From 75503b8055419db419196530cc16685a054aebac Mon Sep 17 00:00:00 2001
From: rabbitism <popmessiah@hotmail.com>
Date: Fri, 2 Feb 2024 19:58:52 +0800
Subject: [PATCH] feat: advanced dialog layout.

---
 .../ViewModels/DialogDemoViewModel.cs         |   4 +
 demo/Ursa.Demo/Views/MainView.axaml           |   2 +-
 src/Ursa.Themes.Semi/Controls/Dialog.axaml    |  69 +++++++-
 .../Controls/MessageBox.axaml                 |  16 +-
 src/Ursa.Themes.Semi/Locale/en-us.axaml       |   1 +
 src/Ursa.Themes.Semi/Locale/zh-cn.axaml       |   1 +
 src/Ursa/Controls/Dialog/DialogControl.cs     |  20 ++-
 src/Ursa/Controls/Dialog/OverlayDialog.cs     |  12 +-
 src/Ursa/Controls/Dialog/OverlayDialogHost.cs | 167 ++++++++++++++++--
 9 files changed, 260 insertions(+), 32 deletions(-)

diff --git a/demo/Ursa.Demo/ViewModels/DialogDemoViewModel.cs b/demo/Ursa.Demo/ViewModels/DialogDemoViewModel.cs
index e26fb45..7376432 100644
--- a/demo/Ursa.Demo/ViewModels/DialogDemoViewModel.cs
+++ b/demo/Ursa.Demo/ViewModels/DialogDemoViewModel.cs
@@ -119,6 +119,10 @@ public class DialogDemoViewModel: ObservableObject
                         Mode = SelectedMode,
                         Buttons = SelectedButton,
                         CanClickOnMaskToClose = CanCloseMaskToClose,
+                        HorizontalAnchor = HorizontalPosition.Right,
+                        HorizontalOffset = 50,
+                        VerticalAnchor = VerticalPosition.Top,
+                        VerticalOffset = 50,
                     }
                 );
                 Date = vm.Date;
diff --git a/demo/Ursa.Demo/Views/MainView.axaml b/demo/Ursa.Demo/Views/MainView.axaml
index e038f33..375bf68 100644
--- a/demo/Ursa.Demo/Views/MainView.axaml
+++ b/demo/Ursa.Demo/Views/MainView.axaml
@@ -93,7 +93,7 @@
                 <converters:ViewLocator />
             </ContentControl.ContentTemplate>
         </ContentControl>
-        <u:OverlayDialogHost Grid.Row="0" Grid.Column="0" Grid.RowSpan="2" Grid.ColumnSpan="2"/>
+        <u:OverlayDialogHost Grid.Row="0" Grid.Column="0" Grid.RowSpan="2" Grid.ColumnSpan="2" SnapThickness="20"/>
     </Grid>
 
 </UserControl>
diff --git a/src/Ursa.Themes.Semi/Controls/Dialog.axaml b/src/Ursa.Themes.Semi/Controls/Dialog.axaml
index bf11f76..61fed7a 100644
--- a/src/Ursa.Themes.Semi/Controls/Dialog.axaml
+++ b/src/Ursa.Themes.Semi/Controls/Dialog.axaml
@@ -46,6 +46,23 @@
                 </Border>
             </ControlTemplate>
         </Setter>
+        <Style Selector="^ /template/ Panel#PART_TitleArea">
+            <Setter Property="ContextFlyout">
+                <MenuFlyout>
+                    <MenuItem
+                        Command="{Binding $parent[u:DialogControl].CloseDialog}"
+                        CommandParameter="{x:Static u:DialogLayerChangeType.BringForward}"
+                        Header="{DynamicResource STRING_MENU_DIALOG_CLOSE}">
+                        <MenuItem.Icon>
+                            <PathIcon
+                                Width="12"
+                                Height="12"
+                                Data="{DynamicResource WindowCloseIconGlyph}" />
+                        </MenuItem.Icon>
+                    </MenuItem>
+                </MenuFlyout>
+            </Setter>
+        </Style>
         <Style Selector="^:not(:modal) /template/ Panel#PART_TitleArea">
             <Setter Property="ContextFlyout">
                 <MenuFlyout>
@@ -93,6 +110,17 @@
                                 Data="{DynamicResource DialogArrangeSendToBackGlyph}" />
                         </MenuItem.Icon>
                     </MenuItem>
+                    <MenuItem
+                        Command="{Binding $parent[u:DialogControl].CloseDialog}"
+                        CommandParameter="{x:Static u:DialogLayerChangeType.BringForward}"
+                        Header="{DynamicResource STRING_MENU_DIALOG_CLOSE}">
+                        <MenuItem.Icon>
+                            <PathIcon
+                                Width="12"
+                                Height="12"
+                                Data="{DynamicResource WindowCloseIconGlyph}" />
+                        </MenuItem.Icon>
+                    </MenuItem>
                 </MenuFlyout>
             </Setter>
         </Style>
@@ -115,11 +143,13 @@
                     Theme="{DynamicResource CardBorder}">
                     <Border ClipToBounds="True" CornerRadius="{TemplateBinding CornerRadius}">
                         <Grid RowDefinitions="Auto, *, Auto">
-                            <ContentPresenter
-                                Name="PART_ContentPresenter"
-                                Grid.Row="1"
-                                Margin="24,8"
-                                Content="{TemplateBinding Content}" />
+                            <ScrollViewer Grid.Row="1">
+                                <ContentPresenter
+                                    Name="PART_ContentPresenter"
+                                    Grid.Row="1"
+                                    Margin="24,8"
+                                    Content="{TemplateBinding Content}" />
+                            </ScrollViewer>
                             <Grid Grid.Row="0" ColumnDefinitions="Auto, *, Auto">
                                 <Panel
                                     Name="{x:Static u:DialogControl.PART_TitleArea}"
@@ -304,7 +334,23 @@
                 <Setter Property="theme:ClassHelper.Classes" Value="Tertiary" />
             </Style>
         </Style>
-
+        <Style Selector="^ /template/ Panel#PART_TitleArea">
+            <Setter Property="ContextFlyout">
+                <MenuFlyout>
+                    <MenuItem
+                        Command="{Binding $parent[u:DialogControl].CloseDialog}"
+                        CommandParameter="{x:Static u:DialogLayerChangeType.BringForward}"
+                        Header="{DynamicResource STRING_MENU_DIALOG_CLOSE}">
+                        <MenuItem.Icon>
+                            <PathIcon
+                                Width="12"
+                                Height="12"
+                                Data="{DynamicResource WindowCloseIconGlyph}" />
+                        </MenuItem.Icon>
+                    </MenuItem>
+                </MenuFlyout>
+            </Setter>
+        </Style>
         <Style Selector="^:not(:modal) /template/ Panel#PART_TitleArea">
             <Setter Property="ContextFlyout">
                 <MenuFlyout>
@@ -352,6 +398,17 @@
                                 Data="{DynamicResource DialogArrangeSendToBackGlyph}" />
                         </MenuItem.Icon>
                     </MenuItem>
+                    <MenuItem
+                        Command="{Binding $parent[u:DialogControl].CloseDialog}"
+                        CommandParameter="{x:Static u:DialogLayerChangeType.BringForward}"
+                        Header="{DynamicResource STRING_MENU_DIALOG_CLOSE}">
+                        <MenuItem.Icon>
+                            <PathIcon
+                                Width="12"
+                                Height="12"
+                                Data="{DynamicResource WindowCloseIconGlyph}" />
+                        </MenuItem.Icon>
+                    </MenuItem>
                 </MenuFlyout>
             </Setter>
         </Style>
diff --git a/src/Ursa.Themes.Semi/Controls/MessageBox.axaml b/src/Ursa.Themes.Semi/Controls/MessageBox.axaml
index b79a3e0..dc06e21 100644
--- a/src/Ursa.Themes.Semi/Controls/MessageBox.axaml
+++ b/src/Ursa.Themes.Semi/Controls/MessageBox.axaml
@@ -81,7 +81,7 @@
                         </Grid>
                         <StackPanel
                             Grid.Row="2"
-                            Margin="0,0,24,24"
+                            Margin="24,0,24,24"
                             HorizontalAlignment="Right"
                             Orientation="Horizontal">
                             <Button
@@ -244,6 +244,20 @@
                 </Border>
             </ControlTemplate>
         </Setter>
+        <Style Selector="^ /template/ Panel#PART_TitleArea">
+            <Setter Property="ContextFlyout">
+                <MenuFlyout>
+                    <MenuItem Command="{Binding $parent[u:DialogControl].CloseDialog}" Header="{DynamicResource STRING_MENU_DIALOG_CLOSE}">
+                        <MenuItem.Icon>
+                            <PathIcon
+                                Width="12"
+                                Height="12"
+                                Data="{DynamicResource WindowCloseIconGlyph}" />
+                        </MenuItem.Icon>
+                    </MenuItem>
+                </MenuFlyout>
+            </Setter>
+        </Style>
         <Style Selector="^[MessageIcon=None] /template/ PathIcon#PART_Icon">
             <Setter Property="IsVisible" Value="False" />
         </Style>
diff --git a/src/Ursa.Themes.Semi/Locale/en-us.axaml b/src/Ursa.Themes.Semi/Locale/en-us.axaml
index d294cd0..e6d2f69 100644
--- a/src/Ursa.Themes.Semi/Locale/en-us.axaml
+++ b/src/Ursa.Themes.Semi/Locale/en-us.axaml
@@ -9,4 +9,5 @@
     <x:String x:Key="STRING_MENU_DIALOG_CANCEL">Cancel</x:String>
     <x:String x:Key="STRING_MENU_DIALOG_YES">Yes</x:String>
     <x:String x:Key="STRING_MENU_DIALOG_NO">No</x:String>
+    <x:String x:Key="STRING_MENU_DIALOG_CLOSE">Close</x:String>
 </ResourceDictionary>
diff --git a/src/Ursa.Themes.Semi/Locale/zh-cn.axaml b/src/Ursa.Themes.Semi/Locale/zh-cn.axaml
index ca25cd0..c738313 100644
--- a/src/Ursa.Themes.Semi/Locale/zh-cn.axaml
+++ b/src/Ursa.Themes.Semi/Locale/zh-cn.axaml
@@ -9,4 +9,5 @@
     <x:String x:Key="STRING_MENU_DIALOG_CANCEL">取消</x:String>
     <x:String x:Key="STRING_MENU_DIALOG_YES">是</x:String>
     <x:String x:Key="STRING_MENU_DIALOG_NO">否</x:String>
+    <x:String x:Key="STRING_MENU_DIALOG_CLOSE">关闭</x:String>
 </ResourceDictionary>
diff --git a/src/Ursa/Controls/Dialog/DialogControl.cs b/src/Ursa/Controls/Dialog/DialogControl.cs
index 17e4b98..0534370 100644
--- a/src/Ursa/Controls/Dialog/DialogControl.cs
+++ b/src/Ursa/Controls/Dialog/DialogControl.cs
@@ -3,6 +3,7 @@ using Avalonia.Controls;
 using Avalonia.Controls.Metadata;
 using Avalonia.Controls.Primitives;
 using Avalonia.Input;
+using Avalonia.Input.GestureRecognizers;
 using Avalonia.Interactivity;
 using Ursa.Common;
 
@@ -22,8 +23,12 @@ public class DialogControl: ContentControl
     
     internal HorizontalPosition HorizontalAnchor { get; set; }
     internal VerticalPosition VerticalAnchor { get; set; }
-    internal double? InitialHorizontalOffset { get; set; }
-    internal double? InitialVerticalOffset { get; set; }
+    internal HorizontalPosition ActualHorizontalAnchor { get; set; }
+    internal VerticalPosition ActualVerticalAnchor { get; set; }
+    internal double? HorizontalOffset { get; set; }
+    internal double? VerticalOffset { get; set; }
+    internal double? HorizontalOffsetRatio { get; set; }
+    internal double? VerticalOffsetRatio { get; set; }
     internal bool CanClickOnMaskToClose { get; set; }
     
     public event EventHandler<DialogLayerChangeEventArgs>? LayerChanged;
@@ -55,6 +60,7 @@ public class DialogControl: ContentControl
 
         _titleArea?.RemoveHandler(PointerMovedEvent, OnTitlePointerMove);
         _titleArea?.RemoveHandler(PointerPressedEvent, OnTitlePointerPressed);
+        _titleArea?.RemoveHandler(PointerReleasedEvent, OnTitlePointerRelease);
         
         _closeButton = e.NameScope.Find<Button>(PART_CloseButton);
         _titleArea = e.NameScope.Find<Panel>(PART_TitleArea);
@@ -62,6 +68,7 @@ public class DialogControl: ContentControl
         
         _titleArea?.AddHandler(PointerMovedEvent, OnTitlePointerMove, RoutingStrategies.Bubble);
         _titleArea?.AddHandler(PointerPressedEvent, OnTitlePointerPressed, RoutingStrategies.Bubble);
+        _titleArea?.AddHandler(PointerReleasedEvent, OnTitlePointerRelease, RoutingStrategies.Bubble);
         EventHelper.RegisterClickEvent(Close, _closeButton);
     }
     
@@ -75,11 +82,16 @@ public class DialogControl: ContentControl
         e.Source = this;
     }
 
+    private void OnTitlePointerRelease(object sender, PointerReleasedEventArgs e)
+    {
+        e.Source = this;
+    }
+
 
     public Task<T?> ShowAsync<T>(CancellationToken? token = default)
     { 
         var tcs = new TaskCompletionSource<T?>();
-        token?.Register(Close);
+        token?.Register(CloseDialog);
         void OnCloseHandler(object sender, object? args)
         {
             if (args is T result)
@@ -137,7 +149,7 @@ public class DialogControl: ContentControl
         PseudoClasses.Set(PC_Modal, modal);
     }
 
-    public void Close()
+    public void CloseDialog()
     {
         if (this.DataContext is IDialogContext context)
         {
diff --git a/src/Ursa/Controls/Dialog/OverlayDialog.cs b/src/Ursa/Controls/Dialog/OverlayDialog.cs
index 7635938..8a64e7e 100644
--- a/src/Ursa/Controls/Dialog/OverlayDialog.cs
+++ b/src/Ursa/Controls/Dialog/OverlayDialog.cs
@@ -183,9 +183,11 @@ public static class OverlayDialog
         if (options is null) options = new OverlayDialogOptions();
         control.HorizontalAnchor = options.HorizontalAnchor;
         control.VerticalAnchor = options.VerticalAnchor;
-        control.InitialHorizontalOffset =
+        control.ActualHorizontalAnchor = options.HorizontalAnchor;
+        control.ActualVerticalAnchor = options.VerticalAnchor;
+        control.HorizontalOffset =
             control.HorizontalAnchor == HorizontalPosition.Center ? null : options.HorizontalOffset;
-        control.InitialVerticalOffset =
+        control.VerticalOffset =
             options.VerticalAnchor == VerticalPosition.Center ? null : options.VerticalOffset;
         control.CanClickOnMaskToClose = options.CanClickOnMaskToClose;
     }
@@ -195,9 +197,11 @@ public static class OverlayDialog
         if (options is null) options = new OverlayDialogOptions();
         control.HorizontalAnchor = options.HorizontalAnchor;
         control.VerticalAnchor = options.VerticalAnchor;
-        control.InitialHorizontalOffset =
+        control.ActualHorizontalAnchor = options.HorizontalAnchor;
+        control.ActualVerticalAnchor = options.VerticalAnchor;
+        control.HorizontalOffset =
             control.HorizontalAnchor == HorizontalPosition.Center ? null : options.HorizontalOffset;
-        control.InitialVerticalOffset =
+        control.VerticalOffset =
             options.VerticalAnchor == VerticalPosition.Center ? null : options.VerticalOffset;
         control.CanClickOnMaskToClose = options.CanClickOnMaskToClose;
         control.Mode = options.Mode;
diff --git a/src/Ursa/Controls/Dialog/OverlayDialogHost.cs b/src/Ursa/Controls/Dialog/OverlayDialogHost.cs
index c376883..7b916cb 100644
--- a/src/Ursa/Controls/Dialog/OverlayDialogHost.cs
+++ b/src/Ursa/Controls/Dialog/OverlayDialogHost.cs
@@ -1,4 +1,5 @@
 using Avalonia;
+using Avalonia.Animation;
 using Avalonia.Controls;
 using Avalonia.Controls.Primitives;
 using Avalonia.Controls.Templates;
@@ -21,6 +22,7 @@ public class OverlayDialogHost : Canvas
 
 
     public DataTemplates DialogDataTemplates { get; set; } = new DataTemplates();
+    public Thickness SnapThickness { get; set; } = new Thickness(0);
 
     public static readonly StyledProperty<IBrush?> OverlayMaskBrushProperty =
         AvaloniaProperty.Register<OverlayDialogHost, IBrush?>(
@@ -56,7 +58,7 @@ public class OverlayDialogHost : Canvas
         {
             int i = _masks.IndexOf(border);
             DialogControl dialog = _modalDialogs[i];
-            dialog.Close();
+            dialog.CloseDialog();
             border.RemoveHandler(PointerReleasedEvent, ClickBorderToCloseDialog);
         }
     }
@@ -75,6 +77,44 @@ public class OverlayDialogHost : Canvas
             _masks[i].Width = this.Bounds.Width;
             _masks[i].Height = this.Bounds.Height;
         }
+
+        var oldSize = e.PreviousSize;
+        var newSize = e.NewSize;
+        foreach (var dialog in _dialogs)
+        {
+            ResetDialogPosition(dialog, oldSize, newSize);
+        }
+
+        foreach (var modalDialog in _modalDialogs)
+        {
+            ResetDialogPosition(modalDialog, oldSize, newSize);
+        }
+    }
+    
+    private void ResetDialogPosition(DialogControl control, Size oldSize, Size newSize)
+    {
+        var width = newSize.Width - control.Bounds.Width;
+        var height = newSize.Height - control.Bounds.Height;
+        var newLeft = width * control.HorizontalOffsetRatio??0;
+        var newTop = height * control.VerticalOffsetRatio??0;
+        if(control.ActualHorizontalAnchor == HorizontalPosition.Left)
+        {
+            newLeft = 0;
+        }
+        if (control.ActualHorizontalAnchor == HorizontalPosition.Right)
+        {
+            newLeft = newSize.Width - control.Bounds.Width;
+        }
+        if (control.ActualVerticalAnchor == VerticalPosition.Top)
+        {
+            newTop = 0;
+        }
+        if (control.ActualVerticalAnchor == VerticalPosition.Bottom)
+        {
+            newTop = newSize.Height - control.Bounds.Height;
+        }
+        SetLeft(control, Math.Max(0.0, newLeft));
+        SetTop(control, Math.Max(0.0, newTop));
     }
 
     protected override void OnDetachedFromVisualTree(VisualTreeAttachmentEventArgs e)
@@ -85,7 +125,6 @@ public class OverlayDialogHost : Canvas
 
     protected override void OnPointerMoved(PointerEventArgs e)
     {
-        base.OnPointerMoved(e);
         if (e.Source is DialogControl item)
         {
             if (e.GetCurrentPoint(this).Properties.IsLeftButtonPressed)
@@ -95,28 +134,35 @@ public class OverlayDialogHost : Canvas
                 var top = p.Y - _lastPoint.Y;
                 left = MathUtilities.Clamp(left, 0, Bounds.Width - item.Bounds.Width);
                 top = MathUtilities.Clamp(top, 0, Bounds.Height - item.Bounds.Height);
-                Canvas.SetLeft(item, left);
-                Canvas.SetTop(item, top);
+                SetLeft(item, left);
+                SetTop(item, top);
             }
         }
     }
 
     protected override void OnPointerPressed(PointerPressedEventArgs e)
     {
-        // base.OnPointerPressed(e);
         if (e.Source is DialogControl item)
         {
             _lastPoint = e.GetPosition(item);
         }
     }
 
+    protected override void OnPointerReleased(PointerReleasedEventArgs e)
+    {
+        if (e.Source is DialogControl item)
+        {
+            AnchorDialog(item);
+        }
+    }
+
     internal void AddDialog(DialogControl control)
     {
         this.Children.Add(control);
         _dialogs.Add(control);
         control.Measure(this.Bounds.Size);
         control.Arrange(new Rect(control.DesiredSize));
-        SetToCenter(control);
+        SetToPosition(control);
         control.DialogControlClosing += OnDialogControlClosing;
         control.LayerChanged += OnDialogLayerChanged;
         ResetZIndices();
@@ -126,7 +172,7 @@ public class OverlayDialogHost : Canvas
     {
         if (sender is DialogControl control)
         {
-            this.Children.Remove(control);
+            Children.Remove(control);
             control.DialogControlClosing -= OnDialogControlClosing;
             control.LayerChanged -= OnDialogLayerChanged;
             if (_dialogs.Contains(control))
@@ -170,7 +216,7 @@ public class OverlayDialogHost : Canvas
         this.Children.Add(control);
         control.Measure(this.Bounds.Size);
         control.Arrange(new Rect(control.DesiredSize));
-        SetToCenter(control);
+        SetToPosition(control);
         control.DialogControlClosing += OnDialogControlClosing;
         control.LayerChanged += OnDialogLayerChanged;
     }
@@ -232,16 +278,105 @@ public class OverlayDialogHost : Canvas
         }
     }
 
-    private void SetToCenter(DialogControl? control)
+    private void SetToPosition(DialogControl? control)
     {
-        // return;
         if (control is null) return;
-        double left = (this.Bounds.Width - control.Bounds.Width) / 2;
-        double top = (this.Bounds.Height - control.Bounds.Height) / 2;
-        left = MathUtilities.Clamp(left, 0, Bounds.Width);
-        top = MathUtilities.Clamp(top, 0, Bounds.Height);
-        Canvas.SetLeft(control, left);
-        Canvas.SetTop(control, top);
+        double left = GetLeftPosition(control);
+        double top = GetTopPosition(control);
+        SetLeft(control, left);
+        SetTop(control, top);
+        AnchorDialog(control);
+    }
+    
+    private void AnchorDialog(DialogControl control)
+    {
+        control.ActualHorizontalAnchor = HorizontalPosition.Center;
+        control.ActualVerticalAnchor = VerticalPosition.Center;
+        double left = GetLeft(control);
+        double top = GetTop(control);
+        double right = Bounds.Width - left - control.Bounds.Width;
+        double bottom = Bounds.Height - top - control.Bounds.Height;
+        if(top < SnapThickness.Top)
+        {
+            SetTop(control, 0);
+            control.ActualVerticalAnchor = VerticalPosition.Top;
+            control.VerticalOffsetRatio = 0;
+        }
+        if(bottom > Bounds.Height - SnapThickness.Bottom)
+        {
+            SetTop(control, Bounds.Height - control.Bounds.Height);
+            control.ActualVerticalAnchor = VerticalPosition.Bottom;
+            control.VerticalOffsetRatio = 1;
+        }
+        if(left < SnapThickness.Left)
+        {
+            SetLeft(control, 0);
+            control.ActualHorizontalAnchor = HorizontalPosition.Left;
+            control.HorizontalOffsetRatio = 0;
+        }
+        if(right > Bounds.Width - SnapThickness.Right)
+        {
+            SetLeft(control, Bounds.Width - control.Bounds.Width);
+            control.ActualHorizontalAnchor = HorizontalPosition.Right;
+            control.HorizontalOffsetRatio = 1;
+        }
+        left = GetLeft(control);
+        top = GetTop(control);
+        right = Bounds.Width - left - control.Bounds.Width;
+        bottom = Bounds.Height - top - control.Bounds.Height;
+        control.HorizontalOffsetRatio = left / (left + right);
+        control.VerticalOffsetRatio = top / (top + bottom);
+    }
+
+    private double GetLeftPosition(DialogControl control)
+    {
+        double left = 0;
+        double offset = Math.Max(0, control.HorizontalOffset ?? 0);
+        left = this.Bounds.Width - control.Bounds.Width;
+        if (control.HorizontalAnchor == HorizontalPosition.Center)
+        {
+            left *= 0.5;
+            (double min, double max) = MathUtilities.GetMinMax(0, Bounds.Width * 0.5);
+            left = MathUtilities.Clamp(left, min, max);
+        }
+        else if (control.HorizontalAnchor == HorizontalPosition.Left)
+        {
+            (double min, double max) = MathUtilities.GetMinMax(0, offset);
+            left = MathUtilities.Clamp(left, min, max);
+        }
+        else if (control.HorizontalAnchor == HorizontalPosition.Right)
+        {
+            double leftOffset = Bounds.Width - control.Bounds.Width - offset;
+            leftOffset = Math.Max(0, leftOffset);
+            if(control.HorizontalOffset.HasValue)
+            {
+                left = MathUtilities.Clamp(left, 0, leftOffset);
+            }
+        }
+        return left;
+    }
+
+    private double GetTopPosition(DialogControl control)
+    {
+        double top = 0;
+        double offset = Math.Max(0, control.VerticalOffset ?? 0);
+        top = this.Bounds.Height - control.Bounds.Height;
+        if (control.VerticalAnchor == VerticalPosition.Center)
+        {
+            top *= 0.5;
+            (double min, double max) = MathUtilities.GetMinMax(0, Bounds.Height * 0.5);
+            top = MathUtilities.Clamp(top, min, max);
+        }
+        else if (control.VerticalAnchor == VerticalPosition.Top)
+        {
+            top = MathUtilities.Clamp(top, 0, offset);
+        }
+        else if (control.VerticalAnchor == VerticalPosition.Bottom)
+        {
+            var topOffset = Math.Max(0, Bounds.Height - control.Bounds.Height - offset);
+            top = MathUtilities.Clamp(top, 0, topOffset);
+        }
+        return top;
     }
 
     internal IDataTemplate? GetDataTemplate(object? o)