KEY n

From QB64.org wiki
Revision as of 19:55, 21 September 2017 by SMcNeill (talk) (-)
(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)
Jump to: navigation, search

The KEY n statement is used to assign a "soft key" string or a flag and scan code to a function key or display function soft key assignments.

Syntax

KEY n%, textString$
KEY n%, CHR$(keyFlag%) + CHR$(scanCode)


Function Soft Key Strings (1 to 10, 30 & 31)

Assigning "Softkey" STRING values to function key press events
  • n% is the number 1 to 10 (F1 to F10), 30 or 31 (F11 or F12) of the function key to assign the soft key string.
  • Instead of using an ON KEY(n) GOSUB statement, Function keys F1 to F12 can be assigned a "soft key" string value to return.
  • KEY n, text$ defines a literal or variable STRING "soft key" function key return value.

KEY 1, "Help" 'returns the string "Help" to INPUT variable when F1 is pressed

  • KEY LIST displays each of the 12 softkey function key (F1 to F12) string values going down left side of screen.
  • KEY {ON|OFF} displays or hides the softkey values of function keys F1 to F10 at the bottom of the screen.


Number Pad Arrow Keys (11 to 14)

  • Arrow keys on the Number Pad are predefined KEY numbers 11 to 14 and only work with Number Lock off.
  • Soft Key STRINGs cannot be assigned to these key numbers!
  • To use the extended arrow keys on a keyboard use the Extended Key Flag 128 with corresponding Scan code as User Defined Keys.


User Defined Keys (15 to 29)

Assigning user defined keys or combinations with: KEY n, CHR$(keyflag) + CHR$(scancode)

Function Key Flag Combination Values 0 = no function key combination flag(single key) 1 = Left Shift key flag 2 = Right Shift key flag 4 = Ctrl flag 8 = Alt flag 32 = Number Lock flag 64 = Caps Lock flag 128 = Extended keys (see trapping extended keys below) Flag values can be added to monitor multiple function key combinations.

  • After the keyflag code character the scancode character is added using one of the two trapping methods that follow:

' Soft Key Scan Code Values ' ' 1 2 3 4 5 6 7 8 9 10 30 31 Predefined Keys ' Esc F1 F2 F3 F4 F5 F6 F7 F8 F9 F10 F11 F12 SysReq ScrL Pause ' 1 59 60 61 62 63 64 65 66 67 68 87 88 -- 70 29 ' `~ 1! 2@ 3# 4$ 5% 6^ 7& 8* 9( 0) -_ =+ BkSpc Insert Home PgUp NumL / * - ' 41 2 3 4 5 6 7 8 9 10 11 12 13 14 82 71 73 32/69 53 55 74 ' Tab Q W E R T Y U I O P [{ ]} \| Delete End PgDn 7/Home 8/▲ 9/PU + ' 15 16 17 18 19 20 21 22 23 24 25 26 27 43 83 79 81 71 11/72 73 78 ' CapL A S D F G H J K L  ;: '" Enter 4/◄- 5 6/-► E ' 64/58 30 31 32 33 34 35 36 37 38 39 40 28 12/75 76 13/77 n ' Shift Z X C V B N M ,< .> /? Shift ▲ 1/End 2/▼ 3/PD t ' 1/42 44 45 46 47 48 49 50 51 52 53 2/54 72 79 14/80 81 e ' Ctrl Win Alt Spacebar Alt Win Menu Ctrl ◄- ▼ -► 0/Insert ./Del r ' 4/29 91 8/56 57 56 92 93 29 75 80 77 82 83 28 ' ' Keyflag: Function(0, 1, 2, 4, 8, 32, 64), Extended(128) Scan Code: 1-88, QB64 only(91-93) ' ' Reserved and function key combinations can be made using the scan code instead. ' Add function flag values to 128 for Extended key combinations.

NOTE: The above commented table can be copied and pasted directly into the QB64 IDE


Trapping Ctrl, Alt and Shift key combinations
Keyboard Flag values can be added to monitor more than one control key. For example, flag combination 12 would flag both the Ctrl and Alt key presses. Since the flag already determines the function key to monitor, you don't necessarily have to use it's scancode. You can look for a key combination such as Ctrl + by using the plus key's scancode which is 13 as shown below:

KEY 15, CHR$(4) + CHR$(13) 'enabled event when Ctrl and + key are pressed


Trapping Extended keys (Insert, Home, Page Up, Right Ctrl, R.Alt, and cursor arrow pad)
  • On a 101-key keyboard, you can trap any of the keys on the dedicated cursorpad by assigning the string to any of the keynumber values from 15 to 25 using the 128 keyboard flag. The cursor arrows are not the same as the pre-assigned number pad arrows:

KEY n, CHR$(128) + CHR$(scancode) ' where n = 15 to 29. See: Scancodes KEY 15, CHR$(128) + CHR$(75) 'left arrow cursor pad  KEY 16, CHR$(128) + CHR$(72) 'up arrow cursor pad   KEY 17, CHR$(128) + CHR$(77) 'right arrow cursor pad KEY 18, CHR$(128) + CHR$(80) 'down arrow cursor pad

Use CHR$(0) for the first byte flag for non-function keys. You can substitute a literal STRING value to trap as shown in Example 2.


(Return to Table of Contents)


Examples

Example 1: Shows a list of all the string assignments to the function keys F1-F12 (Prints help every time F1 is pressed in the input)

KEY 1, "Help" KEY LIST INPUT "Press F1 or to quit press ENTER: ", a$

F1 Help F2 F3 F4 F5 F6 F7 F8 F9 F10 F11 F12 Press F1 or to quit press ENTER: HelpHelpHelpHelp


Example 2: Trapping the Control + key combination. Use the Control Keyboard flag 4 and + key scancode 13.

CLS KEY 15, CHR$(4) + CHR$(13) 'scancode for "=" or "+" key is 13 ON KEY(15) GOSUB control 'action of user defined key press KEY(15) ON 'turn ON event trapping for key combination PRINT "Press Ctrl and plus key combination, escape quits!" DO: SLEEP count = count + 1 PRINT count; IF INKEY$ = CHR$(27) THEN END 'escape key exit LOOP control: 'NUMBER LOCK MUST BE OFF! PRINT "Control and + keys pressed!"; RETURN

Code by Ted Weissgerber


Example 3: Differentiating the extended cursor keypad arrows from the predefined Number Pad arrow keys.

'predefined keys 11 to 14 for number pad arrows only ON KEY(11) GOSUB UpNum: KEY(11) ON 'up ON KEY(12) GOSUB LNum: KEY(12) ON 'left ON KEY(13) GOSUB RNum: KEY(13) ON 'right ON KEY(14) GOSUB DnNum: KEY(14) ON 'down 'user defined keys use extended key flag 128 + scan code ON KEY(15) GOSUB UpPad KEY 15, CHR$(128) + CHR$(72): KEY(15) ON 'cursor up ON KEY(16) GOSUB LPad KEY 16, CHR$(128) + CHR$(75): KEY(16) ON 'cursor left ON KEY(17) GOSUB RPad KEY 17, CHR$(128) + CHR$(77): KEY(17) ON 'cursor right ON KEY(18) GOSUB DnPad KEY 18, CHR$(128) + CHR$(80): KEY(18) ON 'cursor down DEF SEG = 0 DO numL = PEEK(1047) AND 32 '32 if on capL = PEEK(1047) AND 64 '64 on IF numL OR capL THEN COLOR 12: LOCATE 13, 50: PRINT "Turn Num or Cap Lock OFF!" ELSE : COLOR 10: LOCATE 13, 50: PRINT "Number and Cap Lock OK! " SLEEP ' KEY or TIMER event breaks a sleep END IF LOOP UNTIL INKEY$ = CHR$(27) DEF SEG KEY(15) OFF: KEY(16) OFF: KEY(17) OFF: KEY(18) OFF KEY(11) OFF: KEY(12) OFF: KEY(13) OFF: KEY(14) OFF END UpPad: COLOR 14: LOCATE 11, 26: PRINT " Up cursor pad " RETURN LPad: COLOR 14: LOCATE 11, 26: PRINT "Left cursor pad " RETURN RPad: COLOR 14: LOCATE 11, 26: PRINT "Right cursor pad" RETURN DnPad: COLOR 14: LOCATE 11, 26: PRINT "Down cursor pad " RETURN UpNum: COLOR 11: LOCATE 11, 26: PRINT " Up number pad " RETURN LNum: COLOR 11: LOCATE 11, 26: PRINT "Left number pad " RETURN RNum: COLOR 11: LOCATE 11, 26: PRINT "Right number pad" RETURN DnNum: COLOR 11: LOCATE 11, 26: PRINT "Down number pad " RETURN

Explanation: The Number Lock or Caps Lock keys ON may hinder extended key reads in Qbasic but not QB64!


(Return to Table of Contents)


See also



Navigation:
Go to Keyword Reference - Alphabetical
Go to Keyword Reference - By usage
Go to Main WIKI Page