Question

So much reading, and so much about inheritance, I can’t find any direct answers, so here goes.

If you have a base-class derived to do certain things, look or act a certain way, you can subclass it and get all the functionality of the parent class with only slightly modified differential. The same does not appear to be the same for working with WPF Themes… more specifically, the combobox control (similar issues with textbox, but that’s obviously less complex).

By looking at the Control Template Examples, they discuss the entire structure of it, the borders, backgrounds, glyphs, actions, properties, etc.

If the ONLY thing I want to do with a combobox is to change the border of it to Red if there is an error in it, it appears, I have to basically redefine the entire thing and somehow put in my custom trigger setting / color to be implemented.

Somewhat similar is that of the textbox control and how its created. It has the named control when trying to nuts around with the background color… you can’t just say… background = some static brush value.

What shortcuts are out there to only allow overriding these small elements without having to re-create the entire template control. I can just imagine what would go on with grids, tabbed controls, and others that could get extremely messed up if you miss one simple thing.

I also see that some controls are made up of OTHER Control.Templates, so how might I be able to attach to changing the property setting on just the single element of the control template… Such as the combobox has the control template for the Toggle Button. From that, it has a border via x:Name=”Border” and I want to change THAT element within a derived style.

Thanks

Answer 1

I might not understand your question here. But from what i get is:
Yes you can’t partially implement Templates, in fact i wouldn’t know how this could be possible. But, if you want to change certain things, you can of course do that. You can create Styles, Templates, Brushes etc. as DependencyProperties and use TemplateBinding to bind to them, on the given child control.

Remember that WPF allows always to change the template on the fly. if we could partially change the template this would might hurt performance or could get messy and complicated. Still, you can do that using ContentControls and TemplateBinding or simply Triggers.

For my custom controls, which might contain multiple part sub controls, i usually add a style for them. For example, a custom ComboBox would contain a ToggleButtonStyle.

One thing that would be nice though, would be to add control template triggers without the need to reimplement the template.