wip: simplify container preparation.

demo/Ursa.Demo/Pages/NavMenuDemo.axaml

@@ -48,9 +48,15 @@
             <u:NavMenu
                 Name="menu"
                 ItemsSource="{Binding MenuItems}"
-                HeaderBinding="{Binding}"
+                HeaderBinding="{Binding Header}"
                 SubMenuBinding="{Binding  Children}"
-                IconBinding="{Binding Header}"/>
+                IconBinding="{Binding}">
+                <u:NavMenu.IconTemplate>
+                    <DataTemplate>
+                        <Rectangle Width="10" Height="10" Fill="Blue"></Rectangle>
+                    </DataTemplate>
+                </u:NavMenu.IconTemplate>
+            </u:NavMenu>
         </StackPanel>
     </ScrollViewer>
 </UserControl>

src/Ursa.Themes.Semi/Controls/NavMenu.axaml

@@ -17,7 +17,7 @@
     <ControlTheme x:Key="{x:Type u:NavMenuItem}" TargetType="u:NavMenuItem">
         <Setter Property="Template">
             <ControlTemplate TargetType="u:NavMenuItem">
-                <Grid RowDefinitions="Auto, *" Background="{TemplateBinding Background}">
+                <Grid Background="{TemplateBinding Background}" RowDefinitions="Auto, *">
                     <Grid Grid.Row="0">
                         <Grid.ColumnDefinitions>
                             <ColumnDefinition Width="Auto" SharedSizeGroup="Icon" />
@@ -25,15 +25,16 @@
                             <ColumnDefinition Width="Auto" SharedSizeGroup="Expander" />
                         </Grid.ColumnDefinitions>
                         <ContentPresenter
-                            HorizontalAlignment="Left"
                             Padding="8"
+                            HorizontalAlignment="Left"
                             Background="Transparent"
-                            Content="{TemplateBinding Icon}" />
+                            Content="{TemplateBinding Icon}"
+                            ContentTemplate="{TemplateBinding IconTemplate}" />
                         <ContentPresenter
                             Grid.Column="1"
-                            Padding="0 8"
+                            Padding="0,8"
                             Background="Transparent"
-                            Content="{TemplateBinding Header}" />
+                            Content="{TemplateBinding Header}" ContentTemplate="{TemplateBinding HeaderTemplate}" />
                     </Grid>
                     <ItemsPresenter
                         Grid.Row="1"

src/Ursa/Controls/NavMenu/NavMenu.cs

@@ -2,6 +2,7 @@
 using Avalonia;
 using Avalonia.Controls;
 using Avalonia.Controls.Primitives;
+using Avalonia.Controls.Templates;
 using Avalonia.Data;
 using Avalonia.LogicalTree;
 using Avalonia.Metadata;
@@ -63,6 +64,24 @@ public class NavMenu: ItemsControl
         set => SetValue(CommandBindingProperty, value);
     }
 
+    public static readonly StyledProperty<IDataTemplate?> HeaderTemplateProperty = AvaloniaProperty.Register<NavMenu, IDataTemplate?>(
+        nameof(HeaderTemplate));
+
+    public IDataTemplate? HeaderTemplate
+    {
+        get => GetValue(HeaderTemplateProperty);
+        set => SetValue(HeaderTemplateProperty, value);
+    }
+
+    public static readonly StyledProperty<IDataTemplate?> IconTemplateProperty = AvaloniaProperty.Register<NavMenu, IDataTemplate?>(
+        nameof(IconTemplate));
+
+    public IDataTemplate? IconTemplate
+    {
+        get => GetValue(IconTemplateProperty);
+        set => SetValue(IconTemplateProperty, value);
+    }
+
     static NavMenu()
     {
         SelectedItemProperty.Changed.AddClassHandler<NavMenu, object?>((o, e) => o.OnSelectedItemChange(e));
@@ -83,30 +102,6 @@ public class NavMenu: ItemsControl
         return new NavMenuItem();
     }
 
-    protected override void PrepareContainerForItemOverride(Control container, object? item, int index)
-    {
-        base.PrepareContainerForItemOverride(container, item, index);
-        if (container is NavMenuItem navMenuItem)
-        {
-            if (IconBinding is not null)
-            {
-                navMenuItem[!NavMenuItem.IconProperty] = IconBinding;
-            }
-            if (HeaderBinding is not null)
-            {
-                navMenuItem[!HeaderedItemsControl.HeaderProperty] = HeaderBinding;
-            }
-            if (SubMenuBinding is not null)
-            {
-                navMenuItem[!ItemsSourceProperty] = SubMenuBinding;
-            }
-            if (CommandBinding is not null)
-            {
-                navMenuItem[!NavMenuItem.CommandProperty] = CommandBinding;
-            }
-        }
-    }
-
     internal void SelectItem(NavMenuItem item, NavMenuItem parent)
     {
         // if (item.IsSelected) return;
@@ -116,12 +111,9 @@ public class NavMenu: ItemsControl
             {
                 continue;
             }
-            else
+            if (child is NavMenuItem navMenuItem)
             {
-                if (child is NavMenuItem navMenuItem)
+                navMenuItem.ClearSelection();
-                {
-                    navMenuItem.ClearSelection();
-                }
             }
         }
         if (item.DataContext is not null && item.DataContext != this.DataContext)

src/Ursa/Controls/NavMenu/NavMenuItem.cs

@@ -84,6 +84,28 @@ public class NavMenuItem: HeaderedSelectingItemsControl
         private set => SetAndRaise(IsHighlightedProperty, ref _isHighlighted, value);
     }
 
+    private bool _isCollapsed;
+
+    public static readonly DirectProperty<NavMenuItem, bool> IsCollapsedProperty = AvaloniaProperty.RegisterDirect<NavMenuItem, bool>(
+        nameof(IsCollapsed), o => o.IsCollapsed, (o, v) => o.IsCollapsed = v);
+
+    public bool IsCollapsed
+    {
+        get => _isCollapsed;
+        set => SetAndRaise(IsCollapsedProperty, ref _isCollapsed, value);
+    }
+
+    private bool _isClosed;
+
+    public static readonly DirectProperty<NavMenuItem, bool> IsClosedProperty = AvaloniaProperty.RegisterDirect<NavMenuItem, bool>(
+        nameof(IsClosed), o => o.IsClosed, (o, v) => o.IsClosed = v);
+
+    public bool IsClosed
+    {
+        get => _isClosed;
+        set => SetAndRaise(IsClosedProperty, ref _isClosed, value);
+    }
+    
     
     internal int Level { get; set; }
     
@@ -110,34 +132,32 @@ public class NavMenuItem: HeaderedSelectingItemsControl
         return new NavMenuItem();
     }
     
-    protected override void PrepareContainerForItemOverride(Control container, object? item, int index)
-    {
-        base.PrepareContainerForItemOverride(container, item, index);
-        if (container is NavMenuItem navMenuItem)
-        {
-            if (_rootMenu?.HeaderBinding is not null)
-            {
-                container[!HeaderProperty] = _rootMenu.HeaderBinding;
-            }
-            if (_rootMenu?.IconBinding is not null)
-            {
-                container[!IconProperty] = _rootMenu.IconBinding;
-            }
-            if (_rootMenu?.SubMenuBinding is not null)
-            {
-                container[!ItemsSourceProperty] = _rootMenu.SubMenuBinding;
-            }
-            if (_rootMenu?.CommandBinding is not null)
-            {
-                container[!CommandProperty] = _rootMenu.CommandBinding;
-            }
-        }
-    }
-
     protected override void OnAttachedToVisualTree(VisualTreeAttachmentEventArgs e)
     {
         base.OnAttachedToVisualTree(e);
         _rootMenu = GetRootMenu();
+        if (_rootMenu is not null)
+        {
+            if (_rootMenu.IconBinding is not null)
+            {
+                this[!IconProperty] = _rootMenu.IconBinding;
+            }
+            if (_rootMenu.HeaderBinding is not null)
+            {
+                this[!HeaderProperty] = _rootMenu.HeaderBinding;
+            }
+            if (_rootMenu.SubMenuBinding is not null)
+            {
+                this[!ItemsSourceProperty] = _rootMenu.SubMenuBinding;
+            }
+            if (_rootMenu.CommandBinding is not null)
+            {
+                this[!CommandProperty] = _rootMenu.CommandBinding;
+            }
+            this[!IconTemplateProperty] = _rootMenu[!NavMenu.IconTemplateProperty];
+            this[!HeaderTemplateProperty] = _rootMenu[!NavMenu.HeaderTemplateProperty];
+        }
+        
     }
 
     protected override void OnApplyTemplate(TemplateAppliedEventArgs e)
@@ -154,6 +174,10 @@ public class NavMenuItem: HeaderedSelectingItemsControl
         if (this.ItemCount == 0)
         {
             SelectItem(this);
+        }
+        else
+        {
+            
         }
         Command?.Execute(CommandParameter);
         e.Handled = true;