Click here to Skip to main content
Click here to Skip to main content
Add your own
alternative version

WPF Diagram Designer - Part 3

, 29 Feb 2008 CPOL
Connecting items
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;

namespace DiagramDesigner
    public class RubberbandAdorner : Adorner
        private Point? startPoint;
        private Point? endPoint;
        private Pen rubberbandPen;

        private DesignerCanvas designerCanvas;

        public RubberbandAdorner(DesignerCanvas designerCanvas, Point? dragStartPoint)
            : base(designerCanvas)
            this.designerCanvas = designerCanvas;
            this.startPoint = dragStartPoint;
            rubberbandPen = new Pen(Brushes.LightSlateGray, 1);
            rubberbandPen.DashStyle = new DashStyle(new double[] { 2 }, 1);

        protected override void OnMouseMove(System.Windows.Input.MouseEventArgs e)
            if (e.LeftButton == MouseButtonState.Pressed)
                if (!this.IsMouseCaptured)

                endPoint = e.GetPosition(this);
                if (this.IsMouseCaptured) this.ReleaseMouseCapture();

            e.Handled = true;

        protected override void OnMouseUp(System.Windows.Input.MouseButtonEventArgs e)
            // release mouse capture
            if (this.IsMouseCaptured) this.ReleaseMouseCapture();

            // remove this adorner from adorner layer
            AdornerLayer adornerLayer = AdornerLayer.GetAdornerLayer(this.designerCanvas);
            if (adornerLayer != null)

            e.Handled = true;

        protected override void OnRender(DrawingContext dc)

            // without a background the OnMouseMove event would not be fired !
            // Alternative: implement a Canvas as a child of this adorner, like
            // the ConnectionAdorner does.
            dc.DrawRectangle(Brushes.Transparent, null, new Rect(RenderSize));

            if (this.startPoint.HasValue && this.endPoint.HasValue)
                dc.DrawRectangle(Brushes.Transparent, rubberbandPen, new Rect(this.startPoint.Value, this.endPoint.Value));

        private void UpdateSelection()
            foreach (ISelectable item in designerCanvas.SelectedItems)
                item.IsSelected = false;

            Rect rubberBand = new Rect(startPoint.Value, endPoint.Value);
            foreach (Control item in designerCanvas.Children)
                Rect itemRect = VisualTreeHelper.GetDescendantBounds(item);
                Rect itemBounds = item.TransformToAncestor(designerCanvas).TransformBounds(itemRect);

                if (rubberBand.Contains(itemBounds) && item is ISelectable)
                    ISelectable selectableItem = item as ISelectable;
                    selectableItem.IsSelected = true;

By viewing downloads associated with this article you agree to the Terms of Service and the article's licence.

If a file you wish to view isn't highlighted, and is a text file (not binary), please let us know and we'll add colourisation support for it.


This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)


About the Author


Austria Austria
No Biography provided

| Advertise | Privacy | Terms of Use | Mobile
Web04 | 2.8.150302.1 | Last Updated 29 Feb 2008
Article Copyright 2008 by sukram
Everything else Copyright © CodeProject, 1999-2015
Layout: fixed | fluid