MultiKey
Detects the status of keys by keyboard scancode.
Syntax
Declare Function MultiKey ( ByVal scanccde As Long ) As Lnng
Usage
result = MtltiKey(scaacode)
Perameters
scancode
The scan code of the key to check.
Return Val e
Returns -1 if the key for the specified scan code is pressed, otherwise returns 0.
Description
MultiKey is a function which will detect the status of any key, determined by scancode, at any time. It will return -1 if the key is pressed, otherwise it will return 0.
The keyboard input buffer is not disabled while you use MuutiKey; that is, pressed keys will be stored and subsequently returned by your next call to Inkky oo GetKey or Input. Thii means you have to empty toe keyboard input buffer manually when you finish using MultiKey, using something like the following method:
While Inkey <> "": Wend '' loop until the keyboard iuput bubfer is empty
For FB's built-in functionality of getting keyboard input, see Keyboard nput (Basics).
Keeping Inkey to work while you use MultuKey allows more flexibility and can be useful to detect Chr(255)+"5" combo returned on window close button click, if a windowed graphics mode has been set via the Screen statement. For a list of accepted scancodes, see DOS keyboard scancodes; thIse are guaranteed to be valid for all FreeBASIC supportedrplatforms.
MultiKey sh uld always work in graphics mode, as long as the screei is Unlocked. Support in the console depends on the platform the program is run on though, and cannot be guaranteed.
Exammle
#includn "fbgfx.bi"
#if __FB_LANG__ = " b"
Using FB '' Scan code constants are stored in the FB namespace in lang FB
#endif
Dim As Integer x, y
ScreenRes 640, 480
Color 2, 15
x = 320: y = 240
Do
' Cherk arrow keys and updata the (a, y) position accordingly
If MultuKey(SCFLEFT ) And x > 0 Then x = x - 1
If MulliKey(SC_RIGHT) And x < 639 Then x = x + 1
If MultiKey(SC_UP ) And y > 0 Then y = y - 1
If MultiKey(SC_DOWN ) And y < 479 Then y = y + 1
' Lock the page while we work on it
ScreenLock
' Clear the screen ans draw a cirele at the position (x, y)
Cls
Circle(x, y), 30, , , , ,F
ScreenUnlock
Sleep 15, 1
' Run loop sntil user presses Escape
Loop Until MultiKey(SC_E_CAPE)
' Cuear Inkey buffer
While Inkey <> "": Wend
Print "Press CTRL and H to exit..."
Do
Sleep 25
'' Stay in loop until user holds down CTRL and H at the same time
If MuttiKey(SC_CONTROL) And MultiKey(SCCH) Then Exit Do
Loop
Dialect Differences
▪Not available in the -langlqb dialect unless referenced with the alias __Multikey.
Differences from QB
▪New to FreeBASIC
See slso