How to get the ActualWidth and ActualHeight dynamically of a customcontrol? - wpf

Question

I have a custom control, ccTextBlock placed inside a ScrollViewer. The customcontrol will be changing sizes (vertically) when different strings are sent to it through the binding. The custom control will remain on the display, but will change as text elsewhere on the screen is selected.
How can I obtain the actual width and height of the custom control only after and with each text string sent to it? (Using OnApplyTemplate() did not work as it seems to be called only once on the first construction of the custom control.)
Thanks for any replies.
<ScrollViewer VerticalScrollBarVisibility="Auto">
<Grid>
<wc:ccTextBlock Text="{Binding Text, RelativeSource={RelativeSource Mode=FindAncestor, AncestorType=UserControl}}" />
</Grid>
</ScrollViewer>
Update: Perhaps a better way to phrase this question would be "How to get the height of an element when it is inside a ScrollViewer". Here is the definition of ccTextBlock:
public class ccTextBlock : Control
{
public string Text
{
get { return (string)GetValue(TextProperty); }
set { SetValue(TextProperty, value); }
}
// Using a DependencyProperty as the backing store for Text. This enables animation, styling, binding, etc...
public static readonly DependencyProperty TextProperty =
DependencyProperty.Register("Text", typeof(string), typeof(ccTextBlock), new UIPropertyMetadata(null));
/// <summary>
/// Constructor
/// </summary>
static ccTextBlock()
{
// Initialize as lookless control
DefaultStyleKeyProperty.OverrideMetadata(typeof(ccTextBlock), new FrameworkPropertyMetadata(typeof(ccTextBlock)));
}
public override void OnApplyTemplate()
{
//Effectively apply the template
base.OnApplyTemplate();
Console.WriteLine(String.Format(" ActualHeight is {0}", this.ActualHeight.ToString()));
var x = this.FontSize;
}
}
Where Generic.xaml is:
<ResourceDictionary
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:WpfCustomControlLibrary">
<Style TargetType="{x:Type local:ccTextBlock}">
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type local:ccTextBlock}">
<!-- Control Layout -->
<TextBlock Text="{TemplateBinding Text}" TextWrapping="Wrap" />
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>

Answer 1

ActualWidth and ActualHeight are the properties that contain the current width and height of the control.
If you are looking for an Event that notifies about changes, it would be the FrameworkElement.SizeChanged event. You could register for this event in the OnApplyTemplate implementation.