Give the bounding box of a text rectangle using PostScript Type1 fonts in PHP

<?php/*from  w w w . ja  v  a2  s  .co m*/
// Create image handle
$im = imagecreatetruecolor(200, 200);

// Allocate colors
$black = imagecolorallocate($im, 0, 0, 0);
$white = imagecolorallocate($im, 255, 255, 255);

// Load the PostScript Font
$font = imagepsloadfont('font.pfm');

// Make a bounding box for the font
$bbox = imagepsbbox('Sample text is simple', $font, 12);

// Define our X and Y cordinates
$x = ($bbox[2] / 2) - 10;
$y = ($bbox[3] / 2) - 10;

// Write the font to the image
imagepstext($im, 'Sample text is simple', $font, 12, $black, $white, $x, $y);

// Output and free memory
header('Content-type: image/png');

imagepng($im);
imagedestroy($im);
?>