Question

I have a canvas, on this canvas there are several elements. I can get the bounds of these elements separately.

How can I calculate the bounds of all elements with that data?

Please look at this graphical representation, hope that clarifies things.

Answer 1

Pull the Point values for each corner of your elements into a list and then get the min and max X and Y values

        List<Point> Points = new List<Point>();

        foreach (UIElement x in cvsMain.Children.Where(ui => ui.GetType() == typeof(Rectangle)))
        {
            // Obtain transform information based off element you need to find position within
            GeneralTransform gt = x.TransformToVisual(cvsMain);

            // Find the four corners of the element
            Points.Add(gt.Transform(new Point(0, 0)));
            Points.Add(gt.Transform(new Point((x as Rectangle).Width, 0)));
            Points.Add(gt.Transform(new Point(0, (x as Rectangle).Height)));
            Points.Add(gt.Transform(new Point((x as Rectangle).Width, (x as Rectangle).Height)));
        }

        Double Left = Points.Min(p => p.X);
        Double Right = Points.Max(p => p.X);
        Double Top = Points.Min(p => p.Y);
        Double Bottom = Points.Max(p => p.Y);

This site shows how to find the values for each corner
http://forums.silverlight.net/t/12160.aspx/1