Replicating a Visio Page Using a Silverlight Panel - Part II

The arrange method can be modified to account for the object being positioned so that the center of rotation is exactly at the pin location.

Under the covers, the Visio shape sheet uses four other cells to render the shape's positioning transform -- Width, Height, LocPinX and LocPinY. This can be managed in the following function LocalPin():

        public virtual void DoArrange(Size finalSize)
        {
            foreach (UIElement oChild in Children)
            {
                double dX = (double)oChild.GetValue(SketchPanel.PinXProperty);
                double dY = (double)oChild.GetValue(SketchPanel.PinYProperty);
                double dAngle = (double)oChild.GetValue(SketchPanel.AngleProperty);
                Point oLocal = (Point)LocalPin(oChild);

                dX -= oLocal.X;
                dY -= oLocal.Y;
                Point oPoint = new Point(dX, dY);
                SetRenderTransform(oChild, dAngle, oPoint);

                oChild.Arrange(new Rect(0, 0, oChild.DesiredSize.Width, oChild.DesiredSize.Height));
            }
        }



        public Point LocalPin(UIElement oChild)
        {
            double dWidth = (double)oChild.GetValue(SketchPanel.WidthProperty);
            double dHeight = (double)oChild.GetValue(SketchPanel.HeightProperty);
            Point oOrigin = (Point)oChild.GetValue(SketchPanel.RenderTransformOriginProperty);

            double dLocPinX = double.NaN.Equals(dWidth) ? 0.0 : dWidth * oOrigin.X;
            double dLocPinY = double.NaN.Equals(dHeight) ? 0.0 : dHeight * oOrigin.Y;
            return new Point(dLocPinX, dLocPinY);
        }