KeyPressed (Function)

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To manage all the keyboard keys with KeyPressed:
Testing a key combination
Interrupting a process in a browse loop
Asynchronous status report
Using the KeyPressed function

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KeyPressed (Function)

In french: ToucheEnfoncée

Checks which key is pressed.

Example

// Include the "KeyConst.wl" file to manage the keyboard keys
EXTERN "KeyConst.WL"
FOR I = 1 TO 5000
HourGlass(True)
Multitask(-1)
// Check Space key
IF KeyPressed(VK_SPACE) = True THEN Info("Space key down")
// Check A key
IF KeyPressed(Asc("A")) = True THEN Trace("A key down")
END
HourGlass(False)

Syntax

<Result> = KeyPressed(<Constant> [, <Change of status>])

<Result>: Boolean

True if the control key is pressed or if its status changed since the last call to KeyPressed,
False otherwise.
Specific operating mode:
True if the control key is currently pressed,
False otherwise.

<Constant>: Integer constant

Identifies the control key:
kpAlt Alt key.
kpControl Ctrl key.
kpEscape Esc key.
kpLButton Left mouse button.
This constant is not available.
kpRButton Right mouse button.
This constant is not available.
kpShift Shift key.

Additional constants are available in the "KeyConst.wl" file. These constants are used to identify all the keyboard keys. This file is available in the WINDEV "Personal\External" subdirectory.

<Change of status>: Optional boolean

True (default) to get a synchronous status: key currently pressed,
False to get an asynchronous status: the key status changed since the last call to KeyPressed.
This parameter is ignored. The status code is always synchronous.

Remarks

To manage all the keyboard keys with KeyPressed:

Include the KeyConst.WL file in your project. This file associates a specific constant with each keyboard key. This file is available in the \Personal\Extern directory of WINDEV. To include this file in your applications, you need to use the EXTERN keyword as follows:
EXTERN "KEYCONST.wl"
Use the constants in KeyPressed:
IF KeyPressed(VK_Space) THEN...

Remarks:

To manage character keys, simply use the ASCII code of that character (returned by Asc).
All the constants found in the KeyConst.WL file start with the letters VK_. These constants are displayed by the code completion in the code editor from the moment the file has been integrated with the EXTERN keyword.

Testing a key combination

To run the test of a key combination, run the test of two keys pressed:

IF KeyPressed(kpShift) AND KeyPressed(VK_TAB) THEN
Trace("OK")
END

Interrupting a process in a browse loop

In a loop, to interrupt the process by pressing Esc, Multitask must be called before KeyPressed.

Example:

HReadFirst(Customer, CustNum)
WHILE HOut() = False
// Abandon via Esc?
Multitask(-1)
IF KeyPressed(kpEscape) = True THEN BREAK
// Process
HReadNext(Customer, CustNum)
END

Asynchronous status report

To avoid retrieving a key that was pressed beforehand (in another process for example), the status of the key to test must be reinitialized by the following line of code:

KeyPressed(<Key>, False)

Using the KeyPressed function

The application must have focus for KeyPressed to check whether the specified key is pressed.

Component: wd300std.dll