Specifies a command that executes when you press a specific key or key combination or click the mouse button.

ON KEY [LABEL KeyLabelName] [Command]

Parameters

LABEL KeyLabelName

Specifies the key label name assigned to the key. The KeyLabelName is the letter or digit on the key or a special name assigned to the key. The following table lists the special key label names.

Visual FoxPro key label assignments

For this key	Specify this KeyLabelName value
	LEFTARROW
	RIGHTARROW
	UPARROW
	DNARROW
HOME	HOME
END	END
PAGE UP	PGUP
PAGE DOWN	PGDN
DEL	DEL
BACKSPACE	BACKSPACE
SPACEBAR	SPACEBAR
INS	INS
TAB	TAB
SHIFT+TAB	BACKTAB
Left Brace	LBRACE
Right Brace	RBRACE
ENTER	ENTER
F1 to F12	F1, F2, F3 ...
CTRL+F1 to CTRL+F12	CTRL+F1, CTRL+F2 ...
SHIFT+F1 to SHIFT+F12	SHIFT+F1, SHIFT+F2 ...
ALT+F1 to ALT+F12	ALT+F1, ALT+F2, ALT+F3 ...
ALT+0 to ALT+9	ALT+0, ALT+1, ALT+2 ...
ALT+A to ALT+Z	ALT+A, ALT+B, ALT+C ...
CTRL+LEFT ARROW	CTRL+LEFTARROW
CTRL+RIGHT ARROW	CTRL+RIGHTARROW
CTRL+HOME	CTRL+HOME
CTRL+END	CTRL+END
CTRL+PAGE UP	CTRL+PGUP
CTRL+PAGE DOWN	CTRL+PGDN
CTRL+A TO CTRL+Z	CTRL+A, CTRL+B, CTRL+C ...
CTRL+0	CTRL+0
RIGHT MOUSE BUTTON	RIGHTMOUSE
LEFT MOUSE BUTTON	LEFTMOUSE
MOUSE BUTTON	MOUSE
ESC	ESC

Command

Specifies the command that executes when you press the specified key or key combination or click the mouse button.

You can include parameter or parameter expressions with the command that you assign to the key, as in the following example:

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ON KEY LABEL ALT+V WAIT WINDOW "Version: " + VERSION()

You can include variables in the assignment, but they must be public. For example:

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PUBLIC message message = "Default drive: " + SYS(5) ON KEY LABEL ALT+D WAIT WINDOW message

Remarks

ON KEY LABEL typically uses DO to execute a procedure.

ON KEY LABEL executes the command immediately during the execution of READ, BROWSE, EDIT, CHANGE, and user-defined menus. If a program is executing when you press the key or click the mouse button, Visual FoxPro executes the current program line and then executes the ON KEY LABEL command. Any ON KEY LABEL key assignments created in a program remain in effect after the program is run. You can also create key assignments in the Command window.

To restore the behavior of a specific key to normal, issue ON KEY LABEL KeyLabelName. To restore all keys to their default behavior, issue ON KEY.

Tip
To prevent recursive calls during the execution of an ON KEY LABEL procedure, include PUSH KEY CLEAR early in the procedure to disable all active ON KEY LABEL commands. Issue POP KEY at the end of the procedure to enable the ON KEY LABEL commands.

The ON KEY LABEL key assignments aren't in effect in the Visual FoxPro system menu bar, system menus, dialog boxes, alerts, and so on. The key assignments are effective in the Visual FoxPro system windows — the Visual FoxPro text editor, the Command window, the Trace window, and so on.

Unlike ON KEY, there can be multiple active ON KEY LABEL commands. For example, you can assign a command to each of the arrow keys and a mouse button.

Executing an ON KEY LABEL resets PARAMETERS( ) to 0. For more information, see PARAMETERS( ) Function.

In Visual FoxPro, certain events cannot be trapped because they are under the control of Windows. In particular, ON KEY LABEL MOUSE, ON KEY LABEL LEFTMOUSE, and ON KEY LABEL RIGHTMOUSE are not executed when you click a Windows control such as a Control menu, scroll bar, or the like. Also, CTRL+0 is supported in ON KEY LABEL in Visual FoxPro, allowing you to redefine the key combination used to enter a null value into a field.

Note that ON KEY LABEL operates outside of the scope of a form; the KeyPress event can be used within forms to execute code when a key is pressed.

Example

The following example displays a message when an arrow key is pressed.

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CLEAR PUBLIC msg msg = CHR(13) + CHR(13) + "Press F9 to " + ; "restore default key definition." ON KEY LABEL RIGHTARROW Wait Window "Right Arrow " + msg NOWAIT ON KEY LABEL LEFTARROW Wait Window "Left Arrow " + msg NOWAIT ON KEY LABEL UPARROW Wait Window "Up Arrow " + msg NOWAIT ON KEY LABEL DNARROW Wait Window "Down Arrow " + msg NOWAIT * Press F9 to clear the ON KEY LABEL assignments ON KEY LABEL F9 ON KEY

See Also