[Mac] NSButton that handles ICommands. Needed for Binding Dialog and Variations PRs. Slight fix to CommandMenuItem too.

2 files changed, 43 insertions, 1 deletions

diff --git a/Xamarin.PropertyEditing.Mac/Controls/Custom/CommandButton.cs b/Xamarin.PropertyEditing.Mac/Controls/Custom/CommandButton.cs
new file mode 100644
index 0000000..4904bd8
--- /dev/null
+++ b/Xamarin.PropertyEditing.Mac/Controls/Custom/CommandButton.cs
@@ -0,0 +1,40 @@
+using System;
+using System.Windows.Input;
+using AppKit;
+
+namespace Xamarin.PropertyEditing.Mac.Controls.Custom
+{
+	internal class CommandButton : NSButton
+	{
+		private ICommand command;
+
+		public ICommand Command
+		{
+			get { return this.command; }
+			set
+			{
+				if (this.command != null)
+					this.command.CanExecuteChanged -= CanExecuteChanged;
+
+				this.command = value;
+
+				if (this.command != null)
+					this.command.CanExecuteChanged += CanExecuteChanged;
+			}
+		}
+
+		public CommandButton ()
+		{
+			Activated += (object sender, EventArgs e) => {
+				var button = (CommandButton)sender;
+				button.command?.Execute (null);
+			};
+		}
+
+		private void CanExecuteChanged (object sender, EventArgs e)
+		{
+			if (sender is ICommand cmd)
+				this.Enabled = cmd.CanExecute (null);
+		}
+	}
+}
diff --git a/Xamarin.PropertyEditing.Mac/Controls/Custom/CommandMenuItem.cs b/Xamarin.PropertyEditing.Mac/Controls/Custom/CommandMenuItem.cs
index c945a80..1a84424 100644
--- a/Xamarin.PropertyEditing.Mac/Controls/Custom/CommandMenuItem.cs
+++ b/Xamarin.PropertyEditing.Mac/Controls/Custom/CommandMenuItem.cs
@@ -15,7 +15,9 @@ namespace Xamarin.PropertyEditing.Mac
 					this.command.CanExecuteChanged -= CanExecuteChanged;
 
 				this.command = value;
-				this.command.CanExecuteChanged += CanExecuteChanged;
+
+				if (this.command != null)
+					this.command.CanExecuteChanged += CanExecuteChanged;
 			}
 		}