I tried the following codes in the MouseMove event handler of the Canvas, but it does not work.

public void ParentMouseMove(object sender, MouseEventArgs e)
{
            if (shallPaint)
            {
                Shape tmp = paintShape; // paintShape is an Ellipse object which looks like a red dot. Defined in the Page_Loaded handler
                tmp.SetValue(Canvas.LeftProperty, e.GetPosition(this).X);
                tmp.SetValue(Canvas.TopProperty, e.GetPosition(this).Y);
                this.Children.Add(tmp);
                tmp = null;
            }
}

The ellipse object is not copied as I move the mouse, instead, there remains only one red dot on the canvas as I'm moving the cursor.

Anybody explains why it is like this and how to solve this problem?

Thanks a lot.

Where is my way?

Unfortunately you need to create a new shape.  The "Shape tmp = paintShp;" doesn't make a copy.  You'll need to copy the values one after another to make this work.  There is no Clone method (yet?) which is how I'd expect it to work. 

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Shawn Wildermuth
C# MVP, MCSD, Speaker and Author

Silverlight 2 Workshop
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http://www.silverlight-tour.com

Yes, you have to create a new Ellipse. Also note that you can’t simply copy paintShape’s Fill to the new Ellipse. One Brush can only be used once.

            Ellipse tmp = new Ellipse();

            //This won't work because a Brush can only be used once.

            //tmp.Fill = paintShape.Fill;

            //Since you know you need red, just create a new red Brush.

            tmp.Fill = new SolidColorBrush(Colors.Red);

            tmp.Width = paintShape.Width;

            tmp.Height = paintShape.Height;

            tmp.SetValue(Canvas.LeftProperty, e.GetPosition(this).X);

            tmp.SetValue(Canvas.TopProperty, e.GetPosition(this).Y);

            this.Children.Add(tmp);

            tmp = null;

shanaolanxing - Please mark the posts as answers if they help and unmark if they don't.

I got it, thanks a lot. :D

Where is my way?