On occasion, HyperCard programmers need to know how many lines are in a
field. There are two ways of looking at this question. One is how to
determine the number of display lines in a field due to word wrap. The other
thing you might want to know is how many return characters are in a field.
HyperCard tells you this, if you ask how many lines are in the given field.
The question of how many display lines are in a field is a bit more
difficult. The script at the end of this article can get this information
for you.
The script works by taking the given field, changing it to a scrolling field
(if it isn't already), and then making the height of it the smallest multiple
of the size of the text height greater than 50 pixels. This is done because
the next step it does is to scroll from the top of the field to the bottom.
If field is not at least 50 pixels high, it will not scroll.
Once HyperCard has scrolled to the bottom of the field, it can tell you how
much text has been scrolled off. With this information, the size of the
window, and the height of the text, you can calculate the number of lines.
The height of the field is made smaller, because if the visible field is not
filled enough to scroll, there is no way to determine how much of the field
(number of lines) has text in it. However, as stated above, the field also
has to be tall enough to scroll. The combination of these two requirements
means that the script below can determine the number display lines, if that
number is greater than 3. If there are less than three lines, it tells you
there are 3, anyway. Here's the script:
on mouseUp
put empty
lock screen
put the style of fld test into holdStyle
-- so you can reset the style
get the rect of fld test
put it into holdRect
-- so you can reset the rect
if the style of fld test does not "scrolling"
then
set the style of fld test to "scrolling"
add 15 to item 3 of it
-- to account for the scroll bar
end if
set the scroll of fld test to 0
-- get to the top
put (item 2 of the rect of fld test + 50) into item 4 of it
-- make the field as small as possible to account for small amounts
-- data and still scroll
set the rect of fld test to it
drag from item 3 of the rect of fld test - 8,item 2 of the rect of
fld test + 20 to item 3 of the rect of fld test - 8,item 4 of
the rect of fld test - 20
-- grab the thumb and drag to the end of the field
put the scroll of fld test + (item 4 of the rect of fld test - item
2 of the rect of fld test) into fldHeight
-- gives the height of the field in pixels
put fldHeight / the textHeight of fld test into numLines
-- gives the number of displayed lines
-- NOTE! this does not account for carriage returns in the field
put "the number of lines is" && numLines
set the style of fld test to holdStyle
set the rect of fld test to holdRect
unlock screen
end mouseUp