonia.Controls.UnitTests
                 Assert.True(true);
             }
         }
+        
+        [Theory]
+        [InlineData(Key.Up)]
+        [InlineData(Key.Down)]
+        [InlineData(Key.Home)]
+        [InlineData(Key.End)]
+        public void Textbox_doesnt_crash_when_Receives_input_and_template_not_applied(Key key)
+        {
+            using (UnitTestApplication.Start(FocusServices))
+            {
+                var target1 = new TextBox
+                {
+                    Template = CreateTemplate(),
+                    Text = "1234",
+                    IsVisible = false
+                };
+
+                var root = new TestRoot { Child = target1 };
+
+                target1.Focus();
+                Assert.True(target1.IsFocused);
+                
+                RaiseKeyEvent(target1, key, KeyModifiers.None);
+            }
+        }
 
         [Fact]
         public void TextBox_GotFocus_And_LostFocus_Work_Properly()
@@ -763,6 +789,9 @@ namespace Avalonia.Controls.UnitTests
             keyboardDevice: () => new KeyboardDevice(),
             keyboardNavigation: new KeyboardNavigationHandler(),
             inputManager: new InputManager(),
+            renderInterface: new MockPlatformRenderInterface(),
+            fontManagerImpl: new MockFontManagerImpl(),
+            textShaperImpl: new MockTextShaperImpl(),
             standardCursorFactory: Mock.Of<ICursorFactory>());
 
         private static TestServices Services => TestServices.MockThreadingInterface.With(