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 */
44class HTMLPurifier_AttrDef_CSS_BackgroundPosition extends HTMLPurifier_AttrDef
45{
46
47    /**
48     * @type HTMLPurifier_AttrDef_CSS_Length
49     */
50    protected $length;
51
52    /**
53     * @type HTMLPurifier_AttrDef_CSS_Percentage
54     */
55    protected $percentage;
56
57    public function __construct()
58    {
59        $this->length = new HTMLPurifier_AttrDef_CSS_Length();
60        $this->percentage = new HTMLPurifier_AttrDef_CSS_Percentage();
61    }
62
63    /**
64     * @param string $string
65     * @param HTMLPurifier_Config $config
66     * @param HTMLPurifier_Context $context
67     * @return bool|string
68     */
69    public function validate($string, $config, $context)
70    {
71        $string = $this->parseCDATA($string);
72        $bits = explode(' ', $string);
73
74        $keywords = array();
75        $keywords['h'] = false; // left, right
76        $keywords['v'] = false; // top, bottom
77        $keywords['ch'] = false; // center (first word)
78        $keywords['cv'] = false; // center (second word)
79        $measures = array();
80
81        $i = 0;
82
83        $lookup = array(
84            'top' => 'v',
85            'bottom' => 'v',
86            'left' => 'h',
87            'right' => 'h',
88            'center' => 'c'
89        );
90
91        foreach ($bits as $bit) {
92            if ($bit === '') {
93                continue;
94            }
95
96            // test for keyword
97            $lbit = ctype_lower($bit) ? $bit : strtolower($bit);
98            if (isset($lookup[$lbit])) {
99                $status = $lookup[$lbit];
100                if ($status == 'c') {
101                    if ($i == 0) {
102                        $status = 'ch';
103                    } else {
104                        $status = 'cv';
105                    }
106                }
107                $keywords[$status] = $lbit;
108                $i++;
109            }
110
111            // test for length
112            $r = $this->length->validate($bit, $config, $context);
113            if ($r !== false) {
114                $measures[] = $r;
115                $i++;
116            }
117
118            // test for percentage
119            $r = $this->percentage->validate($bit, $config, $context);
120            if ($r !== false) {
121                $measures[] = $r;
122                $i++;
123            }
124        }
125
126        if (!$i) {
127            return false;
128        } // no valid values were caught
129
130        $ret = array();
131
132        // first keyword
133        if ($keywords['h']) {
134            $ret[] = $keywords['h'];
135        } elseif ($keywords['ch']) {
136            $ret[] = $keywords['ch'];
137            $keywords['cv'] = false; // prevent re-use: center = center center
138        } elseif (count($measures)) {
139            $ret[] = array_shift($measures);
140        }
141
142        if ($keywords['v']) {
143            $ret[] = $keywords['v'];
144        } elseif ($keywords['cv']) {
145            $ret[] = $keywords['cv'];
146        } elseif (count($measures)) {
147            $ret[] = array_shift($measures);
148        }
149
150        if (empty($ret)) {
151            return false;
152        }
153        return implode(' ', $ret);
154    }
155}
156
157// vim: et sw=4 sts=4
158