Adorners

AdornerView.cs

public AdornerView()
{
  InitializeComponent();
  Loaded += View_Loaded;
}

 
private void View_Loaded(object sender, RoutedEventArgs e) 
{ 
  AdornerLayer adornerLayer = AdornerLayer.GetAdornerLayer(Canvas); 
  foreach (UIElement uiElement in Canvas.Children) 
  { 
    adornerLayer.Add(new ResizeAdorner(uiElement)); 
  } 
} 

AdornerView.xaml

<Canvas Name="Canvas"> 
  <Rectangle Canvas.Top="50" Canvas.Left="50" Fill="Lime"  
    Stroke="Black" StrokeThickness="3" Width="150" Height="50" /> 
  <Rectangle Canvas.Top="25" Canvas.Left="250" Fill="Yellow"  
    Stroke="Black" StrokeThickness="3" Width="100" Height="150" /> 
</Canvas> 

ResizeAdorner.cs

using System; 
using System.Windows; 
using System.Windows.Controls; 
using System.Windows.Controls.Primitives; 
using System.Windows.Documents; 
using System.Windows.Input; 
using System.Windows.Media; 
 
namespace CompanyName.ApplicationName.Views.Adorners 
{ 
  public class ResizeAdorner : Adorner 
  { 
    private VisualCollection visualChildren; 
    private Thumb top, left, bottom, right; 
 
    public ResizeAdorner(UIElement adornedElement) : base(adornedElement) 
    { 
      visualChildren = new VisualCollection(this); 
      top = InitializeThumb(Cursors.SizeNS, Top_DragDelta); 
      left = InitializeThumb(Cursors.SizeWE, Left_DragDelta); 
      bottom = InitializeThumb(Cursors.SizeNS, Bottom_DragDelta); 
      right = InitializeThumb(Cursors.SizeWE, Right_DragDelta); 
    } 
 
    private Thumb InitializeThumb(Cursor cursor, 
      DragDeltaEventHandler eventHandler) 
    { 
      Thumb thumb = new Thumb(); 
      thumb.BorderBrush = Brushes.Black; 
      thumb.BorderThickness = new Thickness(1); 
      thumb.Cursor = cursor; 
      thumb.DragDelta += eventHandler; 
      thumb.Height = thumb.Width = 6.0; 
      visualChildren.Add(thumb); 
      return thumb; 
    } 
 
    private void Top_DragDelta(object sender, DragDeltaEventArgs e) 
    { 
      FrameworkElement adornedElement = (FrameworkElement)AdornedElement; 
      adornedElement.Height =  
        Math.Max(adornedElement.Height - e.VerticalChange, 6); 
      Canvas.SetTop(adornedElement, 
        Canvas.GetTop(adornedElement) + e.VerticalChange); 
    } 
 
    private void Left_DragDelta(object sender, DragDeltaEventArgs e) 
    { 
      FrameworkElement adornedElement = (FrameworkElement)AdornedElement; 
      adornedElement.Width =  
        Math.Max(adornedElement.Width - e.HorizontalChange, 6); 
      Canvas.SetLeft(adornedElement, 
        Canvas.GetLeft(adornedElement) + e.HorizontalChange); 
    } 
 
    private void Bottom_DragDelta(object sender, DragDeltaEventArgs e) 
    { 
      FrameworkElement adornedElement = (FrameworkElement)AdornedElement; 
      adornedElement.Height =  
        Math.Max(adornedElement.Height + e.VerticalChange, 6); 
    } 
 
    private void Right_DragDelta(object sender, DragDeltaEventArgs e) 
    { 
      FrameworkElement adornedElement = (FrameworkElement)AdornedElement; 
      adornedElement.Width =  
        Math.Max(adornedElement.Width + e.HorizontalChange, 6); 
    } 
 
    protected override void OnRender(DrawingContext drawingContext) 
    { 
      SolidColorBrush brush = new SolidColorBrush(Colors.Transparent); 
      Pen pen = new Pen(new SolidColorBrush(Colors.DeepSkyBlue), 1.0); 
      drawingContext.DrawRectangle(brush, pen,  
        new Rect(-2, -2, AdornedElement.DesiredSize.Width + 4, 
        AdornedElement.DesiredSize.Height + 4)); 
    } 
 
    protected override Size ArrangeOverride(Size finalSize) 
    { 
      top.Arrange(
        new Rect(AdornedElement.DesiredSize.Width / 2 - 3, -8, 6, 6)); 
      left.Arrange(
        new Rect(-8, AdornedElement.DesiredSize.Height / 2 - 3, 6, 6)); 
      bottom.Arrange(new Rect(AdornedElement.DesiredSize.Width / 2 - 3, 
        AdornedElement.DesiredSize.Height + 2, 6, 6)); 
      right.Arrange(new Rect(AdornedElement.DesiredSize.Width + 2,  
        AdornedElement.DesiredSize.Height / 2 - 3, 6, 6)); 
      return finalSize;
    } 

    protected override int VisualChildrenCount 
    { 
      get { return visualChildren.Count; } 
    } 
 
    protected override Visual GetVisualChild(int index) 
    { 
      return visualChildren[index]; 
    } 
  } 
}