How can I measure the size of a TextBlock before it is rendered

Question

I need to know the size of my Textblock before it is rendered. I have gone through this link but its not working (may be I am doing something wrong). My Textblock is binded to the property in a ViewModel and in code behind I am monitoring the text changed event.

XAML:

<TextBlock Text="{Binding Path=MyProperty, NotifyOnTargetUpdated=True}" 
           TargetUpdated="OnTargetUpdated"/>

and code behind:

 private void OnTargetUpdated(object sender, DataTransferEventArgs e)
    {    
        var tb = sender as TextBlock;
        var text =  tb .Text; // here I can see updated Text 
        var size = tb.DesiredSize; // here DesireSize value is 0
        tb.Measure(new Size(Double.PositiveInfinity,
                                   Double.PositiveInfinity));
        tb.Arrange(new Rect(tb.DesiredSize));
        var width = tb.ActualWidth; // here actual width is coming 0
    }

you have to look at the ActualWidth and ActualHeight properties, DesiredSize is what the programmer specifies — thumbmunkeys, Jun 06 '14 at 11:28
subscribe to the SizeChanged event and see if the size even changes, maybe you got a problem in your layout — thumbmunkeys, Jun 06 '14 at 12:13

score 1 · Answer 1 · answered Nov 15 '16 at 17:16

I had same problem. I called UpdateLayout() method which updated ActualHeight and ActualWidth

var viewbox = new Viewbox { Child = contentPresenter };
        viewbox.Measure(new Size(double.PositiveInfinity, double.PositiveInfinity));
        viewbox.Arrange(new Rect(viewbox.DesiredSize));
        viewbox.UpdateLayout();
        viewbox.Child = null;

score 0 · Answer 2 · edited May 23 '17 at 12:18

0

try this: how to calculate the textbock height and width in on load if i create textblock from code?

Call Measure() then Arrange() and then ActualWidth and ActualHeight will be updated.

edited May 23 '17 at 12:18

Community

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answered Jun 06 '14 at 11:29

user1666620

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I have called Mesaure() and Arrange() (see my edited code above); but its still not working. – Mohd Ahmed Jun 06 '14 at 11:45

How can I measure the size of a TextBlock before it is rendered

2 Answers2