#1,180 – By Default, FrameworkElement Doesn’t Have Desired Size

If you create a custom control that derives from FrameworkElement, the control won’t by default have any particular desired size.  You can see this by setting alignment properties on a simple custom control without also setting explicit Width and Height.

    <Grid ShowGridLines="True">
        <Grid.RowDefinitions>
            <RowDefinition/>
            <RowDefinition/>
        </Grid.RowDefinitions>

        <loc:MyFrameworkElement HorizontalAlignment="Center"
                                VerticalAlignment="Top"/>
        <loc:MyFrameworkElement Grid.Row="1" Margin="20,10"/>
    </Grid>

You can see in the designer that the first instance of MyFrameworkElement is not visible, because it has no size.

1180-001

A custom control will typically define its desired size based on its content.  In the example above, the custom control hasn’t specified any desired size, size the control has a size of (0,0) and disappears.

 

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About Sean
Software developer in the Twin Cities area, passionate about software development and sailing.

One Response to #1,180 – By Default, FrameworkElement Doesn’t Have Desired Size

  1. Pingback: Dew Drop – October 15, 2014 (#1877) | Morning Dew

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