Working with images and text, we need to set image size based on font size is very useful for dynamic image processing. like CAPTCHA and text images. if you looking for PHP script to set image size based on font size here is the solution for you.
<?php
if($_GET['fontsize']!="" and is_numeric($_GET['fontsize']))
$size=$_GET['fontsize'];
else
$size=20;
define("F_SIZE", $size);
define("F_ANGLE", 0);
define("F_FONT", "verdana.ttf");
$text = "W3 Lessons";
$Leading=0;
$W=0;
$H=0;
$X=0;
$Y=0;
$_bx = imagettfbbox(F_SIZE, F_ANGLE, F_FONT, $text);
$s = preg_split("/\n]+/", $text); // Array of lines
$nL = count($s); // Number of lines
$W = ($W==0)?abs($_bx[2]-$_bx[0]):$W;
$H = ($H==0)?abs($_bx[5]-$_bx[3])+2+($nL>1?($nL*$Leading):0):$H;
$W*=1.05;
$H*=1.5;
$img = @imagecreate($W+8, $H) or die("Cannot Initialize new GD image stream");
$white = imagecolorallocate($img, 255,255,255);
$txtColor = imagecolorallocate($img, 29,56,131);
// Adjust padding right:
$W+=8;
$bgwhite = imagecolorallocatealpha($img,238,238,238,0);
imagefilledrectangle($img, 0, 0,$W,$H, $bgwhite);
$alpha = "".range("a", "z");
$alpha = $alpha.strtoupper($alpha).range(0, 9);
// Use the string to determine the height of a line
$_b = imageTTFBbox(F_SIZE, F_ANGLE, F_FONT, $alpha);
$_H = abs($_b[5]-$_b[3]);
$__H = 0;
// Use the string to determine the width of a line
$_b = imagettfbbox(F_SIZE, F_ANGLE, F_FONT, $text);
$_W = abs($_b[2]-$_b[0]);
// Final width and height
$_X = abs($W/2)-abs($_W/2);
$__H += $_H;
imagettftext($img, F_SIZE, F_ANGLE, $_X, $__H, $txtColor, F_FONT, $text);
header("Content-Type: image/png");
imagepng($img);
imagedestroy($img);
// END EMAIL IMAGE
exit();
?>
