How can I achieve this mix of StackPanel and UniformGrid behavior?

Question

I want to put elements inside a control so that they initially fit like this (like a StackPanel with Horizontal orientation):

Answer 1

Easiest/Quickest route, throw it in a ViewBox with it set to Stretch="Uniform" to do it for you, as an example like below, just add/subtract rectangles and you'll get the concept...

Hope this helps. Cheers