Use actual map canvas variables & values for symbology widgets

python/gui/qgsdatadefinedbutton.sip

@@ -11,7 +11,24 @@ class QgsDataDefinedAssistant: QDialog
 #include <qgsdatadefinedbutton.h>
 %End
   public:
+    QgsDataDefinedAssistant();
+
     virtual QgsDataDefined dataDefined() const = 0;
+
+    /** Sets the map canvas associated with the widget. This allows the widget to retrieve the current
+     * map scale and other properties from the canvas.
+     * @param canvas map canvas
+     * @see mapCanvas()
+     * @note added in QGIS 2.12
+     */
+    virtual void setMapCanvas( QgsMapCanvas* canvas );
+
+    /** Returns the map canvas associated with the widget.
+     * @see setMapCanvas
+     * @note added in QGIS 2.12
+     */
+    const QgsMapCanvas* mapCanvas() const;
+
 };
 
 /** \ingroup gui
@@ -187,9 +204,16 @@ class QgsDataDefinedButton : QToolButton
      * @param assistant data defined assistant. Set to null to remove the assistant
      * option from the button.
      * @note added in 2.10
+     * @see assistant()
      */
     void setAssistant( const QString& title, QgsDataDefinedAssistant * assistant /Transfer/ );
 
+    /** Returns the assistant used to defined the data defined object properties, if set.
+     * @see setAssistant()
+     * @note added in QGIS 2.12
+     */
+    QgsDataDefinedAssistant* assistant();
+
     /**
      * Common descriptions for expected input values
      */

python/gui/qgsmapcanvas.sip

@@ -356,6 +356,12 @@ class QgsMapCanvas : QGraphicsView
      */
     QgsExpressionContextScope& expressionContextScope();
 
+    /** Returns a const reference to the expression context scope for the map canvas.
+     * @note added in QGIS 2.12
+     * @see setExpressionContextScope()
+     */
+    // const QgsExpressionContextScope& expressionContextScope() const;
+
   public slots:
 
     /** Repaints the canvas map*/

python/gui/symbology-ng/qgsrendererv2widget.sip

@@ -18,10 +18,22 @@ class QgsRendererV2Widget : QWidget
     /** Sets the map canvas associated with the widget. This allows the widget to retrieve the current
      * map scale and other properties from the canvas.
      * @param canvas map canvas
+     * @see mapCanvas()
      * @note added in QGIS 2.12
      */
     virtual void setMapCanvas( QgsMapCanvas* canvas );
 
+    /** Returns the map canvas associated with the widget.
+     * @see setMapCanvas
+     * @note added in QGIS 2.12
+     */
+    const QgsMapCanvas* mapCanvas() const;
+
+    /** Returns the vector layer associated with the widget.
+     * @note added in QGIS 2.12
+     */
+    const QgsVectorLayer* vectorLayer() const;
+
   protected:
     /** Subclasses may provide the capability of changing multiple symbols at once by implementing the following two methods
       and by connecting the slot contextMenuViewCategories(const QPoint&)*/
@@ -45,3 +57,105 @@ class QgsRendererV2Widget : QWidget
     virtual void paste();
 
 };
+
+
+/**
+Utility classes for "en masse" size definition
+*/
+class QgsDataDefinedValueDialog : QDialog
+{
+%TypeHeaderCode
+#include <qgsrendererv2widget.h>
+%End
+
+  public:
+    /** Constructor
+     * @param symbolList must not be empty
+     * @param layer must not be null
+     * @param label value label
+     */
+    QgsDataDefinedValueDialog( const QList<QgsSymbolV2*>& symbolList, QgsVectorLayer * layer, const QString & label );
+    virtual ~QgsDataDefinedValueDialog();
+
+    /** Sets the map canvas associated with the dialog. This allows the dialog to retrieve the current
+     * map scale and other properties from the canvas.
+     * @param canvas map canvas
+     * @see mapCanvas()
+     * @note added in QGIS 2.12
+     */
+    virtual void setMapCanvas( QgsMapCanvas* canvas );
+
+    /** Returns the map canvas associated with the widget.
+     * @see setMapCanvas
+     * @note added in QGIS 2.12
+     */
+    const QgsMapCanvas* mapCanvas() const;
+
+    /** Returns the vector layer associated with the widget.
+     * @note added in QGIS 2.12
+     */
+    const QgsVectorLayer* vectorLayer() const;
+
+  public slots:
+    void dataDefinedChanged();
+
+  protected:
+    QgsDataDefined symbolDataDefined() const;
+    void init( const QString & description ); // needed in children ctor to call virtual
+
+    virtual QgsDataDefined symbolDataDefined( const QgsSymbolV2 * ) const = 0;
+    virtual double value( const QgsSymbolV2 * ) const = 0;
+    virtual void setDataDefined( QgsSymbolV2* symbol, const QgsDataDefined& dd ) = 0;
+};
+
+class QgsDataDefinedSizeDialog : QgsDataDefinedValueDialog
+{
+%TypeHeaderCode
+#include <qgsrendererv2widget.h>
+%End
+
+  public:
+    QgsDataDefinedSizeDialog( const QList<QgsSymbolV2*>& symbolList, QgsVectorLayer * layer );
+
+  protected:
+    QgsDataDefined symbolDataDefined( const QgsSymbolV2 * symbol ) const;
+
+    double value( const QgsSymbolV2 * symbol ) const;
+
+    void setDataDefined( QgsSymbolV2* symbol, const QgsDataDefined& dd );
+};
+
+class QgsDataDefinedRotationDialog : QgsDataDefinedValueDialog
+{
+%TypeHeaderCode
+#include <qgsrendererv2widget.h>
+%End
+
+  public:
+    QgsDataDefinedRotationDialog( const QList<QgsSymbolV2*>& symbolList, QgsVectorLayer * layer );
+
+  protected:
+    QgsDataDefined symbolDataDefined( const QgsSymbolV2 * symbol ) const;
+
+    double value( const QgsSymbolV2 * symbol ) const;
+
+    void setDataDefined( QgsSymbolV2* symbol, const QgsDataDefined& dd );
+};
+
+
+class QgsDataDefinedWidthDialog : QgsDataDefinedValueDialog
+{
+%TypeHeaderCode
+#include <qgsrendererv2widget.h>
+%End
+
+  public:
+    QgsDataDefinedWidthDialog( const QList<QgsSymbolV2*>& symbolList, QgsVectorLayer * layer );
+
+  protected:
+    QgsDataDefined symbolDataDefined( const QgsSymbolV2 * symbol ) const;
+
+    double value( const QgsSymbolV2 * symbol ) const;
+
+    void setDataDefined( QgsSymbolV2* symbol, const QgsDataDefined& dd );
+};

python/gui/symbology-ng/qgssizescalewidget.sip

@@ -8,6 +8,11 @@ class QgsSizeScaleWidget : QgsDataDefinedAssistant
 
     QgsDataDefined dataDefined() const;
 
+    /** Returns the vector layer associated with the widget.
+     * @note added in QGIS 2.12
+     */
+    const QgsVectorLayer* layer() const;
+
   protected:
 
     virtual void showEvent( QShowEvent * );

python/gui/symbology-ng/qgssymbollayerv2widget.sip

@@ -23,10 +23,17 @@ class QgsSymbolLayerV2Widget : QWidget
     /** Sets the map canvas associated with the widget. This allows the widget to retrieve the current
      * map scale and other properties from the canvas.
      * @param canvas map canvas
+     * @see mapCanvas()
      * @note added in QGIS 2.12
      */
     virtual void setMapCanvas( QgsMapCanvas* canvas );
 
+    /** Returns the map canvas associated with the widget.
+     * @see setMapCanvas
+     * @note added in QGIS 2.12
+     */
+    const QgsMapCanvas* mapCanvas() const;
+
     /** Returns the vector layer associated with the widget.
      * @note added in QGIS 2.12
      */

python/gui/symbology-ng/qgssymbolslistwidget.sip

@@ -17,10 +17,17 @@ class QgsSymbolsListWidget : QWidget
     /** Sets the map canvas associated with the widget. This allows the widget to retrieve the current
      * map scale and other properties from the canvas.
      * @param canvas map canvas
+     * @see mapCanvas()
      * @note added in QGIS 2.12
      */
     virtual void setMapCanvas( QgsMapCanvas* canvas );
 
+    /** Returns the map canvas associated with the widget.
+     * @see setMapCanvas
+     * @note added in QGIS 2.12
+     */
+    const QgsMapCanvas* mapCanvas() const;
+
     /** Returns the vector layer associated with the widget.
      * @note added in QGIS 2.12
      */

src/gui/qgsdatadefinedbutton.cpp

@@ -698,6 +698,11 @@ void QgsDataDefinedButton::setAssistant( const QString& title, QgsDataDefinedAss
   mAssistant.data()->setParent( this, Qt::Dialog );
 }
 
+QgsDataDefinedAssistant *QgsDataDefinedButton::assistant()
+{
+  return mAssistant.data();
+}
+
 void QgsDataDefinedButton::checkCheckedWidgets( bool check )
 {
   // don't uncheck, only set to checked

src/gui/qgsdatadefinedbutton.h

@@ -25,6 +25,7 @@
 
 class QgsVectorLayer;
 class QgsDataDefined;
+class QgsMapCanvas;
 
 /** \ingroup gui
  * \class QgsDataDefinedAssistant
@@ -36,7 +37,27 @@ class QgsDataDefined;
 class GUI_EXPORT QgsDataDefinedAssistant: public QDialog
 {
   public:
+    QgsDataDefinedAssistant() : mMapCanvas( 0 ) {}
+
     virtual QgsDataDefined dataDefined() const = 0;
+
+    /** Sets the map canvas associated with the widget. This allows the widget to retrieve the current
+     * map scale and other properties from the canvas.
+     * @param canvas map canvas
+     * @see mapCanvas()
+     * @note added in QGIS 2.12
+     */
+    virtual void setMapCanvas( QgsMapCanvas* canvas ) { mMapCanvas = canvas; }
+
+    /** Returns the map canvas associated with the widget.
+     * @see setMapCanvas
+     * @note added in QGIS 2.12
+     */
+    const QgsMapCanvas* mapCanvas() const { return mMapCanvas; }
+
+  protected:
+
+    QgsMapCanvas* mMapCanvas;
 };
 
 /** \ingroup gui
@@ -214,9 +235,16 @@ class GUI_EXPORT QgsDataDefinedButton: public QToolButton
      * @param assistant data defined assistant. Set to null to remove the assistant
      * option from the button.
      * @note added in 2.10
+     * @see assistant()
      */
     void setAssistant( const QString& title, QgsDataDefinedAssistant * assistant );
 
+    /** Returns the assistant used to defined the data defined object properties, if set.
+     * @see setAssistant()
+     * @note added in QGIS 2.12
+     */
+    QgsDataDefinedAssistant* assistant();
+
     /**
      * Common descriptions for expected input values
      */

src/gui/qgsmapcanvas.h

@@ -428,6 +428,12 @@ class GUI_EXPORT QgsMapCanvas : public QGraphicsView
      */
     QgsExpressionContextScope& expressionContextScope() { return mExpressionContextScope; }
 
+    /** Returns a const reference to the expression context scope for the map canvas.
+     * @note added in QGIS 2.12
+     * @see setExpressionContextScope()
+     */
+    const QgsExpressionContextScope& expressionContextScope() const { return mExpressionContextScope; }
+
   public slots:
 
     /** Repaints the canvas map*/

src/gui/symbology-ng/qgscategorizedsymbolrendererv2widget.cpp

@@ -29,6 +29,7 @@
 
 #include "qgsproject.h"
 #include "qgsexpression.h"
+#include "qgsmapcanvas.h"
 
 #include <QKeyEvent>
 #include <QMenu>
@@ -372,16 +373,25 @@ QgsRendererV2Widget* QgsCategorizedSymbolRendererV2Widget::create( QgsVectorLaye
 
 static QgsExpressionContext _getExpressionContext( const void* context )
 {
+  const QgsCategorizedSymbolRendererV2Widget* widget = ( const QgsCategorizedSymbolRendererV2Widget* ) context;
+
   QgsExpressionContext expContext;
   expContext << QgsExpressionContextUtils::globalScope()
   << QgsExpressionContextUtils::projectScope()
-  << QgsExpressionContextUtils::atlasScope( 0 )
-  //TODO - use actual map canvas settings
-  << QgsExpressionContextUtils::mapSettingsScope( QgsMapSettings() );
+  << QgsExpressionContextUtils::atlasScope( 0 );
 
-  const QgsVectorLayer* layer = ( const QgsVectorLayer* ) context;
-  if ( layer )
-    expContext << QgsExpressionContextUtils::layerScope( layer );
+  if ( widget->mapCanvas() )
+  {
+    expContext << QgsExpressionContextUtils::mapSettingsScope( widget->mapCanvas()->mapSettings() )
+    << new QgsExpressionContextScope( widget->mapCanvas()->expressionContextScope() );
+  }
+  else
+  {
+    expContext << QgsExpressionContextUtils::mapSettingsScope( QgsMapSettings() );
+  }
+
+  if ( widget->vectorLayer() )
+    expContext << QgsExpressionContextUtils::layerScope( widget->vectorLayer() );
 
   return expContext;
 }
@@ -468,7 +478,7 @@ QgsCategorizedSymbolRendererV2Widget::QgsCategorizedSymbolRendererV2Widget( QgsV
 
   btnAdvanced->setMenu( advMenu );
 
-  mExpressionWidget->registerGetExpressionContextCallback( &_getExpressionContext, layer );
+  mExpressionWidget->registerGetExpressionContextCallback( &_getExpressionContext, this );
 }
 
 QgsCategorizedSymbolRendererV2Widget::~QgsCategorizedSymbolRendererV2Widget()

src/gui/symbology-ng/qgsgraduatedsymbolrendererv2widget.cpp

@@ -27,6 +27,7 @@
 #include "qgsludialog.h"
 
 #include "qgsproject.h"
+#include "qgsmapcanvas.h"
 
 #include <QKeyEvent>
 #include <QMenu>
@@ -381,16 +382,25 @@ QgsRendererV2Widget* QgsGraduatedSymbolRendererV2Widget::create( QgsVectorLayer*
 
 static QgsExpressionContext _getExpressionContext( const void* context )
 {
+  const QgsGraduatedSymbolRendererV2Widget* widget = ( const QgsGraduatedSymbolRendererV2Widget* ) context;
+
   QgsExpressionContext expContext;
   expContext << QgsExpressionContextUtils::globalScope()
   << QgsExpressionContextUtils::projectScope()
-  << QgsExpressionContextUtils::atlasScope( 0 )
-  //TODO - use actual map canvas settings
-  << QgsExpressionContextUtils::mapSettingsScope( QgsMapSettings() );
+  << QgsExpressionContextUtils::atlasScope( 0 );
 
-  const QgsVectorLayer* layer = ( const QgsVectorLayer* ) context;
-  if ( layer )
-    expContext << QgsExpressionContextUtils::layerScope( layer );
+  if ( widget->mapCanvas() )
+  {
+    expContext << QgsExpressionContextUtils::mapSettingsScope( widget->mapCanvas()->mapSettings() )
+    << new QgsExpressionContextScope( widget->mapCanvas()->expressionContextScope() );
+  }
+  else
+  {
+    expContext << QgsExpressionContextUtils::mapSettingsScope( QgsMapSettings() );
+  }
+
+  if ( widget->vectorLayer() )
+    expContext << QgsExpressionContextUtils::layerScope( widget->vectorLayer() );
 
   return expContext;
 }
@@ -489,7 +499,7 @@ QgsGraduatedSymbolRendererV2Widget::QgsGraduatedSymbolRendererV2Widget( QgsVecto
   connect( mHistogramWidget, SIGNAL( rangesModified( bool ) ), this, SLOT( refreshRanges( bool ) ) );
   connect( mExpressionWidget, SIGNAL( fieldChanged( QString ) ), mHistogramWidget, SLOT( setSourceFieldExp( QString ) ) );
 
-  mExpressionWidget->registerGetExpressionContextCallback( &_getExpressionContext, mLayer );
+  mExpressionWidget->registerGetExpressionContextCallback( &_getExpressionContext, this );
 }
 
 void QgsGraduatedSymbolRendererV2Widget::on_mSizeUnitWidget_changed()

src/gui/symbology-ng/qgsheatmaprendererwidget.cpp

@@ -23,6 +23,7 @@
 #include "qgsvectorcolorrampv2.h"
 #include "qgsstylev2.h"
 #include "qgsproject.h"
+#include "qgsmapcanvas.h"
 #include <QGridLayout>
 #include <QLabel>
 
@@ -33,16 +34,25 @@ QgsRendererV2Widget* QgsHeatmapRendererWidget::create( QgsVectorLayer* layer, Qg
 
 static QgsExpressionContext _getExpressionContext( const void* context )
 {
+  const QgsHeatmapRendererWidget* widget = ( const QgsHeatmapRendererWidget* ) context;
+
   QgsExpressionContext expContext;
   expContext << QgsExpressionContextUtils::globalScope()
   << QgsExpressionContextUtils::projectScope()
-  << QgsExpressionContextUtils::atlasScope( 0 )
-  //TODO - use actual map canvas settings
-  << QgsExpressionContextUtils::mapSettingsScope( QgsMapSettings() );
+  << QgsExpressionContextUtils::atlasScope( 0 );
 
-  const QgsVectorLayer* layer = ( const QgsVectorLayer* ) context;
-  if ( layer )
-    expContext << QgsExpressionContextUtils::layerScope( layer );
+  if ( widget->mapCanvas() )
+  {
+    expContext << QgsExpressionContextUtils::mapSettingsScope( widget->mapCanvas()->mapSettings() )
+    << new QgsExpressionContextScope( widget->mapCanvas()->expressionContextScope() );
+  }
+  else
+  {
+    expContext << QgsExpressionContextUtils::mapSettingsScope( QgsMapSettings() );
+  }
+
+  if ( widget->vectorLayer() )
+    expContext << QgsExpressionContextUtils::layerScope( widget->vectorLayer() );
 
   return expContext;
 }

src/gui/symbology-ng/qgsrendererv2widget.cpp

@@ -18,6 +18,7 @@
 #include "qgscolordialog.h"
 #include "qgssymbollevelsv2dialog.h"
 #include "qgsexpressionbuilderdialog.h"
+#include "qgsmapcanvas.h"
 
 #include <QMessageBox>
 #include <QInputDialog>
@@ -132,6 +133,7 @@ void QgsRendererV2Widget::changeSymbolWidth()
   }
 
   QgsDataDefinedWidthDialog dlg( symbolList, mLayer );
+  dlg.setMapCanvas( mMapCanvas );
 
   if ( QDialog::Accepted == dlg.exec() )
   {
@@ -157,6 +159,7 @@ void QgsRendererV2Widget::changeSymbolSize()
   }
 
   QgsDataDefinedSizeDialog dlg( symbolList, mLayer );
+  dlg.setMapCanvas( mMapCanvas );
 
   if ( QDialog::Accepted == dlg.exec() )
   {
@@ -182,6 +185,7 @@ void QgsRendererV2Widget::changeSymbolAngle()
   }
 
   QgsDataDefinedRotationDialog dlg( symbolList, mLayer );
+  dlg.setMapCanvas( mMapCanvas );
 
   if ( QDialog::Accepted == dlg.exec() )
   {
@@ -215,6 +219,11 @@ void QgsRendererV2Widget::setMapCanvas( QgsMapCanvas *canvas )
   mMapCanvas = canvas;
 }
 
+const QgsMapCanvas*QgsRendererV2Widget::mapCanvas() const
+{
+  return mMapCanvas;
+}
+
 
 ////////////
 
@@ -397,6 +406,7 @@ void QgsRendererV2DataDefinedMenus::updateMenu( QActionGroup* actionGroup, QStri
 QgsDataDefinedValueDialog::QgsDataDefinedValueDialog( const QList<QgsSymbolV2*>& symbolList, QgsVectorLayer * layer, const QString & label )
     : mSymbolList( symbolList )
     , mLayer( layer )
+    , mMapCanvas( 0 )
 {
   setupUi( this );
   setWindowFlags( Qt::WindowStaysOnTopHint );
@@ -406,18 +416,41 @@ QgsDataDefinedValueDialog::QgsDataDefinedValueDialog( const QList<QgsSymbolV2*>&
 
 }
 
+void QgsDataDefinedValueDialog::setMapCanvas( QgsMapCanvas *canvas )
+{
+  mMapCanvas = canvas;
+  Q_FOREACH ( QgsDataDefinedButton* ddButton, findChildren<QgsDataDefinedButton*>() )
+  {
+    if ( ddButton->assistant() )
+      ddButton->assistant()->setMapCanvas( mMapCanvas );
+  }
+}
+
+const QgsMapCanvas *QgsDataDefinedValueDialog::mapCanvas() const
+{
+  return mMapCanvas;
+}
+
 static QgsExpressionContext _getExpressionContext( const void* context )
 {
+  const QgsDataDefinedValueDialog* widget = ( const QgsDataDefinedValueDialog* ) context;
+
   QgsExpressionContext expContext;
   expContext << QgsExpressionContextUtils::globalScope()
   << QgsExpressionContextUtils::projectScope()
-  << QgsExpressionContextUtils::atlasScope( 0 )
-  //TODO - use actual map canvas settings
-  << QgsExpressionContextUtils::mapSettingsScope( QgsMapSettings() );
+  << QgsExpressionContextUtils::atlasScope( 0 );
+  if ( widget->mapCanvas() )
+  {
+    expContext << QgsExpressionContextUtils::mapSettingsScope( widget->mapCanvas()->mapSettings() )
+    << new QgsExpressionContextScope( widget->mapCanvas()->expressionContextScope() );
+  }
+  else
+  {
+    expContext << QgsExpressionContextUtils::mapSettingsScope( QgsMapSettings() );
+  }
 
-  const QgsVectorLayer* layer = ( const QgsVectorLayer* ) context;
-  if ( layer )
-    expContext << QgsExpressionContextUtils::layerScope( layer );
+  if ( widget->vectorLayer() )
+    expContext << QgsExpressionContextUtils::layerScope( widget->vectorLayer() );
 
   return expContext;
 }
@@ -426,7 +459,7 @@ void QgsDataDefinedValueDialog::init( const QString & description )
 {
   QgsDataDefined dd = symbolDataDefined();
   mDDBtn->init( mLayer, &dd, QgsDataDefinedButton::Double, description );
-  mDDBtn->registerGetExpressionContextCallback( &_getExpressionContext, const_cast< QgsVectorLayer* >( mLayer ) );
+  mDDBtn->registerGetExpressionContextCallback( &_getExpressionContext, this );
   mSpinBox->setValue( value( mSymbolList.back() ) );
   mSpinBox->setEnabled( !mDDBtn->isActive() );
 }

src/gui/symbology-ng/qgsrendererv2widget.h

@@ -53,10 +53,22 @@ class GUI_EXPORT QgsRendererV2Widget : public QWidget
     /** Sets the map canvas associated with the widget. This allows the widget to retrieve the current
      * map scale and other properties from the canvas.
      * @param canvas map canvas
+     * @see mapCanvas()
      * @note added in QGIS 2.12
      */
     virtual void setMapCanvas( QgsMapCanvas* canvas );
 
+    /** Returns the map canvas associated with the widget.
+     * @see setMapCanvas
+     * @note added in QGIS 2.12
+     */
+    const QgsMapCanvas* mapCanvas() const;
+
+    /** Returns the vector layer associated with the widget.
+     * @note added in QGIS 2.12
+     */
+    const QgsVectorLayer* vectorLayer() const { return mLayer; }
+
   protected:
     QgsVectorLayer* mLayer;
     QgsStyleV2* mStyle;
@@ -159,6 +171,25 @@ class GUI_EXPORT QgsDataDefinedValueDialog : public QDialog, public Ui::QgsDataD
     QgsDataDefinedValueDialog( const QList<QgsSymbolV2*>& symbolList, QgsVectorLayer * layer, const QString & label );
     virtual ~QgsDataDefinedValueDialog() {}
 
+    /** Sets the map canvas associated with the dialog. This allows the dialog to retrieve the current
+     * map scale and other properties from the canvas.
+     * @param canvas map canvas
+     * @see mapCanvas()
+     * @note added in QGIS 2.12
+     */
+    virtual void setMapCanvas( QgsMapCanvas* canvas );
+
+    /** Returns the map canvas associated with the widget.
+     * @see setMapCanvas
+     * @note added in QGIS 2.12
+     */
+    const QgsMapCanvas* mapCanvas() const;
+
+    /** Returns the vector layer associated with the widget.
+     * @note added in QGIS 2.12
+     */
+    const QgsVectorLayer* vectorLayer() const { return mLayer; }
+
   public slots:
     void dataDefinedChanged();
 
@@ -172,6 +203,7 @@ class GUI_EXPORT QgsDataDefinedValueDialog : public QDialog, public Ui::QgsDataD
 
     QList<QgsSymbolV2*> mSymbolList;
     QgsVectorLayer* mLayer;
+    QgsMapCanvas* mMapCanvas;
 };
 
 class GUI_EXPORT QgsDataDefinedSizeDialog : public QgsDataDefinedValueDialog

src/gui/symbology-ng/qgsrulebasedrendererv2widget.cpp

@@ -510,10 +510,17 @@ void QgsRuleBasedRendererV2Widget::countFeatures()
   QgsExpressionContext context;
   context << QgsExpressionContextUtils::globalScope()
   << QgsExpressionContextUtils::projectScope()
-  << QgsExpressionContextUtils::atlasScope( 0 )
-  //TODO - use actual map canvas settings
-  << QgsExpressionContextUtils::mapSettingsScope( QgsMapSettings() )
-  << QgsExpressionContextUtils::layerScope( mLayer );
+  << QgsExpressionContextUtils::atlasScope( 0 );
+  if ( mMapCanvas )
+  {
+    context << QgsExpressionContextUtils::mapSettingsScope( mMapCanvas->mapSettings() )
+    << new QgsExpressionContextScope( mMapCanvas->expressionContextScope() );
+  }
+  else
+  {
+    context << QgsExpressionContextUtils::mapSettingsScope( QgsMapSettings() );
+  }
+  context << QgsExpressionContextUtils::layerScope( mLayer );
 
   renderContext.setExpressionContext( context );
 
@@ -637,10 +644,17 @@ void QgsRendererRulePropsDialog::buildExpression()
   QgsExpressionContext context;
   context << QgsExpressionContextUtils::globalScope()
   << QgsExpressionContextUtils::projectScope()
-  << QgsExpressionContextUtils::atlasScope( 0 )
-  //TODO - use actual map canvas settings
-  << QgsExpressionContextUtils::mapSettingsScope( QgsMapSettings() )
-  << QgsExpressionContextUtils::layerScope( mLayer );
+  << QgsExpressionContextUtils::atlasScope( 0 );
+  if ( mMapCanvas )
+  {
+    context << QgsExpressionContextUtils::mapSettingsScope( mMapCanvas->mapSettings() )
+    << new QgsExpressionContextScope( mMapCanvas->expressionContextScope() );
+  }
+  else
+  {
+    context << QgsExpressionContextUtils::mapSettingsScope( QgsMapSettings() );
+  }
+  context << QgsExpressionContextUtils::layerScope( mLayer );
 
   QgsExpressionBuilderDialog dlg( mLayer, editFilter->text(), this, "generic", context );
 
@@ -660,10 +674,17 @@ void QgsRendererRulePropsDialog::testFilter()
   QgsExpressionContext context;
   context << QgsExpressionContextUtils::globalScope()
   << QgsExpressionContextUtils::projectScope()
-  << QgsExpressionContextUtils::atlasScope( 0 )
-  //TODO - use actual map canvas settings
-  << QgsExpressionContextUtils::mapSettingsScope( QgsMapSettings() )
-  << QgsExpressionContextUtils::layerScope( mLayer );
+  << QgsExpressionContextUtils::atlasScope( 0 );
+  if ( mMapCanvas )
+  {
+    context << QgsExpressionContextUtils::mapSettingsScope( mMapCanvas->mapSettings() )
+    << new QgsExpressionContextScope( mMapCanvas->expressionContextScope() );
+  }
+  else
+  {
+    context << QgsExpressionContextUtils::mapSettingsScope( QgsMapSettings() );
+  }
+  context << QgsExpressionContextUtils::layerScope( mLayer );
 
   if ( !filter.prepare( &context ) )
   {

src/gui/symbology-ng/qgssizescalewidget.cpp

@@ -24,6 +24,7 @@
 #include "qgssymbollayerv2utils.h"
 #include "qgsscaleexpression.h"
 #include "qgsdatadefined.h"
+#include "qgsmapcanvas.h"
 
 #include <QMenu>
 #include <QAction>
@@ -80,16 +81,25 @@ void QgsSizeScaleWidget::setFromSymbol()
 
 static QgsExpressionContext _getExpressionContext( const void* context )
 {
+  const QgsSizeScaleWidget* widget = ( const QgsSizeScaleWidget* ) context;
+
   QgsExpressionContext expContext;
   expContext << QgsExpressionContextUtils::globalScope()
   << QgsExpressionContextUtils::projectScope()
-  << QgsExpressionContextUtils::atlasScope( 0 )
-  //TODO - use actual map canvas settings
-  << QgsExpressionContextUtils::mapSettingsScope( QgsMapSettings() );
+  << QgsExpressionContextUtils::atlasScope( 0 );
 
-  const QgsVectorLayer* layer = ( const QgsVectorLayer* ) context;
-  if ( layer )
-    expContext << QgsExpressionContextUtils::layerScope( layer );
+  if ( widget->mapCanvas() )
+  {
+    expContext << QgsExpressionContextUtils::mapSettingsScope( widget->mapCanvas()->mapSettings() )
+    << new QgsExpressionContextScope( widget->mapCanvas()->expressionContextScope() );
+  }
+  else
+  {
+    expContext << QgsExpressionContextUtils::mapSettingsScope( QgsMapSettings() );
+  }
+
+  if ( widget->layer() )
+    expContext << QgsExpressionContextUtils::layerScope( widget->layer() );
 
   return expContext;
 }
@@ -99,11 +109,12 @@ QgsSizeScaleWidget::QgsSizeScaleWidget( const QgsVectorLayer * layer, const QgsM
     // we just use the minimumValue and maximumValue from the layer, unfortunately they are
     // non const, so we get the layer from the registry instead
     , mLayer( layer ? dynamic_cast<QgsVectorLayer *>( QgsMapLayerRegistry::instance()->mapLayer( layer->id() ) ) : 0 )
+    , mMapCanvas( 0 )
 {
   setupUi( this );
   setWindowFlags( Qt::WindowStaysOnTopHint );
 
-  mExpressionWidget->registerGetExpressionContextCallback( &_getExpressionContext, mLayer );
+  mExpressionWidget->registerGetExpressionContextCallback( &_getExpressionContext, this );
 
   if ( mLayer )
   {

src/gui/symbology-ng/qgssizescalewidget.h

@@ -28,6 +28,7 @@ class QgsMarkerSymbolV2;
 class QgsLayerTreeLayer;
 class QgsScaleExpression;
 class QgsDataDefined;
+class QgsMapCanvas;
 
 class GUI_EXPORT QgsSizeScaleWidget : public QgsDataDefinedAssistant, private Ui_SizeScaleBase
 {
@@ -38,6 +39,11 @@ class GUI_EXPORT QgsSizeScaleWidget : public QgsDataDefinedAssistant, private Ui
 
     QgsDataDefined dataDefined() const override;
 
+    /** Returns the vector layer associated with the widget.
+     * @note added in QGIS 2.12
+     */
+    const QgsVectorLayer* layer() const { return mLayer; }
+
   protected:
 
     virtual void showEvent( QShowEvent * ) override;
@@ -53,6 +59,7 @@ class GUI_EXPORT QgsSizeScaleWidget : public QgsDataDefinedAssistant, private Ui
     QgsLayerTreeLayer* mLayerTreeLayer;
     QgsLayerTreeGroup mRoot;
     QStandardItemModel mPreviewList;
+    QgsMapCanvas* mMapCanvas;
 
     QgsScaleExpression* createExpression() const;
     void setFromSymbol();

src/gui/symbology-ng/qgssymbollayerv2widget.cpp

@@ -30,7 +30,7 @@
 #include "qgsvectorgradientcolorrampv2dialog.h"
 #include "qgsdatadefined.h"
 #include "qgsstylev2.h" //for symbol selector dialog
-
+#include "qgsmapcanvas.h"
 #include "qgsapplication.h"
 
 #include "qgslogger.h"
@@ -57,9 +57,17 @@ static QgsExpressionContext _getExpressionContext( const void* context )
   QgsExpressionContext expContext;
   expContext << QgsExpressionContextUtils::globalScope()
   << QgsExpressionContextUtils::projectScope()
-  << QgsExpressionContextUtils::atlasScope( 0 )
-  //TODO - use actual map canvas settings
-  << QgsExpressionContextUtils::mapSettingsScope( QgsMapSettings() );
+  << QgsExpressionContextUtils::atlasScope( 0 );
+
+  if ( widget->mapCanvas() )
+  {
+    expContext << QgsExpressionContextUtils::mapSettingsScope( widget->mapCanvas()->mapSettings() )
+    << new QgsExpressionContextScope( widget->mapCanvas()->expressionContextScope() );
+  }
+  else
+  {
+    expContext << QgsExpressionContextUtils::mapSettingsScope( QgsMapSettings() );
+  }
 
   const QgsVectorLayer* layer = widget->vectorLayer();
   if ( layer )
@@ -75,6 +83,16 @@ void QgsSymbolLayerV2Widget::setMapCanvas( QgsMapCanvas *canvas )
   {
     unitWidget->setMapCanvas( mMapCanvas );
   }
+  Q_FOREACH ( QgsDataDefinedButton* ddButton, findChildren<QgsDataDefinedButton*>() )
+  {
+    if ( ddButton->assistant() )
+      ddButton->assistant()->setMapCanvas( mMapCanvas );
+  }
+}
+
+const QgsMapCanvas* QgsSymbolLayerV2Widget::mapCanvas() const
+{
+  return mMapCanvas;
 }
 
 void QgsSymbolLayerV2Widget::registerDataDefinedButton( QgsDataDefinedButton * button, const QString & propertyName, QgsDataDefinedButton::DataType type, const QString & description )

src/gui/symbology-ng/qgssymbollayerv2widget.h

@@ -47,10 +47,17 @@ class GUI_EXPORT QgsSymbolLayerV2Widget : public QWidget
     /** Sets the map canvas associated with the widget. This allows the widget to retrieve the current
      * map scale and other properties from the canvas.
      * @param canvas map canvas
+     * @see mapCanvas()
      * @note added in QGIS 2.12
      */
     virtual void setMapCanvas( QgsMapCanvas* canvas );
 
+    /** Returns the map canvas associated with the widget.
+     * @see setMapCanvas
+     * @note added in QGIS 2.12
+     */
+    const QgsMapCanvas* mapCanvas() const;
+
     /** Returns the vector layer associated with the widget.
      * @note added in QGIS 2.12
      */

src/gui/symbology-ng/qgssymbolslistwidget.cpp

@@ -25,7 +25,7 @@
 #include "qgsstylev2.h"
 #include "qgssymbollayerv2utils.h"
 #include "qgsmarkersymbollayerv2.h"
-
+#include "qgsmapcanvas.h"
 #include "qgsapplication.h"
 
 #include <QString>
@@ -47,6 +47,7 @@ QgsSymbolsListWidget::QgsSymbolsListWidget( QgsSymbolV2* symbol, QgsStyleV2* sty
     , mAdvancedMenu( 0 )
     , mClipFeaturesAction( 0 )
     , mLayer( layer )
+    , mMapCanvas( 0 )
     , mPresetExpressionContext( 0 )
 {
   setupUi( this );
@@ -119,10 +120,21 @@ QgsSymbolsListWidget::QgsSymbolsListWidget( QgsSymbolV2* symbol, QgsStyleV2* sty
 
 void QgsSymbolsListWidget::setMapCanvas( QgsMapCanvas* canvas )
 {
+  mMapCanvas = canvas;
   Q_FOREACH ( QgsUnitSelectionWidget* unitWidget, findChildren<QgsUnitSelectionWidget*>() )
   {
     unitWidget->setMapCanvas( canvas );
   }
+  Q_FOREACH ( QgsDataDefinedButton* ddButton, findChildren<QgsDataDefinedButton*>() )
+  {
+    if ( ddButton->assistant() )
+      ddButton->assistant()->setMapCanvas( mMapCanvas );
+  }
+}
+
+const QgsMapCanvas*QgsSymbolsListWidget::mapCanvas() const
+{
+  return mMapCanvas;
 }
 
 void QgsSymbolsListWidget::setExpressionContext( QgsExpressionContext *context )
@@ -385,9 +397,17 @@ static QgsExpressionContext _getExpressionContext( const void* context )
   QgsExpressionContext expContext;
   expContext << QgsExpressionContextUtils::globalScope()
   << QgsExpressionContextUtils::projectScope()
-  << QgsExpressionContextUtils::atlasScope( 0 )
-  //TODO - use actual map canvas settings
-  << QgsExpressionContextUtils::mapSettingsScope( QgsMapSettings() );
+  << QgsExpressionContextUtils::atlasScope( 0 );
+
+  if ( widget->mapCanvas() )
+  {
+    expContext << QgsExpressionContextUtils::mapSettingsScope( widget->mapCanvas()->mapSettings() )
+    << new QgsExpressionContextScope( widget->mapCanvas()->expressionContextScope() );
+  }
+  else
+  {
+    expContext << QgsExpressionContextUtils::mapSettingsScope( QgsMapSettings() );
+  }
 
   const QgsVectorLayer* layer = widget->layer();
   if ( layer )

src/gui/symbology-ng/qgssymbolslistwidget.h

@@ -43,10 +43,17 @@ class GUI_EXPORT QgsSymbolsListWidget : public QWidget, private Ui::SymbolsListW
     /** Sets the map canvas associated with the widget. This allows the widget to retrieve the current
      * map scale and other properties from the canvas.
      * @param canvas map canvas
+     * @see mapCanvas()
      * @note added in QGIS 2.12
      */
     virtual void setMapCanvas( QgsMapCanvas* canvas );
 
+    /** Returns the map canvas associated with the widget.
+     * @see setMapCanvas
+     * @note added in QGIS 2.12
+     */
+    const QgsMapCanvas* mapCanvas() const;
+
     /** Returns the vector layer associated with the widget.
      * @note added in QGIS 2.12
      */
@@ -93,6 +100,7 @@ class GUI_EXPORT QgsSymbolsListWidget : public QWidget, private Ui::SymbolsListW
     QMenu* mAdvancedMenu;
     QAction* mClipFeaturesAction;
     const QgsVectorLayer* mLayer;
+    QgsMapCanvas* mMapCanvas;
 
     void populateSymbolView();
     void populateSymbols( QStringList symbols );