From aa7a2a27644b974b06da0f4108c5a30d3c7368e9 Mon Sep 17 00:00:00 2001
From: startewho <hoolooday@live.com>
Date: Thu, 13 Jul 2023 17:11:07 +0800
Subject: [PATCH 1/2] fix 12161

---
 src/Avalonia.Controls/Utils/StringUtils.cs | 22 +++++++++++++---------
 1 file changed, 13 insertions(+), 9 deletions(-)

diff --git a/src/Avalonia.Controls/Utils/StringUtils.cs b/src/Avalonia.Controls/Utils/StringUtils.cs
index 2ea47b442a..b664687650 100644
--- a/src/Avalonia.Controls/Utils/StringUtils.cs
+++ b/src/Avalonia.Controls/Utils/StringUtils.cs
@@ -76,7 +76,7 @@ namespace Avalonia.Controls.Utils
             }
 
             var codepoint = new Codepoint(text[index]);
-        
+
             if (!codepoint.IsWhiteSpace)
             {
                 return false;
@@ -85,12 +85,16 @@ namespace Avalonia.Controls.Utils
             // preceeded by lwsp.
             if (index > 0)
             {
-                var nextCodePoint = new Codepoint(text[index + 1]);
-
-                if (nextCodePoint.IsBreakChar)
+                if (index + 1 < text.Length)
                 {
-                    return true;
+                    var nextCodePoint = new Codepoint(text[index + 1]);
+
+                    if (nextCodePoint.IsBreakChar)
+                    {
+                        return true;
+                    }
                 }
+                return true;
             }
 
             switch (codepoint.GeneralCategory)
@@ -125,7 +129,7 @@ namespace Avalonia.Controls.Utils
             }
 
             cursor = Math.Min(cursor, text.Length);
-            
+
             int begin;
             int i;
             int cr;
@@ -181,7 +185,7 @@ namespace Avalonia.Controls.Utils
             {
                 return cursor;
             }
-            
+
             if (cr < text.Length && text[cr] == '\r' && cr + 1 < text.Length && text[cr + 1] == '\n')
             {
                 lf = cr + 1;
@@ -214,9 +218,9 @@ namespace Avalonia.Controls.Utils
             {
                 return i;
             }
-            
+
             var cc = GetCharClass(text[i]);
-            
+
             // skip over the word, punctuation, or run of whitespace
             while (i < cr && GetCharClass(text[i]) == cc)
             {

From 4c1d7b4a204e437ac0f1e648361522753d650800 Mon Sep 17 00:00:00 2001
From: startewho <hoolooday@live.com>
Date: Fri, 14 Jul 2023 08:38:00 +0800
Subject: [PATCH 2/2] Update StringUtils.cs

---
 src/Avalonia.Controls/Utils/StringUtils.cs | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/Avalonia.Controls/Utils/StringUtils.cs b/src/Avalonia.Controls/Utils/StringUtils.cs
index b664687650..0ae1ef0b97 100644
--- a/src/Avalonia.Controls/Utils/StringUtils.cs
+++ b/src/Avalonia.Controls/Utils/StringUtils.cs
@@ -94,7 +94,11 @@ namespace Avalonia.Controls.Utils
                         return true;
                     }
                 }
-                return true;
+                else
+                {
+                    return true;
+                }
+               
             }
 
             switch (codepoint.GeneralCategory)