#2355 Ctrl+A hotkey for SelectingItemsControl

src/Avalonia.Controls/Generators/TreeContainerIndex.cs

@@ -34,7 +34,12 @@ public class TreeContainerIndex
         /// <summary>
         /// Gets the currently materialized containers.
         /// </summary>
-        public IEnumerable<IControl> Items => _containerToItem.Keys;
+        public IEnumerable<IControl> Containers => _containerToItem.Keys;
+
+        /// <summary>
+        /// Gets the items of currently materialized containers.
+        /// </summary>
+        public IEnumerable<object> Objects => _containerToItem.Values;
 
         /// <summary>
         /// Adds an entry to the index.

src/Avalonia.Controls/Primitives/SelectingItemsControl.cs

@@ -10,6 +10,7 @@
 using Avalonia.Controls.Generators;
 using Avalonia.Data;
 using Avalonia.Input;
+using Avalonia.Input.Platform;
 using Avalonia.Interactivity;
 using Avalonia.Styling;
 using Avalonia.VisualTree;
@@ -459,6 +460,23 @@ protected override void OnDataContextEndUpdate()
             }
         }
 
+        protected override void OnKeyDown(KeyEventArgs e)
+        {
+            base.OnKeyDown(e);
+
+            if (!e.Handled)
+            {
+                var keymap = AvaloniaLocator.Current.GetService<PlatformHotkeyConfiguration>();
+                bool Match(List<KeyGesture> gestures) => gestures.Any(g => g.Matches(e));
+
+                if (this.SelectionMode == SelectionMode.Multiple && Match(keymap.SelectAll))
+                {
+                    SynchronizeItems(SelectedItems, Items?.Cast<object>());
+                    e.Handled = true;
+                }
+            }
+        }
+
         /// <summary>
         /// Moves the selection in the specified direction relative to the current selection.
         /// </summary>

src/Avalonia.Controls/TreeView.cs

@@ -10,6 +10,7 @@
 using Avalonia.Controls.Generators;
 using Avalonia.Controls.Primitives;
 using Avalonia.Input;
+using Avalonia.Input.Platform;
 using Avalonia.Interactivity;
 using Avalonia.Threading;
 using Avalonia.VisualTree;
@@ -244,7 +245,7 @@ private void SelectedItemsCollectionChanged(object sender, NotifyCollectionChang
                     break;
                 case NotifyCollectionChangedAction.Reset:
 
-                    foreach (IControl container in ItemContainerGenerator.Index.Items)
+                    foreach (IControl container in ItemContainerGenerator.Index.Containers)
                     {
                         MarkContainerSelected(container, false);
                     }
@@ -402,6 +403,18 @@ protected override void OnKeyDown(KeyEventArgs e)
                     SelectedItem = ElementAt(Items, 0);
                 }
             }
+
+            if (!e.Handled)
+            {
+                var keymap = AvaloniaLocator.Current.GetService<PlatformHotkeyConfiguration>();
+                bool Match(List<KeyGesture> gestures) => gestures.Any(g => g.Matches(e));
+
+                if (this.SelectionMode == SelectionMode.Multiple && Match(keymap.SelectAll))
+                {
+                    SelectingItemsControl.SynchronizeItems(SelectedItems, ItemContainerGenerator.Index.Objects);
+                    e.Handled = true;
+                }
+            }
         }
 
         private TreeViewItem GetContainerInDirection(

tests/Avalonia.Controls.UnitTests/TreeViewTests.cs

@@ -54,7 +54,7 @@ public void Items_Should_Be_Created_Using_ItemTemplate_If_Present()
 
             ApplyTemplates(target);
 
-            var items = target.ItemContainerGenerator.Index.Items
+            var items = target.ItemContainerGenerator.Index.Containers
                 .OfType<TreeViewItem>()
                 .ToList();
 
@@ -463,11 +463,11 @@ public void Removing_Item_Should_Remove_Itself_And_Children_From_Index()
             CreateNodeDataTemplate(target);
             ApplyTemplates(target);
 
-            Assert.Equal(5, target.ItemContainerGenerator.Index.Items.Count());
+            Assert.Equal(5, target.ItemContainerGenerator.Index.Containers.Count());
 
             tree[0].Children.RemoveAt(1);
 
-            Assert.Equal(3, target.ItemContainerGenerator.Index.Items.Count());
+            Assert.Equal(3, target.ItemContainerGenerator.Index.Containers.Count());
         }
 
         [Fact]