← All changes | modules/latex.php +181 -0 16.2-beta → 16.3 View file →

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	1	+<?php
	2	+/**
	3	+ * Module Name: Beautiful Math
	4	+ * Module Description: Add beautifully formatted math equations to your posts and pages using LaTeX.
	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	+if ( ! defined( 'ABSPATH' ) ) {
	17	+ exit( 0 );
	18	+}
	19	+
	20	+/**
	21	+ * LaTeX support.
	22	+ *
	23	+ * Backward compatibility requires support for both "[latex][/latex]", and
	24	+ * "$latex $" shortcodes.
	25	+ *
	26	+ * $latex e^{\i \pi} + 1 = 0$ -> [latex]e^{\i \pi} + 1 = 0[/latex]
	27	+ * $latex [a, b]$ -> [latex][a, b][/latex]
	28	+ */
	29	+
	30	+/**
	31	+ * Markup LaTeX content.
	32	+ *
	33	+ * @param string $content Post or comment contents to markup.
	34	+ */
	35	+function latex_markup( $content ) {
	36	+ $textarr = wp_html_split( $content );
	37	+
	38	+ $regex = '%
	39	+ \$latex(?:=\s*|\s+)
	40	+ ((?:
	41	+ [^$]+ # Not a dollar
	42	+ |
	43	+ (?<=(?<!\\\\)\\\\)\$ # Dollar preceded by exactly one slash
	44	+ )+)
	45	+ (?<!\\\\)\$ # Dollar preceded by zero slashes
	46	+ %ix';
	47	+
	48	+ foreach ( $textarr as &$element ) {
	49	+ if ( '' === $element || '<' === $element[0] ) {
	50	+ continue;
	51	+ }
	52	+
	53	+ if ( false === stripos( $element, '$latex' ) ) {
	54	+ continue;
	55	+ }
	56	+
	57	+ $element = preg_replace_callback( $regex, 'latex_src', $element );
	58	+ }
	59	+
	60	+ return implode( '', $textarr );
	61	+}
	62	+
	63	+/**
	64	+ * Process LaTeX string to rendered image.
	65	+ *
	66	+ * @param array $matches Matched regex results.
	67	+ */
	68	+function latex_src( $matches ) {
	69	+ $latex = $matches[1];
	70	+
	71	+ $bg = latex_get_default_color( 'bg' );
	72	+ $fg = latex_get_default_color( 'text', '000' );
	73	+ $s = 0;
	74	+
	75	+ $latex = latex_entity_decode( $latex );
	76	+ if ( preg_match( '/.+(&fg=[0-9a-f]{6}).*/i', $latex, $fg_matches ) ) {
	77	+ $fg = substr( $fg_matches[1], 4 );
	78	+ $latex = str_replace( $fg_matches[1], '', $latex );
	79	+ }
	80	+ if ( preg_match( '/.+(&bg=[0-9a-f]{6}).*/i', $latex, $bg_matches ) ) {
	81	+ $bg = substr( $bg_matches[1], 4 );
	82	+ $latex = str_replace( $bg_matches[1], '', $latex );
	83	+ }
	84	+ if ( preg_match( '/.+(&s=[0-9-]{1,2}).*/i', $latex, $s_matches ) ) {
	85	+ $s = (int) substr( $s_matches[1], 3 );
	86	+ $latex = str_replace( $s_matches[1], '', $latex );
	87	+ }
	88	+
	89	+ return latex_render( $latex, $fg, $bg, $s );
	90	+}
	91	+
	92	+/**
	93	+ * Get the default color for an attribute.
	94	+ *
	95	+ * @param string $color Attribute to color (e.g. bg).
	96	+ * @param string $default_color Default fallback color to use.
	97	+ */
	98	+function latex_get_default_color( $color, $default_color = 'ffffff' ) {
	99	+ global $themecolors;
	100	+ return $themecolors[ $color ] ?? $default_color;
	101	+}
	102	+
	103	+/**
	104	+ * Decode special characters in a LaTeX string.
	105	+ *
	106	+ * @param string $latex Character encoded content.
	107	+ */
	108	+function latex_entity_decode( $latex ) {
	109	+ return str_replace( array( '&lt;', '&gt;', '&quot;', '&#039;', '&#038;', '&amp;', "\n", "\r" ), array( '<', '>', '"', "'", '&', '&', ' ', ' ' ), $latex );
	110	+}
	111	+
	112	+/**
	113	+ * Returns the URL for the server-side rendered image of LaTeX.
	114	+ *
	115	+ * @param string $latex LaTeX string.
	116	+ * @param string $fg Foreground color.
	117	+ * @param string $bg Background color.
	118	+ * @param int $s Matches.
	119	+ *
	120	+ * @return string Image URL for the rendered LaTeX.
	121	+ */
	122	+function latex_render( $latex, $fg, $bg, $s = 0 ) {
	123	+ $url = add_query_arg(
	124	+ urlencode_deep(
	125	+ array(
	126	+ 'latex' => $latex,
	127	+ 'bg' => $bg,
	128	+ 'fg' => $fg,
	129	+ 's' => $s,
	130	+ 'c' => '20201002', // cache buster. Added 2020-10-02 after server migration caused faulty rendering.
	131	+ )
	132	+ ),
	133	+ ( is_ssl() ? 'https://' : 'http://' ) . 's0.wp.com/latex.php'
	134	+ );
	135	+
	136	+ $alt = str_replace( '\\', '&#92;', esc_attr( $latex ) );
	137	+
	138	+ return sprintf(
	139	+ '<img src="%1$s" alt="%2$s" class="latex" />',
	140	+ esc_url( $url ),
	141	+ $alt
	142	+ );
	143	+}
	144	+
	145	+/**
	146	+ * The shortcode way. The attributes are the same as the old ones - 'fg' and 'bg', instead of foreground
	147	+ * and background, and 's' is for the font size.
	148	+ *
	149	+ * Example: [latex s=4 bg=00f fg=ff0]\LaTeX[/latex]
	150	+ *
	151	+ * @param array $atts Shortcode attributes.
	152	+ * @param string $content Content to format.
	153	+ */
	154	+function latex_shortcode( $atts, $content = '' ) {
	155	+ $attr = shortcode_atts(
	156	+ array(
	157	+ 's' => 0,
	158	+ 'bg' => latex_get_default_color( 'bg' ),
	159	+ 'fg' => latex_get_default_color( 'text', '000' ),
	160	+ ),
	161	+ $atts,
	162	+ 'latex'
	163	+ );
	164	+
	165	+ return latex_render( latex_entity_decode( $content ), $attr['fg'], $attr['bg'], $attr['s'] );
	166	+}
	167	+
	168	+/**
	169	+ * LaTeX needs to be untexturized.
	170	+ *
	171	+ * @param array $shortcodes Array of shortcodes not to texturize.
	172	+ */
	173	+function latex_no_texturize( $shortcodes ) {
	174	+ $shortcodes[] = 'latex';
	175	+ return $shortcodes;
	176	+}
	177	+add_filter( 'no_texturize_shortcodes', 'latex_no_texturize' );
	178	+
	179	+add_filter( 'the_content', 'latex_markup', 9 ); // Before wptexturize.
	180	+add_filter( 'comment_text', 'latex_markup', 9 ); // Before wptexturize.
	181	+add_shortcode( 'latex', 'latex_shortcode' );