1<?php
2// The background-position value is an array containing two array for X and Y position correspondingly
3// each coordinate-position array, in its turn containes two values:
4// first, the numeric value of percentage or units
5// second, flag indication that this value is a percentage (true) or plain unit value (false)
6
7define('LENGTH_REGEXP',"(?:-?\d*\.?\d+(?:em|ex|px|in|cm|mm|pt|pc)\b|-?\d+(?:em|ex|px|in|cm|mm|pt|pc)\b)");
8define('PERCENTAGE_REGEXP',"\b\d+%");
9define('TEXT_REGEXP',"\b(?:top|bottom|left|right|center)\b");
10
11define('BG_POSITION_SUBVALUE_TYPE_HORZ',1);
12define('BG_POSITION_SUBVALUE_TYPE_VERT',2);
13
14class CSSBackgroundPosition extends CSSSubFieldProperty {
15  function get_property_code() {
16    return CSS_BACKGROUND_POSITION;
17  }
18
19  function get_property_name() {
20    return 'background-position';
21  }
22
23  function default_value() {
24    return new BackgroundPosition(0,true,
25                                  0,true);
26  }
27
28  function build_subvalue($value) {
29    if ($value === "left" ||
30        $value === "top") {
31      return array(0, true);
32    };
33
34    if ($value === "right" ||
35        $value === "bottom") {
36      return array(100, true);
37    };
38
39    if ($value === "center") {
40      return array(50, true);
41    };
42
43    if (substr($value, strlen($value)-1,1) === "%") {
44      return array((int)$value, true);
45    } else {
46      return array($value, false);
47    };
48  }
49
50  function build_value($x, $y) {
51    return array(CSSBackgroundPosition::build_subvalue($x),
52                 CSSBackgroundPosition::build_subvalue($y));
53  }
54
55  function detect_type($value) {
56    if ($value === "left" || $value === "right") { return BG_POSITION_SUBVALUE_TYPE_HORZ; };
57    if ($value === "top" || $value === "bottom") { return BG_POSITION_SUBVALUE_TYPE_VERT; };
58    return null;
59  }
60
61  // See CSS 2.1 'background-position' for description of possible values
62  //
63  function parse_in($value) {
64    if (preg_match("/(".LENGTH_REGEXP."|".PERCENTAGE_REGEXP."|".TEXT_REGEXP."|\b0\b)\s+(".LENGTH_REGEXP."|".PERCENTAGE_REGEXP."|".TEXT_REGEXP."|\b0\b)/", $value, $matches)) {
65      $x = $matches[1];
66      $y = $matches[2];
67
68      $type_x = CSSBackgroundPosition::detect_type($x);
69      $type_y = CSSBackgroundPosition::detect_type($y);
70
71      if (is_null($type_x) && is_null($type_y)) {
72        return CSSBackgroundPosition::build_value($x,$y);
73      };
74
75      if ($type_x == BG_POSITION_SUBVALUE_TYPE_HORZ ||
76          $type_y == BG_POSITION_SUBVALUE_TYPE_VERT) {
77        return CSSBackgroundPosition::build_value($x,$y);
78      };
79
80      return CSSBackgroundPosition::build_value($y,$x);
81    };
82
83    // These values should be processed separately at lastt
84    if (preg_match("/\b(top)\b/",$value))    { return array(array(50, true),  array(0, true)); };
85    if (preg_match("/\b(center)\b/",$value)) { return array(array(50, true),  array(50, true)); };
86    if (preg_match("/\b(bottom)\b/",$value)) { return array(array(50, true),  array(100, true)); };
87    if (preg_match("/\b(left)\b/",$value))   { return array(array(0, true),   array(50, true)); };
88    if (preg_match("/\b(right)\b/",$value))  { return array(array(100, true), array(50, true)); };
89
90    if (preg_match("/".LENGTH_REGEXP."|".PERCENTAGE_REGEXP."/", $value, $matches)) {
91      $x = $matches[0];
92      return CSSBackgroundPosition::build_value($x,"50%");
93    };
94
95    return null;
96  }
97
98  function parse($value) {
99    if ($value === 'inherit') {
100      return CSS_PROPERTY_INHERIT;
101    };
102
103    $value = CSSBackgroundPosition::parse_in($value);
104    return new BackgroundPosition($value[0][0], $value[0][1],
105                                  $value[1][0], $value[1][1]);
106  }
107}
108?>