How can I change a style setter using code?

Question

I have several Labels using the same Style:
<Canvas.Resources>
<
Style TargetType="{x:Type Label}" x:Key="TitleStyle">
<
Setter Property="FontSize" Value="24"/>
<Setter Property="FontWeight" Value="Bold"/>
</Style>
</Canvas.Resources>
I'd like to change the Setter "FontSize" using some code.
Any idea?

Answer 1

You cannot change a setter (or anything else in a style) once the style is in use.
You can create a new style, remove the current style from the resources, and add the new style as the value for key "TitleStyle".  Elements that used DynamicResource to refer to the style will change, but elements that used StaticResource will not.
Another approach is to add a trigger to your style.  Then you can get the effect of changing FontSize from code:  just have the code change the value that the trigger reads as its input.
Yet another approach is to data-bind the FontSize to some property that you can change from code, and attach a ValueConverter to the binding that chooses the size you want.