[FEATURE] add default class to unique value renderer (fixes #1750)

- unique value enull" now default class (ie. class for values without a defined class)
- "add class" and "classify" now add the default class



git-svn-id: http://svn.osgeo.org/qgis/trunk/qgis@10986 c8812cc2-4d05-0410-92ff-de0c093fc19c

src/app/qgsuniquevaluedialog.cpp

@@ -200,15 +200,15 @@ void QgsUniqueValueDialog::setSymbolColor( QgsSymbol *symbol, QColor thecolor )
 void QgsUniqueValueDialog::addClass( QString value )
 {
   QgsDebugMsg( "called." );
-  if ( value.isNull() || mValues.contains( value ) )
+  if ( mValues.contains( value ) )
   {
     int i;
     for ( i = 0; mValues.contains( value + QString::number( i ) ); i++ )
       ;
     value += QString::number( i );
   }
 
-  QgsSymbol *symbol = new QgsSymbol( mVectorLayer->geometryType(), value );
+  QgsSymbol *symbol = new QgsSymbol( mVectorLayer->geometryType(), value, value, value.isNull() ? tr( "default" ) : "" );
   mValues.insert( value, symbol );
 
   QListWidgetItem *item = new QListWidgetItem( value );
@@ -306,6 +306,9 @@ void QgsUniqueValueDialog::changeClassificationAttribute()
       if ( !mValues.contains( values[i].toString() ) )
         addClass( values[i].toString() );
     }
+
+    if ( !mValues.contains( QString::null ) )
+      addClass( QString::null );
   }
 }
 

src/core/renderer/qgsuniquevaluerenderer.cpp

@@ -183,6 +183,11 @@ QgsSymbol *QgsUniqueValueRenderer::symbolForFeature( const QgsFeature *f )
   QString value = attrs[mClassificationField].toString();
 
   QMap<QString, QgsSymbol*>::iterator it = mSymbols.find( value );
+  if ( it == mSymbols.end() )
+  {
+    it = mSymbols.find( QString::null );
+  }
+
   if ( it == mSymbols.end() )
   {
     return 0;

src/core/symbology/qgssymbol.cpp

@@ -445,6 +445,10 @@ void QgsSymbol::appendText( QDomElement &symbol, QDomDocument &document, QString
 {
   QDomElement node = document.createElement( name );
   QDomText txt = document.createTextNode( value );
+  if ( value.isNull() )
+  {
+    node.setAttribute( "null", "1" );
+  }
   symbol.appendChild( node );
   node.appendChild( txt );
 }
@@ -542,7 +546,14 @@ bool QgsSymbol::readXML( QDomNode &synode, const QgsVectorLayer *vl )
   if ( ! lvalnode.isNull() )
   {
     QDomElement lvalelement = lvalnode.toElement();
-    mLowerValue = lvalelement.text();
+    if ( lvalelement.attribute( "null" ).toInt() == 1 )
+    {
+      mLowerValue = QString::null;
+    }
+    else
+    {
+      mLowerValue = lvalelement.text();
+    }
   }
 
   QDomNode uvalnode = synode.namedItem( "uppervalue" );