Warum UI von Aufgaben trennen

Wie kann die WPF hier helfen?

• Commands müssen das UI aktualisieren
• Commands können komplett frei von allen UI-Einflüssen ausgeführt werden

• ApplicationCommands
• ComponentCommands
• NavigationCommands
• MediaCommands
• EditingCommands

<UserControl.CommandBindings>
    <CommandBinding 
      Command="MediaCommands.Play" 
      CanExecute="OnQueryExecute" 
      Executed="Execute"/>
</UserControl.CommandBindings>

<StackPanel Grid.Row="2" Orientation="Horizontal">
    <Button 
      Command="MediaCommands.Play" 
      Content="{Binding RelativeSource={RelativeSource Self}, 
        Path=Command.Text}" />
</StackPanel>

Eigene Commands via ICommand implementieren

• CanExecute
• Execute
• CanExecuteChanged

public class MySaveCommand : ICommand
{
    #region ICommand Members

    public bool CanExecute(object parameter)
    {
        return true;
    }

    public event EventHandler CanExecuteChanged;

    public void Execute(object parameter)
    {
        if (parameter is EasySum)
        {
            EasySum es = (EasySum)parameter;
            es.Result = es.Summand1 + es.Summand2;
        }
    }

    #endregion
}

RoutedCommand erstellen

public static RoutedCommand ChangeBackgroundCommand = new RoutedCommand();

private void ChangeBackgroundCommandCanExecute(
    object sender, CanExecuteRoutedEventArgs e)
{
    if (sender is Panel)
        e.CanExecute = true;
    else
        e.CanExecute = false;

}

private void ChangeBackgroundCommandExecuted(
    object sender, ExecutedRoutedEventArgs e)
{
    Panel target = e.Source as Panel;
    if (target != null)
    {
        if (target.Background == Brushes.AliceBlue)
        {
            target.Background = Brushes.LemonChiffon;
        }
        else
        {
            target.Background = Brushes.AliceBlue;
        }

    }
}

<StackPanel Name="MyStackPanel"
    Background="AliceBlue"
    Focusable="True">
    <StackPanel.CommandBindings>
        <CommandBinding 
            Command="{x:Static custom:Window1.ChangeBackgroundCommand}"
            Executed="ChangeBackgroundCommandExecuted"
            CanExecute="ChangeBackgroundCommandCanExecute"/>
    </StackPanel.CommandBindings>
    <Label>A StackPanel</Label>
    <Button Command="{x:Static custom:Window1.ChangeBackgroundCommand}"
      CommandParameter="ButtonOne"
      CommandTarget="{Binding ElementName=MyStackPanel}" 
      Content="Change Background" />
</StackPanel>

Fazit

Ein kurzer Rückblick

2007 in ein paar wenigen Zahlen

Ausblick 2008

Abschluss