[Mac] TextEntry completion support

TestApps/Samples/Samples/TextEntries.cs

@@ -42,6 +42,16 @@ public TextEntries ()
 				la.Text = "Text: " + te1.Text;
 			};
 
+			te1.SetCompletions(new string [] {
+				"Lorem",
+				"Ipsum",
+				"Word1",
+				"Word2",
+				"Lorem Ipsum",
+				"Sample",
+				"Text"
+			});
+
 			HBox selBox = new HBox ();
 
 			Label las = new Label ("Selection:");

Xwt.XamMac/Xwt.Mac/ComboBoxEntryBackend.cs

@@ -43,7 +43,7 @@ public ComboBoxEntryBackend ()
 		public override void Initialize ()
 		{
 			base.Initialize ();
-			ViewObject = new MacComboBox (EventSink, ApplicationContext);
+			ViewObject = new MacComboBox (this);
 		}
 
 		protected override Size GetNaturalSize ()
@@ -56,7 +56,11 @@ protected override Size GetNaturalSize ()
 		public ITextEntryBackend TextEntryBackend {
 			get {
 				if (entryBackend == null)
+				{
 					entryBackend = new Xwt.Mac.TextEntryBackend ((MacComboBox)ViewObject);
+					if (Widget.Delegate is TextFieldDelegate)
+						((TextFieldDelegate)Widget.Delegate).Backend = entryBackend;
+				}
 				return entryBackend;
 			}
 		}
@@ -102,7 +106,31 @@ public void SetTextColumn (int column)
 		#endregion
 	}
 
-	class MacComboBox : NSComboBox, IViewObject, INSComboBoxDelegate
+	sealed class MacComboBoxDelegate : TextFieldDelegate, INSComboBoxDelegate
+	{
+		WeakReference weakBackend;
+
+		public ComboBoxEntryBackend ComboBoxEntryBackend
+		{
+			get { return weakBackend?.Target as ComboBoxEntryBackend; }
+			set { weakBackend = new WeakReference(value); }
+		}
+
+		[Export("comboBoxSelectionDidChange:")]
+		public void SelectionChanged (NSNotification notification)
+		{
+			var combobackend = ComboBoxEntryBackend;
+			if (combobackend?.EventSink != null)
+			{
+				combobackend.ApplicationContext.InvokeUserCode(delegate {
+					Backend?.EventSink?.OnChanged();
+					combobackend.EventSink.OnSelectionChanged();
+				});
+			}
+		}
+	}
+
+	sealed class MacComboBox : NSComboBox, IViewObject
 	{
 		IComboBoxEventSink eventSink;
 		ITextEntryEventSink entryEventSink;
@@ -111,11 +139,11 @@ class MacComboBox : NSComboBox, IViewObject, INSComboBoxDelegate
 		int cacheSelectionStart, cacheSelectionLength;
 		bool checkMouseMovement;
 
-		public MacComboBox (IComboBoxEventSink eventSink, ApplicationContext context)
+		public MacComboBox (ComboBoxEntryBackend backend)
 		{
-			this.context = context;
-			this.eventSink = eventSink;
-			Delegate = this;
+			context = backend.ApplicationContext;
+			eventSink = backend.EventSink;
+			Delegate = new MacComboBoxDelegate { ComboBoxEntryBackend = backend };
 		}
 
 		public void SetEntryEventSink (ITextEntryEventSink entryEventSink)
@@ -131,34 +159,12 @@ public NSView View {
 
 		public ViewBackend Backend { get; set; }
 
-		[Export ("comboBoxSelectionDidChange:")]
-		public new void SelectionChanged (NSNotification notification)
-		{
-			if (entryEventSink != null) {
-				context.InvokeUserCode (delegate {
-					entryEventSink.OnChanged ();
-					eventSink.OnSelectionChanged ();
-				});
-			}
-		}
-
-		public override void DidChange (NSNotification notification)
-		{
-			base.DidChange (notification);
-			if (entryEventSink != null) {
-				context.InvokeUserCode (delegate {
-					entryEventSink.OnChanged ();
-					entryEventSink.OnSelectionChanged ();
-				});
-			}
-		}
 		public override void KeyUp (NSEvent theEvent)
 		{
 			base.KeyUp (theEvent);
 			HandleSelectionChanged ();
 		}
 
-
 		NSTrackingArea trackingArea;
 		public override void UpdateTrackingAreas ()
 		{
@@ -329,4 +335,3 @@ protected override void Dispose (bool disposing)
 		}
 	}
 }
-

Xwt.XamMac/Xwt.Mac/TextEntryBackend.cs

@@ -25,6 +25,7 @@
 // THE SOFTWARE.
 
 using System;
+using System.Linq;
 using AppKit;
 using CoreGraphics;
 using Foundation;
@@ -52,7 +53,7 @@ public override void Initialize ()
 			if (ViewObject is MacComboBox) {
 				((MacComboBox)ViewObject).SetEntryEventSink (EventSink);
 			} else if (ViewObject == null) {
-				var view = new CustomTextField (EventSink, ApplicationContext);
+				var view = new CustomTextField (EventSink, ApplicationContext) { Backend = this };
 				ViewObject = new CustomAlignedContainer (EventSink, ApplicationContext, (NSView)view) { DrawsBackground = false };
 				Container.ExpandVertically = true;
 				MultiLine = false;
@@ -232,16 +233,51 @@ void HandleSelectionChanged ()
 			}
 		}
 
+		string[] completions;
+		Func<string, string, bool> completionsMatchFunc;
+
 		public bool HasCompletions {
-			get { return false; }
+			get {
+				return completions?.Length > 0;
+			}
 		}
 
 		public void SetCompletions (string[] completions)
 		{
+			this.completions = completions;
+			if (completions != null) {
+				var entryDelegate = Widget.Delegate;
+				if (entryDelegate == null) {
+					entryDelegate = Widget.Delegate = new TextFieldDelegate ();
+				}
+				if (entryDelegate is TextFieldDelegate) {
+					((TextFieldDelegate)entryDelegate).Backend = this;
+				}
+			}
+			if (completionsMatchFunc == null) {
+				completionsMatchFunc = DefaultCompletionMatchFunc;
+			}
 		}
 
 		public void SetCompletionMatchFunc (Func<string, string, bool> matchFunc)
 		{
+			completionsMatchFunc = matchFunc ?? DefaultCompletionMatchFunc;
+		}
+
+		bool DefaultCompletionMatchFunc (string word, string completion)
+		{
+			if (word == null || completion == null)
+				return false;
+			return completion.StartsWith (word, StringComparison.CurrentCulture);
+		}
+
+		internal string [] GetCompletions (string word)
+		{
+			if (completions?.Length > 0)
+			{
+				return completions.Where (c => completionsMatchFunc(word, c)).ToArray ();
+			}
+			return new string[0];
 		}
 
 		#endregion
@@ -283,6 +319,65 @@ public override Drawing.Color BackgroundColor {
 				Widget.Cell.BackgroundColor = value.ToNSColor ();
 			}
 		}
+
+		protected override void Dispose(bool disposing)
+		{
+			completions = null;
+			base.Dispose (disposing);
+		}
+	}
+
+	class TextFieldDelegate : NSTextFieldDelegate
+	{
+		WeakReference weakBackend;
+
+		public TextEntryBackend Backend
+		{
+			get { return weakBackend?.Target as TextEntryBackend; }
+			set { weakBackend = new WeakReference (value); }
+		}
+
+		public override string[] GetCompletions (NSControl control, NSTextView textView, string[] words, NSRange charRange, ref nint index)
+		{
+			var backend = Backend;
+			if (backend != null)
+			{
+				string word;
+				try {
+					word = textView.String.Substring ((int)charRange.Location, (int)charRange.Length);
+				} catch (ArgumentOutOfRangeException) {
+					return new string[0];
+				}
+				return backend.GetCompletions (word);
+			}
+			return new string[0];
+		}
+
+		bool isCompleting;
+		[Export("controlTextDidChange:")]
+		public void DidChange (NSNotification notification)
+		{
+			var editor = notification.Object as NSTextView ?? (notification.Object as NSTextField)?.CurrentEditor as NSTextView;
+			if (!isCompleting && editor != null && editor.String.Length > 0 && Backend?.HasCompletions == true) {
+				// Cocoa will call DidChange for each completion, even if the text didn't change
+				// avoid an infinite loop with an isCompleting check.
+				isCompleting = true;
+				editor.Complete (null);
+				isCompleting = false;
+			}
+			if (Backend.EventSink != null) {
+				Backend.ApplicationContext.InvokeUserCode (delegate {
+					Backend.EventSink.OnChanged ();
+					Backend.EventSink.OnSelectionChanged ();
+				});
+			}
+		}
+
+		protected override void Dispose(bool disposing)
+		{
+			weakBackend = null;
+			base.Dispose(disposing);
+		}
 	}
 
 	class CustomTextField: NSTextField, IViewObject
@@ -313,15 +408,6 @@ public NSView View {
 		}
 
 		public ViewBackend Backend { get; set; }
-
-		public override void DidChange (NSNotification notification)
-		{
-			base.DidChange (notification);
-			context.InvokeUserCode (delegate {
-				eventSink.OnChanged ();
-				eventSink.OnSelectionChanged ();
-			});
-		}
 
 		public override string StringValue
 		{