fix loss of expression when subsymbol is changed

bug mentionned in issue #13033
if the angle, size, width or offset is changed for a subsymbol which
parent (a marker) has data-defined size, angle or width, restore the
data-defined property for the marker.

src/gui/symbology-ng/qgssymbolv2selectordialog.cpp

@@ -46,6 +46,70 @@
 
 static const int SymbolLayerItemType = QStandardItem::UserType + 1;
 
+DataDefinedRestorer::DataDefinedRestorer( QgsSymbolV2* symbol, const QgsSymbolLayerV2* symbolLayer )
+  : mMarker( NULL )
+  , mMarkerSymbolLayer( NULL )
+  , mLine( NULL )
+  , mLineSymbolLayer( NULL )
+{
+  if ( symbolLayer->type() == QgsSymbolV2::Marker && symbol->type() == QgsSymbolV2::Marker )
+  {
+    Q_ASSERT( symbol->type() == QgsSymbolV2::Marker );
+    mMarker = static_cast<QgsMarkerSymbolV2*>( symbol );
+    mMarkerSymbolLayer = static_cast<const QgsMarkerSymbolLayerV2*>( symbolLayer );
+    mDDSize = mMarker->dataDefinedSize();
+    mDDAngle = mMarker->dataDefinedAngle();
+    // check if restore is actually needed
+    if ( mDDSize == QgsDataDefined() && mDDAngle == QgsDataDefined() )
+        mMarker = NULL;
+  }
+  else if( symbolLayer->type() == QgsSymbolV2::Line && symbol->type() == QgsSymbolV2::Line )
+  {
+    mLine = static_cast<QgsLineSymbolV2*>( symbol );
+    mLineSymbolLayer = static_cast<const QgsLineSymbolLayerV2*>( symbolLayer );
+    mDDWidth = mLine->dataDefinedWidth();
+    // check if restore is actually needed
+    if ( mDDWidth == QgsDataDefined() )
+        mLine = NULL;
+  }
+  save();
+}
+
+void DataDefinedRestorer::save()
+{
+  if ( mMarker )
+  {
+    mSize = mMarkerSymbolLayer->size();
+    mAngle = mMarkerSymbolLayer->angle();
+    mMarkerOffset = mMarkerSymbolLayer->offset();
+  }
+  else if ( mLine )
+  {
+    mWidth = mLineSymbolLayer->width();
+    mLineOffset = mLineSymbolLayer->offset();
+  }
+}
+
+void DataDefinedRestorer::restore()
+{
+  if ( mMarker )
+  {
+    if ( mDDSize != QgsDataDefined() &&
+        (mSize != mMarkerSymbolLayer->size() || mMarkerOffset != mMarkerSymbolLayer->offset()) )
+      mMarker->setDataDefinedSize( mDDSize );
+    if ( mDDAngle != QgsDataDefined() &&
+        mAngle != mMarkerSymbolLayer->angle() )
+      mMarker->setDataDefinedAngle( mDDAngle );
+  }
+  else if ( mLine )
+  {
+    if ( mDDWidth != QgsDataDefined() &&
+        (mWidth != mLineSymbolLayer->width() || mLineOffset != mLineSymbolLayer->offset()) )
+      mLine->setDataDefinedWidth( mDDWidth );
+  }
+  save();
+}
+
 // Hybrid item which may represent a symbol or a layer
 // Check using item->isLayer()
 class SymbolLayerItem : public QStandardItem
@@ -325,14 +389,17 @@ void QgsSymbolV2SelectorDialog::layerChanged()
   if ( currentItem->isLayer() )
   {
     SymbolLayerItem *parent = static_cast<SymbolLayerItem*>( currentItem->parent() );
+    mDataDefineRestorer.reset( new DataDefinedRestorer( parent->symbol(), currentItem->layer() ) );
     QWidget *layerProp = new QgsLayerPropertiesWidget( currentItem->layer(), parent->symbol(), mVectorLayer );
     setWidget( layerProp );
+    connect( layerProp, SIGNAL( changed() ), mDataDefineRestorer.data(), SLOT( restore() ) );
     connect( layerProp, SIGNAL( changed() ), this, SLOT( updateLayerPreview() ) );
     // This connection when layer type is changed
     connect( layerProp, SIGNAL( changeLayer( QgsSymbolLayerV2* ) ), this, SLOT( changeLayer( QgsSymbolLayerV2* ) ) );
   }
   else
   {
+    mDataDefineRestorer.reset();
     // then it must be a symbol
     currentItem->symbol()->setLayer( mVectorLayer );
     // Now populate symbols of that type using the symbols list widget:

src/gui/symbology-ng/qgssymbolv2selectordialog.h

@@ -20,7 +20,10 @@
 
 #include "ui_qgssymbolv2selectordialogbase.h"
 
+#include "qgsdatadefined.h"
+
 #include <QStandardItemModel>
+#include <QScopedPointer>
 
 class QgsStyleV2;
 class QgsSymbolV2;
@@ -31,6 +34,37 @@ class QMenu;
 class QWidget;
 
 class SymbolLayerItem;
+class QgsMarkerSymbolV2;
+class QgsLineSymbolV2;
+class QgsMarkerSymbolLayerV2;
+class QgsLineSymbolLayerV2;
+
+class DataDefinedRestorer: public QObject
+{
+  Q_OBJECT
+  public:
+    DataDefinedRestorer( QgsSymbolV2* symbol, const QgsSymbolLayerV2* symbolLayer);
+
+  public slots:
+    void restore();
+
+  private:
+    QgsMarkerSymbolV2* mMarker;
+    const QgsMarkerSymbolLayerV2* mMarkerSymbolLayer;
+    double mSize;
+    double mAngle;
+    QPointF mMarkerOffset;
+    QgsDataDefined mDDSize;
+    QgsDataDefined mDDAngle;
+
+    QgsLineSymbolV2* mLine;
+    const QgsLineSymbolLayerV2* mLineSymbolLayer;
+    double mWidth; 
+    double mLineOffset;
+    QgsDataDefined mDDWidth;
+
+    void save();
+};
 
 class GUI_EXPORT QgsSymbolV2SelectorDialog : public QDialog, private Ui::QgsSymbolV2SelectorDialogBase
 {
@@ -95,6 +129,9 @@ class GUI_EXPORT QgsSymbolV2SelectorDialog : public QDialog, private Ui::QgsSymb
 
     QStandardItemModel* model;
     QWidget *mPresentWidget;
+
+  private:
+    QScopedPointer<DataDefinedRestorer> mDataDefineRestorer;
 };
 
 #endif