Using the Open File Dialog Window - Page 2
       by kirupa  |  7 August 2007

In the previous page, you got a brief overview of what the Open File dialog window is, and you downloaded the source files needed to create our sample application.

OpenFileDialog
The Open File dialog window provides an Explorer-like view for navigating through your files and selecting a file for you to open. What is returned after your journey through the Open File dialog window is the path to the file you selected.

To use this dialog window, you use the OpenFileDialog class. Copy and paste the following two lines into your WindowLauncher method:

private void WindowLauncher(object sender, RoutedEventArgs e)

{

OpenFileDialog ofd = new OpenFileDialog();

ofd.ShowDialog();

}

Once you have added the above two lines to your WindowLauncher method, run your application by press F5. Click on your Launch Window button to see your Open File dialog appear.

If you look at our code, we declare an OpenFileDialog object called ofd. We then call ofd's ShowDialog() method:

ofd.ShowDialog();

When you use the ShowDialog() method, you are launching a window that is modal. A modal window borrows focus from your entire application to itself. You will be unable to access the window that spawned the modal window until your modal window is closed.

Opening a File
One of the primary functions of your Open File dialog window is to return the path of the file you selected. To retrieve the path of the selected file, replace the code inside your WindowLauncher with the following code:

private void WindowLauncher(object sender, RoutedEventArgs e)

{

OpenFileDialog ofd = new OpenFileDialog();

 

if (ofd.ShowDialog() == true)

{

string filePath = ofd.FileName;

string safeFilePath = ofd.SafeFileName;

}

}

This time, if you select a file by double-clicking on it or by selecting it and pressing your Open button, the file's name is stored in two variables called filePath and safeFilePath. Before we get to the file names itself, notice how I check to make sure that a file has been specified for opening:

if (ofd.ShowDialog() == true)

{

string filePath = ofd.FileName;

string safeFilePath = ofd.SafeFileName;

}

Your ShowDialog() method returns an object of type bool? which is a nullable boolean. A nullable boolean returns a value that is true, false, and a third type that is null. If you select a file for Open, your ShowDialog method returns true. If you click Cancel or close your Open File dialog window, the value is false.

Since we are interested in dealing with the result of a file that is specified for opening, we only check the true property. Now, let's look at our filePath and safeFilePath variables:

string filePath = ofd.FileName;

string safeFilePath = ofd.SafeFileName;

The filePath variable gets its data by accessing ofd's FileName property, and safeFilePath gets its data by accessing ofd's SafeFileName property. Your FileName is the full path to your file plust your file's name and extension. The SafeFileName returns just the name of your file and its extension. The path is not returned.

For example, let's say you decide to open a file located in your C:\Windows path called regedit:

[ opening a file using the Open File dialog window ]

When you select that file for opening, your FileName will be C:\Windows\regedit.exe, and your SafeFileName will be regedit.exe. Depending on what you are doing, you will need to decide whether you want to use FileName or SafeFileName.

In the next page, let's take what we've done a step further and look at opening multiple files at once.

Onwards to the next page!

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