Measuring text in WPF

Question

Using WPF, what is the most efficient way to measure a large number of short strings? Specifically, I'd like to determine the display height of each string, given uniform formatting (same font, size, weight, etc.) and the maximum width the string may occupy?

Answer 1

You can use the DesiredSize property on a rendered TextBox to get the height and width

using System.Windows.Threading;

...

Double TextWidth = 0;
Double TextHeight = 0;
...

MyTextBox.Text = "Words to measure size of";
this.Dispatcher.BeginInvoke(
    DispatcherPriority.Background,
    new DispatcherOperationCallback(delegate(Object state) {
        var size = MyTextBox.DesiredSize;
        this.TextWidth = size.Width;
        this.TextHeight = size.Height;
        return null; 
    }
) , null);

If you have a large number of strings it may be quicker to first pre-calualte the height and width of every indiviudal letter and symbol in a given font, and then do a calculation based on the string chars. This may not be 100% acurate due to kerning etc

Answer 2

The most low-level technique (and therefore giving the most scope for creative optimisations) is to use GlyphRuns.

It's not very well documented but I wrote up a little example here:

http://incrediblejourneysintotheknown.blogspot.com/2008/07/glyphrun-and-so-forth.html

The example works out the length of the string as a necessary step before rendering it.