C# 4 and .NET 4

766 ❘ ChaPTer 28 mAnAGed extensibility frAmewOrk
to all available exports from the catalog. Because here multiple add-ins are dynamically loaded (the user
can select the add-in to use), the Menu control is dynamically extended. The application iterates through all
the calculator extensions, and a new MenuItem is created for each extension. The header of the MenuItem
control contains a Label with the Title property of the extension and a CheckBox. The CheckBox will
later be used to remove the export dynamically. The ToolTip property of the MenuItem is set to the
Description property of the extender control. The Tag property is set to the extender control itself,
which makes it easy to get to the extender control when the menu item is selected. The Click event of the
MenuItem is set to the method ShowAddIn(). This method invokes the GetUI() method of the extender
control for displaying the control within a new TabItem of a TabControl.
private void RefreshExensions()
{
catalog.Refresh();
calcExtensionImport = new CalculatorExtensionImport();
calcExtensionImport.ImportsSatisfied += (sender, e) =>
{
this.textStatus.Text += String.Format("{0}\n", e.StatusMessage);
};
container.ComposeParts(calcExtensionImport);
menuAddins.Items.Clear();
foreach (var extension in calcExtensionImport.CalculatorExtensions)
{
var menuItemHeader = new StackPanel { Orientation = Orientation.Horizontal };
menuItemHeader.Children.Add(new Label { Content = extension.Title });
var menuCheck = new CheckBox { IsChecked = true };
menuItemHeader.Children.Add(menuCheck);
}
}
var menuItem = new MenuItem {
Header = menuItemHeader,
ToolTip = extension.Description,
Tag = extension
};
menuCheck.Tag = menuItem;
menuItem.Click += ShowAddIn;
menuAddins.Items.Add(menuItem);
private void ShowAddIn(object sender, RoutedEventArgs e)
{
var mi = e.Source as MenuItem;
var ext = mi.Tag as ICalculatorExtension;
FrameworkElement uiControl = ext.GetUI();
var headerPanel = new StackPanel { Orientation = Orientation.Horizontal };
headerPanel.Children.Add(new Label { Content = ext.Title });
var closeButton = new Button { Content = "X" };
var ti = new TabItem { Header = headerPanel, Content = uiControl };
closeButton.Click += delegate
{
tabExtensions.Items.Remove(ti);
};
headerPanel.Children.Add(closeButton);
}
tabExtensions.SelectedIndex = tabExtensions.Items.Add(ti);
code snippet WPFCalculator/MainWindow.xaml.cs
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