How to know the height of a wrapped textbox? - wpf

Question

I need to know the height of a wrapped textBox. I am using this code:
MyView myView = new MyView();
myView.MyTextBox.Text = "my large text";
myView.UpdateLayout();
double myHeight = myView.MyTextBox.Actualheight;
No matter how large is the text, I always get 12.96 as actualheight.
If I do the same with a datagrid in which I am add new items, I am getting the right height, so I am wondering if sometimes a wrapped textbox has another behavior.
Thanks.
EDIT: i have realized that the size depends of the size of the font. At first I setted 8, but if I set 16, the actual height is the double too. So it seems that the height of the textBox depends of the font size, and it has not account if it is wrapped or not.

Answer 1

Running a simple test in XAML, when the text wraps, it causes the textbox ActualHeight to increase as expected as shown in the image below.
<StackPanel Orientation="Horizontal">
<TextBox Width="100" HorizontalAlignment="Left" Margin="10"
FontSize="10" Name="tbx1"
TextWrapping="Wrap" Text="Some short text"/>
<TextBlock Foreground="White" VerticalAlignment="Center"
FontSize="20"
Text="{Binding ActualHeight, ElementName=tbx1, Mode=OneWay}" />
</StackPanel>
<StackPanel Orientation="Horizontal">
<TextBox Width="100" HorizontalAlignment="Left" Margin="10"
FontSize="10" Name="tbx2"
TextWrapping="Wrap" Text="Some text that is longer"/>
<TextBlock Foreground="White" VerticalAlignment="Center"
FontSize="20"
Text="{Binding ActualHeight, ElementName=tbx2, Mode=OneWay}" />
</StackPanel>
<StackPanel Orientation="Horizontal">
<TextBox Width="100" HorizontalAlignment="Left" Margin="10"
FontSize="15" Name="tbx3"
TextWrapping="Wrap" Text="Short text"/>
<TextBlock Foreground="White" VerticalAlignment="Center"
FontSize="20"
Text="{Binding ActualHeight, ElementName=tbx3, Mode=OneWay}" />
</StackPanel>
<StackPanel Orientation="Horizontal">
<TextBox Width="100" HorizontalAlignment="Left" Margin="10"
FontSize="15" Name="tbx4"
TextWrapping="Wrap" Text="Some text that is longer"/>
<TextBlock Foreground="White" VerticalAlignment="Center"
FontSize="20"
Text="{Binding ActualHeight, ElementName=tbx4, Mode=OneWay}" />
</StackPanel>
UpdateLayout doesn't actually cause anything to be rendered, it just prepares it. So until you render your view or window with myView.Show() or something equivalent, the textbox doesn't get rendered so the ActualHeight value doesn't get calculated.