I want to add a constant value onto an incoming bound integer. In fact I have several places where I want to bind to the same source value but add different constants. So the ideal solution would be something like this...
<TextBox Canvas.Top="{Binding ElementName=mySource, Path=myInt, Constant=5}"/>
<TextBox Canvas.Top="{Binding ElementName=mySource, Path=myInt, Constant=8}"/>
<TextBox Canvas.Top="{Binding ElementName=mySource, Path=myInt, Constant=24}"/>
(NOTE: This is an example to show the idea, my actual binding scenario is not to the canvas property of a TextBox. But this shows the idea more clearly)
At the moment the only solution I can think of is to expose many different source properties each of which adds on a different constant to the same internal value. So I could do something like this...
<TextBox Canvas.Top="{Binding ElementName=mySource, Path=myIntPlus5}"/>
<TextBox Canvas.Top="{Binding ElementName=mySource, Path=myIntPlus8}"/>
<TextBox Canvas.Top="{Binding ElementName=mySource, Path=myIntPlus24}"/>
But this is pretty grim because in the future I might need to keep adding new properties for new constants. Also if I need to change the value added I need to go an alter the source object which is pretty naff.
There must be a more generic way than this? Any WPF experts got any ideas?
I believe you can do this with a value converter. Here is a blog entry that addresses passing a parameter to the value converter in the xaml. And this blog gives some details of implementing a value converter.