In WPF how do I implement ICommandSource to give my custom control ability to use Command from xaml?

Question

Could you please provide a sample, of how do you implement the ICommandSource interface. As I want my UserControl , which doesn't have the ability to Specify command in xaml, to have this ability. And to be able to handle the command when user clicks on the CustomControl .

Answer 1

Here's an example :

public partial class MyUserControl : UserControl, ICommandSource
{
    public MyUserControl()
    {
        InitializeComponent();
    }



    public ICommand Command
    {
        get { return (ICommand)GetValue(CommandProperty); }
        set { SetValue(CommandProperty, value); }
    }

    public static readonly DependencyProperty CommandProperty =
        DependencyProperty.Register("Command", typeof(ICommand), typeof(MyUserControl), new UIPropertyMetadata(null));


    public object CommandParameter
    {
        get { return (object)GetValue(CommandParameterProperty); }
        set { SetValue(CommandParameterProperty, value); }
    }

    // Using a DependencyProperty as the backing store for CommandParameter.  This enables animation, styling, binding, etc...
    public static readonly DependencyProperty CommandParameterProperty =
        DependencyProperty.Register("CommandParameter", typeof(object), typeof(MyUserControl), new UIPropertyMetadata(null));

    public IInputElement CommandTarget
    {
        get { return (IInputElement)GetValue(CommandTargetProperty); }
        set { SetValue(CommandTargetProperty, value); }
    }

    // Using a DependencyProperty as the backing store for CommandTarget.  This enables animation, styling, binding, etc...
    public static readonly DependencyProperty CommandTargetProperty =
        DependencyProperty.Register("CommandTarget", typeof(IInputElement), typeof(MyUserControl), new UIPropertyMetadata(null));


    protected override void OnMouseLeftButtonUp(MouseButtonEventArgs e)
    {
        base.OnMouseLeftButtonUp(e);

        var command = Command;
        var parameter = CommandParameter;
        var target = CommandTarget;

        var routedCmd = command as RoutedCommand;
        if (routedCmd != null && routedCmd.CanExecute(parameter, target))
        {
            routedCmd.Execute(parameter, target);
        }
        else if (command != null && command.CanExecute(parameter))
        {
            command.Execute(parameter);
        }
    }

}

Note that the CommandTarget property is only used for RoutedCommands

Answer 2

您的UserControl将在文件cs或vb后面有一个代码，您必须实现接口ICommandSource，一旦实现它，在某些情况下您将必须实际调用该命令并检查CanExecute。