library/HTMLPurifier/AttrDef/CSS/BackgroundPosition.php

   1 <?php
   2
   3 /* W3C says:
   4     [ // adjective and number must be in correct order, even if
   5       // you could switch them without introducing ambiguity.
   6       // some browsers support that syntax
   7         [
   8             <percentage> | <length> | left | center | right
   9         ]
  10         [
  11             <percentage> | <length> | top | center | bottom
  12         ]?
  13     ] |
  14     [ // this signifies that the vertical and horizontal adjectives
  15       // can be arbitrarily ordered, however, there can only be two,
  16       // one of each, or none at all
  17         [
  18             left | center | right
  19         ] ||
  20         [
  21             top | center | bottom
  22         ]
  23     ]
  24     top, left = 0%
  25     center, (none) = 50%
  26     bottom, right = 100%
  27 */
  28
  29 /* QuirksMode says:
  30     keyword + length/percentage must be ordered correctly, as per W3C
  31
  32     Internet Explorer and Opera, however, support arbitrary ordering. We
  33     should fix it up.
  34
  35     Minor issue though, not strictly necessary.
  36 */
  37
  38 // control freaks may appreciate the ability to convert these to
  39 // percentages or something, but it's not necessary
  40
  41 /**
  42  * Validates the value of background-position.
  43  */
  44 class HTMLPurifier_AttrDef_CSS_BackgroundPosition extends HTMLPurifier_AttrDef
  45 {
  46
  47     protected $length;
  48     protected $percentage;
  49
  50     public function __construct() {
  51         $this->length     = new HTMLPurifier_AttrDef_CSS_Length();
  52         $this->percentage = new HTMLPurifier_AttrDef_CSS_Percentage();
  53     }
  54
  55     public function validate($string, $config, $context) {
  56         $string = $this->parseCDATA($string);
  57         $bits = explode(' ', $string);
  58
  59         $keywords = array();
  60         $keywords['h'] = false; // left, right
  61         $keywords['v'] = false; // top, bottom
  62         $keywords['ch'] = false; // center (first word)
  63         $keywords['cv'] = false; // center (second word)
  64         $measures = array();
  65
  66         $i = 0;
  67
  68         $lookup = array(
  69             'top' => 'v',
  70             'bottom' => 'v',
  71             'left' => 'h',
  72             'right' => 'h',
  73             'center' => 'c'
  74         );
  75
  76         foreach ($bits as $bit) {
  77             if ($bit === '') continue;
  78
  79             // test for keyword
  80             $lbit = ctype_lower($bit) ? $bit : strtolower($bit);
  81             if (isset($lookup[$lbit])) {
  82                 $status = $lookup[$lbit];
  83                 if ($status == 'c') {
  84                     if ($i == 0) {
  85                         $status = 'ch';
  86                     } else {
  87                         $status = 'cv';
  88                     }
  89                 }
  90                 $keywords[$status] = $lbit;
  91                 $i++;
  92             }
  93
  94             // test for length
  95             $r = $this->length->validate($bit, $config, $context);
  96             if ($r !== false) {
  97                 $measures[] = $r;
  98                 $i++;
  99             }
 100
 101             // test for percentage
 102             $r = $this->percentage->validate($bit, $config, $context);
 103             if ($r !== false) {
 104                 $measures[] = $r;
 105                 $i++;
 106             }
 107
 108         }
 109
 110         if (!$i) return false; // no valid values were caught
 111
 112         $ret = array();
 113
 114         // first keyword
 115         if     ($keywords['h'])     $ret[] = $keywords['h'];
 116         elseif ($keywords['ch']) {
 117             $ret[] = $keywords['ch'];
 118             $keywords['cv'] = false; // prevent re-use: center = center center
 119         }
 120         elseif (count($measures))   $ret[] = array_shift($measures);
 121
 122         if     ($keywords['v'])     $ret[] = $keywords['v'];
 123         elseif ($keywords['cv'])    $ret[] = $keywords['cv'];
 124         elseif (count($measures))   $ret[] = array_shift($measures);
 125
 126         if (empty($ret)) return false;
 127         return implode(' ', $ret);
 128
 129     }
 130
 131 }
 132
 133 // vim: et sw=4 sts=4