jetpack / modules / latex.php

latex.php in Jetpack – WP Security, Backup, Speed, & Growth 11.8.4, at modules/latex.php

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1	<?php
2	/**
3	* Module Name: Beautiful Math
4	* Module Description: Use the LaTeX markup language to write mathematical equations and formulas
5	* Sort Order: 12
6	* First Introduced: 1.1
7	* Requires Connection: No
8	* Auto Activate: No
9	* Module Tags: Writing
10	* Feature: Writing
11	* Additional Search Queries: latex, math, equation, equations, formula, code
12	*
13	* @package automattic/jetpack
14	*/
15
16	/**
17	* LaTeX support.
18	*
19	* Backward compatibility requires support for both "[latex][/latex]", and
20	* "$latex $" shortcodes.
21	*
22	* $latex e^{\i \pi} + 1 = 0$ -> [latex]e^{\i \pi} + 1 = 0[/latex]
23	* $latex [a, b]$ -> [latex][a, b][/latex]
24	*/
25
26	/**
27	* Markup LaTeX content.
28	*
29	* @param string $content Post or comment contents to markup.
30	*/
31	function latex_markup( $content ) {
32	$textarr = wp_html_split( $content );
33
34	$regex = '%
35	\$latex(?:=\s*\|\s+)
36	((?:
37	[^$]+ # Not a dollar
38	\|
39	(?<=(?<!\\\\)\\\\)\$ # Dollar preceded by exactly one slash
40	)+)
41	(?<!\\\\)\$ # Dollar preceded by zero slashes
42	%ix';
43
44	foreach ( $textarr as &$element ) {
45	if ( '' === $element \|\| '<' === $element[0] ) {
46	continue;
47	}
48
49	if ( false === stripos( $element, '$latex' ) ) {
50	continue;
51	}
52
53	$element = preg_replace_callback( $regex, 'latex_src', $element );
54	}
55
56	return implode( '', $textarr );
57	}
58
59	/**
60	* Process LaTeX string to rendered image.
61	*
62	* @param array $matches Matched regex results.
63	*/
64	function latex_src( $matches ) {
65	$latex = $matches[1];
66
67	$bg = latex_get_default_color( 'bg' );
68	$fg = latex_get_default_color( 'text', '000' );
69	$s = 0;
70
71	$latex = latex_entity_decode( $latex );
72	if ( preg_match( '/.+(&fg=[0-9a-f]{6}).*/i', $latex, $fg_matches ) ) {
73	$fg = substr( $fg_matches[1], 4 );
74	$latex = str_replace( $fg_matches[1], '', $latex );
75	}
76	if ( preg_match( '/.+(&bg=[0-9a-f]{6}).*/i', $latex, $bg_matches ) ) {
77	$bg = substr( $bg_matches[1], 4 );
78	$latex = str_replace( $bg_matches[1], '', $latex );
79	}
80	if ( preg_match( '/.+(&s=[0-9-]{1,2}).*/i', $latex, $s_matches ) ) {
81	$s = (int) substr( $s_matches[1], 3 );
82	$latex = str_replace( $s_matches[1], '', $latex );
83	}
84
85	return latex_render( $latex, $fg, $bg, $s );
86	}
87
88	/**
89	* Get the default color for an attribute.
90	*
91	* @param string $color Attribute to color (e.g. bg).
92	* @param string $default_color Default fallback color to use.
93	*/
94	function latex_get_default_color( $color, $default_color = 'ffffff' ) {
95	global $themecolors;
96	return isset( $themecolors[ $color ] ) ? $themecolors[ $color ] : $default_color;
97	}
98
99	/**
100	* Decode special characters in a LaTeX string.
101	*
102	* @param string $latex Character encoded content.
103	*/
104	function latex_entity_decode( $latex ) {
105	return str_replace( array( '<', '>', '"', ''', '&', '&', "\n", "\r" ), array( '<', '>', '"', "'", '&', '&', ' ', ' ' ), $latex );
106	}
107
108	/**
109	* Returns the URL for the server-side rendered image of LaTeX.
110	*
111	* @param string $latex LaTeX string.
112	* @param string $fg Foreground color.
113	* @param string $bg Background color.
114	* @param int $s Matches.
115	*
116	* @return string Image URL for the rendered LaTeX.
117	*/
118	function latex_render( $latex, $fg, $bg, $s = 0 ) {
119	$url = add_query_arg(
120	urlencode_deep(
121	array(
122	'latex' => $latex,
123	'bg' => $bg,
124	'fg' => $fg,
125	's' => $s,
126	'c' => '20201002', // cache buster. Added 2020-10-02 after server migration caused faulty rendering.
127	)
128	),
129	( is_ssl() ? 'https://' : 'http://' ) . 's0.wp.com/latex.php'
130	);
131
132	$alt = str_replace( '\\', '\', esc_attr( $latex ) );
133
134	return sprintf(
135	'<img src="%1$s" alt="%2$s" class="latex" />',
136	esc_url( $url ),
137	$alt
138	);
139	}
140
141	/**
142	* The shortcode way. The attributes are the same as the old ones - 'fg' and 'bg', instead of foreground
143	* and background, and 's' is for the font size.
144	*
145	* Example: [latex s=4 bg=00f fg=ff0]\LaTeX[/latex]
146	*
147	* @param array $atts Shortcode attributes.
148	* @param string $content Content to format.
149	*/
150	function latex_shortcode( $atts, $content = '' ) {
151	$attr = shortcode_atts(
152	array(
153	's' => 0,
154	'bg' => latex_get_default_color( 'bg' ),
155	'fg' => latex_get_default_color( 'text', '000' ),
156	),
157	$atts,
158	'latex'
159	);
160
161	return latex_render( latex_entity_decode( $content ), $attr['fg'], $attr['bg'], $attr['s'] );
162	}
163
164	/**
165	* LaTeX needs to be untexturized.
166	*
167	* @param array $shortcodes Array of shortcodes not to texturize.
168	*/
169	function latex_no_texturize( $shortcodes ) {
170	$shortcodes[] = 'latex';
171	return $shortcodes;
172	}
173	add_filter( 'no_texturize_shortcodes', 'latex_no_texturize' );
174
175	add_filter( 'the_content', 'latex_markup', 9 ); // Before wptexturize.
176	add_filter( 'comment_text', 'latex_markup', 9 ); // Before wptexturize.
177	add_shortcode( 'latex', 'latex_shortcode' );
178