[Mac] More generalized solution for restoring focus when popover is repopped up

3 files changed, 61 insertions, 31 deletions

diff --git a/Xamarin.PropertyEditing.Mac/Controls/BrushEditorControl.cs b/Xamarin.PropertyEditing.Mac/Controls/BrushEditorControl.cs
index 7520f31..cb8bc44 100644
--- a/Xamarin.PropertyEditing.Mac/Controls/BrushEditorControl.cs
+++ b/Xamarin.PropertyEditing.Mac/Controls/BrushEditorControl.cs
@@ -22,8 +22,6 @@ namespace Xamarin.PropertyEditing.Mac
 
 			if (!Popover.Shown) {
 				Popover.Show (new CGRect (26, this.Frame.Height / 2 - 2, 2, 2), this, NSRectEdge.MinYEdge);
-				Window.MakeFirstResponder (this);
-				Window.MakeFirstResponder (Popover);
 			}
 		}
 
@@ -37,33 +35,6 @@ namespace Xamarin.PropertyEditing.Mac
 		}
 	}
 
-	internal class ColorPopOverDelegate : NSPopoverDelegate
-	{
-		private BrushTabViewController brushTabViewController;
-		private CommonBrushType selectedBrushType = CommonBrushType.None;
-
-		internal ColorPopOverDelegate (BrushTabViewController brushTabViewController)
-		{
-			if (brushTabViewController == null)

-				throw new ArgumentNullException (nameof (brushTabViewController));
-
-			this.brushTabViewController = brushTabViewController;
-		}
-
-		public override void WillShow (NSNotification notification)
-		{
-			if (this.brushTabViewController.ViewModel != null) {
-				var ct = new CancellationTokenSource ();
-				Task.Factory.StartNew (()=> {
-					if (this.selectedBrushType == CommonBrushType.None)
-						this.selectedBrushType = this.brushTabViewController.ViewModel.SelectedBrushType;
-					else
-						this.brushTabViewController.ViewModel.SelectedBrushType = this.selectedBrushType;
-				}, ct.Token, TaskCreationOptions.None, TaskScheduler.FromCurrentSynchronizationContext ());
-			}
-		}
-	}
-
 	internal class BrushEditorControl : PropertyEditorControl<BrushPropertyViewModel>
 	{
 		public BrushEditorControl (IHostResourceProvider hostResources)
@@ -81,8 +52,6 @@ namespace Xamarin.PropertyEditing.Mac
 				}
 			};
 
-			this.popover.Delegate = new ColorPopOverDelegate (this.brushTabViewController);
-
 			this.popUpButton = new ColorPopUpButton {
 				ControlSize = NSControlSize.Small,
 				Font = NSFont.SystemFontOfSize (NSFont.SystemFontSizeForControlSize (NSControlSize.Small)),
diff --git a/Xamarin.PropertyEditing.Mac/Controls/Custom/AutoClosePopOver.cs b/Xamarin.PropertyEditing.Mac/Controls/Custom/AutoClosePopOver.cs
index f3a25ac..bb1fafd 100644
--- a/Xamarin.PropertyEditing.Mac/Controls/Custom/AutoClosePopOver.cs
+++ b/Xamarin.PropertyEditing.Mac/Controls/Custom/AutoClosePopOver.cs
@@ -1,5 +1,6 @@
 using System;
 using AppKit;
+using Foundation;
 
 namespace Xamarin.PropertyEditing.Mac
 {
@@ -17,6 +18,7 @@ namespace Xamarin.PropertyEditing.Mac
 			this.hostResources = hostResources;
 
 			Behavior = NSPopoverBehavior.Semitransient;
+			Delegate = new PopoverFocusRestoreDelegate ();
 			CloseOnEnter = true;
 
 			this.SetAppearance (this.hostResources.GetVibrantAppearance (effectiveAppearance));
diff --git a/Xamarin.PropertyEditing.Mac/Controls/Custom/PopoverFocusRestoreDelegate.cs b/Xamarin.PropertyEditing.Mac/Controls/Custom/PopoverFocusRestoreDelegate.cs
new file mode 100644
index 0000000..4092a8a
--- /dev/null
+++ b/Xamarin.PropertyEditing.Mac/Controls/Custom/PopoverFocusRestoreDelegate.cs
@@ -0,0 +1,59 @@
+using System;
+using AppKit;
+using Foundation;
+
+namespace Xamarin.PropertyEditing.Mac
+{
+	internal class PopoverFocusRestoreDelegate : NSPopoverDelegate
+	{
+		static readonly NSString key = new NSString ("firstResponder");
+
+		private bool ignore;
+		private NSResponder prevFirstResponder;
+
+		public PopoverFocusRestoreDelegate ()
+		{
+		}
+
+		public override void DidShow (NSNotification notification)
+		{
+			this.ignore = false;
+			var window = ((NSPopover)notification.Object).ContentViewController.View.Window;
+
+			if (this.prevFirstResponder != null) {
+				window.MakeFirstResponder (this.prevFirstResponder);
+			} else {
+				window.AddObserver (this, key, NSKeyValueObservingOptions.Initial | NSKeyValueObservingOptions.New, IntPtr.Zero);
+			}
+		}
+
+		public override void WillClose (NSNotification notification)
+		{
+			this.ignore = true;
+		}
+
+		public override void ObserveValue (NSString keyPath, NSObject ofObject, NSDictionary change, IntPtr context)
+		{
+			var window = ofObject as NSWindow;
+			if (window != null && keyPath == key) {
+				if (!ignore) {
+					var firstResponder = change [ChangeNewKey] as NSResponder;
+					if (firstResponder != null && !(firstResponder is NSWindow))
+						this.prevFirstResponder = ResolveResponder (firstResponder);
+				}
+			} else {
+				base.ObserveValue (keyPath, ofObject, change, context);
+			}
+		}
+
+		// See first paragraph under "How the Field Editor Works"
+		// https://developer.apple.com/library/archive/documentation/TextFonts/Conceptual/CocoaTextArchitecture/TextEditing/TextEditing.html#//apple_ref/doc/uid/TP40009459-CH3-SW29
+		static NSResponder ResolveResponder (NSResponder responder)
+		{
+			if (responder is NSText text && text.FieldEditor)
+				return (text.WeakDelegate as NSResponder) ?? responder;
+
+			return responder;
+		}
+	}
+}