chasing the thumb in a scrollbar
Phil Davis
revdev at pdslabs.net
Fri Feb 6 01:27:18 EST 2009
Mark Swindell wrote:
> The thumbPosition will give you the position of the thumb relative to
> the endvalue of the scrollbar itself. So that if the scrollbar's
> endvalue is set to 100 (default) and it's halfway along, the thumbpos
> will be 50. If the endvalue is set to 200, it will show 100. But I'm
> trying to place a graphic based on the actual thumb position relative
> to the screen, not the scrollbar.
>
> Mark
Hi Mark,
This isn't perfect but it's a starting point if you want to do it this
way. I broke the formula down to its parts instead of doing a one-liner:
on scrollbarDrag pNewPosition
put the left of me into tWindowOffset
put the thumbSize of me div 2 into tThumbOffset
put (the endValue of me - the startValue of me) into tMyUnits
put the width of me / tMyUnits into tPixelsPerUnit
put round(tPixelsPerUnit * (pNewPosition - tThumbOffset)) into tThumbH
set the right of btn 1 to (tThumbH) + tWindowOffset
end scrollbarDrag
I created a button that follows the thumb around - not perfectly, but
you want to tweak it anyway, right? ;o)
Hope this helps -
Phil Davis
> On Feb 5, 2009, at 9:44 PM, dunbarx wrote:
>
>> mark.
>>
>> So this is a scrollbar control, not a field. Right. I have not played
>> with these yet, but don't I remember that there is a property that
>> indicates the relative position of the thumb with respect to the
>> amount of "progress" in the control, and isn't this even closer to
>> what is needed without all that stuff I mentioned?
>>
>> Craig Newman
>>
>>
>> On Feb 6, 2009, at 12:38:06 AM, "Mark Swindell"
>> <mdswindell at cruzio.com> wrote:
>> That won't work in this case as it's just a horizontal scrollbar not
>> attached to a field or group.
>>
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--
Phil Davis
PDS Labs
Professional Software Development
http://pdslabs.net
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