Question

I have a Popup control in WPF that loades it’s content dynamically and each time I need to set it’s size, how could this be automatically done, so it allways keeps it’s size to it’s content size.

<Popup 
      Name="popup1" 
      StaysOpen="False" 
      PlacementTarget="{Binding ElementName=myButton}" 
      Placement="Custom" 
      PopupAnimation="Fade" 
      AllowsTransparency="True">

Answer 1

A Popup already sizes according to content.

By default, a Popup is automatically sized to its content. When
auto-sizing occurs, some bitmap effects may be hidden because the
default size of the screen area that is defined for the Popup content
does not provide enough space for the bitmap effects to display.

Popup content can also be obscured when you set a RenderTransform on
the content. In this scenario, some content might be hidden if the
content of the transformed Popup extends beyond the area of the
original Popup. If a bitmap effect or transform requires more space,
you can define a margin around the Popup content in order to provide
more area for the control.

Perhaps your Popup content is having sizing issues due to you restricting growth within your layout container? Your Popup is thus sized accordingly but your Grid for example may have a fixed width.