This is a JavaScript solution wrapped in perl which I did for a project a couple months ago. merlyn is quite right, of course, about XHTML being unpredictable in different browsers and user settings. I usually do percentage and em based layouts to try to compensate for this but there is no perfect solution.

You can transfer the "algorithm" to perl code pretty easily. It's just trying to get the text area somewhere between 3 and (update 42) 40 ems high and fit the text inside as well as possible. Takes into account character count and line breaks and tries to get a reasonable middle ground. You can play with it dynamically and salt the settings and CSS to taste. 

use CGI qw(:standard);

print
    header(),
    start_html(-title => 'Textarea madness!',
               -script=> <<'EndJS',
 function fixTextarea ( elemId ) {
    var box = document.getElementById(elemId);
    var height = Math.floor( box.value.length / 50 );
    var newlines = box.value.match(/(\n)/g);
    if ( newlines ) height += Math.floor( newlines.length * .7 ) + 3;
    if ( height < 3 ) height = 3;
    if ( height > 40 ) height = 40;
    box.style.height = height + 'em';
 }
EndJS
              ),
    h2("Textarea with JavaScript assisted dynamic resize"),
    start_form(),
    textarea(
             -style => 'width:40em;line-height:120%;overflow:auto;',
             -id => 'response',
             -onfocus => "fixTextarea('response')",
             -onkeypress => "fixTextarea('response')",
             -name => 'response',
            ),
    script({-type=>'text/javascript'}, # call it up front
           "fixTextarea('response')"
          ),
    end_form();

[download]

In reply to Re: Estimating height of TEXTAREA from content by Your Mother
in thread Estimating height of TEXTAREA from content by tomazos

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