From ac3e2bc19bc3e0c4a6373b7444f497dac3d4d2a7 Mon Sep 17 00:00:00 2001
From: Martin Garstenauer <martin.garstenauer@outlook.com>
Date: Thu, 29 Aug 2024 14:21:57 +0200
Subject: [PATCH] Add option to insert completion item on
 PointerPressed/PointerReleased/DoubleTapped

---
 src/AvaloniaEdit.Demo/MainWindow.xaml.cs      |   1 +
 .../CodeCompletion/CompletionAcceptAction.cs  |  25 ++++
 .../CodeCompletion/CompletionList.cs          | 115 ++++++++++++++----
 .../CodeCompletion/CompletionWindow.cs        |  13 +-
 .../CodeCompletion/CompletionWindowBase.cs    |   1 -
 src/AvaloniaEdit/TextEditorOptions.cs         |  20 +++
 6 files changed, 143 insertions(+), 32 deletions(-)
 create mode 100644 src/AvaloniaEdit/CodeCompletion/CompletionAcceptAction.cs

diff --git a/src/AvaloniaEdit.Demo/MainWindow.xaml.cs b/src/AvaloniaEdit.Demo/MainWindow.xaml.cs
index 600d6bdc..789eabd9 100644
--- a/src/AvaloniaEdit.Demo/MainWindow.xaml.cs
+++ b/src/AvaloniaEdit.Demo/MainWindow.xaml.cs
@@ -61,6 +61,7 @@ public MainWindow()
             _textEditor.TextArea.Caret.PositionChanged += Caret_PositionChanged;
             _textEditor.TextArea.RightClickMovesCaret = true;
             _textEditor.Options.HighlightCurrentLine = true;
+            _textEditor.Options.CompletionAcceptAction = CompletionAcceptAction.DoubleTapped;
 
             _addControlButton = this.FindControl<Button>("addControlBtn");
             _addControlButton.Click += AddControlButton_Click;
diff --git a/src/AvaloniaEdit/CodeCompletion/CompletionAcceptAction.cs b/src/AvaloniaEdit/CodeCompletion/CompletionAcceptAction.cs
new file mode 100644
index 00000000..8d092729
--- /dev/null
+++ b/src/AvaloniaEdit/CodeCompletion/CompletionAcceptAction.cs
@@ -0,0 +1,25 @@
+namespace AvaloniaEdit.CodeCompletion;
+
+/// <summary>
+/// Defines the pointer action used to request the insertion of a completion item.
+/// </summary>
+public enum CompletionAcceptAction
+{
+    /// <summary>
+    /// Insert the completion item when the pointer is pressed. (This option makes the completion
+    /// list behave similar to the completion list in Visual Studio Code.)
+    /// </summary>
+    PointerPressed,
+
+    /// <summary>
+    /// Insert the completion item when the pointer is pressed. (This option makes the completion
+    /// list behave similar to a context menu.)
+    /// </summary>
+    PointerReleased,
+
+    /// <summary>
+    /// Insert the code completion item when the item is double-tapped. (This option makes the
+    /// completion list behave similar to the completion list in Visual Studio.)
+    /// </summary>
+    DoubleTapped
+}
diff --git a/src/AvaloniaEdit/CodeCompletion/CompletionList.cs b/src/AvaloniaEdit/CodeCompletion/CompletionList.cs
index 6a1cdbcf..c57ee9a5 100644
--- a/src/AvaloniaEdit/CodeCompletion/CompletionList.cs
+++ b/src/AvaloniaEdit/CodeCompletion/CompletionList.cs
@@ -27,6 +27,7 @@
 using Avalonia.Input;
 using Avalonia.Interactivity;
 using Avalonia.Markup.Xaml.Templates;
+using Avalonia.VisualTree;
 using AvaloniaEdit.Utils;
 
 namespace AvaloniaEdit.CodeCompletion
@@ -36,18 +37,6 @@ namespace AvaloniaEdit.CodeCompletion
     /// </summary>
     public class CompletionList : TemplatedControl
     {
-        public CompletionList()
-        {
-            AddHandler(PointerPressedEvent, OnPointerPressed, RoutingStrategies.Bubble, true);
-
-            CompletionAcceptKeys = new[]
-            {
-                Key.Enter,
-                Key.Tab,
-            };
-        }
-
-
         /// <summary>
         /// If true, the CompletionList is filtered to show only matching items. Also enables search by substring.
         /// If false, enables the old behavior: no filtering, search by string.StartsWith.
@@ -94,6 +83,7 @@ protected override void OnApplyTemplate(TemplateAppliedEventArgs e)
             if (_listBox != null)
             {
                 _listBox.ItemsSource = _completionData;
+                AddPointerHandler(CompletionAcceptAction);
             }
         }
 
@@ -110,10 +100,29 @@ public CompletionListBox ListBox
             }
         }
 
+        /// <summary>
+        /// Gets or sets the pointer action used to request insertion of a completion item.
+        /// </summary>
+        public CompletionAcceptAction CompletionAcceptAction
+        {
+            get => _completionAcceptAction;
+            set
+            {
+                if (_completionAcceptAction == value)
+                    return;
+
+                RemovePointerHandler(_completionAcceptAction);
+                _completionAcceptAction = value;
+                AddPointerHandler(value);
+            }
+        }
+
+        private CompletionAcceptAction _completionAcceptAction;
+
         /// <summary>
         /// Gets or sets the array of keys that are supposed to request insertion of the completion.
         /// </summary>
-        public Key[] CompletionAcceptKeys { get; set; }
+        public Key[] CompletionAcceptKeys { get; set; } = new[] { Key.Enter, Key.Tab };
 
         /// <summary>
         /// Gets the scroll viewer used in this list box.
@@ -186,26 +195,78 @@ public void HandleKey(KeyEventArgs e)
             }
         }
 
-        private void OnPointerPressed(object sender, PointerPressedEventArgs e)
+        private void AddPointerHandler(CompletionAcceptAction completionAcceptAction)
         {
-            var visual = e.Source as Visual;
-            if (e.GetCurrentPoint(visual).Properties.IsLeftButtonPressed)
+            if (_listBox == null)
+                return;
+
+            switch (completionAcceptAction)
             {
-                var listBoxItem = visual.VisualAncestorsAndSelf()
-                    .TakeWhile(v => v != this)
-                    .OfType<ListBoxItem>()
-                    .FirstOrDefault();
+                case CompletionAcceptAction.PointerPressed:
+                    _listBox.AddHandler(PointerPressedEvent, OnPointerPressed, RoutingStrategies.Bubble, true);
+                    break;
+                case CompletionAcceptAction.PointerReleased:
+                    _listBox.AddHandler(PointerReleasedEvent, OnPointerReleased);
+                    break;
+                case CompletionAcceptAction.DoubleTapped:
+                    AddHandler(DoubleTappedEvent, OnDoubleTapped);
+                    _listBox.AddHandler(DoubleTappedEvent, OnDoubleTapped);
+                    break;
+                default:
+                    Debug.Fail("Invalid CompletionAcceptAction");
+                    break;
+            }
+        }
 
-                if (listBoxItem != null)
-                {
-                    // A completion item was clicked.
-                    Debug.Assert(e.Handled, "Click expected to be handled by ListBoxItem.");
-                    Debug.Assert(listBoxItem.IsSelected, "Completion item expected to be selected.");
-                    RequestInsertion(e);
-                }
+        private void RemovePointerHandler(CompletionAcceptAction completionAcceptAction)
+        {
+            if (_listBox == null)
+                return;
+
+            switch (completionAcceptAction)
+            {
+                case CompletionAcceptAction.PointerPressed:
+                    _listBox.RemoveHandler(PointerPressedEvent, OnPointerPressed);
+                    break;
+                case CompletionAcceptAction.PointerReleased:
+                    _listBox.RemoveHandler(PointerReleasedEvent, OnPointerReleased);
+                    break;
+                case CompletionAcceptAction.DoubleTapped:
+                    _listBox.RemoveHandler(DoubleTappedEvent, OnDoubleTapped);
+                    break;
+                default:
+                    Debug.Fail("Invalid CompletionAcceptAction");
+                    break;
             }
         }
 
+        private void OnPointerPressed(object sender, PointerPressedEventArgs e)
+        {
+            var visual = e.Source as Visual;
+            if (!e.GetCurrentPoint(visual).Properties.IsLeftButtonPressed) 
+                return;
+
+            RequestInsertion(e);
+        }
+
+        private void OnPointerReleased(object sender, PointerReleasedEventArgs e)
+        {
+            if (e.InitialPressMouseButton != MouseButton.Left)
+                return;
+
+            // Ignore event if pointer is released outside the selected item.
+            var listBoxItem = _listBox.ContainerFromIndex(_listBox.SelectedIndex);
+            if (listBoxItem == null || !this.GetVisualsAt(e.GetPosition(this)).Any(v => v == listBoxItem || listBoxItem.IsVisualAncestorOf(v)))
+                return;
+
+            RequestInsertion(e);
+        }
+
+        private void OnDoubleTapped(object sender, TappedEventArgs e)
+        {
+            RequestInsertion(e);
+        }
+
         /// <summary>
         /// Gets/Sets the selected item.
         /// </summary>
diff --git a/src/AvaloniaEdit/CodeCompletion/CompletionWindow.cs b/src/AvaloniaEdit/CodeCompletion/CompletionWindow.cs
index 51892b23..ad2e9157 100644
--- a/src/AvaloniaEdit/CodeCompletion/CompletionWindow.cs
+++ b/src/AvaloniaEdit/CodeCompletion/CompletionWindow.cs
@@ -21,9 +21,7 @@
 using AvaloniaEdit.Document;
 using AvaloniaEdit.Editing;
 using Avalonia.Controls;
-using Avalonia.Controls.Primitives;
 using Avalonia.Input;
-using Avalonia.Media;
 
 namespace AvaloniaEdit.CodeCompletion
 {
@@ -45,7 +43,11 @@ public class CompletionWindow : CompletionWindowBase
         /// </summary>
         public CompletionWindow(TextArea textArea) : base(textArea)
         {
-            CompletionList = new CompletionList();
+            CompletionList = new CompletionList
+            {
+                CompletionAcceptAction = textArea.Options.CompletionAcceptAction
+            };
+
             // keep height automatic
             CloseAutomatically = true;
             MaxHeight = 225;
@@ -59,7 +61,10 @@ public CompletionWindow(TextArea textArea) : base(textArea)
 
             _toolTip = new PopupWithCustomPosition
             {
-                IsLightDismissEnabled = true,
+                // The popup should not interfere with the pointer input. Popup visibility is
+                // controlled explicitly.
+                IsLightDismissEnabled = false,
+
                 PlacementTarget = this,
                 Child = _toolTipContent,
             };
diff --git a/src/AvaloniaEdit/CodeCompletion/CompletionWindowBase.cs b/src/AvaloniaEdit/CodeCompletion/CompletionWindowBase.cs
index de21a325..bfda08d4 100644
--- a/src/AvaloniaEdit/CodeCompletion/CompletionWindowBase.cs
+++ b/src/AvaloniaEdit/CodeCompletion/CompletionWindowBase.cs
@@ -260,7 +260,6 @@ private void ParentWindow_LocationChanged(object sender, EventArgs e)
             UpdatePosition();
         }
 
-        /// <inheritdoc/>
         private void OnDeactivated(object sender, EventArgs e)
         {
             Dispatcher.UIThread.Post(CloseIfFocusLost, DispatcherPriority.Background);
diff --git a/src/AvaloniaEdit/TextEditorOptions.cs b/src/AvaloniaEdit/TextEditorOptions.cs
index 3dcd720c..6bdf51cf 100644
--- a/src/AvaloniaEdit/TextEditorOptions.cs
+++ b/src/AvaloniaEdit/TextEditorOptions.cs
@@ -20,6 +20,7 @@
 using System.Collections.Generic;
 using System.ComponentModel;
 using System.Reflection;
+using AvaloniaEdit.CodeCompletion;
 
 namespace AvaloniaEdit
 {
@@ -677,5 +678,24 @@ public bool ExtendSelectionOnMouseUp
                 }
             }
         }
+
+        private CompletionAcceptAction _completionAcceptAction = CompletionAcceptAction.PointerPressed;
+
+        /// <summary>
+        /// Gets/Sets the pointer action used to request the insertion of a completion item.
+        /// </summary>
+        [DefaultValue(CompletionAcceptAction.PointerPressed)]
+        public CompletionAcceptAction CompletionAcceptAction
+        {
+            get { return _completionAcceptAction; }
+            set
+            {
+                if (_completionAcceptAction != value)
+                {
+                    _completionAcceptAction = value;
+                    OnPropertyChanged(nameof(CompletionAcceptAction));
+                }
+            }
+        }
     }
 }