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Two Labels will simultaneously display the character in both upper- and lowercase, irrespective of how it was entered. During the course of the example, you will also see how to translate keystrokes from one character to another. The Reset button will clear the Text properties of the Text Boxes and Labels. Alternatively, you could use any of the language-specific techniques described earlier in this chapter. e is used just as it was in the actual event handler method, described above.
To implement this functionality, add an event handler for the Reset button. In any case, this will bring up a code window with an empty skeleton for the btn Reset_Click event in place and the cursor placed for code entry. Append Text(vb Cr Lf) End Sub Private Sub txt Input_Key Down(By Val sender As Object, _ By Val e As System. The call to the helper method is simple; it involves passing in the name of the event and event argument: Now that you have the Key Down event handler implemented with a helper method to do the work, it is very simple to implement the Key Up event handler in a similar fashion because both events use the same Key Event Args event argument.
This Property Grid control for Windows Forms allows the users easily to validate data before the data is committed.
A larger multiline Text Box will display the keystroke events and event argument properties so that you can see what is going on. When done, the form should look something like Figure 4-7. The first argument is used in the first line in the method to display which event is being handled.
For example, you may want to disallow certain characters or convert all lowercase characters to uppercase.
Keyboard events provide access to this type of functionality.
The Key Event Args event data associated with the Key Down and Key Up events provides low-level information about the keystroke, listed in Table 4-6.
This information allows you to determine, for example, if an upper- or lowercase character was pressed. Like the Modifiers Key Event Args property, it is of type Keys.
The Key Char property is used to retrieve the composed ASCII character.