how to add snap grid on canvas in c#

Border CreateDesignerCanvas(string rungName)

{

Border border = new Border();

border.BorderBrush = Brushes.Black;

border.BorderThickness = new Thickness(.5);

DesignerCanvas designerCanvas = new DesignerCanvas()

{

Focusable = true,

ContextMenu = (ContextMenu)FindResource("DesignerCanvasContextMenu"),

Background = Brushes.Transparent,

Name = rungName,

//Margin = new Thickness(3)

};

border.Child = designerCanvas;

selectedCanvas = designerCanvas;

return border;

}

i create two canvas on oone window .now i want to add snap grid without usinmg xaml