diff -r fa3d7ce5d0a7 -r 8396f7857013 plot.cc
--- a/plot.cc	Fri Jan 27 17:16:26 2012 +0100
+++ b/plot.cc	Fri Jan 27 17:21:51 2012 +0100
@@ -28,3 +28,21 @@
     addLine(QLineF(zero, QPointF(0, -1 * (max - min))));
     if (!step) return;
 }
+
+void Plot::draw(QList< QPair<QTime, int> >::const_iterator current,
+    QList< QPair<QTime, int> >::const_iterator end)
+{
+    QTime t0 = current->first;
+    int offset = current->second;
+
+    QPolygonF poly;
+    QPainterPath path;
+
+    while (current != end) {
+	QPoint p(t0.secsTo(current->first), -1 * (current->second - offset));
+	path.lineTo(p);
+	++current;
+    }
+
+    addPath(path);
+}