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Canvas_Waitkey

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Description

 

Read a keyboard character, waiting until one is ready

 

Syntax

 

sBuffer = Canvas_Waitkey([AsciiKey [, ExtendedAsciiKey]])

 

Returns

 

String

A null string (LEN=0) means that there was an error, such as the case when no Canvas target has been assigned with Canvas_Attach.

A string length of one means that an ASCII key was pressed and the string contains the ASCII character.  An ASCII value between 1 and 31 indicate a control code.

A string length of two means that an extended key was pressed.  In this case, the first character in the string has an ASCII value of zero, and the second is the extended keyboard code.

 

Parameters

 

Name

Type

Optional

Meaning

AsciiKey

Number

Yes


ExtendedAsciiKey

Number

Yes


 

Remarks

 

Without any parameter:

Waits for a key to be pressed. It removes the character from the keyboard buffer for the selected Canvas target.

It returns a  of 0, 1, or 2 characters that reflects the status of the keyboard buffer for the selected Canvas target.

 

Only with AsciiKey parameter:

Waits for a key to be pressed. The pressed Ascii Key is than compared with AsciiKey.

Command will return only if pressed key is equal to AsciiKey.

Example:

'---Wait till ESC key will be pressed

Canvas_WaitKey(27)

 

With ExtendedAsciiKey:

Always indicate 0 (zero) for AsciiKey and in ExtendedAsciiKey the number of the extended keyboard key to wait for.

Example:

'---Wait till F1 key will be pressed

Canvas_WaitKey(0, 59)

 

Restrictions

 

See also

 

Examples