CREATE THE PASSWORD SECTION OF THE ALBUMEDITDLG FORM

CREATE THE PASSWORD SECTION OF THE ALBUMEDITDLG FORM (continued)

CREATE THE PASSWORD SECTION OF THE ALBUMEDITDLG FORM (continued)

This code demonstrates a couple of new concepts, such as setting the focus and validating the contents of a control. Let’s look at these changes in a bit more detail.

private void txtAlbumPwd_Validating

(object sender, System.ComponentModel.CancelEventArgs e)

if ((cbtnPassword.Checked)

&& (txtConfirmPwd.Text != txtAlbumPwd.Text))

{

MessageBox.Show(this,

"The password and confirm values do not match", "Password Error",

MessageBoxButtons.OK,

MessageBoxIcon.Error);

return false;

}

return true;

}

The numbered sections in this code warrant the following commentary.

bThe AutoCheck property handles the Click event automatically on behalf of our CheckBox control. To process the change in button state that occurs when this happens, we handle the CheckedChanged event. The value of the Checked property is used to enable or display the associated controls, as required.

cWhen our radio button is checked, the focus, by default, would remain with the cbtnPassword control. Typically, when a user checks this button, he or she would immediately want to edit the password field. Calling the Focus method does this automatically and saves the user an extra step.

dThe Validating event is one of a series of events related to entering and leaving a control. Collectively, these events are sometimes referred to as the focus events. The

focus events, in the order in which they occur, are as follows: Enter, GotFocus,

Leave, Validating, Validated, and LostFocus.These events can be used to fine-tune the behavior of a control as the user moves from one control to the next.

The validation events, namely Validating and Validated, occur during and after validation whenever the CausesValidation property is set to true. This property defaults to true, so the validation events normally occur. The Validating event receives a CancelEventArgs parameter much like the OnClosing event we discussed for the Form class in chapter 6. The CancelEventArgs.Cancel property is used to cancel the operation when the validation fails.

In our case, we want to verify that the password provided is not blank. When this occurs, we display a message box to inform the user of the problem, and cancel the operation to indicate that validation has failed. The .NET Framework returns focus to the control, forcing the user to correct the problem.