qtypes: MDL-18711 Allow qtype plugins to have custom CSS and JavaScri…

…pt on the editing page.

lib/questionlib.php

@@ -2084,6 +2084,19 @@ function get_html_head_contributions($questionlist, &$questions, &$states) {
     return implode("\n", array_unique($contributions));
 }
 
+/**
+ * Like @see{get_html_head_contributions} but for the editing page
+ * question/question.php.
+ *
+ * @param $question A question object. Only $question->qtype is used.
+ * @return string some HTML code that can go inside the head tag.
+ */
+function get_editing_head_contributions($question) {
+    global $QTYPES;
+    $contributions = $QTYPES[$question->qtype]->get_editing_head_contributions();
+    return implode("\n", array_unique($contributions));
+}
+
 /**
  * Prints a question
  *

question/question.php

@@ -239,6 +239,7 @@
 } else {
 
     $streditingquestion = $QTYPES[$question->qtype]->get_heading();
+    $headtags = get_editing_head_contributions($question);
     if ($cm !== null) {
         $strmodule = get_string('modulename', $cm->modname);
         $strupdatemodule = has_capability('moodle/course:manageactivities', get_context_instance(CONTEXT_COURSE, $COURSE->id))
@@ -256,7 +257,7 @@
         }
         $navlinks[] = array('name' => $streditingquestion, 'link' => '', 'type' => 'title');
         $navigation = build_navigation($navlinks);
-        print_header_simple($streditingquestion, '', $navigation, "", "", true, $strupdatemodule);
+        print_header_simple($streditingquestion, '', $navigation, '', $headtags, true, $strupdatemodule);
 
     } else {
         $navlinks = array();
@@ -265,7 +266,7 @@
         $strediting = '<a href="edit.php?courseid='.$COURSE->id.'">'.
                 get_string("editquestions", "quiz").'</a> -> '.$streditingquestion;
         $navigation = build_navigation($navlinks);
-        print_header_simple($streditingquestion, '', $navigation);
+        print_header_simple($streditingquestion, '', $navigation, '', $headtags);
     }
 
     // Display a heading, question editing form and possibly some extra content needed for

question/type/questiontype.php

@@ -804,13 +804,16 @@ function check_response(&$question, &$state){
     }
 
     // Used by the following function, so that it only returns results once per quiz page.
-    var $already_done = false;
+    private $htmlheadalreadydone = false;
     /**
      * If this question type requires extra CSS or JavaScript to function,
      * then this method will return an array of <link ...> tags that reference
      * those stylesheets. This function will also call require_js()
      * from ajaxlib.php, to get any necessary JavaScript linked in too.
      *
+     * Remember that there may be more than one question of this type on a page.
+     * try to avoid including JS and CSS more than once.
+     *
      * The two parameters match the first two parameters of print_question.
      *
      * @param object $question The question object.
@@ -821,33 +824,62 @@ function check_response(&$question, &$state){
      * integer array keys, which have no significance.
      */
     function get_html_head_contributions(&$question, &$state) {
+        // We only do this once for this question type, no matter how often this
+        // method is called on one page.
+        if ($this->htmlheadalreadydone) {
+            return array();
+        }
+        $this->htmlheadalreadydone = true;
+
         // By default, we link to any of the files styles.css, styles.php,
         // script.js or script.php that exist in the plugin folder.
         // Core question types should not use this mechanism. Their styles
         // should be included in the standard theme.
+        return $this->find_standard_scripts_and_css();
+    }
 
-        // We only do this once
-        // for this question type, no matter how often this method is called.
-        if ($this->already_done) {
-            return array();
-        }
-        $this->already_done = true;
+    /**
+     * Like @see{get_html_head_contributions}, but this method is for CSS and
+     * JavaScript required on the question editing page question/question.php.
+     *
+     * @return an array of bits of HTML to add to the head of pages where
+     * this question is print_question-ed in the body. The array should use
+     * integer array keys, which have no significance.
+     */
+    function get_editing_head_contributions() {
+        // By default, we link to any of the files styles.css, styles.php,
+        // script.js or script.php that exist in the plugin folder.
+        // Core question types should not use this mechanism. Their styles
+        // should be included in the standard theme.
+        return $this->find_standard_scripts_and_css();
+    }
 
+    /**
+     * Utility method used by @see{get_html_head_contributions} and
+     * @see{get_editing_head_contributions}. This looks for any of the files
+     * styles.css, styles.php, script.js or script.php that exist in the plugin
+     * folder and ensures they get included.
+     *
+     * @return array as required by get_html_head_contributions or get_editing_head_contributions.
+     */
+    protected function find_standard_scripts_and_css() {
         $plugindir = $this->plugin_dir();
         $baseurl = $this->plugin_baseurl();
+
+        if (file_exists($plugindir . '/script.js')) {
+            require_js($baseurl . '/script.js');
+        }
+        if (file_exists($plugindir . '/script.php')) {
+            require_js($baseurl . '/script.php');
+        }
+
         $stylesheets = array();
         if (file_exists($plugindir . '/styles.css')) {
             $stylesheets[] = 'styles.css';
         }
         if (file_exists($plugindir . '/styles.php')) {
             $stylesheets[] = 'styles.php';
         }
-        if (file_exists($plugindir . '/script.js')) {
-            require_js($baseurl . '/script.js');
-        }
-        if (file_exists($plugindir . '/script.php')) {
-            require_js($baseurl . '/script.php');
-        }
         $contributions = array();
         foreach ($stylesheets as $stylesheet) {
             $contributions[] = '<link rel="stylesheet" type="text/css" href="' .