A drop-in replacement for wordwrap() for proportional fonts

pwordwrap.php

<?php

/**
 * Proportional word-wrap (approximation)
 *
 * Attempts to work as a drop-in replacement for wordwrap()
 *
 * Based on http://www.php.net/manual/en/function.wordwrap.php#82580
 */
function pwordwrap($str, $width=75, $break="\n")
{
  $width *= 0.4;
  
  static $charwidth = array(
    0 => 0.1847, 
    1 => 0.2753,
    2 => 0.3659,
    3 => 0.4565,
    4 => 0.5471,
    5 => 0.6377,
    6 => 0.7282,
    7 => 0.9094,
    8 => 1,
  );
  
  static $charset = array(
    33 => 0, # !
    34 => 2, # "
    35 => 4, # #
    36 => 4, # $
    37 => 7, # %
    38 => 5, # &
    39 => 0, # '
    40 => 2, # (
    41 => 2, # )
    42 => 2, # *
    43 => 4, # +
    44 => 1, # ,
    45 => 2, # -
    46 => 1, # .
    47 => 1, # /
    48 => 4, # 0
    49 => 4, # 1
    50 => 4, # 2
    51 => 4, # 3
    52 => 4, # 4
    53 => 4, # 5
    54 => 4, # 6
    55 => 4, # 7
    56 => 4, # 8
    57 => 4, # 9
    58 => 1, # :
    59 => 1, # ;
    60 => 4, # <
    61 => 4, # =
    62 => 4, # >
    63 => 4, # ?
    64 => 8, # @
    65 => 6, # A
    66 => 5, # B
    67 => 5, # C
    68 => 5, # D
    69 => 4, # E
    70 => 4, # F
    71 => 6, # G
    72 => 5, # H
    73 => 0, # I
    74 => 3, # J
    75 => 5, # K
    76 => 4, # L
    77 => 6, # M
    78 => 5, # N
    79 => 6, # O
    80 => 4, # P
    81 => 6, # Q
    82 => 5, # R
    83 => 5, # S
    84 => 4, # T
    85 => 5, # U
    86 => 6, # V
    87 => 7, # W
    88 => 5, # X
    89 => 6, # Y
    90 => 5, # Z
    91 => 1, # [
    92 => 1, # \
    93 => 1, # ]
    94 => 3, # ^
    95 => 4, # _
    96 => 2, # `
    97 => 4, # a
    98 => 4, # b
    99 => 4, # c
    100 => 4, # d
    101 => 4, # e
    102 => 2, # f
    103 => 4, # g
    104 => 4, # h
    105 => 0, # i
    106 => 0, # j
    107 => 3, # k
    108 => 0, # l
    109 => 6, # m
    110 => 4, # n
    111 => 4, # o
    112 => 4, # p
    113 => 4, # q
    114 => 2, # r
    115 => 4, # s
    116 => 1, # t
    117 => 4, # u
    118 => 4, # v
    119 => 7, # w
    120 => 4, # x
    121 => 4, # y
    122 => 4, # z
    123 => 2, # {
    124 => 0, # |
    125 => 2, # }
    126 => 4, # ~
  );
  
  $lines = array();
  $line = '';
  $word = '';
  $wordw = 0;
  $linew = 0;

  for ($i=0; $i<strlen($str); $i++)
  {
    $char = substr($str, $i, 1);
    
    if ($char === ' ')
    {
      $word = trim($word);
      
      if (strlen($word))
      {
        if ($linew + $wordw >= $width)
        {
          $lines[] = $line;
          $line = $word;
          $linew = $wordw;
        }
        else
        {
          $line .= (strlen($line) ? ' ' : '') . $word;
          $linew += $wordw;
        }
      }
      
      $word = '';
      $wordw = 0;
    }
    else if ($char == "\n")
    {
      $lines[] = $line . ' ' . $word;
      $line = '';
      $linew = 0;
      $word = '';
      $wordw = 0;
    }
    else
    {
      $word .= $char;
      $wordw += @$charwidth[$charset[ord($char)]];
    }
  }
  
  if (strlen($word))
    $line .= ' '.$word;
  
  if (strlen($line))
    $lines[] = $line;
  
  return implode($break, $lines);
}