Fix layout size when iOS swipe-back gesture is aborted, fixes #14763

Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Issue14763.cs

@@ -0,0 +1,108 @@
+using Xamarin.Forms.CustomAttributes;
+using Xamarin.Forms.Internals;
+using System.Linq;
+using System.Threading.Tasks;
+#if UITEST
+using Xamarin.UITest;
+using NUnit.Framework;
+using Xamarin.Forms.Core.UITests;
+#endif
+
+namespace Xamarin.Forms.Controls.Issues
+{
+#if UITEST
+	[NUnit.Framework.Category(Core.UITests.UITestCategories.Github10000)]
+#endif
+	[Preserve(AllMembers = true)]
+	[Issue(IssueTracker.Github, 14763, "[iOS] Resize on back-swipe stays when going back is cancelled", PlatformAffected.iOS)]
+	public class Issue14763 : TestNavigationPage
+	{
+		public Issue14763() : base()
+		{ }
+
+		class HomePage : ContentPage
+		{
+			public HomePage()
+			{
+				Title = "Home";
+				var grd = new Grid { BackgroundColor = Color.Brown };
+				grd.RowDefinitions.Add(new RowDefinition());
+				grd.RowDefinitions.Add(new RowDefinition());
+				grd.RowDefinitions.Add(new RowDefinition());
+
+				NavigationPage.SetHasNavigationBar(this, false);
+
+				var boxView = new BoxView { BackgroundColor = Color.Blue };
+				grd.Children.Add(boxView, 0, 0);
+				var stackLayout = new StackLayout()
+				{
+					BackgroundColor = Color.Yellow,
+					AutomationId = "ChildLayout"
+				};
+				var btnPop = new Button {
+					Text = "Back (I get cut off)", AutomationId = "PopButtonId", Command = new Command(async () => await Navigation.PopAsync()),
+					BackgroundColor = Color.Red
+				};
+				stackLayout.Children.Add(btnPop);
+				btnPop.VerticalOptions = new LayoutOptions(LayoutAlignment.End, expands: true);
+				var btn = new Button()
+				{
+					BackgroundColor = Color.Pink,
+					Text = "NextButtonID",
+					AutomationId = "NextButtonID",
+
+					Command = new Command(async () =>
+					{
+
+						var page = new ContentPage
+						{
+							Title = "Detail",
+							Content = stackLayout,
+							AutomationId = "ChildPage"
+						};
+
+						NavigationPage.SetHasNavigationBar(page, true);
+						await Navigation.PushAsync(page, false);
+					})
+				};
+
+				grd.Children.Add(btn, 0, 1);
+				var image = new Image() { Source = "coffee.png", AutomationId = "CoffeeImageId", BackgroundColor = Color.Yellow };
+				image.VerticalOptions = LayoutOptions.End;
+				grd.Children.Add(image, 0, 2);
+				Content = grd;
+
+			}
+		}
+
+		protected override void Init()
+		{
+			PushAsync(new HomePage());
+		}
+
+#if UITEST && __IOS__
+		[Test]
+		public async Task PopButtonStillVisibleAfterSwipeBack()
+		{
+			RunningApp.WaitForElement("NextButtonID");
+			// Navigate to child page
+			RunningApp.Tap("NextButtonID");
+			var childLayout = RunningApp.WaitForElement("ChildLayout").First();
+			RunningApp.WaitForElement("PopButtonId");
+			await Task.Delay(1000);
+			var origLayoutRect = childLayout.Rect;
+
+			// Swipe-back/Swipe in from left across 1/2 of screen width to start back nav without completing it
+			var screenBounds = RunningApp.ScreenBounds();
+			RunningApp.DragCoordinates(0, screenBounds.CenterY, screenBounds.CenterX, screenBounds.CenterY);			
+			// Wait for swipe-back and UI to settle
+			await Task.Delay(3000);
+			childLayout = RunningApp.WaitForElement("ChildLayout").First();
+			var newLayoutRect = childLayout.Rect;
+
+			// Assert that child page has same height as before
+			Assert.That(newLayoutRect.Height, Is.EqualTo(origLayoutRect.Height));
+		}
+#endif
+	}
+}

Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Xamarin.Forms.Controls.Issues.Shared.projitems

@@ -37,6 +37,7 @@
     <Compile Include="$(MSBuildThisFileDirectory)Issue14095.xaml.cs">
       <DependentUpon>Issue14095.xaml</DependentUpon>
     </Compile>
+    <Compile Include="$(MSBuildThisFileDirectory)Issue14763.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue14523.xaml.cs">
       <DependentUpon>Issue14523.xaml</DependentUpon>
     </Compile>
@@ -1845,6 +1846,7 @@
     <Compile Include="$(MSBuildThisFileDirectory)Issue8383.xaml.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue8383-2.xaml.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue8384.xaml.cs" />
+	  <Compile Include="$(MSBuildThisFileDirectory)Issue8384.xaml.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue13577.xaml.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue14505.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue14505-II.cs" />

Xamarin.Forms.Platform.iOS/Renderers/NavigationRenderer.cs

@@ -173,10 +173,10 @@ public override void ViewDidLayoutSubviews()
 			var toolbar = _secondaryToolbar;
 
 			//save the state of the Current page we are calculating, this will fire before Current is updated
-			_hasNavigationBar = NavigationPage.GetHasNavigationBar(Current);
+			_hasNavigationBar = NavigationPage.GetHasNavigationBar(Current) && !(NavigationBarHidden || NavigationBar.Translucent);
 
 			// Use 0 if the NavBar is hidden or will be hidden
-			var toolbarY = NavigationBarHidden || NavigationBar.Translucent || !_hasNavigationBar ? 0 : navBarFrameBottom;
+			var toolbarY = !_hasNavigationBar ? 0 : navBarFrameBottom;
 			toolbar.Frame = new RectangleF(0, toolbarY, View.Frame.Width, toolbar.Frame.Height);
 
 			double trueBottom = toolbar.Hidden ? toolbarY : toolbar.Frame.Bottom;
@@ -1402,6 +1402,11 @@ void UpdateNavigationBarVisibility(bool animated)
 					current.IgnoresContainerArea = !hasNavBar;
 					NavigationController.SetNavigationBarHidden(!hasNavBar, animated);
 				}
+
+				// Esnure correct nav bar state and layout dimension after swipe-back gesture was
+				// aborted, see  https://github.com/xamarin/Xamarin.Forms/issues/14763.
+				if (_navigation.TryGetTarget(out var n))
+					n.ValidateNavbarExists(current);
 			}
 
 			void UpdateToolbarItems()