diff --git a/src/plotdomain.cpp b/src/plotdomain.cpp
index 1fe5001..5e4bc84 100644
--- a/src/plotdomain.cpp
+++ b/src/plotdomain.cpp
@@ -28,4 +28,18 @@ qreal PlotDomain::spanY() const
 	return m_maxY - m_minY;
 }
 
+PlotDomain PlotDomain::subDomain(const QRect& rect, qreal maxWidth,qreal maxHeight) const
+{
+  PlotDomain domain;
+
+  qreal dx = spanX() / maxWidth;
+  qreal dy = spanY() / maxHeight;
+
+  domain.m_minX = m_minX + dx * rect.left();
+  domain.m_maxX = m_minX + dx * rect.right();
+  domain.m_minY = m_maxY - dy * rect.bottom();
+  domain.m_maxY = m_maxY - dy * rect.top();
+
+  return domain;
+}
 QTCOMMERCIALCHART_END_NAMESPACE
diff --git a/src/plotdomain_p.h b/src/plotdomain_p.h
index 74a1e1d..7681b62 100644
--- a/src/plotdomain_p.h
+++ b/src/plotdomain_p.h
@@ -13,6 +13,9 @@ public:
 	qreal spanX() const;
 	qreal spanY() const;
 
+	PlotDomain subDomain(const QRect& rect, qreal maxWidth, qreal maxHeight) const;
+
+
 public:
 	qreal m_minX;
 	qreal m_maxX;
diff --git a/src/qchart.cpp b/src/qchart.cpp
index 3b5e7aa..63f69ab 100644
--- a/src/qchart.cpp
+++ b/src/qchart.cpp
@@ -269,18 +269,11 @@ void QChart::zoomInToRect(const QRect& rectangle)
     rect.translate(-margin, -margin);
 
     PlotDomain& oldDomain = m_plotDomainList[m_plotDataIndex];
-    PlotDomain newDomain;
 
-    qreal dx = oldDomain.spanX() / (m_rect.width() - 2 * margin);
-    qreal dy = oldDomain.spanY() / (m_rect.height() - 2 * margin);
-
-    newDomain.m_minX = oldDomain.m_minX + dx * rect.left();
-    newDomain.m_maxX = oldDomain.m_minX + dx * rect.right();
-    newDomain.m_minY = oldDomain.m_maxY - dy * rect.bottom();
-    newDomain.m_maxY = oldDomain.m_maxY - dy * rect.top();
+    PlotDomain domain = oldDomain.subDomain(rect,m_rect.width() - 2 * margin,m_rect.height() - 2 * margin);
 
     m_plotDomainList.resize(m_plotDataIndex + 1);
-    m_plotDomainList<<newDomain;
+    m_plotDomainList<<domain;
     m_plotDataIndex++;
 
     foreach (ChartItem* item ,m_chartItems)