fix(android): various issues with readonly textblock

- IsReadOnly=True breaks AcceptsReturn=True (multi-line)
- IsReadOnly=True can still bring up keyboard on click

src/SamplesApp/SamplesApp.UITests/Windows_UI_Xaml_Controls/TextBoxTests/TextBoxTests.cs

@@ -447,5 +447,76 @@ public void Focus_Programmatic()
 
 			_app.WaitForText("TargetTextBox", "orangutan");
 		}
+
+		[Test]
+		[AutoRetry]
+		[ActivePlatforms(Platform.Android)]
+		public void TextBox_Readonly_ShouldNotBringUpKeyboard()
+		{
+			Run("Uno.UI.Samples.UITests.TextBoxControl.TextBox_IsReadOnly");
+
+			var target = _app.Marked("txt");
+			var readonlyToggle = _app.Marked("tglReadonly"); // default: checked
+
+			// initial state
+			_app.WaitForElement(target);
+			var screenshot1 = TakeScreenshot("textbox readonly", ignoreInSnapshotCompare: true);
+
+			// remove readonly and focus textbox
+			readonlyToggle.Tap(); // now: unchecked
+			target.Tap();
+			_app.Wait(seconds: 1); // allow keyboard to fully open
+			var screenshot2 = TakeScreenshot("textbox focused with keyboard", ignoreInSnapshotCompare: true);
+
+			// reapply readonly and try focus textbox
+			readonlyToggle.Tap(); // now: checked
+			target.Tap();
+			_app.Wait(seconds: 1); // allow keyboard to fully open (if ever possible)
+			_app.WaitForElement(target);
+			var screenshot3 = TakeScreenshot("textbox readonly again", ignoreInSnapshotCompare: true);
+
+			// the bottom half should only contains the keyboard and some blank space,
+			// but not the textbox nor the toggle buttons that needs to be excluded.
+			var screen = _app.GetScreenDimensions();
+			var bottomHalfRect = new Rectangle(
+				0, (int)screen.Height / 2,
+				(int)screen.Width, (int)screen.Height / 2
+			);
+
+			ImageAssert.AreNotEqual(screenshot1, screenshot2, bottomHalfRect); // no keyboard != keyboard
+			ImageAssert.AreEqual(screenshot1, screenshot3, bottomHalfRect); // no keyboard == no keyboard
+		}
+
+		[Test]
+		[AutoRetry]
+		[ActivePlatforms(Platform.Android)]
+		public void TextBox_IsReadOnly_AcceptsReturn_Test()
+		{
+			/* test disabled for ios and wasm, due to #
+			 *-ios: when setting AcceptsReturn to false, the TextBox doesn't resize appropriately
+			 * -wasm: AcceptsReturn is not implemented or does nothing */
+
+			Run("UITests.Shared.Windows_UI_Xaml_Controls.TextBoxTests.TextBox_IsReadOnly_AcceptsReturn");
+			// for context, IsReadOnly=True used to break AcceptsReturn=True on android
+
+			var target = _app.Marked("TargetTextBox");
+			var readonlyCheckBox = _app.Marked("IsReadOnlyCheckBox"); // default: checked
+			var multilineCheckBox = _app.Marked("AcceptsReturnCheckBox"); // default: checked
+
+			// initial state
+			_app.WaitForElement(target);
+			var multilineReadonlyTextRect = target.FirstResult().Rect;
+
+			// remove readonly
+			readonlyCheckBox.Tap(); // now: unchecked
+			var multilineTextRect = target.FirstResult().Rect;
+
+			// remove multiline
+			multilineCheckBox.Tap(); // now: unchecked
+			var normalTextRect = target.FirstResult().Rect;
+
+			multilineTextRect.Height.Should().Be(multilineReadonlyTextRect.Height, because: "toggling IsReadOnly should not affect AcceptsReturn=True(multiline) TextBox.Height");
+			normalTextRect.Height.Should().NotBe(multilineTextRect.Height, because: "toggling AcceptsReturn should not affect TextBox.Height");
+		}
 	}
 }

src/SamplesApp/UITests.Shared/UITests.Shared.projitems

@@ -917,6 +917,10 @@
       <SubType>Designer</SubType>
       <Generator>MSBuild:Compile</Generator>
     </Page>
+    <Page Include="$(MSBuildThisFileDirectory)Windows_UI_Xaml_Controls\TextBox\TextBox_IsReadOnly_AcceptsReturn.xaml">
+      <SubType>Designer</SubType>
+      <Generator>MSBuild:Compile</Generator>
+    </Page>
     <Page Include="$(MSBuildThisFileDirectory)Windows_UI_Xaml_Controls\TextBox\TextBox_MaxLength.xaml">
       <SubType>Designer</SubType>
       <Generator>MSBuild:Compile</Generator>
@@ -3701,6 +3705,9 @@
     <Compile Include="$(MSBuildThisFileDirectory)Windows_UI_Xaml_Controls\TextBox\TextBox_Margin.xaml.cs">
       <DependentUpon>TextBox_Margin.xaml</DependentUpon>
     </Compile>
+    <Compile Include="$(MSBuildThisFileDirectory)Windows_UI_Xaml_Controls\TextBox\TextBox_IsReadOnly_AcceptsReturn.xaml.cs">
+      <DependentUpon>TextBox_IsReadOnly_AcceptsReturn.xaml</DependentUpon>
+    </Compile>
     <Compile Include="$(MSBuildThisFileDirectory)Windows_UI_Xaml_Controls\TextBox\TextBox_MaxLength.xaml.cs">
       <DependentUpon>TextBox_MaxLength.xaml</DependentUpon>
     </Compile>

src/SamplesApp/UITests.Shared/Windows_UI_Xaml_Controls/TextBox/TextBox_IsReadOnly_AcceptsReturn.xaml

@@ -0,0 +1,27 @@
+<UserControl
+    x:Class="UITests.Shared.Windows_UI_Xaml_Controls.TextBoxTests.TextBox_IsReadOnly_AcceptsReturn"
+    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+    xmlns:local="using:UITests.Windows_UI_Xaml_Controls.TextBox"
+    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+    mc:Ignorable="d"
+    d:DesignHeight="300"
+    d:DesignWidth="400">
+
+	<StackPanel>
+		<StackPanel Orientation="Horizontal">
+			<TextBlock Text="IsReadOnly:" />
+			<CheckBox x:Name="IsReadOnlyCheckBox" IsChecked="{Binding ElementName=TargetTextBox, Path=IsReadOnly, Mode=TwoWay}" />
+		</StackPanel>
+		<StackPanel Orientation="Horizontal">
+			<TextBlock Text="AcceptsReturn:" />
+			<CheckBox x:Name="AcceptsReturnCheckBox" IsChecked="{Binding ElementName=TargetTextBox, Path=AcceptsReturn, Mode=TwoWay}" />
+		</StackPanel>
+
+		<TextBox x:Name="TargetTextBox"
+				 Text="lorem&#x0a;ipsum&#x0a;asd&#x0a;asd&#x0a;asd"
+				 AcceptsReturn="True"
+				 IsReadOnly="True" />
+	</StackPanel>
+</UserControl>

src/SamplesApp/UITests.Shared/Windows_UI_Xaml_Controls/TextBox/TextBox_IsReadOnly_AcceptsReturn.xaml.cs

@@ -0,0 +1,16 @@
+using Uno.UI.Samples.Controls;
+using Windows.UI.Xaml.Controls;
+
+// The User Control item template is documented at https://go.microsoft.com/fwlink/?LinkId=234236
+
+namespace UITests.Shared.Windows_UI_Xaml_Controls.TextBoxTests
+{
+	[SampleControlInfo("TextBox", description: "#2700: Setting IsReadOnly=True breaks AcceptReturns=True on android")]
+	public sealed partial class TextBox_IsReadOnly_AcceptsReturn : UserControl
+    {
+        public TextBox_IsReadOnly_AcceptsReturn()
+        {
+            this.InitializeComponent();
+        }
+    }
+}

src/Uno.UI/UI/Xaml/Controls/TextBox/TextBox.Android.cs

@@ -322,24 +322,7 @@ private void UpdateInputScope(InputScope inputScope)
 					inputType |= InputTypes.TextFlagMultiLine;
 				}
 
-				if (IsReadOnly)
-				{
-					_textBoxView.InputType = InputTypes.Null;
-
-					// Clear the listener so the inputs have no effect.
-					// Setting the input type to InputTypes.Null is not enough.
-					_listener = _textBoxView.KeyListener;
-					_textBoxView.KeyListener = null;
-				}
-				else
-				{
-					if (_listener != null)
-					{
-						_textBoxView.KeyListener = _listener;
-					}
-
-					_textBoxView.InputType = inputType;
-				}
+				_textBoxView.InputType = inputType;
 			}
 		}
 
@@ -407,7 +390,26 @@ partial void OnIsReadonlyChangedPartial(DependencyPropertyChangedEventArgs e)
 		{
 			if (_textBoxView != null)
 			{
-				UpdateInputScope(InputScope);
+				var isReadOnly = IsReadOnly;
+
+				_textBoxView.Focusable = !isReadOnly;
+				_textBoxView.FocusableInTouchMode = !isReadOnly;
+				_textBoxView.Clickable = !isReadOnly;
+				_textBoxView.LongClickable = !isReadOnly;
+				_textBoxView.SetCursorVisible(!isReadOnly);
+
+				if (isReadOnly)
+				{
+					_listener = _textBoxView.KeyListener;
+					_textBoxView.KeyListener = null;
+				}
+				else
+				{
+					if (_listener != null)
+					{
+						_textBoxView.KeyListener = _listener;
+					}
+				}
 			}
 		}