Display a VisualBrush from a hidden control - wpf

Question

I got the following xaml
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="Auto" />
<RowDefinition Height="Auto" />
</Grid.RowDefinitions>
<TextBlock x:Name="_sampleText"
Grid.Row="0"
VerticalAlignment="Stretch"
HorizontalAlignment="Stretch"
Width="200"
Height="50"
FontSize="36"
Text="Hello world"
TextAlignment="Center"
Visibility="Collapsed" />
<Border Grid.Row="1"
Width="{Binding ActualWidth, ElementName=_sampleText}"
Height="{Binding ActualHeight, ElementName=_sampleText}">
<Border.Background>
<VisualBrush Stretch="None"
Visual="{Binding ElementName=_sampleText}" />
</Border.Background>
</Border>
</Grid>
I want my visual to be render even if the control he bind too is not visible. Is there a way of doing that?

Answer 1

You could also place the TextBlock in a Border and make that Hidden:
<Border Visibility="Hidden">
<TextBlock ... />
</Border>

Answer 2

No. If the Visibility=Collapsed then it won't take part in the measure/arrange layout pass and not be rendered (the Width and Height will be 0).
What effect are you trying to achieve? It looks like you want a preview pane? Reply in the comments and we can figure out the best approach.
Edit: There is a way to call the measure/update on a UIElement from code-behind however I think the best-approach for you would be use a BoolToVisibilityConverter.
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="Auto" />
<RowDefinition Height="Auto" />
</Grid.RowDefinitions>
<CheckBox x:Name="OptionCheckBox" Grid.Row="0" />
<Border Grid.Row="1" Visibility="{Binding Path=IsChecked, ElementName=OptionCheckBox", Converter={StaticResouce BoolToVisibilityConverter}}">
<TextBlock Width="200" Height="50" FontSize="36" Text="Hello world" TextAlignment="Center"/>
</Border>
</Grid>