library/HTMLPurifier/AttrDef/CSS/BackgroundPosition.php

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