问题
I have a UserControl (boxes) that can have varying size based on the number of items in its ItemsControl.
Many such usercontrols are added to a Canvas programmatically.
I need to draw arrows interconnecting these usercontrols. What is the best way to get the origin coordinates of the control w.r.t the Canvas and the rendered Width/Height so that I can figure out the arrow start and endpoints.
回答1:
Canvas provides the coordinates of each control via Canvas.Left and Canvas.Top attached properties - which you know if you positioned them yourself anyway. So the (slightly) harder part is getting the other coordinate, and for that you want to know the rendered height/width. ActualHeight and ActualWidth give you this, assuming the control has already been laid out:
double top = Canvas.GetTop(control)
double bottom = top + control.ActualHeight
double left = Canvas.GetLeft(control)
double right = left + control.ActualWidth
If you're doing this before the controls have had a chance to be rendered on the screen, you can first do control.UpdateLayout() (or control.Measure()) to ensure the layout system measures their size.
来源：https://stackoverflow.com/questions/8657787/estimate-position-and-width-height-of-rendered-usercontrol