PHP获取一段文本显示点阵宽度和高度的方法

define("F_SIZE", 8);
define("F_FONT", "arial.ttf");
function get_bbox($text){
  return imagettfbbox(F_SIZE, 0, F_FONT, $text);
}
function text_height ($text) {
  $box = get_bbox($text);
  $height = $box[3] - $box[5];
  return $height;
}
function text_width ($text) {
  $box = get_bbox($text);
  $width = $box[4] - $box[6];
  return $width;
}