_MOUSEBUTTON - QB64Official/qb64 GitHub Wiki

The _MOUSEBUTTON function returns the button status of a specified mouse button when read after _MOUSEINPUT.

Syntax

buttonStatus%% = _MOUSEBUTTON(buttoNumber)

Parameter(s)

  • INTEGER buttoNumber designates the mouse button to read (See _DEVICES for more than 3).
    • 1 = Left mouse button
    • 2 = Right mouse button
    • 3 = Center or scroll button

Description

  • Returns -1 if the corresponding buttoNumber is pressed or zero when released.
  • Read _MOUSEINPUT first to return the current button up or down status. (See Example 2)
  • Button clicks and mouse movements will be remembered and should be cleared after an INPUT statement or other interruption.
  • To clear unread mouse input, use a _MOUSEINPUT loop that loops until it returns 0.
  • Use _DEVICE$ to find the "[MOUSE]" _DEVICES number to find the number of buttons available using _LASTBUTTON.
  • Note: The center mouse button can also be read as _BUTTON(2) on _DEVICEINPUT(2) when a mouse is present.

Example(s)

Finding the number of mouse buttons available in QB64. This could also be used for other controller devices.


FOR d = 1 TO _DEVICES  'number of input devices found
  dev$ = _DEVICE$(d)
  IF INSTR(dev$, "[MOUSE]") THEN buttons = _LASTBUTTON(d): EXIT FOR
NEXT
PRINT buttons; "mouse buttons available"

How to monitor when a button is down or wait until a mouse button is not held down.


PRINT "Hold down the left mouse button until you want to quit!"
DO
    i = _MOUSEINPUT ' read #1
    IF _MOUSEBUTTON(1) THEN PRINT "Left button down!": EXIT DO
LOOP
DO '                                                      need to wait
    i = _MOUSEINPUT '  read #2                         until the mouse
LOOP UNTIL NOT _MOUSEBUTTON(1) '                       button is released

PRINT "DONE!"

Checking for a click or a double-click by the user.


DO  'main program loop

  DO WHILE _MOUSEINPUT                'check mouse status
    buttondown = _MOUSEBUTTON(1)
  LOOP
  DO WHILE buttondown                 'check for button release
    i = _MOUSEINPUT
    buttondown = _MOUSEBUTTON(1)
    Click = 1
  LOOP

  IF Click = 1 THEN                   'if button was pressed and released
    t = TIMER + .3
    DO WHILE TIMER < t      'check for a second press within .3 seconds
      i = _MOUSEINPUT
      IF _MOUSEBUTTON(1) THEN Click = 2: EXIT DO
    LOOP
    IF Click = 2 THEN PRINT "Double click" ELSE PRINT "Click"
  END IF
  Click = 0: buttondown = 0            'reset where needed
LOOP UNTIL INKEY$ = CHR$(27)

Explanation: To find the current button status read _MOUSEINPUT repeatedly. The TIMER loop looks for a second click.

Verifying that a user clicked and released a mouse button on a program button.


SCREEN 12
LINE (250, 250)-(300, 300), 14, BF

DO
  Mouser mx, my, mb
  IF mb THEN
    IF mx >= 250 AND my >= 250 AND mx <= 300 AND my <= 300 THEN 'button down
      DO WHILE mb 'wait for button release
        Mouser mx, my, mb
      LOOP
      'verify mouse still in box area
      IF mx >= 250 AND my >= 250 AND mx <= 300 AND my <= 300 THEN PRINT "Click verified on yellow box!"
    END IF
  END IF
LOOP

SUB Mouser (x, y, b)
mi = _MOUSEINPUT
b = _MOUSEBUTTON(1)
x = _MOUSEX
y = _MOUSEY
END SUB

Explanation: The mouse SUB has no internal _MOUSEINPUT loop so that no button presses, releases or moves are missed. If the above read procedure goes to another one, it may be advisable to skip over unread input in a _MOUSEINPUT only loop.


SUB Catchup
DO WHILE _MOUSEINPUT: LOOP 
END SUB

The above procedure can be used to catch up after INPUT, LINE INPUT or INPUT$ delays when mouse input may accumulate.

Combining mouse button or keyboard selections in a menu or test:


DO 'main program loop in demo only
  LOCATE 10, 10: PRINT "A" 'position A, B & C in same position on every question
  LOCATE 12, 10: PRINT "B"
  LOCATE 14, 10: PRINT "C" 'demo only

  DO: _LIMIT 10 'get user answer loop
    DO WHILE _MOUSEINPUT: LOOP 'read mouse
    K$ = UCASE$(INKEY$) 'read keypresses also
    x% = _MOUSEX
    y% = _MOUSEY
    Lclick = _MOUSEBUTTON(1)

    LOCATE 20, 10: PRINT x%, y%, Lclick 'only used to find mouse coordinates
    IF x% = 10 AND y% = 10 AND Lclick THEN 'position clicked
      DO
        i = _MOUSEINPUT
        x% = _MOUSEX
        y% = _MOUSEY
      LOOP WHILE _MOUSEBUTTON(1)
      IF x% = 10 AND y% = 10 THEN K$ = "A" 'position released
    END IF
    IF x% = 10 AND y% = 12 AND Lclick THEN 'position clicked
      DO
        i = _MOUSEINPUT
        x% = _MOUSEX
        y% = _MOUSEY
      LOOP WHILE _MOUSEBUTTON(1)
      IF x% = 10 AND y% = 12 THEN K$ = "B" 'position released
    END IF
    IF x% = 10 AND y% = 14 AND Lclick THEN 'position clicked
      DO
        i = _MOUSEINPUT
        x% = _MOUSEX
        y% = _MOUSEY
      LOOP WHILE _MOUSEBUTTON(1)
      IF x% = 10 AND y% = 14 THEN K$ = "C" 'position released
    END IF
  LOOP UNTIL K$ = "A" OR K$ = "B" OR K$ = "C" 'GOTO next question

  IF LEN(K$) THEN 'DEMO ONLY
    LOCATE 22, 35: PRINT "  Answer = "; K$ 'display user answer at location
    _DELAY 2 'allow time for user to view answer
    LOCATE 22, 35: PRINT "SELECT AGAIN"
    K$ = "" 'reset K$
  END IF
LOOP 'DEMO only loop use red X box to quit

Explanation: User can cancel letter selection by moving pointer off letter before releasing the left mouse button.

See Also