From 2cdcb9055389993e25c90d42fd3df071c2a5e373 Mon Sep 17 00:00:00 2001
From: Tim Hunt <T.J.Hunt@open.ac.uk>
Date: Sat, 14 Jul 2012 09:06:07 +0100
Subject: [PATCH] MDL-34164 quiz reports: only try to show graphs if GD is
 installed.

if (empty($CFG->gdversion)) { seems to be the common idiom for this.
I refactored the graph output into the renderer, to avoid having to
duplicate that test three times.
---
 mod/quiz/renderer.php                 | 18 ++++++++++++++++++
 mod/quiz/report/overview/report.php   | 21 ++++++++-------------
 mod/quiz/report/statistics/report.php |  9 ++++-----
 3 files changed, 30 insertions(+), 18 deletions(-)

diff --git a/mod/quiz/renderer.php b/mod/quiz/renderer.php
index 165ec10e47c..b7961aaeae9 100644
--- a/mod/quiz/renderer.php
+++ b/mod/quiz/renderer.php
@@ -1149,6 +1149,24 @@ class mod_quiz_renderer extends plugin_renderer_base {
                 'id' => $cm->id, 'mode' => quiz_report_default_report($context)));
         return html_writer::link($url, $summary);
     }
+
+    /**
+     * Output a graph, or a message saying that GD is required.
+     * @param moodle_url $url the URL of the graph.
+     * @param string $title the title to display above the graph.
+     * @return string HTML fragment for the graph.
+     */
+    public function graph(moodle_url $url, $title) {
+        global $CFG;
+
+        if (empty($CFG->gdversion)) {
+            $graph = get_string('gdneed');
+        } else {
+            $graph = html_writer::empty_tag('img', array('src' => $url, 'alt' => $title));
+        }
+
+        return $this->heading($title) . html_writer::tag('div', $graph, array('class' => 'graph'));
+    }
 }
 
 class mod_quiz_links_to_other_attempts implements renderable {
diff --git a/mod/quiz/report/overview/report.php b/mod/quiz/report/overview/report.php
index ae2e1f66fa4..27b4df5cbe1 100644
--- a/mod/quiz/report/overview/report.php
+++ b/mod/quiz/report/overview/report.php
@@ -40,7 +40,7 @@ require_once($CFG->dirroot . '/mod/quiz/report/overview/overview_table.php');
 class quiz_overview_report extends quiz_attempts_report {
 
     public function display($quiz, $cm, $course) {
-        global $CFG, $DB, $OUTPUT;
+        global $CFG, $DB, $OUTPUT, $PAGE;
 
         list($currentgroup, $students, $groupstudents, $allowed) =
                 $this->init('overview', 'quiz_overview_settings_form', $quiz, $cm, $course);
@@ -237,30 +237,25 @@ class quiz_overview_report extends quiz_attempts_report {
         }
 
         if (!$table->is_downloading() && $options->usercanseegrades) {
+            $output = $PAGE->get_renderer('mod_quiz');
             if ($currentgroup && $groupstudents) {
                 list($usql, $params) = $DB->get_in_or_equal($groupstudents);
                 $params[] = $quiz->id;
                 if ($DB->record_exists_select('quiz_grades', "userid $usql AND quiz = ?",
                         $params)) {
-                     $imageurl = new moodle_url('/mod/quiz/report/overview/overviewgraph.php',
+                    $imageurl = new moodle_url('/mod/quiz/report/overview/overviewgraph.php',
                             array('id' => $quiz->id, 'groupid' => $currentgroup));
-                     $graphname = get_string('overviewreportgraphgroup', 'quiz_overview',
+                    $graphname = get_string('overviewreportgraphgroup', 'quiz_overview',
                             groups_get_group_name($currentgroup));
-                     echo $OUTPUT->heading($graphname);
-                     echo html_writer::tag('div', html_writer::empty_tag('img',
-                            array('src' => $imageurl, 'alt' => $graphname)),
-                            array('class' => 'graph'));
+                    echo $output->graph($imageurl, $graphname);
                 }
             }
 
             if ($DB->record_exists('quiz_grades', array('quiz'=> $quiz->id))) {
-                 $graphname = get_string('overviewreportgraph', 'quiz_overview');
-                 $imageurl = new moodle_url('/mod/quiz/report/overview/overviewgraph.php',
+                $imageurl = new moodle_url('/mod/quiz/report/overview/overviewgraph.php',
                         array('id' => $quiz->id));
-                 echo $OUTPUT->heading($graphname);
-                 echo html_writer::tag('div', html_writer::empty_tag('img',
-                        array('src' => $imageurl, 'alt' => $graphname)),
-                        array('class' => 'graph'));
+                $graphname = get_string('overviewreportgraph', 'quiz_overview');
+                echo $output->graph($imageurl, $graphname);
             }
         }
         return true;
diff --git a/mod/quiz/report/statistics/report.php b/mod/quiz/report/statistics/report.php
index 99cbd31fdc4..48c91eebb03 100644
--- a/mod/quiz/report/statistics/report.php
+++ b/mod/quiz/report/statistics/report.php
@@ -579,18 +579,17 @@ class quiz_statistics_report extends quiz_default_report {
      * @param int $quizstatsid the id of the statistics to show in the graph.
      */
     protected function output_statistics_graph($quizstatsid, $s) {
-        global $OUTPUT;
+        global $PAGE;
 
         if ($s == 0) {
             return;
         }
 
+        $output = $PAGE->get_renderer('mod_quiz');
         $imageurl = new moodle_url('/mod/quiz/report/statistics/statistics_graph.php',
                 array('id' => $quizstatsid));
-        $OUTPUT->heading(get_string('statisticsreportgraph', 'quiz_statistics'));
-        echo html_writer::tag('div', html_writer::empty_tag('img', array('src' => $imageurl,
-                'alt' => get_string('statisticsreportgraph', 'quiz_statistics'))),
-                array('class' => 'graph'));
+        $graphname = get_string('statisticsreportgraph', 'quiz_statistics');
+        echo $output->graph($imageurl, $graphname);
     }
 
     /**