[REBOL] Text-List Slider Question (reply to a lost email)
From: brett::codeconscious::com at: 23-Apr-2002 0:39
Someone emailed me directly about a slider question for text-list.
Unfortunately I lost the message when my machine crashed. So if the
sender happens to be subscribed to this list - you're best off posting
your question here - it is not as likely to be lost! :^)
Nevertheless, I think it was something like - given an element how do
you set the slider to show it?
To which I believe the answer is that you need to ensure the textual
part is scrolled properly and the slider can then be synchronised with
that change.
In the text-list style (TL) there is a field TL/LC ("line count") that
holds the number of lines that can be displayed. Another field TL/SN
(perhaps "scroll number") that is equals the number of lines scrolled
off the top.
To be consistent with the default text-list functionality, TL/SN should
be less than or equal to (1 + length? head TL/LINES)
Finally to change the slider position modify TL/SLD/DATA.
This example code will scroll the line you click on to the top and
synchronise the slider to match.
tl-scroll-to: function [
face line-num
][max-scroll-num][
max-scroll-num: (1 + length? head face/lines) - face/lc
face/sn: line-num - 1
face/sld/data: face/sn / max-scroll-num
show face
]
view layout [
text-list 200x50 data copy system/locale/months [
if not empty? face/picked [
num: index? find face/lines first face/picked
tl-scroll-to face num
]
]
]
Brett.
