Add a way of setting style classes using bindings

We really need a way to be able to apply to apply style classes to controls based on values from view models. This would be needed to e.g. trigger animations from the view model.

AvaloniaBehaviors has a behavior for this, but I think we should really have something in-box.

A few ideas:

Simple binding

<Button Classes="{Binding ButtonClasses}">

Pros:

• Simple

Cons:

• Will need to either specify actual classes in view model or supply a converter
• Would not be able to specify classes in XAML as well as get them from the binding

Class Setters

<Button>
  <Button.Classes>
    <ClassSetter Name="foo"/>
    <ClassSetter Name="animated" Trigger="{Binding IsButtonAnimating}"/>
  </Button.Casses>
</Button>

Access DataContext from Selectors

An alternative to binding classes would be to allow selectors to select into the DataContext.

Pros:

• Probably pretty flexible

Cons:

• Syntax?

[maxkatz6]

Implemented with https://github.com/AvaloniaUI/Avalonia/pull/5710

New syntax is:

<Button Classes.myClass="{Binding xxx}"/>

[maxkatz6]

Just created behavior for this. Hope it will be useful for somebody https://gist.github.com/maxkatz6/2c765560767f20cf0483be8fac29ff22