WPF Command bindings - how can I get to event handlers

Hi Is there any way to choose from where XAML should use command bindings event handlers? I added copule of command binding to my cusotm control, however functions which are resonsible for execute and can_execute are not directly in code开发者_如何学编程 behind but in another class. This class is derived from Canvas and I create instance of this class in XAML.

<s:MyCanvas  Focusable="true"  Background="Transparent" x:Name="OwnCanvas" FocusVisualStyle="{x:Null}" ScrollViewer.CanContentScroll="True" >

I add command bindings this way

<UserControl.CommandBindings>
    <CommandBinding Command="{x:Static ApplicationCommands.Copy}" CanExecute="event handler from object OwnCanvas" />
</UserControl.CommandBindings>

Is there any way to do that ? Or I have to transfer event handler directly to codebehind ??

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I think you're gonna have to transfer the handler in codebehind as I don't think that's possible. I could be wrong and would love to be corrected if it is possible though.

What I usually do is just define the CommandBinding in your MyCanvas class (code behind) and then reference that MyCanvas as the CommandTarget in the custom control. Like this:

    public MyCanvas()
    {
        ...

        CommandBindings.Add(
            new CommandBinding(ApplicationCommands.Copy,
                (sender, e) => {
                    // Execute Stuff
                },
                (sender, e) => {
                    e.CanExecute = true; 
                    e.Handled = true; 
                }));
        ...
    }

And in your custom control (given it lies within the visual tree of MyCanvas)...

<Button Command="{x:Static ApplicationCommands.Copy}" CommandTarget="{Binding RelativeSource={RelativeSource AncestorType={x:Type s:MyCanvas}}}"/>

With your CommandTarget set up like that the Execute and CanExecute methods will be called on it.