namespace HostDemo {
?public class HostCanvas : Canvas {
? public HostCanvas() {
?? InitializeComponent();
? }

?

? private void InitializeComponent() {
?? this.Loaded += OnLoad;
?? this.MouseDown += OnMouseDown;
?? this.MouseMove += OnMouseMove;
?? this.MouseUp += OnMouseUp;
?? locus = new Path();
?? locus.Fill = new SolidColorBrush(Color.FromArgb(1, 255, 255, 255));
?? locus.Stroke = Brushes.Red;
?? locus.StrokeThickness = 1;
?? locus.IsManipulationEnabled = true;
? }

? void OnMouseUp(object sender, System.Windows.Input.MouseButtonEventArgs e) {
?? ispath = false;
? }

? void OnMouseMove(object sender, System.Windows.Input.MouseEventArgs e) {
?? if(ispath){
??? endpoint = e.GetPosition(this);
??? locus.Data = DrawingRect(startpoint,endpoint);
?? }
? }

? void OnMouseDown(object sender, System.Windows.Input.MouseButtonEventArgs e) {
?? if(!this.Children.Contains(locus)) this.Children.Add(locus);
?? if (locus.Data != null) locus.Data = null;
?? startpoint = e.GetPosition(this);
?? ispath = true;
? }

? void OnLoad(object sender, System.Windows.RoutedEventArgs e) {
?? this.Background = new SolidColorBrush(Color.FromArgb(35, 255, 255, 255));
? }

? private PathGeometry DrawingRect(Point beginpoint, Point closepoint) {
?? PathGeometry result = new PathGeometry();?
?? PathFigure figure = new PathFigure();
?? figure.IsClosed = true;
?? figure.StartPoint = beginpoint;
?? PathSegmentCollection pathSegmentCollection = new PathSegmentCollection();
?? PathFigureCollection pathFigureCollection = new PathFigureCollection();??
?? LineSegment m1 = new LineSegment();
?? m1.Point = new Point(closepoint.X, beginpoint.Y);
?? LineSegment m2 = new LineSegment();
?? m2.Point = closepoint;
?? LineSegment m3 = new LineSegment();
?? m3.Point = new Point(beginpoint.X, closepoint.Y);
?? pathSegmentCollection.Add(m1);
?? pathSegmentCollection.Add(m2);
?? pathSegmentCollection.Add(m3);
?? figure.Segments = pathSegmentCollection;
?? pathFigureCollection.Add(figure);
?? result.Figures = pathFigureCollection;

?? return result();
? }

? private Path locus;
? private bool ispath = false;
? private Point startpoint;
? private Point endpoint;
?}
}