Resizing canvas items

Question

I\'m trying to create canvas which resizes its children when canvas itself is resized. So I create my own class which inherits from canvas and overrides method ArrangeOverride w

Answer 1

Ok, so I tried messing around with this and I found some hacky way to make it work. I don't really understand why it works this way (yet), but this works for me:

public class CustomPanel : Canvas
{
    private bool isFirstArrange = true;

    protected override Size ArrangeOverride(Size arrangeSize)
    {
        var ret = new Size();
        bool isFirstArrangeLocal = isFirstArrange;
        if (isFirstArrangeLocal)
        {
            ret = base.ArrangeOverride(arrangeSize);
            isFirstArrange = false;
        }

        var top = 0;
        foreach (UIElement child in Children)
        {
            Canvas.SetLeft(child, arrangeSize.Width - 20.0);
            child.SetValue(WidthProperty, arrangeSize.Width - Canvas.GetLeft(child));
            Canvas.SetTop(child, top);
            child.SetValue(HeightProperty, 20.0);

            top += 30;
        }

        if (!isFirstArrangeLocal)
        {
            ret = base.ArrangeOverride(arrangeSize);
        }

        return ret;
    }
}

So the idea is to put ArrangeOverride() after the foreach loop in all situations except on first call.

The first call must be before foreach or for some reason I get this: