.NET Table 14.7 LabelEditEventArgs class

The LabelEditEventArgs class represents the event arguments received by BeforeLabelEdit and AfterLabelEdit event handlers for the ListView class. This class is part of the System.Windows.Forms namespace, and inherits from the System.EventArgs class.

Since we are not in a production environment, we will take the easy way out and only handle the AfterLabelEdit event. This means a user may edit an album only to find that he or she cannot save his changes, which is not the best interface from a usability perspective.

The code changes required are given in the following steps:

INITIATE LABEL EDITING (continued)

That’s all it takes to begin an edit. The actual work of interacting with the user is handled by the framework. When the user is finished, we can pick up the result in an AfterLabelEdit event handler. There is also a BeforeLabelEdit event that is useful for selectively permitting an edit or altering an item before the edit begins. For our purposes, the AfterLabelEdit event will suffice.

PROCESS A LABEL EDIT (continued)

This code uses some methods from the Path and File classes to manipulate the file name strings and rename the album file. Our application now supports displaying album properties and editing of album labels. The next topic of discussion is item activation.

14.5ITEM ACTIVATION

As you might expect, item activation is the means by which an item is displayed or otherwise activated by the control. Normally, activation is just a fancy way to say double-click. In our ListBox class in chapter 10, we activated an item in the list by handling the DoubleClick event and displaying the properties dialog associated with the item. Such behavior is activation.

The reason for the fancy term is that the ListView class allows activation other than a double-click to be supported. The Activation property determines the type of activation supported, based on the ItemActivation enumeration. The possible values for this enumeration are shown in .NET Table 14.8. Note that the OneClick style is similar to an HTML link in a Web browser. In our program, we will stick with the standard activation.

.NET Table 14.8 ItemActivation enumeration

The ItemActivation enumeration specifies the type of activation supported by a control. This enumeration is part of the System.Windows.Forms namespace.

Regardless of how items are activated, an ItemActivate event occurs whenever an item is activated. The event handler for this event receives a standard System.EventArgs parameter, so the activated item is obtained from the SelectedItems collection.

The activation behavior for our MyAlbumExplorer application will display the Photographs in the selected album. This is a rather complicated change, since the columns and list item behavior must now accommodate the display of both albums and photos here. The fact that we were careful to separate much of the album logic into individual methods along the way will help us keep our code straight. Figure 14.6 shows our application with photographs displayed in the ListView control. These photographs are sorted by the date each photo was taken. The icon used here might not be your first choice for a photograph icon, but it will suffice for our purposes. If you find another icon you prefer, or are feeling creative, you can use an alternate icon in your application.