feat(styles): [Android] [iOS] Allow MessageDialog.ShowAsync() from ba…

…ckground UWP allows this method to be called from a background thread. This fixes the existing MessageDialog.xaml sample.
unoplatform · Jun 3, 2020 · 43a2189 · 43a2189
1 parent c25177d
commit 43a2189
Show file tree

Hide file tree

Showing 3 changed files with 79 additions and 43 deletions.
diff --git a/src/Uno.UWP/UI/Popups/MessageDialog.Android.cs b/src/Uno.UWP/UI/Popups/MessageDialog.Android.cs
@@ -13,17 +13,16 @@
 using Android.Widget;
 using Windows.UI.Core;
 using Windows.Foundation;
+using System.Threading;
 
 namespace Windows.UI.Popups
 {
 	public partial class MessageDialog
 	{
 		const int MaximumCommands = 3;
 
-		public IAsyncOperation<IUICommand> ShowAsync()
+		private void ShowInner(CancellationToken ct, TaskCompletionSource<IUICommand> invokedCommand)
 		{
-			var invokedCommand = new TaskCompletionSource<IUICommand>();
-
 			// Android recommends placing buttons in this order:
 			//  1) positive (default accept)
 			//  2) negative (default cancel)
@@ -35,7 +34,7 @@ public IAsyncOperation<IUICommand> ShowAsync()
 				.Where(command => !(command is UICommandSeparator)) // Not supported on Android
 				.DefaultIfEmpty(new UICommand("Close")) // TODO: Localize (PBI 28711)
 				.Reverse()
-				.Select((command, index) => 
+				.Select((command, index) =>
 					new
 					{
 						Command = command,
@@ -62,20 +61,15 @@ public IAsyncOperation<IUICommand> ShowAsync()
 					}
 				);
 
-			return new AsyncOperation<IUICommand>(async ct =>
+			using (ct.Register(() =>
 			{
-				using (ct.Register(() =>
-					{
-						// If the cancellation token itself gets cancelled, we cancel as well.
-						invokedCommand.TrySetCanceled();
-						dialog.Dismiss();
-					}))
-				{
-					dialog.Show();
-
-					return await invokedCommand.Task;
-				}
-			});
+				// If the cancellation token itself gets cancelled, we cancel as well.
+				invokedCommand.TrySetCanceled();
+				dialog.Dismiss();
+			}))
+			{
+				dialog.Show();
+			}
 		}
 
 		partial void ValidateCommands()

diff --git a/src/Uno.UWP/UI/Popups/MessageDialog.cs b/src/Uno.UWP/UI/Popups/MessageDialog.cs
@@ -5,6 +5,8 @@
 using System.Text;
 using System.Threading;
 using System.Threading.Tasks;
+using Windows.Foundation;
+using Windows.UI.Core;
 
 namespace Windows.UI.Popups
 {
@@ -14,7 +16,7 @@ public sealed partial class MessageDialog
 		/// Creates a new instance of the MessageDialog class, using the specified message content and no title.
 		/// </summary>
 		/// <param name="content"></param>
-		public MessageDialog(string content) 
+		public MessageDialog(string content)
 			: this(content, "")
 		{
 		}
@@ -46,6 +48,53 @@ public MessageDialog(string content, string title)
 			Commands = collection;
 		}
 
+#if __ANDROID__ || __IOS__
+
+		public IAsyncOperation<IUICommand> ShowAsync()
+		{
+			var invokedCommand = new TaskCompletionSource<IUICommand>();
+
+			return new AsyncOperation<IUICommand>(async ct =>
+			{
+				if (CoreDispatcher.Main.HasThreadAccess)
+				{
+					try
+					{
+						ShowInner(ct, invokedCommand);
+					}
+					catch (Exception e)
+					{
+						invokedCommand.TrySetException(e);
+					}
+				}
+
+				else
+				{
+					Exception ex = null;
+					await CoreDispatcher.Main.RunAsync(CoreDispatcherPriority.Normal, CallShow);
+
+					if (ex != null)
+					{
+						invokedCommand.TrySetException(ex);
+					}
+
+					void CallShow()
+					{
+						try
+						{
+							ShowInner(ct, invokedCommand);
+						}
+						catch (Exception e)
+						{
+							ex = e;
+						}
+					}
+				}
+				return await invokedCommand.Task;
+			});
+		}
+#endif
+
 		public uint CancelCommandIndex { get; set; } = uint.MaxValue;
 		public IList<IUICommand> Commands { get; }
 		public string Content { get; set; }

diff --git a/src/Uno.UWP/UI/Popups/MessageDialog.iOS.cs b/src/Uno.UWP/UI/Popups/MessageDialog.iOS.cs
@@ -16,10 +16,8 @@ public partial class MessageDialog
 	{
 		private static readonly SemaphoreSlim _viewControllerAccess = new SemaphoreSlim(1, 1);
 
-		public IAsyncOperation<IUICommand> ShowAsync()
+		private async void ShowInner(CancellationToken ct, TaskCompletionSource<IUICommand> invokedCommand)
 		{
-			var invokedCommand = new TaskCompletionSource<IUICommand>();
-
 			var alertActions = Commands
 				.Where(command => !(command is UICommandSeparator)) // Not supported on iOS
 				.DefaultIfEmpty(new UICommand("OK")) // TODO: Localize (PBI 28711)
@@ -51,36 +49,31 @@ public IAsyncOperation<IUICommand> ShowAsync()
 				alertController.PreferredAction = alertActions.ElementAtOrDefault((int)DefaultCommandIndex);
 			}
 
-			return new AsyncOperation<IUICommand>(async ct =>
-			{
-				using (ct.Register(() =>
-					{
-						// If the cancellation token itself gets cancelled, we cancel as well.
-						invokedCommand.TrySetCanceled();
-						UIApplication.SharedApplication.KeyWindow?.RootViewController?.DismissViewController(false, () => { });
-					}))
+			using (ct.Register(() =>
 				{
-					await _viewControllerAccess.WaitAsync(ct);
+					// If the cancellation token itself gets cancelled, we cancel as well.
+					invokedCommand.TrySetCanceled();
+					UIApplication.SharedApplication.KeyWindow?.RootViewController?.DismissViewController(false, () => { });
+				}))
+			{
+				await _viewControllerAccess.WaitAsync(ct);
 
+				try
+				{
 					try
 					{
-						try
-						{
-							await UIApplication.SharedApplication.KeyWindow?.RootViewController?.PresentViewControllerAsync(alertController, animated: true);
-						}
-						catch (Exception error)
-						{
-							invokedCommand.TrySetException(error);
-						}
-
-						return await invokedCommand.Task;
+						await UIApplication.SharedApplication.KeyWindow?.RootViewController?.PresentViewControllerAsync(alertController, animated: true);
 					}
-					finally
+					catch (Exception error)
 					{
-						_viewControllerAccess.Release();
+						invokedCommand.TrySetException(error);
 					}
 				}
-			});
+				finally
+				{
+					_viewControllerAccess.Release();
+				}
+			}
 		}
 
 		partial void ValidateCommands()