Programming WPF, 2nd Edition

DockPanel

DockPanel is useful for describing the overall layout of a simple user interface. You can carve up the basic structure of your window using a DockPanel, and then use the other panels to manage the details.

A DockPanel arranges each child element so that it fills a particular edge of the panel. If multiple children are docked to the same edge, they simply stack up against that edge in order. By default, the final child fills any remaining space not occupied by controls docked to the panel's edges.

Example 3-4 shows a simple DockPanel-based layout. Five buttons have been added to illustrate each option. Notice that four of them have a DockPanel.Dock attribute applied. This property is defined by DockPanel to allow elements inside a DockPanel to specify their position. DockPanel.Dock is an attached property (as described in the upcoming sidebar, "Attached Properties and Layout").

Example 3-4. Simple DockPanel layout

<DockPanel>
  <Button DockPanel.Dock="Top">Top</Button>
  <Button DockPanel.Dock="Bottom">Bottom</Button>
  <Button DockPanel.Dock="Left">Left</Button>
  <Button DockPanel.Dock="Right">Right</Button>
  <Button>Fill</Button>
</DockPanel>

Attached Properties and Layout

Most WPF panels allow child elements to specify their layout requirements. For example, a child of a DockPanel needs to be able to specify to which edge it would like to dock.

The obvious solution would be for a base class such as FrameworkElement to define a Dock property—all WPF user interface elements derive from ...