_BUTTONCHANGE - QB64Official/qb64 GitHub Wiki

The _BUTTONCHANGE function returns -1 or 1 when a specified button number on a controller device has been pressed or released.

Syntax

press% = _BUTTONCHANGE(button_number%)

Description

  • The _DEVICEINPUT function should be read first to specify which device _BUTTONCHANGE is intended to check.
  • Values returned are -1 for a press and 1 when a button is released. No press or release event returns zero.
  • The button_number% must be a number which does not exceed the number of buttons found by the _LASTBUTTON function.
  • The number of _DEVICES must be read before using _DEVICE$, _DEVICEINPUT or _LASTBUTTON.
  • Note: The center mouse button is button number 2. Center can also be read using _MOUSEBUTTON(3).

Example(s)

Reading multiple controller device buttons, axis and wheels.


FOR i = 1 TO _DEVICES
  PRINT STR$(i) + ") " + _DEVICE$(i) + " Buttons:"; _LASTBUTTON(i); ",Axis:"; _LASTAXIS(i); ",Wheel:"; _LASTWHEEL(i)
NEXT

DO
  d& = _DEVICEINPUT
  IF d& THEN '             the device number cannot be zero!
    PRINT "Found"; d&;
    FOR b = 1 TO _LASTBUTTON(d&)
      PRINT _BUTTONCHANGE(b); _BUTTON(b);
    NEXT
    FOR a = 1 TO _LASTAXIS(d&)
      PRINT _AXIS(a);
    NEXT
    FOR w = 1 TO _LASTWHEEL(d&)
      PRINT _WHEEL(w);
    NEXT
    PRINT
  END IF
LOOP UNTIL INKEY$ = CHR$(27) 'escape key exit

END

Note: When there is no device control to read, a FOR...NEXT n = 1 TO 0 loop will not run thus avoiding a control function read error.

See Also