New Year, New Ideas, Problems Solved¶
Well its now 2010, Happy New Year!!!, and my mailserver guide is still not on the site. It has not been forgotten and in fact part of the guide is already hidden away under going editing. One of the issues that was delaying progress was finding the best way to display code on the site. There are alot of plugins for Wordpress that will do syntax highlighting using Geshi. What I have wanted to do is highlight specific lines of highlighted syntax to make it easier to show changes. I did a little research and found that Geshi already supports the functionality I required but it hadn’t been implemented in any Wordpress plugins. So I decided to modify one. I selected CodeColorer to modify as it already had a method of processing arguments within the “cc” tag it uses.
The modification is simple but has a few limitations. Firstly each line that needs to be selectively highlighted needs to be referenced by line number. This is easy for a few lines but is going to mean alot of number typing for large chunks of code. That said for really big chunks of code they are probably best split off from the rest of the file anyway. The line highlight only stretches to the limit of the longest line and not the whole of the code window. Only a single colour can be specified for the selective highlight and it only works if the Geshi style is selected rather the the custom CodeColorer themes.
Lets now have a look at the modification and what it does. I only needed to modify the codecolorer-core.php file in the plugin directory with a few lines. I have highlighted the changes on lines 161-167 using the modification. To achieve this I placed a new argument ‘highlight’ into the tag after the language argument [cc lang=”html” inline=”true”][cc lang=”php” highlight=”161,162,163,164,165,166,167”][/cc]. The ‘highlight’ argument takes a comma separated list of line numbers to highlight. Thats basically it, the modification takes the line numbers, puts them into an array and passes it on to the inbuilt functionality of Geshi which handles the rest.
Note
Since moving to the static site CodeColourer is no longer used. The image below shows it in use on a WordPress site.

Note
Here is is the full code using the static site syntax highlighter which ironically has issues highlighting it.
1<?php
2 /*
3 CodeColorer plugin core part
4 https://kpumuk.info/projects/wordpress-plugins/codecolorer
5 */
6 /*
7 Copyright 2006 - 2009 Dmytro Shteflyuk <kpumuk@kpumuk.info>
8
9 This program is free software; you can redistribute it and/or modify
10 it under the terms of the GNU General Public License as published by
11 the Free Software Foundation; either version 2 of the License, or
12 (at your option) any later version.
13
14 This program is distributed in the hope that it will be useful,
15 but WITHOUT ANY WARRANTY; without even the implied warranty of
16 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 GNU General Public License for more details.
18
19 You should have received a copy of the GNU General Public License
20 along with this program; if not, write to the Free Software
21 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
22 */
23
24 class CodeColorer {
25 var $blocks = array();
26 var $comments = array();
27
28 var $geshiExternal = false;
29 var $geshiVersion = '1.0.8.4';
30
31 var $samplePhpCode = '
32 [cc_php]
33 /**
34 * Comment
35 */
36 function hello() {
37 echo "Hello!";
38 return null;
39 }
40 exit();
41 [/cc_php]
42 ';
43
44 /** Search content for code tags and replace it */
45 function BeforeHighlightCodeBlock($content) {
46 $content = preg_replace('#(\s*)\[cc([^\s\]_]*(?:_[^\s\]]*)?)([^\]]*)\](.*?)\[/cc\2\](\s*)#sie', '$this->PerformHighlightCodeBlock(\'\\4\', \'\\3\', $content, \'\\2\', \'\\1\', \'\\5\');', $content);
47 $content = preg_replace('#(\s*)\<code (.*?)\>(.*?)\</code>(\s*)#sie', '$this->PerformHighlightCodeBlock(\'\\3\', \'\\2\', $content, \'\', \'\\1\', \'\\4\');', $content);
48
49 return $content;
50 }
51
52 function AfterHighlightCodeBlock($content) {
53 $content = str_replace(array_keys($this->blocks), array_values($this->blocks), $content);
54
55 return $content;
56 }
57
58 function BeforeProtectComment($content) {
59 $content = preg_replace('#(\s*)(\[cc[^\s\]_]*(?:_[^\s\]]*)?[^\]]*\].*?\[/cc\1\])(\s*)#sie', '$this->PerformProtectComment(\'\\2\', $content, \'\\1\', \'\\3\');', $content);
60 $content = preg_replace('#(\s*)(\<code .*?\>.*?\</code>)(\s*)#sie', '$this->PerformProtectComment(\'\\2\', $content, \'\\1\', \'\\3\');', $content);
61
62 return $content;
63 }
64
65 function AfterProtectComment($content) {
66 $content = str_replace(array_keys($this->comments), array_values($this->comments), $content);
67 $this->comments = array();
68
69 return $content;
70 }
71
72 /**
73 *Perform code highlightning
74 */
75 function PerformHighlightCodeBlock($text, $opts, $content, $suffix = '', $before = '', $after = '') {
76 // Preprocess source text
77 $text = str_replace(array("\\"", "\\'"), array (""", "\'"), $text);
78 $text = preg_replace('/(< \?php)/i', '<?php', $text);
79 $text = preg_replace('/(?:^(?:\s*[\r\n])+|\s+$)/', '', $text);
80
81 // Parse options
82 $options = CodeColorerOptions::ParseOptions($opts, $suffix);
83
84 if ($options['escaped']) {
85 $text = html_entity_decode($text, ENT_QUOTES);
86 $text = preg_replace('~�*([0-9a-f]+);~ei', 'chr(hexdec("\\1"))', $text);
87 $text = preg_replace('~�*([0-9]+);~e', 'chr(\\1)', $text);
88 }
89
90 $result = '';
91 // Check if CodeColorer has been disabled for this particular block
92 if (!$options['enabled']) {
93 $result = '<code>' . $text . '';
94 } else {
95 // See if we should force a height
96 $num_lines = count(explode("\n", $text));
97
98 $result = $this->PerformHighlightGeshi($text, $options);
99
100 $result = $this->AddContainer($result, $options, $num_lines);
101 }
102
103 if ($options['inline']) {
104 $blockID = $this->GetBlockID($content, false, '<span>', '</span>');
105 } else {
106 $blockID = $this->GetBlockID($content);
107 }
108 $this->blocks[$blockID] = $result;
109
110 if ($options['inline']) {
111 $result = $before . $blockID . $after;
112 } else {
113 $result = "\n\n$blockID\n\n";
114 }
115
116 return $result;
117 }
118
119 /**
120 * Perform code protecting from mangling by Wordpress (used in Comments)
121 */
122 function PerformProtectComment($text, $content, $before, $after) {
123 $text = str_replace(array("\\"", "\\'"), array (""", "\'"), $text);
124
125 $blockID = $this->GetBlockID($content, true, '', '');
126 $this->comments[$blockID] = $text;
127
128 return $before . $blockID . $after;
129 }
130
131 /**
132 * Perform code highlighting using GESHi engine
133 */
134 function PerformHighlightGeshi($content, $options) {
135 /* Geshi configuration */
136 if (!$this->geshi) {
137 $this->geshi = new GeSHi();
138 $this->geshi->enable_line_numbers(GESHI_NO_LINE_NUMBERS, 1);
139 if (is_feed()) {
140 $this->geshi->set_overall_style('padding:5px;font:normal 12px/1.4em Monaco, Lucida Console, monospace;white-space:nowrap');
141 }
142 }
143
144 $geshi = $this->geshi;
145 $geshi->set_source($content);
146 $geshi->set_language($options['lang']);
147 $geshi->set_overall_class('codecolorer');
148 $geshi->set_tab_width($options['tab_size']);
149 if (!is_feed()) {
150 $geshi->enable_classes($options['theme'] != 'geshi');
151 if ($options['nowrap']) {
152 $geshi->set_overall_style('white-space:nowrap');
153 } else {
154 $geshi->set_overall_style('');
155 }
156 } else {
157 $geshi->enable_classes(false);
158 }
159 if (!is_null($options['strict'])) $geshi->enable_strict_mode($options['strict']);
160 if ($options['no_links']) $geshi->enable_keyword_links(false);
161 /* My Custom Bit */
162 if ($options['highlight']){
163 $myarray = explode(",",$options['highlight']);
164 $geshi->highlight_lines_extra($myarray);
165 $geshi->set_highlight_lines_extra_style('background-color: #ffff66;'); /* Select the colour of the highlight */
166 }
167 /* End My Custom Bit */
168 if ($options['inline']) {
169 $geshi->set_header_type(GESHI_HEADER_NONE);
170 } else {
171 $geshi->set_header_type(GESHI_HEADER_DIV);
172 }
173
174 $result = $geshi->parse_code();
175
176 if ($geshi->error()) {
177 return $geshi->error();
178 }
179
180 if ($options['line_numbers'] && !$options['inline']) {
181 $table = '<table cellspacing="0" cellpadding="0"><tbody><tr><td ';
182 if (is_feed()) {
183 $table .= 'style="padding:5px;text-align:center;color:#888888;background-color:#EEEEEE;border-right: 1px solid #9F9F9F;font: normal 12px/1.4em Monaco, Lucida Console, monospace;"';
184 } else {
185 $table .= 'class="line-numbers"';
186 }
187 $table .= '><div>';
188 for ($i = 0, $count = substr_count($result, '<br />') + 1; $i < $count; $i++) {
189 $table .= ($i + $options['first_line']) . '<br />';
190 }
191 $result = $table . '</div></td><td>' . $result . '</td></tr></tbody></table>';
192 }
193
194 return $result;
195 }
196
197 function AddContainer($html, $options, $num_lines) {
198 $custom_css_class = empty($options['class']) ? '' : ' ' . $options['class'];
199 if ($options['inline']) {
200 $theme = empty($options['inline_theme']) ? 'default' : $options['inline_theme'];
201 $result = '<code class="codecolorer ' . $options['lang'] . ' ' . $theme . $custom_css_class . '">';
202 $result .= '<span class="' . $options['lang'] . '">' . $html . '</span>';
203 $result .= '</code>';
204 } else {
205 $theme = empty($options['theme']) ? 'default' : $options['theme'];
206 $style = 'style="';
207 if ($options['nowrap']) $style .= 'overflow:auto;white-space:nowrap;';
208 if (is_feed()) $style .= 'border: 1px solid #9F9F9F;';
209 $style .= $this->GetDimensionRule('width', is_feed() ? $options['rss_width'] : $options['width']);
210 if($num_lines > $options['lines'] && $options['lines'] > 0) {
211 $style .= $this->GetDimensionRule('height', $options['height']);
212 }
213 $style .= '"';
214
215 $css_class = 'codecolorer-container ' . $options['lang'] . ' ' . $theme . $custom_css_class;
216 if ($options['noborder']) $css_class .= ' codecolorer-noborder';
217 $result = '<div class="' . $css_class . '" ' . $style . '>' . $html . '</div>';
218 }
219 return $result;
220 }
221
222 /**
223 * Generate a block ID that will be replaced at the end (after all that
224 * crazy WP text work!) with the right code
225 */
226 function GetBlockID($content, $comment = false, $before = '<div>', $after = '</div>') {
227 static $num = 0;
228
229 $block = $comment ? 'COMMENT' : 'BLOCK';
230 $before = $before . '::CODECOLORER_' . $block . '_';
231 $after = '::' . $after;
232
233 // Just do a check to make sure the user
234 // hasn't (however unlikely) input block replacements
235 // as legit text
236 do {
237 ++$num;
238 $blockID = $before . $num . $after;
239 } while (strpos($content, $blockID) !== false);
240
241 return $blockID;
242 }
243
244 function GetDimensionRule($dimension, $value) {
245 $rule = '';
246 if (!empty($value)) $rule = "$dimension:$value" . (is_numeric($value) ? 'px;' : ';');
247 return $rule;
248 }
249
250 function ShowWarning($type, $title, $message) {
251 $disable = ' <a href="options-general.php?page=codecolorer.php&disable=' . $type . '">' . __('Close', 'codecolorer') . '</a>';
252 echo '<div id="codecolorer-' . $type . '" class="updated fade"><p><strong>' . $title . "</strong> " . $message . $disable . "</p></div>\n";
253 }
254
255 function ShowGeshiWarning() {
256 if ($this->geshiExternal) {
257 $this->ShowWarning('concurrent', __('CodeColorer has detected a problem.', 'codecolorer'), sprintf(__('We found another plugin based on GeSHi library in your system. CodeColorer will work, but our version of GeSHi contain some patches, so we can\'t guarantee an ideal code highlighting now. Please review your <a href="%1$s">plugins</a>, maybe you don\'t need them all.', 'codecolorer'), "plugins.php"));
258 }
259 }
260
261 function ShowOptionsPage() {
262 $page = $this->GetOptionsPage();
263 $page->Show();
264 }
265
266 function GetOptionsPage() {
267 if (!$this->optionsPage) {
268 if (!class_exists('CodeColorerAdmin')) {
269 $path = dirname(__FILE__);
270 if (!file_exists("$path/codecolorer-admin.php")) return false;
271 require_once("$path/codecolorer-admin.php");
272 }
273 $this->optionsPage = new CodeColorerAdmin($this);
274 }
275 return $this->optionsPage;
276 }
277
278 function GetCodeHighlighted($code) {
279 $content = $this->BeforeHighlightCodeBlock($code);
280 return $this->AfterHighlightCodeBlock($content);
281 }
282
283 function GetSampleCodeHighlighted() {
284 return $this->GetCodeHighlighted($this->samplePhpCode);
285 }
286
287 function &GetInstance() {
288 static $instance = null;
289
290 if (null === $instance) {
291 $path = dirname(__FILE__);
292 if (!class_exists('CodeColorerOptions')) {
293 if (!file_exists("$path/codecolorer-options.php")) return null;
294 require_once("$path/codecolorer-options.php");
295 }
296
297 $instance = new CodeColorer();
298
299 # Maybe GeSHi has been loaded by some another plugin?
300 if (!class_exists('GeSHi')) {
301 if (!file_exists("$path/lib/geshi.php")) return null;
302 require_once("$path/lib/geshi.php");
303 } else {
304 $instance->geshiExternal = true;
305 }
306 }
307
308 return $instance;
309 }
310 }
311?>