[FEATURE] add expressions at the symbollist level

Size and Rotation can be defined by an expression for all symbols
composing a marker. Width can be defined by an expression for all
symbols composing a line.

For markers, a legend is generated for varying sizes. This allows
multivariate analysis legend in the case of classified/graduated colors.

The offset is now set along with size to maintain the relative position
of symbols composing a marker.

An asistant, with preview, is accessible through the data defined button
to help the user define the size expression. Three methods are
available: Frannery, Area and Radius.

Added a widget for use in categorized/classified symbology gui to set
the expression if needed. The assistant is also available from it.

Author: vmora

python/gui/gui.sip

@@ -172,6 +172,7 @@
 %Include symbology-ng/characterwidget.sip
 %Include symbology-ng/qgsdashspacedialog.sip
 %Include symbology-ng/qgsdatadefinedsymboldialog.sip
+%Include symbology-ng/qgssizescalewidget.sip
 %Include symbology-ng/qgsstylev2exportimportdialog.sip
 %Include symbology-ng/qgssvgselectorwidget.sip
 %Include symbology-ng/qgsgraduatedhistogramwidget.sip

python/gui/qgsdatadefinedbutton.sip

@@ -11,7 +11,7 @@ class QgsDataDefinedAssistant: QDialog
 #include <qgsdatadefinedbutton.h>
 %End
   public:
-    virtual QgsDataDefined* dataDefined() const = 0 /Factory/;
+    virtual QgsDataDefined dataDefined() const = 0;
 };
 
 /** \ingroup gui

python/gui/symbology-ng/qgssizescalewidget.sip

@@ -0,0 +1,11 @@
+class QgsSizeScaleWidget : QgsDataDefinedAssistant
+{
+%TypeHeaderCode
+#include <qgssizescalewidget.h>
+%End
+  public:
+    QgsSizeScaleWidget( const QgsVectorLayer * layer, const QgsMarkerSymbolV2 * symbol );
+
+    QgsDataDefined dataDefined() const;
+};
+

python/gui/symbology-ng/qgssymbolslistwidget.sip

@@ -4,7 +4,7 @@ class QgsSymbolsListWidget : QWidget
 #include <qgssymbolslistwidget.h>
 %End
   public:
-    QgsSymbolsListWidget( QgsSymbolV2* symbol, QgsStyleV2* style, QMenu* menu, QWidget* parent /TransferThis/ = 0 );
+    QgsSymbolsListWidget( QgsSymbolV2* symbol, QgsStyleV2* style, QMenu* menu, QWidget* parent /TransferThis/ = 0, const QgsVectorLayer * layer = 0 );
 
   public slots:
     void setSymbolFromStyle( const QModelIndex & index );

src/core/symbology-ng/qgscategorizedsymbolrendererv2.cpp

@@ -22,6 +22,8 @@
 #include "qgspointdisplacementrenderer.h"
 #include "qgsinvertedpolygonrenderer.h"
 #include "qgspainteffect.h"
+#include "qgsscaleexpression.h"
+#include "qgsdatadefined.h"
 
 #include "qgsfeature.h"
 #include "qgsvectorlayer.h"
@@ -695,6 +697,56 @@ QgsLegendSymbolList QgsCategorizedSymbolRendererV2::legendSymbolItems( double sc
   return lst;
 }
 
+QgsLegendSymbolListV2 QgsCategorizedSymbolRendererV2::legendSymbolItemsV2() const
+{
+  QgsLegendSymbolListV2 lst;
+  if ( mSourceSymbol.data() && mSourceSymbol->type() == QgsSymbolV2::Marker )
+  {
+    // check that all symbols that have the same size expression
+    QgsDataDefined ddSize;
+    foreach ( QgsRendererCategoryV2 category, mCategories )
+    {
+      const QgsMarkerSymbolV2 * symbol = static_cast<const QgsMarkerSymbolV2 *>( category.symbol() );
+      if ( !ddSize.hasDefaultValues() && symbol->dataDefinedSize() != ddSize )
+      {
+        // no common size expression
+        return QgsFeatureRendererV2::legendSymbolItemsV2();
+      }
+      else
+      {
+        ddSize = symbol->dataDefinedSize();
+      }
+    }
+
+    if ( !ddSize.isActive() || !ddSize.useExpression() )
+    {
+      return QgsFeatureRendererV2::legendSymbolItemsV2();
+    }
+
+    QgsScaleExpression exp( ddSize.expressionString() );
+    if ( exp.type() != QgsScaleExpression::Unknown )
+    {
+      QgsLegendSymbolItemV2 title( NULL, exp.baseExpression(), "" );
+      lst << title;
+      foreach ( double v, QgsSymbolLayerV2Utils::prettyBreaks( exp.minValue(), exp.maxValue(), 4 ) )
+      {
+        QgsLegendSymbolItemV2 si( mSourceSymbol.data(), QString::number( v ), "" );
+        QgsMarkerSymbolV2 * s = static_cast<QgsMarkerSymbolV2 *>( si.symbol() );
+        s->setColor( QColor( 0, 0, 0 ) );
+        s->setDataDefinedSize( QgsDataDefined() );
+        s->setSize( exp.size( v ) );
+        lst << si;
+      }
+      // now list the categorized symbols
+      const QgsLegendSymbolListV2 list2 = QgsFeatureRendererV2::legendSymbolItemsV2() ;
+      foreach ( QgsLegendSymbolItemV2 item, list2 )
+        lst << item;
+      return lst;
+    }
+  }
+
+  return QgsFeatureRendererV2::legendSymbolItemsV2();
+}
 
 QgsSymbolV2* QgsCategorizedSymbolRendererV2::sourceSymbol()
 {

src/core/symbology-ng/qgscategorizedsymbolrendererv2.h

@@ -139,6 +139,9 @@ class CORE_EXPORT QgsCategorizedSymbolRendererV2 : public QgsFeatureRendererV2
     //! @note not available in python bindings
     virtual QgsLegendSymbolList legendSymbolItems( double scaleDenominator = -1, QString rule = QString() ) override;
 
+    //! @note added in 2.10
+    QgsLegendSymbolListV2 legendSymbolItemsV2() const override;
+
     QgsSymbolV2* sourceSymbol();
     void setSourceSymbol( QgsSymbolV2* sym );
 

src/core/symbology-ng/qgsgraduatedsymbolrendererv2.cpp

@@ -21,6 +21,8 @@
 #include "qgspointdisplacementrenderer.h"
 #include "qgsinvertedpolygonrenderer.h"
 #include "qgspainteffect.h"
+#include "qgsscaleexpression.h"
+#include "qgsdatadefined.h"
 
 #include "qgsfeature.h"
 #include "qgsvectorlayer.h"
@@ -1151,6 +1153,57 @@ QgsLegendSymbologyList QgsGraduatedSymbolRendererV2::legendSymbologyItems( QSize
   return lst;
 }
 
+QgsLegendSymbolListV2 QgsGraduatedSymbolRendererV2::legendSymbolItemsV2() const
+{
+  QgsLegendSymbolListV2 list;
+  if ( mSourceSymbol.data() && mSourceSymbol->type() == QgsSymbolV2::Marker )
+  {
+    // check that all symbols that have the same size expression
+    QgsDataDefined ddSize;
+    foreach ( QgsRendererRangeV2 range, mRanges )
+    {
+      const QgsMarkerSymbolV2 * symbol = static_cast<const QgsMarkerSymbolV2 *>( range.symbol() );
+      if ( !ddSize.hasDefaultValues() && symbol->dataDefinedSize() != ddSize )
+      {
+        // no common size expression
+        return QgsFeatureRendererV2::legendSymbolItemsV2();
+      }
+      else
+      {
+        ddSize = symbol->dataDefinedSize();
+      }
+    }
+
+    if ( !ddSize.isActive() || !ddSize.useExpression() )
+    {
+      return QgsFeatureRendererV2::legendSymbolItemsV2();
+    }
+
+    QgsScaleExpression exp( ddSize.expressionString() );
+    if ( exp.type() != QgsScaleExpression::Unknown )
+    {
+      QgsLegendSymbolItemV2 title( NULL, exp.baseExpression(), "" );
+      list << title;
+      foreach ( double v, QgsSymbolLayerV2Utils::prettyBreaks( exp.minValue(), exp.maxValue(), 4 ) )
+      {
+        QgsLegendSymbolItemV2 si( mSourceSymbol.data(), QString::number( v ), "" );
+        QgsMarkerSymbolV2 * s = static_cast<QgsMarkerSymbolV2 *>( si.symbol() );
+        s->setColor( QColor( 0, 0, 0 ) );
+        s->setDataDefinedSize( QgsDataDefined() );
+        s->setSize( exp.size( v ) );
+        list << si;
+      }
+      // now list the graduated symbols
+      const QgsLegendSymbolListV2 list2 = QgsFeatureRendererV2::legendSymbolItemsV2() ;
+      foreach ( QgsLegendSymbolItemV2 item, list2 )
+        list << item;
+      return list;
+    }
+  }
+
+  return QgsFeatureRendererV2::legendSymbolItemsV2();
+}
+
 QgsLegendSymbolList QgsGraduatedSymbolRendererV2::legendSymbolItems( double scaleDenominator, QString rule )
 {
   Q_UNUSED( scaleDenominator );

src/core/symbology-ng/qgsgraduatedsymbolrendererv2.h

@@ -239,6 +239,10 @@ class CORE_EXPORT QgsGraduatedSymbolRendererV2 : public QgsFeatureRendererV2
     //! @note not available in python bindings
     virtual QgsLegendSymbolList legendSymbolItems( double scaleDenominator = -1, QString rule = QString() ) override;
 
+    //! @note added in 2.10
+    QgsLegendSymbolListV2 legendSymbolItemsV2() const override;
+
+
     QgsSymbolV2* sourceSymbol();
     void setSourceSymbol( QgsSymbolV2* sym );
 

src/core/symbology-ng/qgssinglesymbolrendererv2.cpp

@@ -26,6 +26,8 @@
 #include "qgspointdisplacementrenderer.h"
 #include "qgsinvertedpolygonrenderer.h"
 #include "qgspainteffect.h"
+#include "qgsscaleexpression.h"
+#include "qgsdatadefined.h"
 
 #include <QDomDocument>
 #include <QDomElement>
@@ -384,6 +386,30 @@ QgsLegendSymbolList QgsSingleSymbolRendererV2::legendSymbolItems( double scaleDe
 QgsLegendSymbolListV2 QgsSingleSymbolRendererV2::legendSymbolItemsV2() const
 {
   QgsLegendSymbolListV2 lst;
+  if ( mSymbol->type() == QgsSymbolV2::Marker )
+  {
+    const QgsMarkerSymbolV2 * symbol = static_cast<const QgsMarkerSymbolV2 *>( mSymbol.data() );
+    QgsDataDefined sizeDD = symbol->dataDefinedSize();
+    if ( sizeDD.isActive() && sizeDD.useExpression() )
+    {
+      QgsScaleExpression scaleExp( sizeDD.expressionString() );
+      if ( scaleExp.type() != QgsScaleExpression::Unknown )
+      {
+        QgsLegendSymbolItemV2 title( NULL, scaleExp.baseExpression(), 0 );
+        lst << title;
+        foreach ( double v, QgsSymbolLayerV2Utils::prettyBreaks( scaleExp.minValue(), scaleExp.maxValue(), 4 ) )
+        {
+          QgsLegendSymbolItemV2 si( mSymbol.data(), QString::number( v ), 0 );
+          QgsMarkerSymbolV2 * s = static_cast<QgsMarkerSymbolV2 *>( si.symbol() );
+          s->setDataDefinedSize( 0 );
+          s->setSize( scaleExp.size( v ) );
+          lst << si;
+        }
+        return lst;
+      }
+    }
+  }
+
   lst << QgsLegendSymbolItemV2( mSymbol.data(), QString(), 0 );
   return lst;
 }

src/core/symbology-ng/qgssymbollayerv2.h

@@ -21,7 +21,7 @@
 #endif
 
 #define DEG2RAD(x)    ((x)*M_PI/180)
-#define DEFAULT_SCALE_METHOD              QgsSymbolV2::ScaleArea
+#define DEFAULT_SCALE_METHOD              QgsSymbolV2::ScaleDiameter
 
 #include <QColor>
 #include <QMap>
@@ -330,7 +330,7 @@ class CORE_EXPORT QgsMarkerSymbolLayerV2 : public QgsSymbolLayerV2
     QgsSymbolV2::ScaleMethod scaleMethod() const { return mScaleMethod; }
 
     void setOffset( QPointF offset ) { mOffset = offset; }
-    QPointF offset() { return mOffset; }
+    QPointF offset() const { return mOffset; }
 
     virtual void toSld( QDomDocument &doc, QDomElement &element, QgsStringMap props ) const override;