sensekey

sensekey — Returns the ASCII code of a key that has been pressed.

Description

Returns the ASCII code of a key that has been pressed, or -1 if no key has been pressed.

Syntax

kres[, kkeydown] sensekey

Performance

kres - returns the ASCII value of a key which is pressed or released.

kkeydown - returns 1 if the key was pressed, 0 if it was released or if there is no key event.

kres can be used to read keyboard events from stdin and returns the ASCII value of any key that is pressed or released, or it returns -1 when there is no keyboard activity. The value of kkeydown is 1 when a key was pressed, or 0 otherwise. This behavior is emulated by default, so a key release is generated immediately after every key press. To have full functionality, FLTK can be used to capture keyboard events. FLpanel can be used to capture keyboard events and send them to the sensekey opcode, by adding an additional optional argument. See FLpanel for more information.

[Note] Note

This opcode can also be written as sense.

Examples

Here is an example of the sensekey opcode. It uses the file sensekey.csd.

Example 769. Example of the sensekey opcode.

See the sections Real-time Audio and Command Line Flags for more information on using command line flags.

<CsoundSynthesizer>
<CsOptions>
; Select audio/midi flags here according to platform
; Audio out   Audio in
-odac           -iadc    ;;;RT audio I/O
; For Non-realtime ouput leave only the line below:
; -o sensekey.wav -W ;;; for file output any platform
</CsOptions>
<CsInstruments>

; Initialize the global variables.
sr = 44100
kr = 4410
ksmps = 10
nchnls = 1

; Instrument #1.
instr 1
  k1 sensekey
  printk2 k1
endin


</CsInstruments>
<CsScore>

; Play Instrument #1 for thirty seconds.
i 1 0 30
e


</CsScore>
</CsoundSynthesizer>


Here is what the output should look like when the "q" button is pressed...

q i1   113.00000
      

Here is an example of the sensekey opcode in conjucntion with FLpanel. It uses the file FLpanel-sensekey.csd.

Example 770. Example of the sensekey opcode using keyboard capture from an FLpanel.

<CsoundSynthesizer>
<CsOptions>
; Select audio/midi flags here according to platform
; Audio out   Audio in    No messages
-odac           -iadc     -d     ;;;RT audio I/O
; For Non-realtime ouput leave only the line below:
; -o FLpanel-sensekey.wav -W ;;; for file output any platform
</CsOptions>
<CsInstruments>
; Example by Johnathan Murphy

  sr	    =  44100
  ksmps	    =  128
  nchnls    =  2


	; ikbdcapture flag set to 1
  ikey	    init      1 		
 
	    FLpanel   "sensekey", 740, 340, 100, 250, 2, ikey
  gkasc, giasc	FLbutBank	2, 16, 8, 700, 300, 20, 20, -1
	    FLpanelEnd
	    FLrun

    instr 1

  kkey	    sensekey
  kprint    changed   kkey
	    FLsetVal  kprint, kkey, giasc

    endin

</CsInstruments>
<CsScore>
i1 0 60
e
</CsScore>
</CsoundSynthesizer>


The lit button in the FLpanel window shows the last key pressed.

Here is a more complex example of the sensekey opcode in conjucntion with FLpanel. It uses the file FLpanel-sensekey2.csd.

Example 771. Example of the sensekey opcode using keyboard capture from an FLpanel.

<CsoundSynthesizer>
<CsOptions>
; Select audio/midi flags here according to platform
; Audio out   Audio in    No messages
-odac         ; -iadc     -d     ;;;RT audio I/O
; For Non-realtime ouput leave only the line below:
; -o FLpanel-sensekey2.wav -W ;;; for file output any platform
</CsOptions>
<CsInstruments>
sr =  48000
ksmps =  32
nchnls =  1
; Example by Istvan Varga
; if the FLTK opcodes are commented out, sensekey will read keyboard
; events from stdin
        FLpanel "", 150, 50, 100, 100, 0, 1
        FLlabel 18, 10, 1, 0, 0, 0
        FLgroup "Keyboard Input", 150, 50, 0, 0, 0
        FLgroupEnd
        FLpanelEnd

        FLrun

        instr 1

ktrig1 init 1
ktrig2 init 1
nxtKey1:
k1, k2 sensekey
        if (k1 != -1 || k2 != 0) then
        printf "Key code = %02X, state = %d\n", ktrig1, k1, k2
ktrig1 =  3 - ktrig1
        kgoto nxtKey1
        endif
nxtKey2:
k3 sensekey
        if (k3 != -1) then
        printf "Character = '%c'\n", ktrig2, k3
ktrig2 =  3 - ktrig2
        kgoto nxtKey2
        endif

        endin

</CsInstruments>
<CsScore>
i 1 0 3600
e
</CsScore>
</CsoundSynthesizer>


The console output will look something like:


new alloc for instr 1:
Key code = 65, state = 1
Character = 'e'
Key code = 65, state = 0
Key code = 72, state = 1
Character = 'r'
Key code = 72, state = 0
Key code = 61, state = 1
Character = 'a'
Key code = 61, state = 0

See also

FLpanel, FLkeyIn

Credits

Author: John ffitch
University of Bath, Codemist. Ltd.
Bath, UK
October 2000

Examples written by Kevin Conder, Johnathan Murphy and Istvan Varga.

New in Csound version 4.09. Renamed in Csound version 4.10.