Handling Keyboard
Windows passes special keyboard events to your applications
so they can monitor the keyboard events. These events
are the keyPress, keyDown, key Up events. You can
test for keystrokes when a keyboard event occurs.
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Keystroke testing is useful for
validating input and playing games. |
The KeyPress event occurs when users press any key
that corresponds with one of these characters.
- Uppercase and lowercase letters
- Numeric digits
- Punctuation
- Enter, Tab, and Backspace
You can use the KeyPress to determine exactly which
key users pressed.
An event is associated with an object, such as a
command button, text box, etc. The KeyPress event
associates with the currently selected object. If
no object has the focus, this event is associated
with the form.
The KeyPress event tests for most ASCII characters,
but doesn't test for all ASCII characters, such as,
horizontal tab, arrow keys, and other special control
related characters that appear between ASCII values
0 to 31. If you were to write a KeyPress event for
a Text Box, the event procedure might began and end
like this.
Private Sub Text1_KeyPress (KeyAscii
as Integer)
End Sub
The KeyDown event occurs whenever users press a key.
Therefore, both the KeyDown and KeyPress events can
occur at the same time. The KeyDown event is more
complicated than the KeyPress event. The KeyDown event
returns the same value for uppercase and lowercase
letters. It also returns the state of the Shift key.
Private Sub Text1_KeyDown(KeyCode
As Integer, Shift As Integer)
End Sub
KeyCode contains the keystroke and the shift argument
determines the state of the control keys such as Shift,
Ctrl, and Alt.
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