FormattedText Width property does not take trailing spaces into account

I am using System.Windows.Media.FormattedText to do some low level rendering (specifically, trying to render math equations in a typographically pleasing manner). For this, precise metrics on the text blocks I am using are critical.

I am creating several FormattedText objects and using these at the lowest level开发者_Python百科 of rendering. The problem is that if any of these contain trailing spaces, that space is not taken into account when computing the FormattedText.Width property. For example, if I write:

double w1 = new FormattedText ("Hello", ...).Width;
double w2 = new FormattedText ("Hello    ", ...).Width;

w1 and w2 turn out to be the same. Leading spaces are measured correctly. How do I force FormattedText to measure these trailing spaces as well?

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Change from using the Width property to using the WidthIncludingTrailingWhitespace property.

double w1 = new FormattedText ("Hello", ...).WidthIncludingTrailingWhitespace;
double w2 = new FormattedText ("Hello    ", ...).WidthIncludingTrailingWhitespace;

With this code you should see two different width values.