Wpf control size to content?

For most controls, you set its height and width to Auto in the XAML, and it will size to fit its content.

In code, you set the width/height to double.NaN. For details, see FrameworkElement.Width, particularly the "remarks" section.

I had a problem like this whereby I had specified the width of my Window, but had the height set to Auto. The child DockPanel had it's VerticalAlignment set to Top and the Window had it's VerticalContentAlignment set to Top, yet the Window would still be much taller than the contents.

Using Snoop, I discovered that the ContentPresenter within the Window (part of the Window, not something I had put there) has it's VerticalAlignment set to Stretch and can't be changed without retemplating the entire Window!

After a lot of frustration, I discovered the SizeToContent property - you can use this to specify whether you want the Window to size vertically, horizontally or both, according to the size of the contents - everything is sizing nicely now, I just can't believe it took me so long to find that property!

I had a user control which sat on page in a free form way, not constrained by another container, and the contents within the user control would not auto size but expand to the full size of what the user control was handed.

To get the user control to simply size to its content, for height only, I placed it into a grid with on row set to auto size such as this:

<Grid Margin="0,60,10,200">    <Grid.RowDefinitions>        <RowDefinition Height="Auto" />    </Grid.RowDefinitions>    <controls1:HelpPanel x:Name="HelpInfoPanel"                         Visibility="Visible"                         Width="570"                         HorizontalAlignment="Right"                         ItemsSource="{Binding HelpItems}"                         Background="#FF313131" /></Grid>