触发父（画布）Size_Changed时，不会触发Line Size_Changed事件

Question

I have a canvas on which I want to draw several lines. Which works fine. But I also want to move the lines, when the size of the canvas changes to a new position. So I've added an eventhandler of Size_Changed to each line

liMonth.SizeChanged += LiMonth_SizeChanged;

However, when I change the size of the parent window, the Size_Changed Event of the Canvas is fired, but not the Size_Changed event of the line.

How do I get the canvas to fire the size_changed event for its children, when the size changes?

I have the same problem with a rectangle, which is also on the canvas, but I figure it is the same issue.

Answer 1

A Canvas never resizes its child elements, hence there is no SizeChanged event fired for your Lines and Rectangles.

Put the repositioning code in a handler for the Canvas' SizeChanged event:

private void Canvas_SizeChanged(object sender, SizeChangedEventArgs e)
{
    Canvas canvas = (Canvas)sender;

    foreach (var line in canvas.Children.OfType<Line>())
    {
        line.X1 = ...
        line.X2 = ...
    }
}