Difference between revisions of "MOUSEWHEEL"

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The '''_MOUSEWHEEL''' function returns an [[INTEGER]] value which can be negative or positive or 0.
{{DISPLAYTITLE:_MOUSEWHEEL}}
The [[_MOUSEWHEEL]] function returns a positive or negative [[INTEGER]] value indicating mouse scroll events since the last read of [[_MOUSEINPUT]].




''Syntax:'' scroll% = _MOUSEWHEEL
{{PageSyntax}}
: {{Parameter|scrollAmount%}} = [[_MOUSEWHEEL]]




* Positive values represent how many "clicks" the mouse wheel has been moved up.
{{PageDescription}}
* Negative values represent how many "clicks" the mouse wheel has been moved down.
* Returns -1 when scrolling up and 1 when scrolling down with 0 indicating no movement since last read.
* Return values are relative to the last time [[_MOUSEINPUT]] was used, so if no movement on the wheel has occurred since the last time, _MOUSEWHEEL returns 0.
* After an event has been read, the value resets to 0 automatically so cumulative position values must be added.
* If no movement on the wheel has occurred since the last [[_MOUSEINPUT]] read, [[_MOUSEWHEEL]] returns 0.




{{PageExamples}}
''Example 1:'' Reading the cumulative mouse wheel "clicks".
{{CodeStart}} '' ''
DO: {{Cl|_LIMIT}} 100
    DO WHILE {{Cl|_MOUSEINPUT}}
      Scroll = Scroll + {{Cl|_MOUSEWHEEL}}
      LOCATE 10, 20: PRINT Scroll
    LOOP
LOOP UNTIL INKEY$ = CHR$(13) ' press Enter to quit '' ''
{{CodeEnd}}


''See also:'' [[_MOUSEINPUT]], [[_MOUSEX]], [[_MOUSEY]], [[_MOUSEBUTTON]], [[_MOUSESHOW]], [[_MOUSEHIDE]]


''Example 2:'' A simple text scrolling routine using the mouse wheel value to read a text array.
{{CodeStart}} '' ''
{{Cl|DIM}} Array$(100)
{{Cl|LINE INPUT}} "Enter a file name with 100 or more lines of text: ", file$
{{Cl|OPEN}} file$ {{Cl|FOR (file statement)|FOR}} {{Cl|INPUT (file mode)|INPUT}} {{Cl|AS}} #1
{{Cl|DO...LOOP|DO}} {{Cl|UNTIL}} {{Cl|EOF}}(1)
  inputcount = inputcount + 1
  {{Cl|LINE INPUT (file statement)|LINE INPUT}} #1, Array$(inputcount)
  {{Cl|IF...THEN|IF}} inputcount = 100 {{Cl|THEN}} {{Cl|EXIT DO}}
{{Cl|LOOP}}
{{Cl|FOR...NEXT|FOR}} n = 1 {{Cl|TO}} 21: {{Cl|PRINT}} Array$(n): {{Cl|NEXT}}
{{Cl|CLOSE}} #1
DO
  {{Cl|DO...LOOP|DO}} {{Cl|WHILE}} {{Cl|_MOUSEINPUT}}
    {{Cl|IF...THEN|IF}} row >= 0 {{Cl|THEN}} row = row + {{Cl|_MOUSEWHEEL}} {{Cl|ELSE}} row = 0  'prevent under scrolling
    {{Cl|IF...THEN|IF}} row > inputcount - 20 {{Cl|THEN}} row = inputcount - 20    'prevent over scrolling
    {{Cl|IF...THEN|IF}} prevrow <> row {{Cl|THEN}} 'look for a change in row value
      {{Cl|IF...THEN|IF}} row > 0 {{Cl|AND (boolean)|AND}} row <= inputcount - 20 {{Cl|THEN}}
        {{Cl|CLS}}: {{Cl|LOCATE}} 2, 1
        {{Cl|FOR...NEXT|FOR}} n = row {{Cl|TO}} row + 20
          {{Cl|PRINT}} Array$(n)
        {{Cl|NEXT}}
      {{Cl|END IF}}
    {{Cl|END IF}}
    prevrow = row 'store previous row value
  {{Cl|LOOP}}
{{Cl|LOOP}} {{Cl|UNTIL}} {{Cl|INKEY$}} > "" '' ''
{{CodeEnd}}
{{small|Code by Ted Weissgerber}}
<center>Note: You will need a text file that is large enough for this example.</center>




==Navigation:==
{{PageSeeAlso}}
* [[_MOUSEX]], [[_MOUSEY]], [[_MOUSEBUTTON]]
* [[_MOUSEINPUT]], [[_MOUSEMOVE]]
* [[_MOUSESHOW]], [[_MOUSEHIDE]]
* [[Controller Devices]]


[[Keyword_Reference_-_Alphabetical|Go to Keyword Reference - Alphabetical]]


[[Keyword Reference - By usage|Go to Keyword Reference - By usage]]
{{PageNavigation}}

Latest revision as of 17:46, 9 September 2017

The _MOUSEWHEEL function returns a positive or negative INTEGER value indicating mouse scroll events since the last read of _MOUSEINPUT.


Syntax

scrollAmount% = _MOUSEWHEEL


Description

  • Returns -1 when scrolling up and 1 when scrolling down with 0 indicating no movement since last read.
  • After an event has been read, the value resets to 0 automatically so cumulative position values must be added.
  • If no movement on the wheel has occurred since the last _MOUSEINPUT read, _MOUSEWHEEL returns 0.


Examples

Example 1: Reading the cumulative mouse wheel "clicks".

DO: _LIMIT 100 DO WHILE _MOUSEINPUT Scroll = Scroll + _MOUSEWHEEL LOCATE 10, 20: PRINT Scroll LOOP LOOP UNTIL INKEY$ = CHR$(13) ' press Enter to quit


Example 2: A simple text scrolling routine using the mouse wheel value to read a text array.

DIM Array$(100) LINE INPUT "Enter a file name with 100 or more lines of text: ", file$ OPEN file$ FOR INPUT AS #1 DO UNTIL EOF(1) inputcount = inputcount + 1 LINE INPUT #1, Array$(inputcount) IF inputcount = 100 THEN EXIT DO LOOP FOR n = 1 TO 21: PRINT Array$(n): NEXT CLOSE #1 DO DO WHILE _MOUSEINPUT IF row >= 0 THEN row = row + _MOUSEWHEEL ELSE row = 0 'prevent under scrolling IF row > inputcount - 20 THEN row = inputcount - 20 'prevent over scrolling IF prevrow <> row THEN 'look for a change in row value IF row > 0 AND row <= inputcount - 20 THEN CLS: LOCATE 2, 1 FOR n = row TO row + 20 PRINT Array$(n) NEXT END IF END IF prevrow = row 'store previous row value LOOP LOOP UNTIL INKEY$ > ""

Code by Ted Weissgerber
Note: You will need a text file that is large enough for this example.


See also



Navigation:
Keyword Reference - Alphabetical
Keyword Reference - By Usage
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