Compile and run the application to verify that your code produces the screen shown in figure 6.2 earlier in this section.

TRY IT! It would be useful to have First and Last menu items here. These would display the first or last photo in the album, respectively. Add these two menus to the View menu and provide a Click event handler for each menu.

6.5FILES AND PATHS

Before we implement our save methods, a brief talk on the name of an album is in order. While we may store the album in a file such as “C:\Program Files\MyPhotos\sample.abm,” such a name is a bit cumbersome for use in dialogs and on the title bar. The base file name, in this case “sample,” is more appropriate for this purpose. Another issue is where exactly should album files be stored?

This section resolves these issues by defining a default directory where albums are stored and establishing a title bar based on the current album name. These features will then be used to implement a Click event handler for our New menu.

6.5.1CREATING A DEFAULT ALBUM DIRECTORY

While an album file can be placed in any directory, it is nice to provide a common place for such files. This location will be used by default for both opening and saving albums. Common directories for this and other standard information are available from the Environment class, as summarized in .NET Table 6.2.

For our default directory, the GetFolderPath method provides convenient access to the special folders in the system, such as the user’s My Documents directory. There are a number of special folders available, with a few of them listed in .NET Table 6.3. We are interested in the location of the My Documents directory, which corresponds to the Personal enumeration value.

.NET Table 6.2 Environment class

The Environment class represents the current user’s environment, providing the means to retrieve and specify environmental information. This class is sealed and the members defined by this class are static. The Environment class is part of the System namespace.

We will use this value to define a static DefaultDir property in our PhotoAlbum class. We will allow a programmer to modify this value, but this provides a starting point for album storage. To distinguish photo albums from other documents, we will create an Albums directory within the My Documents folder.

.NET Table 6.3 SpecialFolder enumeration

The SpecialFolder enumeration specifies various types of predefined folders in the .NET Framework. This enumeration is used by the GetFolderPath method in the Environment class. This enumeration is defined within the Environment class as part of the System namespace.

Let’s see how this looks by creating the required code.

Set the version number of the MyPhotoAlbum library to 6.5.

CREATE A DEFAULT ALBUM DIRECTORY

CREATE A DEFAULT ALBUM DIRECTORY (continued)

The InitDefaultDir method does much of the work for this property. If an explicit value for the default directory has not been set, then this method assigns a value based on the user’s personal directory for documents, with an Albums subdirectory added.

static private void InitDefaultDir()

{

if (_defaultDir == null)

{

_defaultDir == Environment.GetFolderPath( Environment.SpecialFolder.Personal);

_defaultDir += @"\Albums";

}

Since this directory, or any directory provided by the user, may or may not exist at the start of the program, we create the directories as part of our initialization.

Directory.CreateDirectory(_defaultDir);

}

For programmers familiar with earlier development environments from Microsoft, the lack of directory-related classes and dialogs has been a noticeably missing feature. Microsoft has provided a Directory class .NET containing a number of static methods for dealing with directories. This class resides in the System.IO namespace and should simplify the handling of directories in applications. We will not look at this class in detail here. The CreateDirectories method used in our code ensures that each of a string of directories in a given path exist. Note that if the _defaultDir setting is not a well-formed directory string, then the CreateDirectories method will throw an exception.