Add the NewLine property to TextBox

src/Avalonia.Controls/TextBox.cs

@@ -68,6 +68,10 @@ namespace Avalonia.Controls
         public static readonly StyledProperty<bool> UseFloatingWatermarkProperty =
             AvaloniaProperty.Register<TextBox, bool>(nameof(UseFloatingWatermark));
 
+        public static readonly DirectProperty<TextBox, string> NewLineProperty =
+            AvaloniaProperty.RegisterDirect<TextBox, string>(nameof(NewLine),
+                textbox => textbox.NewLine, (textbox, newline) => textbox.NewLine = newline);
+
         struct UndoRedoState : IEquatable<UndoRedoState>
         {
             public string Text { get; }
@@ -90,6 +94,7 @@ namespace Avalonia.Controls
         private UndoRedoHelper<UndoRedoState> _undoRedoHelper;
         private bool _isUndoingRedoing;
         private bool _ignoreTextChanges;
+        private string _newLine = Environment.NewLine;
         private static readonly string[] invalidCharacters = new String[1] { "\u007f" };
 
         static TextBox()
@@ -241,6 +246,15 @@ namespace Avalonia.Controls
             set { SetValue(TextWrappingProperty, value); }
         }
 
+        /// <summary>
+        /// Gets or sets which characters are inserted when Enter is pressed. Default: <see cref="Environment.NewLine"/>
+        /// </summary>
+        public string NewLine
+        {
+            get { return _newLine; }
+            set { SetAndRaise(NewLineProperty, ref _newLine, value); }
+        }
+
         protected override void OnTemplateApplied(TemplateAppliedEventArgs e)
         {
             _presenter = e.NameScope.Get<TextPresenter>("PART_TextPresenter");
@@ -498,7 +512,7 @@ namespace Avalonia.Controls
                 case Key.Enter:
                     if (AcceptsReturn)
                     {
-                        HandleTextInput("\r\n");
+                        HandleTextInput(NewLine);
                         handled = true;
                     }
 

tests/Avalonia.Controls.UnitTests/TextBoxTests.cs

@@ -247,6 +247,59 @@ namespace Avalonia.Controls.UnitTests
             }
         }
 
+        [Fact]
+        public void Press_Enter_Does_Not_Accept_Return()
+        {
+            using (UnitTestApplication.Start(Services))
+            {
+                var target = new TextBox
+                {
+                    Template = CreateTemplate(),
+                    AcceptsReturn = false,
+                    Text = "1234"
+                };
+
+                RaiseKeyEvent(target, Key.Enter, 0);
+
+                Assert.Equal("1234", target.Text);
+            }
+        }
+
+        [Fact]
+        public void Press_Enter_Add_Default_Newline()
+        {
+            using (UnitTestApplication.Start(Services))
+            {
+                var target = new TextBox
+                {
+                    Template = CreateTemplate(),
+                    AcceptsReturn = true
+                };
+
+                RaiseKeyEvent(target, Key.Enter, 0);
+
+                Assert.Equal(Environment.NewLine, target.Text);
+            }
+        }
+
+        [Fact]
+        public void Press_Enter_Add_Custom_Newline()
+        {
+            using (UnitTestApplication.Start(Services))
+            {
+                var target = new TextBox
+                {
+                    Template = CreateTemplate(),
+                    AcceptsReturn = true,
+                    NewLine = "Test"
+                };
+
+                RaiseKeyEvent(target, Key.Enter, 0);
+
+                Assert.Equal("Test", target.Text);
+            }
+        }
+
         [Theory]
         [InlineData(new object[] { false, TextWrapping.NoWrap, ScrollBarVisibility.Hidden })]
         [InlineData(new object[] { false, TextWrapping.Wrap, ScrollBarVisibility.Hidden })]