How do I get the user controls to Resize themselves properly?

I feel bad about not getting this. But, although I have read several articles on measure pass and arrange pass and written several small programs, I still have a hard time with this.

It makes sense to me that any user control will have a "minimum size" (after which only possible solution would be to shrink it as a whole bitmap wise or add a scroll bar). It will also have a way to use any additional screen real estate given to it.

Ellipses have no minimum size and can collapse to size zero.

So, consider this example

<Grid>
    <StackPanel Orientation="Horizontal" Height="20">
        <Ellipse Fill="Blue"/>
        <Ellipse Fill="Green"/>
        <Ellipse Fill="BlueViolet"/>
    </StackPanel>
</Grid>

what is the least amount of xaml code needed to add to achieve the following effects:

• Make them force a "minimum size" of uniform 40. And dynamically resize uniformly.
• Make them force a "minimum size" of uniform 40. And dynamically resize non-uniformly (so that the they can stretch really wide, but will never size below 40/40).
• Make them force a minimum height, but stretch to available width.
• Ma开发者_运维知识库ke them stretch uniformly fitting a constant height of the stackpanel.
• Make the stackpanel stretch to fill the dynamic height of its container.

Thank you.

In most of those cases you probably want to use a UniformGrid with one column instead of a StackPanel. To force sizes use a Style which sets the MinHeight and MinWidth. If the uniformity is guaranteed to be "one-way" you can just bind the Width to the ActualHeight.