C# 4 and .NET 4

1062 ❘ ChaPTer 36 business ApplicAtiOns with wpf
defining Commands
.NET 4 gives you classes that return predefined commands. The ApplicationCommands class defines
the static properties New, Open, Close, Print, Cut, Copy, Paste, and others. These properties return
RoutedUICommand objects that can be used for a specific purpose. Other classes offering commands are
NavigationCommands and MediaCommands. NavigationCommands gives you commands that are common
for navigation such as GoToPage, NextPage, and PreviousPage. MediaCommands are useful for running a
media player with Play, Pause, Stop, Rewind, and Record.
It’s not hard to define custom commands that fulfill application domain–specific actions. For this, the
BooksCommands class is created that returns a RoutedUICommand with the ShowBooks property. You can
also assign an input gesture to a command, such as KeyGesture or MouseGesture. Here, a KeyGesture is
assigned that defines the key B with the ALT modifier. An input gesture is a command source, so clicking
the ALT-B key invokes the command:
public static class BooksCommands
{
private static RoutedUICommand showBooks;
public static ICommand ShowBooks
{
get
{
if (showBooks == null)
{
showBooks = new RoutedUICommand("Show Books", "ShowBooks",
typeof(BooksCommands));
showBook.InputGestures.Add(
new KeyGesture(Key.B, ModifierKeys.Alt));
}
return showBooks;
}
}
defining Command sources
code snippet BooksDemo/BooksCommands.cs
Every class that implements the ICommandSource interface can be a source of commands, such as
Button and MenuItem. Inside the main window a Menu control is added as a child of the DockPanel.
MenuItem elements are contained within the Menu control and the Command property is assigned to some
predefined commands such as ApplicationCommands.Close, and the custom command BooksCommands.
ShowBooks:
code snippet BooksDemo/MainWindow.xaml
www.it-ebooks.info