Benutzer:MovGP0/WPF/ICommandSource
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ICommandSourcepublic sealed class MyControl : Control, ICommandSource
{
public MyControl()
{
InitializeComponent();
}
private EventHandler CanExecuteChangedHandler { get; set; }
#region Command
private static readonly DependencyProperty CommandProperty =
DependencyProperty.Register(nameof(Command), typeof(ICommand), typeof(MyControl),
new PorpertyMetadata(null, OnCommandChanged));
public ICommand Command
{
get { return (ICommand)GetValue(CommandProperty); }
set { SetValue(CommandProperty, value); }
}
private static void OnCommandChanged(DependencyObject d, DependencyPropertyChangedEventArgs args)
{
var control = d as MyControl;
if(control != null)
control.OnCommandChanged((ICommand)e.OldValue, (ICommand)e.NewValue);
}
private void OnCommandChanged(ICommand oldCommand, ICommand newCommand)
{
if(oldCommand != null)
UnhookCommand(oldCommand);
HookupCommand(newCommand);
CanExecuteChanged(null, null);
}
private void UnhookCommand(ICommand oldCommand)
{
oldCommand.CanExecuteChanged -= CanExecuteChanged;
}
private void HookupCommand(ICommand newCommand)
{
CanExecuteChangedHandler = new EventHandler(CanExecuteChanged);
if(newCommand != null)
newCommand.CanExecuteChanged += CanExecuteChangedHandler;
}
private void CanExecuteChanged(object sender, EventArgs args)
{
if(Command == null) return;
// RoutedCommand
var routedCommand = Command as RoutedCommand;
if(routedCommand != null)
{
IsEnabled = routedCommand.CanExecute(CommandParameter, CommandTarget);
return;
}
// ICommand
IsEnabled = Command.CanExecute(CommandParameter);
}
#endregion
#region CommandParameter
public static readonly DependencyProperty CommandParameterProperty =
DependencyProperty.Register(nameof(CommandParameter), typeof(object), typeof(MyControl), new PropertyMetadata(null));
public object CommandParameter
{
get { return GetValue(CommandParameterProperty); }
set { SetValue(CommandParameterProperty, value); }
}
#endregion
#region CommandTarget
public static readonly DependencyProperty CommandTargetProperty =
DependencyProperty.Register(nameof(CommandTarget), typeof(IInputElement), typeof(MyControl), new PropertyMetadata(null));
public IInputElement CommandTarget
{
get { return (IInputElement)GetValue(CommandTargetProperty); }
set { SetValue(CommandTargetProperty, value); }
}
#endregion
}
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