Save and load alpha of conditional style color

Alpha (saturation) will be saved and loaded for the conditional style color of text and background.
Before there was not only the problem, that it was not saved - it was additional the issue, that background with no color had after reopening the project the alpha(saturation) of FF and the color black.
This is fixed now.

Author: signedav

src/core/qgsconditionalstyle.cpp

@@ -273,7 +273,9 @@ bool QgsConditionalStyle::writeXml( QDomNode &node, QDomDocument &doc, const Qgs
   stylesel.setAttribute( QStringLiteral( "rule" ), mRule );
   stylesel.setAttribute( QStringLiteral( "name" ), mName );
   stylesel.setAttribute( QStringLiteral( "background_color" ), mBackColor.name() );
+  stylesel.setAttribute( QStringLiteral( "background_color_alpha" ), mBackColor.alpha() );
   stylesel.setAttribute( QStringLiteral( "text_color" ), mTextColor.name() );
+  stylesel.setAttribute( QStringLiteral( "text_color_alpha" ), mTextColor.alpha() );
   QDomElement labelFontElem = QgsFontUtils::toXmlElement( mFont, doc, QStringLiteral( "font" ) );
   stylesel.appendChild( labelFontElem );
   if ( mSymbol )
@@ -290,8 +292,18 @@ bool QgsConditionalStyle::readXml( const QDomNode &node, const QgsReadWriteConte
   QDomElement styleElm = node.toElement();
   setRule( styleElm.attribute( QStringLiteral( "rule" ) ) );
   setName( styleElm.attribute( QStringLiteral( "name" ) ) );
-  setBackgroundColor( QColor( styleElm.attribute( QStringLiteral( "background_color" ) ) ) );
-  setTextColor( QColor( styleElm.attribute( QStringLiteral( "text_color" ) ) ) );
+  QColor bColor = QColor( styleElm.attribute( QStringLiteral( "background_color" ) ) );
+  if( styleElm.hasAttribute( "background_color_alpha" ) )
+  {
+    bColor.setAlpha( styleElm.attribute( QStringLiteral( "background_color_alpha" ) ).toInt() );
+  }
+  setBackgroundColor( bColor );
+  QColor tColor = QColor( styleElm.attribute( QStringLiteral( "text_color" ) ) );
+  if( styleElm.hasAttribute( "text_color_alpha" ) )
+  {
+    tColor.setAlpha( styleElm.attribute( QStringLiteral( "text_color_alpha" ) ).toInt() );
+  }
+  setTextColor( tColor );
   QgsFontUtils::setFromXmlChildNode( mFont, styleElm, QStringLiteral( "font" ) );
   QDomElement symbolElm = styleElm.firstChildElement( QStringLiteral( "symbol" ) );
   if ( !symbolElm.isNull() )