Difference between revisions of "MOUSEWHEEL"

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{{DISPLAYTITLE:_MOUSEWHEEL}}
 
{{DISPLAYTITLE:_MOUSEWHEEL}}
The '''_MOUSEWHEEL''' function returns a positive or negative [[INTEGER]] value indicating mouse scroll clicks since the last read.
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The [[_MOUSEWHEEL]] function returns a positive or negative [[INTEGER]] value indicating mouse scroll events since the last read of [[_MOUSEINPUT]].
  
  
 
{{PageSyntax}}
 
{{PageSyntax}}
::: scroll% = '''_MOUSEWHEEL'''
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: {{Parameter|scrollAmount%}} = [[_MOUSEWHEEL]]
  
  
''Usage:''
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{{PageDescription}}
* A return value of 1 represent one "click" the mouse scroll wheel was moved toward the user.
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* Returns -1 when scrolling up and 1 when scrolling down with 0 indicating no movement since last read.
* A return value of -1 represent one "click" the mouse scroll wheel was moved away from the user.
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* After an event has been read, the value resets to 0 automatically so cumulative position values must be added.
* After a "click" has been read, the value resets to 0 automatically so cumulative position values must be added.
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* If no movement on the wheel has occurred since the last [[_MOUSEINPUT]] read, [[_MOUSEWHEEL]] returns 0.
* If no movement on the wheel has occurred since the last [[_MOUSEINPUT]] read, _MOUSEWHEEL returns 0.
 
  
  
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{{PageExamples}}
 
''Example 1:'' Reading the cumulative mouse wheel "clicks".
 
''Example 1:'' Reading the cumulative mouse wheel "clicks".
 
{{CodeStart}} '' ''
 
{{CodeStart}} '' ''
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{{CodeEnd}}
 
{{CodeEnd}}
 
{{small|Code by Ted Weissgerber}}
 
{{small|Code by Ted Weissgerber}}
<center>Note: QB64 comes with a text file called ''readme.txt'' that is large enough for this example.</center>
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<center>Note: You will need a text file that is large enough for this example.</center>
  
  
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* [[_MOUSEINPUT]], [[_MOUSEMOVE]]  
 
* [[_MOUSEINPUT]], [[_MOUSEMOVE]]  
 
* [[_MOUSESHOW]], [[_MOUSEHIDE]]
 
* [[_MOUSESHOW]], [[_MOUSEHIDE]]
* [[Controller_Devices]]
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* [[Controller Devices]]
  
  
 
{{PageNavigation}}
 
{{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



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