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70 lines
2.6 KiB
Plaintext
70 lines
2.6 KiB
Plaintext
{{QBDLDATE:05-20-2022}}
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{{QBDLTIME:23:09:32}}
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{{DISPLAYTITLE:_MOUSEWHEEL}}
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The [[_MOUSEWHEEL]] function returns a positive or negative [[INTEGER]] value indicating mouse scroll events since the last read of [[_MOUSEINPUT]].
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{{PageSyntax}}
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: {{Parameter|scrollAmount%}} = [[_MOUSEWHEEL]]
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{{PageDescription}}
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* Returns -1 when scrolling up and 1 when scrolling down with 0 indicating no movement since last read.
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* After an event 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.
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{{PageExamples}}
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''Example 1:'' Reading the cumulative mouse wheel "clicks".
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{{CodeStart}}
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DO: {{Cl|_LIMIT}} 100
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DO WHILE {{Cl|_MOUSEINPUT}}
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Scroll = Scroll + {{Cl|_MOUSEWHEEL}}
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LOCATE 10, 20: PRINT Scroll
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LOOP
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LOOP UNTIL INKEY$ = CHR$(13) ' press Enter to quit
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{{CodeEnd}}
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''Example 2:'' A simple text scrolling routine using the mouse wheel value to read a text array.
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{{CodeStart}}
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{{Cl|DIM}} Array$(100)
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{{Cl|LINE INPUT}} "Enter a file name with 100 or more lines of text: ", file$
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{{Cl|OPEN}} file$ {{Cl|FOR (file statement)|FOR}} {{Cl|INPUT (file mode)|INPUT}} {{Cl|AS}} #1
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{{Cl|DO...LOOP|DO}} {{Cl|UNTIL}} {{Cl|EOF}}(1)
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inputcount = inputcount + 1
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{{Cl|LINE INPUT (file statement)|LINE INPUT}} #1, Array$(inputcount)
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{{Cl|IF...THEN|IF}} inputcount = 100 {{Cl|THEN}} {{Cl|EXIT DO}}
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{{Cl|LOOP}}
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{{Cl|FOR...NEXT|FOR}} n = 1 {{Cl|TO}} 21: {{Cl|PRINT}} Array$(n): {{Cl|NEXT}}
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{{Cl|CLOSE}} #1
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DO
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{{Cl|DO...LOOP|DO}} {{Cl|WHILE}} {{Cl|_MOUSEINPUT}}
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{{Cl|IF...THEN|IF}} row >= 0 {{Cl|THEN}} row = row + {{Cl|_MOUSEWHEEL}} {{Cl|ELSE}} row = 0 'prevent under scrolling
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{{Cl|IF...THEN|IF}} row > inputcount - 20 {{Cl|THEN}} row = inputcount - 20 'prevent over scrolling
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{{Cl|IF...THEN|IF}} prevrow <> row {{Cl|THEN}} 'look for a change in row value
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{{Cl|IF...THEN|IF}} row > 0 {{Cl|AND (boolean)|AND}} row <= inputcount - 20 {{Cl|THEN}}
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{{Cl|CLS}}: {{Cl|LOCATE}} 2, 1
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{{Cl|FOR...NEXT|FOR}} n = row {{Cl|TO}} row + 20
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{{Cl|PRINT}} Array$(n)
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{{Cl|NEXT}}
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{{Cl|END IF}}
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{{Cl|END IF}}
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prevrow = row 'store previous row value
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{{Cl|LOOP}}
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{{Cl|LOOP}} {{Cl|UNTIL}} {{Cl|INKEY$}} > ""
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{{CodeEnd}}
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{{small|Code by Ted Weissgerber}}
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<center>Note: You will need a text file that is large enough for this example.</center>
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{{PageSeeAlso}}
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* [[_MOUSEX]], [[_MOUSEY]], [[_MOUSEBUTTON]]
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* [[_MOUSEINPUT]], [[_MOUSEMOVE]]
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* [[_MOUSESHOW]], [[_MOUSEHIDE]]
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* [[Controller Devices]]
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{{PageNavigation}}
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