[WPF] Formatting Content Controls

Over the past few years I haven’t done much UI work and what little I did was either with a proprietary Web framework or Windows Forms so I’m more than a little behind the curve with WPF. My most recent project has me learning WPF on the fly and although it’s a daunting task and I still have plenty to learn I’m finding it pretty straightforward. Every once in a while though something works completely different than I expect and throws me for a bit of a curve.

One such example just happened yesterday. I was trying to bind and format a value to a Button‘s Content property. I was trying to bind using the same syntax as binding to the Text property on a TextBox:

<Button Content="{Binding Percentage, StringFormat={}{0:P0}}" />

I was surprised though when the value bound properly but wasn’t formatted. After some investigation I learned that controls like Button that inherit from ContentControl can’t be formatted that way. Instead we need to use the ContentStringFormat to achieve the same effect:

<Button Content="{Binding Percentage}" ContentStringFormat="P0" />

With that change the value started showing up as the percentage just like I expected. Lesson learned.

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2 comments

  1. That’s because the property Content takes every object. Also I was confused when I first use this String Format because it did not worked as expected. The confusing part is that the Binding markup owns the property StringFormat. Hence the wrong thought is that this StringFormat will format the String-Object that was bound previously.

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