$wrap is not the problem slecting wise (both methods offset the same ammount) non wrapped lines still return 1
By non-wrapped lines I mean "lines added with /aline without the -p switch". If such lines are long, $wrap() returns a number > 1, but in the main window they occupy only 1 physical line. The errors caused by this difference can accumulate, resulting in a big offset from the middle, like Line 77 in the example.
In this respect, our versions are equivalent: all mine does is speed up the the whole thing. As I said before, it doesn't solve the problem nor do I know of a way that does fully, at least not without storing the wrap state of each line that is added (and even then the alignment won't be perfect because /sline 'jumps' between entire lines, not wrapped physical lines).
That said, and provided the above kind of error doesn't get too big, the situation can get a little better if, before /sline makes the next jump, the script checks whether it will end up pushing the highlighted text up further from the middle than before. Here's a version that implements this:
alias selectmiddleline {
var %x = $1, %wanted = $calc($window(@ex1).dh / 2 / $window(@ex1).fontsize), %t
window -hf @wrap -1 -1 $window(@ex1).dw $window(@ex1).dh
while $line(@ex1,%x) != $null {
%t = $line(@wrap,0)
echo -h @wrap $v1
if $calc($line(@wrap,0) - %wanted) > 0 {
if ($v1 > $calc(%wanted - %t)) dec %x
sline -a @ex1 %x | close -@ @wrap | return
}
inc %x
}
close -@ @wrap
sline -a @ex1 $line(@ex1,0)
}
