MDL-19270 - Quiz graph - Fix reverse display of Hebrew legend text in RTL mode

lib/classes/text.php

@@ -378,6 +378,18 @@ class core_text {
         }
     }
 
+    /**
+     * Reverse UTF-8 multibytes character sets (used for RTL languages)
+     * (We only do this because there is no mb_strrev or iconv_strrev)
+     *
+     * @param string $str the multibyte string to reverse
+     * @return string the reversed multi byte string
+     */
+    public static function strrev($str) {
+        preg_match_all('/./us', $str, $ar);
+        return join('', array_reverse($ar[0]));
+    }
+
     /**
      * Try to convert upper unicode characters to plain ascii,
      * the returned string may contain unconverted unicode characters.

lib/graphlib.php

@@ -1190,10 +1190,26 @@ class graph {
       //ImageColorTransparent($this->image, $this->colour['white']); // colour for transparency
     }
 
+    /**
+     * Prepare label's text for GD output.
+     *
+     * @param string    $label string to be prepared.
+     * @return string   Reversed input string, if we are in RTL mode and has no numbers.
+     *                  Otherwise, returns the string as is.
+     */
+    private function prepare_label_text($label) {
+        if (right_to_left() and !preg_match('/[0-9]/i', $label)) {
+            return core_text::strrev($label);
+        } else {
+            return $label;
+        }
+    }
+
     function print_TTF($message) {
       $points    = $message['points'];
       $angle     = $message['angle'];
-      $text      = $message['text'];
+      // We have to manually reverse the label, since php GD cannot handle RTL characters properly in UTF8 strings.
+      $text      = $this->prepare_label_text($message['text']);
       $colour    = $this->colour[$message['colour']];
       $font      = $this->parameter['path_to_fonts'].$message['font'];