diff --git a/src/xlsx/xlsxformat.cpp b/src/xlsx/xlsxformat.cpp
index 37c9449..274abba 100755
--- a/src/xlsx/xlsxformat.cpp
+++ b/src/xlsx/xlsxformat.cpp
@@ -232,20 +232,19 @@ void Format::setFontName(const QString &name)
 bool Format::fontIndexValid() const
 {
     Q_D(const Format);
-    return !d->fontData._dirty && d->fontData._indexValid;
+    return d->fontData.indexValid();
 }
 
 int Format::fontIndex() const
 {
     Q_D(const Format);
-    return d->fontData._index;
+    return d->fontData.index();
 }
 
 void Format::setFontIndex(int index)
 {
     Q_D(Format);
-    d->fontData._index = index;
-    d->fontData._indexValid = true;
+    d->fontData.setIndex(index);
 }
 
 int Format::fontFamily() const
@@ -271,21 +270,9 @@ QString Format::fontScheme() const
 QByteArray Format::fontKey() const
 {
     Q_D(const Format);
-    if (d->fontData._dirty) {
-        QByteArray key;
-        QDataStream stream(&key, QIODevice::WriteOnly);
-        stream<<d->fontData.bold<<d->fontData.charset<<d->fontData.color<<d->fontData.condense
-             <<d->fontData.extend<<d->fontData.family<<d->fontData.italic<<d->fontData.name
-            <<d->fontData.outline<<d->fontData.scheme<<d->fontData.scirpt<<d->fontData.shadow
-           <<d->fontData.size<<d->fontData.strikeOut<<d->fontData.underline;
-
-        const_cast<FormatPrivate*>(d)->fontData._key = key;
-        const_cast<FormatPrivate*>(d)->fontData._dirty = false;
-        const_cast<FormatPrivate*>(d)->fontData._indexValid = false; //must re-assign a new index
+    if (d->fontData._dirty)
         const_cast<FormatPrivate*>(d)->dirty = true; //Make sure formatKey() will be re-generated.
-    }
-
-    return d->fontData._key;
+    return d->fontData.key();
 }
 
 Format::HorizontalAlignment Format::horizontalAlignment() const
@@ -621,20 +608,19 @@ void Format::setDiagonalBorderColor(const QColor &color)
 bool Format::borderIndexValid() const
 {
     Q_D(const Format);
-    return !d->borderData._dirty && d->borderData._indexValid;
+    return d->borderData.indexValid();
 }
 
 int Format::borderIndex() const
 {
     Q_D(const Format);
-    return d->borderData._index;
+    return d->borderData.index();
 }
 
 void Format::setBorderIndex(int index)
 {
     Q_D(Format);
-    d->borderData._index = index;
-    d->borderData._indexValid = true;
+    d->borderData.setIndex(index);
 }
 
 /* Internal
@@ -642,21 +628,10 @@ void Format::setBorderIndex(int index)
 QByteArray Format::borderKey() const
 {
     Q_D(const Format);
-    if (d->borderData._dirty) {
-        QByteArray key;
-        QDataStream stream(&key, QIODevice::WriteOnly);
-        stream<<d->borderData.bottom<<d->borderData.bottomColor
-             <<d->borderData.diagonal<<d->borderData.diagonalColor<<d->borderData.diagonalType
-            <<d->borderData.left<<d->borderData.leftColor
-           <<d->borderData.right<<d->borderData.rightColor
-          <<d->borderData.top<<d->borderData.topColor;
-        const_cast<FormatPrivate*>(d)->borderData._key = key;
-        const_cast<FormatPrivate*>(d)->borderData._dirty = false;
-        const_cast<FormatPrivate*>(d)->borderData._indexValid = false;
+    if (d->borderData._dirty)
         const_cast<FormatPrivate*>(d)->dirty = true; //Make sure formatKey() will be re-generated.
-    }
 
-    return d->borderData._key;
+    return d->borderData.key();
 }
 
 Format::FillPattern Format::fillPattern() const
@@ -705,20 +680,19 @@ void Format::setPatternBackgroundColor(const QColor &color)
 bool Format::fillIndexValid() const
 {
     Q_D(const Format);
-    return !d->fillData._dirty && d->fillData._indexValid;
+    return d->fillData.indexValid();
 }
 
 int Format::fillIndex() const
 {
     Q_D(const Format);
-    return d->fillData._index;
+    return d->fillData.index();
 }
 
 void Format::setFillIndex(int index)
 {
     Q_D(Format);
-    d->fillData._index = index;
-    d->fillData._indexValid = true;
+    d->fillData.setIndex(index);
 }
 
 /* Internal
@@ -726,17 +700,10 @@ void Format::setFillIndex(int index)
 QByteArray Format::fillKey() const
 {
     Q_D(const Format);
-    if (d->fillData._dirty) {
-        QByteArray key;
-        QDataStream stream(&key, QIODevice::WriteOnly);
-        stream<<d->fillData.bgColor<<d->fillData.fgColor<<d->fillData.pattern;
-        const_cast<FormatPrivate*>(d)->fillData._key = key;
-        const_cast<FormatPrivate*>(d)->fillData._dirty = false;
-        const_cast<FormatPrivate*>(d)->fillData._indexValid = false;
+    if (d->fillData._dirty)
         const_cast<FormatPrivate*>(d)->dirty = true; //Make sure formatKey() will be re-generated.
-    }
 
-    return d->fillData._key;
+    return d->fillData.key();
 }
 
 bool Format::hidden() const
diff --git a/src/xlsx/xlsxformat_p.h b/src/xlsx/xlsxformat_p.h
index 9418a98..5047068 100644
--- a/src/xlsx/xlsxformat_p.h
+++ b/src/xlsx/xlsxformat_p.h
@@ -65,8 +65,43 @@ struct FontData
     int condense;
     int extend;
 
+    QByteArray key() const
+    {
+        if (_dirty) {
+            QByteArray key;
+            QDataStream stream(&key, QIODevice::WriteOnly);
+            stream<<bold<<charset<<color<<condense
+                 <<extend<<family<<italic<<name
+                <<outline<<scheme<<scirpt<<shadow
+               <<size<<strikeOut<<underline;
+
+            const_cast<FontData*>(this)->_key = key;
+            const_cast<FontData*>(this)->_dirty = false;
+            const_cast<FontData*>(this)->_indexValid = false;//dirty flag can not be simply cleared.
+        }
+        return _key;
+    }
+
+    bool indexValid() const
+    {
+        return !_dirty && _indexValid;
+    }
+
+    int index() const
+    {
+        return _index;
+    }
+
+    void setIndex(int index)
+    {
+        _index = index;
+        _indexValid = true;
+    }
+
     //helper member
-    bool _dirty; //key re-generated is need.
+    bool _dirty; //key re-generated and proper index assign is need.
+
+private:
     QByteArray _key;
     bool _indexValid;  //has a valid index, so no need to assign a new one
     int _index; //index in the Font list
@@ -108,8 +143,41 @@ struct BorderData
     QColor diagonalColor;
     Format::DiagonalBorderType diagonalType;
 
+    QByteArray key() const
+    {
+        if (_dirty) {
+            QByteArray key;
+            QDataStream stream(&key, QIODevice::WriteOnly);
+            stream << bottom << bottomColor << top << topColor
+                 << diagonal << diagonalColor << diagonalType
+                << left << leftColor << right << rightColor;
+            const_cast<BorderData*>(this)->_key = key;
+            const_cast<BorderData*>(this)->_dirty = false;
+            const_cast<BorderData*>(this)->_indexValid = false;
+        }
+        return _key;
+    }
+
+    bool indexValid() const
+    {
+        return !_dirty && _indexValid;
+    }
+
+    int index() const
+    {
+        return _index;
+    }
+
+    void setIndex(int index)
+    {
+        _index = index;
+        _indexValid = true;
+    }
+
     //helper member
-    bool _dirty; //key re-generated is need.
+    bool _dirty; //key re-generated and proper index assign is need.
+
+private:
     QByteArray _key;
     bool _indexValid;  //has a valid index, so no need to assign a new one
     int _index; //index in the border list
@@ -125,8 +193,39 @@ struct FillData {
     QColor bgColor;
     QColor fgColor;
 
+    QByteArray key() const
+    {
+        if (_dirty) {
+            QByteArray key;
+            QDataStream stream(&key, QIODevice::WriteOnly);
+            stream<<bgColor<<fgColor<<pattern;
+            const_cast<FillData*>(this)->_key = key;
+            const_cast<FillData*>(this)->_dirty = false;
+            const_cast<FillData*>(this)->_indexValid = false;
+        }
+        return _key;
+    }
+
+    bool indexValid() const
+    {
+        return !_dirty && _indexValid;
+    }
+
+    int index() const
+    {
+        return _index;
+    }
+
+    void setIndex(int index)
+    {
+        _index = index;
+        _indexValid = true;
+    }
+
     //helper member
-    bool _dirty; //key re-generated is need.
+    bool _dirty; //key re-generated and proper index assign is need.
+
+private:
     QByteArray _key;
     bool _indexValid;  //has a valid index, so no need to assign a new one
     int _index; //index in the border list
diff --git a/src/xlsx/xlsxstyles.cpp b/src/xlsx/xlsxstyles.cpp
index 6097a11..b89b516 100755
--- a/src/xlsx/xlsxstyles.cpp
+++ b/src/xlsx/xlsxstyles.cpp
@@ -42,7 +42,7 @@ Styles::Styles()
     QSharedPointer<FillData> fill = QSharedPointer<FillData>(new FillData);
     fill->pattern = Format::PatternGray125;
     m_fillsList.append(fill);
-    m_fillsHash[fill->_key] = fill;
+    m_fillsHash[fill->key()] = fill;
 }
 
 Styles::~Styles()
@@ -124,33 +124,33 @@ void Styles::addFormat(Format *format)
     if (!format->fontIndexValid()) {
         if (!m_fontsHash.contains(format->fontKey())) {
             QSharedPointer<FontData> font = QSharedPointer<FontData>(new FontData(format->d_func()->fontData));
-            font->_index = m_fontsList.size(); //Assign proper index
+            font->setIndex(m_fontsList.size()); //Assign proper index
             m_fontsList.append(font);
-            m_fontsHash[font->_key] = font;
+            m_fontsHash[font->key()] = font;
         }
-        format->setFontIndex(m_fontsHash[format->fontKey()]->_index);
+        format->setFontIndex(m_fontsHash[format->fontKey()]->index());
     }
 
     //Fill
     if (!format->fillIndexValid()) {
         if (!m_fillsHash.contains(format->fillKey())) {
             QSharedPointer<FillData> fill = QSharedPointer<FillData>(new FillData(format->d_func()->fillData));
-            fill->_index = m_fillsList.size(); //Assign proper index
+            fill->setIndex(m_fillsList.size()); //Assign proper index
             m_fillsList.append(fill);
-            m_fillsHash[fill->_key] = fill;
+            m_fillsHash[fill->key()] = fill;
         }
-        format->setFillIndex(m_fillsHash[format->fillKey()]->_index);
+        format->setFillIndex(m_fillsHash[format->fillKey()]->index());
     }
 
     //Border
     if (!format->borderIndexValid()) {
         if (!m_bordersHash.contains(format->borderKey())) {
             QSharedPointer<BorderData> border = QSharedPointer<BorderData>(new BorderData(format->d_func()->borderData));
-            border->_index = m_bordersList.size(); //Assign proper index
+            border->setIndex(m_bordersList.size()); //Assign proper index
             m_bordersList.append(border);
-            m_bordersHash[border->_key] = border;
+            m_bordersHash[border->key()] = border;
         }
-        format->setBorderIndex(m_bordersHash[format->borderKey()]->_index);
+        format->setBorderIndex(m_bordersHash[format->borderKey()]->index());
     }
 
     //Format