Guard against out-of-bounds asserts in MythUIText::Layout().

Author: stuartm

mythtv/libs/libmythui/mythuitext.cpp

@@ -527,14 +527,24 @@ bool MythUIText::Layout(QString & paragraph, QTextLayout *layout, bool final,
          */
             QFontMetrics fm(GetFontProperties()->face());
             int bearing;
+            int position;
 
-            bearing = fm.leftBearing(m_CutMessage[last_line]);
-            if (m_leftBearing > bearing)
-                m_leftBearing = bearing;
-            bearing = fm.rightBearing
-                      (m_CutMessage[last_line + line.textLength() - 1]);
-            if (m_rightBearing > bearing)
-                m_rightBearing = bearing;
+            position = last_line;
+            if (m_CutMessage.length() > position)
+            {
+                bearing = fm.leftBearing(m_CutMessage[position]);
+                if (m_leftBearing > bearing)
+                    m_leftBearing = bearing;
+            }
+
+            position = (last_line + line.textLength() - 1);
+            if (m_CutMessage.length() > position && position >= 0)
+            {
+                bearing = fm.rightBearing
+                            (m_CutMessage[position]);
+                if (m_rightBearing > bearing)
+                    m_rightBearing = bearing;
+            }
         }
     }