#344 – The CommandBinding CanExecute Event Determines Whether a Button is Enabled

When you associate a button’s Command property with a CommandBinding object,and bind the CommandBinding object to both Executed and CanExecute handlers, the Button control will automatically toggle between enabled/disabled, depending on the code in the CanExecute method.

Suppose we create two buttons, binding them to open/close commands.

    <StackPanel Orientation="Horizontal" HorizontalAlignment="Center">
        <Button Content="Open" Command="ApplicationCommands.Open"
                VerticalAlignment="Center" Padding="10,5" Margin="5"/>
        <Button Content="Close" Command="ApplicationCommands.Close"
                VerticalAlignment="Center" Padding="10,5" Margin="5"/>
    </StackPanel>

Then we create a CommandBinding and associated handlers.

		public MainWindow()
		{
			this.InitializeComponent();

            CommandBindings.Add(new CommandBinding(ApplicationCommands.Open, Open_Executed, Open_CanExecute));
            CommandBindings.Add(new CommandBinding(ApplicationCommands.Close, Close_Executed, Close_CanExecute));
        }

        private bool isOpen = false;

        public void Open_Executed(object sender, ExecutedRoutedEventArgs e)
        {
            MessageBox.Show("Open");
            isOpen = true;
        }

        public void Open_CanExecute(object sender, CanExecuteRoutedEventArgs e)
        {
            e.CanExecute = !isOpen;
        }

        public void Close_Executed(object sender, ExecutedRoutedEventArgs e)
        {
            MessageBox.Show("Close");
            isOpen = false;
        }

        public void Close_CanExecute(object sender, CanExecuteRoutedEventArgs e)
        {
            e.CanExecute = isOpen;
        }

The buttons will now automatically be enabled/disabled, depending on the value of isOpen.

About Sean
Software developer in the Twin Cities area, passionate about .NET technologies. Equally passionate about my own personal projects related to family history and preservation of family stories and photos.

One Response to #344 – The CommandBinding CanExecute Event Determines Whether a Button is Enabled

  1. bpoojary says:

    Found best multi event command binder in codeplex

    Multi Event Command

    Benefits:

    1:Ability to bind multiple event to multiple commands.
    2:In CommandArgs in command handler you can even get original event args this was not possible with existing command binders.
    3:In CommandArgs in command handler you can even get original source of the event this was not possible with existing command binders.
    4:In this you can control individual CanExecute methods.

    Blogs
    Multi Event Command BlogSpot
    Multi Event Command WordPress

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