[FEATURE] Data defined symbol layer visibility

Adds a data defined override to control a symbol layer's
visibility. Allows users to disable drawing certain symbol layers
for matching features.

python/core/symbology-ng/qgssymbollayer.sip

@@ -277,16 +277,19 @@ class QgsSymbolLayer
      */
     void setPaintEffect( QgsPaintEffect* effect /Transfer/);
 
-  protected:
-    QgsSymbolLayer( QgsSymbol::SymbolType type, bool locked = false );
-
     /** Prepares all data defined property expressions for evaluation. This should
      * be called prior to evaluating data defined properties.
      * @param context symbol render context
      * @note added in QGIS 2.12
      */
     virtual void prepareExpressions( const QgsSymbolRenderContext& context );
 
+    //! Data defined layer enabled string
+    static const QString EXPR_LAYER_ENABLED;
+
+  protected:
+    QgsSymbolLayer( QgsSymbol::SymbolType type, bool locked = false );
+
     /** Saves all data defined properties to a string map.
      * @param stringMap destination string map
      * @see restoreDataDefinedProperties

python/gui/symbology-ng/qgslayerpropertieswidget.sip

@@ -1,4 +1,4 @@
-class QgsLayerPropertiesWidget : QgsPanelWidget
+class QgsLayerPropertiesWidget : QgsPanelWidget, QgsExpressionContextGenerator
 {
 %TypeHeaderCode
 #include <qgslayerpropertieswidget.h>

src/core/symbology-ng/qgsellipsesymbollayer.cpp

@@ -353,7 +353,6 @@ void QgsEllipseSymbolLayer::startRender( QgsSymbolRenderContext& context )
   mPen.setJoinStyle( mPenJoinStyle );
   mPen.setWidthF( QgsSymbolLayerUtils::convertToPainterUnits( context.renderContext(), mOutlineWidth, mOutlineWidthUnit, mOutlineWidthMapUnitScale ) );
   mBrush.setColor( mColor );
-  prepareExpressions( context );
 }
 
 void QgsEllipseSymbolLayer::stopRender( QgsSymbolRenderContext & )

src/core/symbology-ng/qgsfillsymbollayer.cpp

@@ -258,7 +258,6 @@ void QgsSimpleFillSymbolLayer::startRender( QgsSymbolRenderContext& context )
   mPen.setStyle( mBorderStyle );
   mPen.setWidthF( QgsSymbolLayerUtils::convertToPainterUnits( context.renderContext(), mBorderWidth, mBorderWidthUnit, mBorderWidthMapUnitScale ) );
   mPen.setJoinStyle( mPenJoinStyle );
-  prepareExpressions( context );
 }
 
 void QgsSimpleFillSymbolLayer::stopRender( QgsSymbolRenderContext& context )
@@ -838,9 +837,6 @@ void QgsGradientFillSymbolLayer::startRender( QgsSymbolRenderContext& context )
   QColor selColor = context.renderContext().selectionColor();
   if ( ! selectionIsOpaque ) selColor.setAlphaF( context.alpha() );
   mSelBrush = QBrush( selColor );
-
-  //update mBrush to use a gradient fill with specified properties
-  prepareExpressions( context );
 }
 
 void QgsGradientFillSymbolLayer::stopRender( QgsSymbolRenderContext& context )
@@ -1132,8 +1128,6 @@ void QgsShapeburstFillSymbolLayer::startRender( QgsSymbolRenderContext& context
   QColor selColor = context.renderContext().selectionColor();
   if ( ! selectionIsOpaque ) selColor.setAlphaF( context.alpha() );
   mSelBrush = QBrush( selColor );
-
-  prepareExpressions( context );
 }
 
 void QgsShapeburstFillSymbolLayer::stopRender( QgsSymbolRenderContext& context )
@@ -1996,8 +1990,6 @@ void QgsSVGFillSymbolLayer::startRender( QgsSymbolRenderContext& context )
   {
     mOutline->startRender( context.renderContext(), context.fields() );
   }
-
-  prepareExpressions( context );
 }
 
 void QgsSVGFillSymbolLayer::stopRender( QgsSymbolRenderContext& context )
@@ -2831,8 +2823,6 @@ void QgsLinePatternFillSymbolLayer::startRender( QgsSymbolRenderContext& context
   {
     mFillLineSymbol->startRender( context.renderContext(), context.fields() );
   }
-
-  prepareExpressions( context );
 }
 
 void QgsLinePatternFillSymbolLayer::stopRender( QgsSymbolRenderContext & )
@@ -3257,7 +3247,6 @@ void QgsPointPatternFillSymbolLayer::startRender( QgsSymbolRenderContext& contex
   {
     mOutline->startRender( context.renderContext(), context.fields() );
   }
-  prepareExpressions( context );
 }
 
 void QgsPointPatternFillSymbolLayer::stopRender( QgsSymbolRenderContext& context )
@@ -3451,6 +3440,8 @@ QgsSymbolLayer* QgsCentroidFillSymbolLayer::create( const QgsStringMap& properti
   if ( properties.contains( "point_on_all_parts" ) )
     sl->setPointOnAllParts( properties["point_on_all_parts"].toInt() != 0 );
 
+  sl->restoreDataDefinedProperties( properties );
+
   return sl;
 }
 
@@ -3533,6 +3524,7 @@ QgsStringMap QgsCentroidFillSymbolLayer::properties() const
   QgsStringMap map;
   map["point_on_surface"] = QString::number( mPointOnSurface );
   map["point_on_all_parts"] = QString::number( mPointOnAllParts );
+  saveDataDefinedProperties( map );
   return map;
 }
 
@@ -3544,6 +3536,7 @@ QgsCentroidFillSymbolLayer* QgsCentroidFillSymbolLayer::clone() const
   x->setSubSymbol( mMarker->clone() );
   x->setPointOnSurface( mPointOnSurface );
   x->setPointOnAllParts( mPointOnAllParts );
+  copyDataDefinedProperties( x );
   copyPaintEffect( x );
   return x;
 }
@@ -3760,7 +3753,6 @@ void QgsRasterFillSymbolLayer::renderPolygon( const QPolygonF &points, QList<QPo
 
 void QgsRasterFillSymbolLayer::startRender( QgsSymbolRenderContext &context )
 {
-  prepareExpressions( context );
   applyPattern( mBrush, mImageFilePath, mWidth, mAlpha, context );
 }
 

src/core/symbology-ng/qgsgeometrygeneratorsymbollayer.cpp

@@ -44,6 +44,7 @@ QgsSymbolLayer* QgsGeometryGeneratorSymbolLayer::create( const QgsStringMap& pro
   {
     symbolLayer->setSubSymbol( QgsFillSymbol::createSimple( properties ) );
   }
+  symbolLayer->restoreDataDefinedProperties( properties );
 
   return symbolLayer;
 }
@@ -117,6 +118,7 @@ QgsSymbolLayer* QgsGeometryGeneratorSymbolLayer::clone() const
 
   clone->setSymbolType( mSymbolType );
 
+  copyDataDefinedProperties( clone );
   copyPaintEffect( clone );
 
   return clone;
@@ -138,6 +140,7 @@ QgsStringMap QgsGeometryGeneratorSymbolLayer::properties() const
       props.insert( "SymbolType", "Fill" );
       break;
   }
+  saveDataDefinedProperties( props );
 
   return props;
 }
@@ -180,7 +183,9 @@ bool QgsGeometryGeneratorSymbolLayer::setSubSymbol( QgsSymbol* symbol )
 
 QSet<QString> QgsGeometryGeneratorSymbolLayer::usedAttributes() const
 {
-  return mSymbol->usedAttributes() + mExpression->referencedColumns();
+  return QgsSymbolLayer::usedAttributes()
+         + mSymbol->usedAttributes()
+         + mExpression->referencedColumns();
 }
 
 bool QgsGeometryGeneratorSymbolLayer::isCompatibleWithSymbol( QgsSymbol* symbol ) const

src/core/symbology-ng/qgslinesymbollayer.cpp

@@ -228,9 +228,6 @@ void QgsSimpleLineSymbolLayer::startRender( QgsSymbolRenderContext& context )
   if ( ! selectionIsOpaque )
     selColor.setAlphaF( context.alpha() );
   mSelPen.setColor( selColor );
-
-  //prepare expressions for data defined properties
-  prepareExpressions( context );
 }
 
 void QgsSimpleLineSymbolLayer::stopRender( QgsSymbolRenderContext& context )
@@ -815,9 +812,6 @@ void QgsMarkerLineSymbolLayer::startRender( QgsSymbolRenderContext& context )
   mMarker->setRenderHints( hints );
 
   mMarker->startRender( context.renderContext(), context.fields() );
-
-  //prepare expressions for data defined properties
-  prepareExpressions( context );
 }
 
 void QgsMarkerLineSymbolLayer::stopRender( QgsSymbolRenderContext& context )

src/core/symbology-ng/qgsmarkersymbollayer.cpp

@@ -160,8 +160,6 @@ void QgsSimpleMarkerSymbolLayerBase::startRender( QgsSymbolRenderContext &contex
   else
     mPath = transform.map( mPath );
 
-  prepareExpressions( context );
-
   QgsMarkerSymbolLayer::startRender( context );
 }
 
@@ -1909,7 +1907,6 @@ void QgsSvgMarkerSymbolLayer::startRender( QgsSymbolRenderContext& context )
 {
   QgsMarkerSymbolLayer::startRender( context ); // get anchor point expressions
   Q_UNUSED( context );
-  prepareExpressions( context );
 }
 
 void QgsSvgMarkerSymbolLayer::stopRender( QgsSymbolRenderContext& context )
@@ -2574,7 +2571,6 @@ void QgsFontMarkerSymbolLayer::startRender( QgsSymbolRenderContext& context )
   mChrWidth =  mFontMetrics->width( mChr );
   mChrOffset = QPointF( mChrWidth / 2.0, -mFontMetrics->ascent() / 2.0 );
   mOrigSize = mSize; // save in case the size would be data defined
-  prepareExpressions( context );
 }
 
 void QgsFontMarkerSymbolLayer::stopRender( QgsSymbolRenderContext& context )

src/core/symbology-ng/qgssymbol.cpp

@@ -400,6 +400,7 @@ void QgsSymbol::startRender( QgsRenderContext& context, const QgsFields& fields
     if ( !layer->enabled() )
       continue;
 
+    layer->prepareExpressions( symbolContext );
     layer->startRender( symbolContext );
   }
 }
@@ -610,6 +611,14 @@ void QgsSymbol::renderUsingLayer( QgsSymbolLayer* layer, QgsSymbolRenderContext&
 {
   Q_ASSERT( layer->type() == Hybrid );
 
+  if ( layer->hasDataDefinedProperty( QgsSymbolLayer::EXPR_LAYER_ENABLED ) )
+  {
+    bool ok = false;
+    bool enabled = layer->evaluateDataDefinedProperty( QgsSymbolLayer::EXPR_LAYER_ENABLED, context, QVariant(), &ok ).toBool();
+    if ( ok && !enabled )
+      return;
+  }
+
   QgsGeometryGeneratorSymbolLayer* generatorLayer = static_cast<QgsGeometryGeneratorSymbolLayer*>( layer );
 
   QgsPaintEffect* effect = generatorLayer->paintEffect();
@@ -1403,6 +1412,14 @@ void QgsMarkerSymbol::renderPointUsingLayer( QgsMarkerSymbolLayer* layer, QPoint
 {
   static QPointF nullPoint( 0, 0 );
 
+  if ( layer->hasDataDefinedProperty( QgsSymbolLayer::EXPR_LAYER_ENABLED ) )
+  {
+    bool ok = false;
+    bool enabled = layer->evaluateDataDefinedProperty( QgsSymbolLayer::EXPR_LAYER_ENABLED, context, QVariant(), &ok ).toBool();
+    if ( ok && !enabled )
+      return;
+  }
+
   QgsPaintEffect* effect = layer->paintEffect();
   if ( effect && effect->enabled() )
   {
@@ -1676,6 +1693,14 @@ void QgsLineSymbol::renderPolyline( const QPolygonF& points, const QgsFeature* f
 
 void QgsLineSymbol::renderPolylineUsingLayer( QgsLineSymbolLayer *layer, const QPolygonF &points, QgsSymbolRenderContext &context )
 {
+  if ( layer->hasDataDefinedProperty( QgsSymbolLayer::EXPR_LAYER_ENABLED ) )
+  {
+    bool ok = false;
+    bool enabled = layer->evaluateDataDefinedProperty( QgsSymbolLayer::EXPR_LAYER_ENABLED, context, QVariant(), &ok ).toBool();
+    if ( ok && !enabled )
+      return;
+  }
+
   QgsPaintEffect* effect = layer->paintEffect();
   if ( effect && effect->enabled() )
   {
@@ -1748,6 +1773,14 @@ void QgsFillSymbol::renderPolygon( const QPolygonF& points, QList<QPolygonF>* ri
 
 void QgsFillSymbol::renderPolygonUsingLayer( QgsSymbolLayer* layer, const QPolygonF& points, QList<QPolygonF>* rings, QgsSymbolRenderContext& context )
 {
+  if ( layer->hasDataDefinedProperty( QgsSymbolLayer::EXPR_LAYER_ENABLED ) )
+  {
+    bool ok = false;
+    bool enabled = layer->evaluateDataDefinedProperty( QgsSymbolLayer::EXPR_LAYER_ENABLED, context, QVariant(), &ok ).toBool();
+    if ( ok && !enabled )
+      return;
+  }
+
   QgsSymbol::SymbolType layertype = layer->type();
 
   QgsPaintEffect* effect = layer->paintEffect();

src/core/symbology-ng/qgssymbollayer.cpp

@@ -89,6 +89,7 @@ const QString QgsSymbolLayer::EXPR_INTERVAL( "interval" );
 const QString QgsSymbolLayer::EXPR_OFFSET_ALONG_LINE( "offset_along_line" );
 const QString QgsSymbolLayer::EXPR_HORIZONTAL_ANCHOR_POINT( "horizontal_anchor_point" );
 const QString QgsSymbolLayer::EXPR_VERTICAL_ANCHOR_POINT( "vertical_anchor_point" );
+const QString QgsSymbolLayer::EXPR_LAYER_ENABLED( "enabled" );
 
 QgsDataDefined *QgsSymbolLayer::getDataDefinedProperty( const QString &property ) const
 {

src/core/symbology-ng/qgssymbollayer.h

@@ -278,6 +278,16 @@ class CORE_EXPORT QgsSymbolLayer
      */
     void setPaintEffect( QgsPaintEffect* effect );
 
+    /** Prepares all data defined property expressions for evaluation. This should
+     * be called prior to evaluating data defined properties.
+     * @param context symbol render context
+     * @note added in QGIS 2.12
+     */
+    virtual void prepareExpressions( const QgsSymbolRenderContext& context );
+
+    //! Data defined layer enabled string
+    static const QString EXPR_LAYER_ENABLED;
+
   protected:
     QgsSymbolLayer( QgsSymbol::SymbolType type, bool locked = false );
 
@@ -299,13 +309,6 @@ class CORE_EXPORT QgsSymbolLayer
     static const bool selectFillBorder = false;  // Fill symbol layer also selects border symbology
     static const bool selectFillStyle = false;   // Fill symbol uses symbol layer style..
 
-    /** Prepares all data defined property expressions for evaluation. This should
-     * be called prior to evaluating data defined properties.
-     * @param context symbol render context
-     * @note added in QGIS 2.12
-     */
-    virtual void prepareExpressions( const QgsSymbolRenderContext& context );
-
     /** Saves all data defined properties to a string map.
      * @param stringMap destination string map
      * @see restoreDataDefinedProperties