feat: support dialog resize.

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

@@ -233,6 +233,7 @@
                                     Content="{DynamicResource STRING_MENU_DIALOG_OK}"
                                     Theme="{DynamicResource SolidButton}" />
                             </StackPanel>
+                            <u:DialogResizer Grid.Row="0" Grid.RowSpan="3"/>
                         </Grid>
                     </Border>
                 </Border>

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

@@ -12,6 +12,32 @@
         </Setter>
     </ControlTheme>
     
+    <ControlTheme TargetType="u:DialogResizerThumb" x:Key="{x:Type u:DialogResizerThumb}">
+        <Setter Property="Background" Value="Red" />
+        <Setter Property="Template">
+            <ControlTemplate TargetType="u:DialogResizerThumb">
+                <iri:PureRectangle HorizontalAlignment="Stretch" VerticalAlignment="Stretch" Background="{TemplateBinding Background}"/>
+            </ControlTemplate>
+        </Setter>
+    </ControlTheme>
+    
+    <ControlTheme TargetType="u:DialogResizer" x:Key="{x:Type u:DialogResizer}">
+        <Setter Property="Template">
+            <ControlTemplate TargetType="u:WindowResizer">
+                <Grid RowDefinitions="Auto, *, Auto" ColumnDefinitions="Auto, *, Auto" >
+                    <u:DialogResizerThumb Grid.Row="0" Grid.Column="0" ResizeDirection="TopLeft" Cursor="TopLeftCorner" />
+                    <u:DialogResizerThumb Grid.Row="0" Grid.Column="1" ResizeDirection="Top" Cursor="TopSide" Height="{DynamicResource ResizerThumbHeight}" />
+                    <u:DialogResizerThumb Grid.Row="0" Grid.Column="2" ResizeDirection="TopRight" Cursor="TopRightCorner" />
+                    <u:DialogResizerThumb Grid.Row="1" Grid.Column="0" ResizeDirection="Left" Cursor="LeftSide" Width="{DynamicResource ResizerThumbWidth}" />
+                    <u:DialogResizerThumb Grid.Row="1" Grid.Column="2" ResizeDirection="Right" Cursor="RightSide" Width="{DynamicResource ResizerThumbWidth}" />
+                    <u:DialogResizerThumb Grid.Row="2" Grid.Column="0" ResizeDirection="BottomLeft" Cursor="BottomLeftCorner" />
+                    <u:DialogResizerThumb Grid.Row="2" Grid.Column="1" ResizeDirection="Bottom" Cursor="BottomSide" Height="{DynamicResource ResizerThumbHeight}" />
+                    <u:DialogResizerThumb Grid.Row="2" Grid.Column="2" ResizeDirection="BottomRight" Cursor="BottomRightCorner" />
+                </Grid>
+            </ControlTemplate>
+        </Setter>
+    </ControlTheme>
+    
     <ControlTheme TargetType="u:WindowResizer" x:Key="{x:Type u:WindowResizer}">
         <Setter Property="Template">
             <ControlTemplate TargetType="u:WindowResizer">

src/Ursa/Controls/OverlayShared/OverlayFeedbackElement.cs

@@ -1,16 +1,40 @@
 using Avalonia;
 using Avalonia.Controls;
+using Avalonia.Input;
 using Avalonia.Interactivity;
 using Avalonia.Threading;
+using Avalonia.VisualTree;
 using Irihi.Avalonia.Shared.Contracts;
+using Irihi.Avalonia.Shared.Helpers;
 using Ursa.EventArgs;
 
 namespace Ursa.Controls.OverlayShared;
 
-public abstract class OverlayFeedbackElement: ContentControl
+public abstract class OverlayFeedbackElement : ContentControl
 {
     public static readonly StyledProperty<bool> IsClosedProperty =
-        AvaloniaProperty.Register<OverlayFeedbackElement, bool>(nameof(IsClosed), defaultValue: true);
+        AvaloniaProperty.Register<OverlayFeedbackElement, bool>(nameof(IsClosed), true);
+
+    public static readonly RoutedEvent<ResultEventArgs> ClosedEvent =
+        RoutedEvent.Register<DrawerControlBase, ResultEventArgs>(
+            nameof(Closed), RoutingStrategies.Bubble);
+
+    private bool _resizeDragging;
+    private bool _moveDragging;
+    
+    private Panel? _containerPanel;
+    private Rect _resizeDragStartBounds;
+    private Point _resizeDragStartPoint;
+    
+    private WindowEdge? _windowEdge;
+
+    static OverlayFeedbackElement()
+    {
+        FocusableProperty.OverrideDefaultValue<OverlayFeedbackElement>(false);
+        DataContextProperty.Changed.AddClassHandler<OverlayFeedbackElement, object?>((o, e) =>
+            o.OnDataContextChange(e));
+        ClosedEvent.AddClassHandler<OverlayFeedbackElement>((o, e) => o.OnClosed(e));
+    }
 
     public bool IsClosed
     {
@@ -18,21 +42,11 @@ public abstract class OverlayFeedbackElement: ContentControl
         set => SetValue(IsClosedProperty, value);
     }
 
-    static OverlayFeedbackElement()
-    {
-        FocusableProperty.OverrideDefaultValue<OverlayFeedbackElement>(false);
-        DataContextProperty.Changed.AddClassHandler<OverlayFeedbackElement, object?>((o, e) => o.OnDataContextChange(e));
-        ClosedEvent.AddClassHandler<OverlayFeedbackElement>((o,e)=>o.OnClosed(e));
-    }
-
     private void OnClosed(ResultEventArgs _)
     {
-        SetCurrentValue(IsClosedProperty,true);
+        SetCurrentValue(IsClosedProperty, true);
     }
 
-    public static readonly RoutedEvent<ResultEventArgs> ClosedEvent = RoutedEvent.Register<DrawerControlBase, ResultEventArgs>(
-        nameof(Closed), RoutingStrategies.Bubble);
-    
     public event EventHandler<ResultEventArgs> Closed
     {
         add => AddHandler(ClosedEvent, value);
@@ -41,14 +55,8 @@ public abstract class OverlayFeedbackElement: ContentControl
 
     private void OnDataContextChange(AvaloniaPropertyChangedEventArgs<object?> args)
     {
-        if (args.OldValue.Value is IDialogContext oldContext)
+        if (args.OldValue.Value is IDialogContext oldContext) oldContext.RequestClose -= OnContextRequestClose;
-        {
+        if (args.NewValue.Value is IDialogContext newContext) newContext.RequestClose += OnContextRequestClose;
-            oldContext.RequestClose -= OnContextRequestClose;
-        }
-        if (args.NewValue.Value is IDialogContext newContext)
-        {
-            newContext.RequestClose += OnContextRequestClose;
-        }
     }
 
     protected virtual void OnElementClosing(object? sender, object? args)
@@ -64,21 +72,14 @@ public abstract class OverlayFeedbackElement: ContentControl
     public Task<T?> ShowAsync<T>(CancellationToken? token = default)
     {
         var tcs = new TaskCompletionSource<T?>();
-        token?.Register(() =>
+        token?.Register(() => { Dispatcher.UIThread.Invoke(Close); });
-        {
-            Dispatcher.UIThread.Invoke(Close);
-        });
 
         void OnCloseHandler(object? sender, ResultEventArgs? args)
         {
             if (args?.Result is T result)
-            {
                 tcs.SetResult(result);
-            }
             else
-            {
                 tcs.SetResult(default);
-            }
             RemoveHandler(ClosedEvent, OnCloseHandler);
         }
 
@@ -87,4 +88,111 @@ public abstract class OverlayFeedbackElement: ContentControl
     }
 
     public abstract void Close();
+
+    internal void BeginResizeDrag(WindowEdge windowEdge, PointerPressedEventArgs e)
+    {
+        if (!e.GetCurrentPoint(this).Properties.IsLeftButtonPressed) return;
+        _resizeDragging = true;
+        _resizeDragStartPoint = e.GetPosition(this);
+        _resizeDragStartBounds = Bounds;
+        _windowEdge = windowEdge;
+    }
+    
+    internal void BeginMoveDrag(PointerPressedEventArgs e)
+    {
+        if (!e.GetCurrentPoint(this).Properties.IsLeftButtonPressed) return;
+        _resizeDragging = true;
+        _resizeDragStartPoint = e.GetPosition(this);
+        _resizeDragStartBounds = Bounds;
+        _windowEdge = null;
+    }
+
+    protected override void OnAttachedToVisualTree(VisualTreeAttachmentEventArgs e)
+    {
+        base.OnAttachedToVisualTree(e);
+        _containerPanel = this.FindAncestorOfType<Panel>();
+    }
+
+    protected override void OnPointerReleased(PointerReleasedEventArgs e)
+    {
+        base.OnPointerReleased(e);
+        _resizeDragging = false;
+    }
+
+    protected override void OnPointerCaptureLost(PointerCaptureLostEventArgs e)
+    {
+        base.OnPointerCaptureLost(e);
+        _resizeDragging = false;
+    }
+
+    protected override void OnPointerMoved(PointerEventArgs e)
+    {
+        base.OnPointerMoved(e);
+        if (!_resizeDragging || _windowEdge is null) return;
+        var point = e.GetPosition(this);
+        var diff = point - _resizeDragStartPoint;
+        var left = Canvas.GetLeft(this);
+        var top = Canvas.GetTop(this);
+        var width = _windowEdge is WindowEdge.West or WindowEdge.NorthWest or WindowEdge.SouthWest
+            ? Bounds.Width : _resizeDragStartBounds.Width;
+        var height = _windowEdge is WindowEdge.North or WindowEdge.NorthEast or WindowEdge.NorthWest
+            ? Bounds.Height : _resizeDragStartBounds.Height;
+        var newBounds = CalculateNewBounds(left, top, width, height, diff, _containerPanel?.Bounds, _windowEdge.Value);
+        Canvas.SetLeft(this, newBounds.Left);
+        Canvas.SetTop(this, newBounds.Top);
+        SetCurrentValue(WidthProperty, newBounds.Width);
+        SetCurrentValue(HeightProperty, newBounds.Height);
+    }
+
+    private Rect CalculateNewBounds(double left, double top, double width, double height, Point diff, Rect? containerBounds,
+        WindowEdge windowEdge)
+    {
+        if (containerBounds is not null)
+        {
+            var minX = -left;
+            var minY = -top;
+            var maxX = containerBounds.Value.Width - left - width;
+            var maxY = containerBounds.Value.Height - top - height;
+            diff = new Point(MathHelpers.SafeClamp(diff.X, minX, maxX), MathHelpers.SafeClamp(diff.Y, minY, maxY));
+        }
+        switch (windowEdge)
+        {
+            case WindowEdge.North:
+                top += diff.Y;
+                height -= diff.Y;
+                top = Math.Max(0, top);
+                break;
+            case WindowEdge.NorthEast:
+                top += diff.Y;
+                width += diff.X;
+                height -= diff.Y;
+                break;
+            case WindowEdge.East:
+                width += diff.X;
+                break;
+            case WindowEdge.SouthEast:
+                width += diff.X;
+                height += diff.Y;
+                break;
+            case WindowEdge.South:
+                height += diff.Y;
+                break;
+            case WindowEdge.SouthWest:
+                left += diff.X;
+                width -= diff.X;
+                height += diff.Y;
+                break;
+            case WindowEdge.West:
+                left += diff.X;
+                width -= diff.X;
+                break;
+            case WindowEdge.NorthWest:
+                left += diff.X;
+                top += diff.Y;
+                width -= diff.X;
+                height -= diff.Y;
+                break;
+        }
+        return new Rect(left, top, width, height);
+    }
 }

src/Ursa/Controls/Resizers/DialogResizer.cs

@@ -0,0 +1,19 @@
+using Avalonia;
+using Avalonia.Controls.Primitives;
+
+namespace Ursa.Controls;
+
+public class DialogResizer: TemplatedControl
+{
+    public static readonly StyledProperty<ResizeDirection> ResizeDirectionProperty = AvaloniaProperty.Register<DialogResizer, ResizeDirection>(
+        nameof(ResizeDirection));
+
+    /// <summary>
+    /// Defines what direction the dialog is allowed to be resized.
+    /// </summary>
+    public ResizeDirection ResizeDirection
+    {
+        get => GetValue(ResizeDirectionProperty);
+        set => SetValue(ResizeDirectionProperty, value);
+    }
+}

src/Ursa/Controls/Resizers/DialogResizerThumb.cs

@@ -0,0 +1,48 @@
+using Avalonia;
+using Avalonia.Controls;
+using Avalonia.Controls.Primitives;
+using Avalonia.Input;
+using Avalonia.LogicalTree;
+using Ursa.Controls.OverlayShared;
+
+namespace Ursa.Controls;
+
+public class DialogResizerThumb: Thumb
+{
+    private OverlayFeedbackElement? _dialog;
+    
+    public static readonly StyledProperty<ResizeDirection> ResizeDirectionProperty = AvaloniaProperty.Register<DialogResizerThumb, ResizeDirection>(
+        nameof(ResizeDirection));
+
+    public ResizeDirection ResizeDirection
+    {
+        get => GetValue(ResizeDirectionProperty);
+        set => SetValue(ResizeDirectionProperty, value);
+    }
+
+    protected override void OnApplyTemplate(TemplateAppliedEventArgs e)
+    {
+        base.OnApplyTemplate(e);
+        _dialog = this.FindLogicalAncestorOfType<OverlayFeedbackElement>();
+    }
+
+    protected override void OnPointerPressed(PointerPressedEventArgs e)
+    {
+        base.OnPointerPressed(e);
+        if (_dialog is null) return;
+        if (!e.GetCurrentPoint(this).Properties.IsLeftButtonPressed) return;
+        var windowEdge = ResizeDirection switch
+        {
+            ResizeDirection.Top => WindowEdge.North,
+            ResizeDirection.TopRight => WindowEdge.NorthEast,
+            ResizeDirection.Right => WindowEdge.East,
+            ResizeDirection.BottomRight => WindowEdge.SouthEast,
+            ResizeDirection.Bottom => WindowEdge.South,
+            ResizeDirection.BottomLeft => WindowEdge.SouthWest,
+            ResizeDirection.Left => WindowEdge.West,
+            ResizeDirection.TopLeft => WindowEdge.NorthWest,
+            _ => throw new ArgumentOutOfRangeException()
+        };
+        _dialog.BeginResizeDrag(windowEdge, e);
+    }
+}

src/Ursa/Controls/Resizers/ResizeDirection.cs

@@ -1,5 +1,6 @@
 namespace Ursa.Controls;
 
+[Flags]
 public enum ResizeDirection
 {
     Top,