On Tuesday, April 22, 2003, at 07:12  PM, mckernon wrote:

> I'm tending to some of the remaining items on my to-do list, and one of
> them is letting users use their mouse wheel to scoll up and down on
> various part of Lightwright. I seem to recall that the Mac OS used to
> handle this automatically, but if it used to, it doesn't now.
>
> Any suggestions how I go about connecting vertical scroll bars with the
> mouse wheel? (Both OS9 and OSX).
>
Dr. Purves offered (on 23 Feb 03) the following (which certainly works 
in X):

There is no direct support in MacOS 8/9 for mouse wheels. An extension 
provided by the mouse vendor converts wheel changes into simulated 
mouse clicks in the up/down parts of a scroll bar.

In OS X you can try something like the example below. I can't test this 
because I don't have a mouse with a wheel. CarbonEvent handlers are 
simple to write and install; the demo may just work anyway :-)


'--------------
'~'A
'                       Runtime : Rntm Appearance.Incl
'                           CPU : Carbon
'~'B

/*
Simple detection of mouse wheel events in OS X.
A CarbonEvent handler for
{_kEventClassMouse, _kEventMouseWheelMoved}
is installed on the window.
Robert P.    23 Feb 2003
*/

include "Tlbx CarbonEvents.Incl"
end globals

local fn InstallMouseWheelHandler( w as WindowRef )
'~'1
dim as EventTypeSpec  mouseEvents
begin globals
dim as proc  sMouseWheelEventUPP // 'static' var
end globals

long if ( sMouseWheelEventUPP == _nil )
    sMouseWheelEventUPP = fn NewEventHandlerUPP( [Proc 
"MouseWheelHandler" ¬
    + _FBprocToProcPtrOffset] )
end if
mouseEvents.eventClass = _kEventClassMouse
mouseEvents.eventKind  = _kEventMouseWheelMoved

end fn = fn InstallEventHandler( fn GetWindowEventTarget( w ), ¬
      sMouseWheelEventUPP, 1, @mouseEvents, #0, #0 )


long if 0
"MouseWheelHandler"
enterproc fn MouseWheelHandler( nextHandler as EventHandlerCallRef, ¬
   theEvent as EventRef, userData as Ptr ) = OSStatus
'~'1
dim as OSStatus                ignore
dim as EventMouseWheelAxis   @ axis
dim as long                  @ delta

ignore = fn GetEventParameter( theEvent, _kEventParamMouseWheelAxis, ¬
    _typeMouseWheelAxis, #0, sizeof( axis ), #0, @axis )

ignore = fn GetEventParameter( theEvent, _kEventParamMouseWheelDelta, ¬
    _typeLongInteger, #0, sizeof( long ), #0, @delta )

print "Wheel axis: " axis  "  Delta: " delta"

exitproc = _noErr // we handled
end if


// Main program
'~'1
long if ( system( _sysVers ) < 1000 )
shutdown "Requires OS X"
end if

window 1
fn InstallMouseWheelHandler( window( _wndRef ) )

do
HandleEvents
until 0
'--------------

Robert P.
--
Ted Spencer
--
Nature, you see, is very difficult to rehearse, and nature has
a bad trick of missing its cues.
(Robertson Davies)