Add @geometry_point_count and @geometry_point_num

Author: Hugo Mercier

src/core/qgsexpression.cpp

@@ -4601,6 +4601,8 @@ void QgsExpression::initVariableHelp()
   //symbol variables
   gVariableHelpTexts.insert( "geometry_part_count", QCoreApplication::translate( "variable_help", "Number of parts in rendered feature's geometry." ) );
   gVariableHelpTexts.insert( "geometry_part_num", QCoreApplication::translate( "variable_help", "Current geometry part number for feature being rendered." ) );
+  gVariableHelpTexts.insert( "geometry_point_count", QCoreApplication::translate( "variable_help", "Number of points in the rendered geometry's part. It is only meaningful for line geometries and for symbol layers that set this variable." ) );
+  gVariableHelpTexts.insert( "geometry_point_num", QCoreApplication::translate( "variable_help", "Current point number in the rendered geometry's part. It is only meaningful for line geometries and for symbol layers that set this variable." ) );
 
   gVariableHelpTexts.insert( "symbol_color", QCoreApplication::translate( "symbol_color", "Color of symbol used to render the feature." ) );
   gVariableHelpTexts.insert( "symbol_angle", QCoreApplication::translate( "symbol_angle", "Angle of symbol used to render the feature (valid for marker symbols only)." ) );

src/core/qgsexpressioncontext.cpp

@@ -37,6 +37,8 @@ const QString QgsExpressionContext::EXPR_SYMBOL_COLOR( "symbol_color" );
 const QString QgsExpressionContext::EXPR_SYMBOL_ANGLE( "symbol_angle" );
 const QString QgsExpressionContext::EXPR_GEOMETRY_PART_COUNT( "geometry_part_count" );
 const QString QgsExpressionContext::EXPR_GEOMETRY_PART_NUM( "geometry_part_num" );
+const QString QgsExpressionContext::EXPR_GEOMETRY_POINT_COUNT( "geometry_point_count" );
+const QString QgsExpressionContext::EXPR_GEOMETRY_POINT_NUM( "geometry_point_num" );
 
 //
 // QgsExpressionContextScope

src/core/qgsexpressioncontext.h

@@ -444,6 +444,10 @@ class CORE_EXPORT QgsExpressionContext
     static const QString EXPR_GEOMETRY_PART_COUNT;
     //! Inbuilt variable name for geometry part number variable
     static const QString EXPR_GEOMETRY_PART_NUM;
+    //! Inbuilt variable name for point count variable
+    static const QString EXPR_GEOMETRY_POINT_COUNT;
+    //! Inbuilt variable name for point number variable
+    static const QString EXPR_GEOMETRY_POINT_NUM;
 
   private:
 

src/core/symbology-ng/qgsarrowsymbollayer.cpp

@@ -150,6 +150,7 @@ QSet<QString> QgsArrowSymbolLayer::usedAttributes() const
 
 void QgsArrowSymbolLayer::startRender( QgsSymbolV2RenderContext& context )
 {
+  mExpressionScope.reset( new QgsExpressionContextScope() );
   mScaledArrowWidth = QgsSymbolLayerV2Utils::convertToPainterUnits( context.renderContext(), arrowWidth(), arrowWidthUnit(), arrowWidthUnitScale() );
   mScaledArrowStartWidth = QgsSymbolLayerV2Utils::convertToPainterUnits( context.renderContext(), arrowStartWidth(), arrowStartWidthUnit(), arrowStartWidthUnitScale() );
   mScaledHeadSize = QgsSymbolLayerV2Utils::convertToPainterUnits( context.renderContext(), headSize(), headSizeUnit(), headSizeUnitScale() );
@@ -543,10 +544,14 @@ void QgsArrowSymbolLayer::renderPolyline( const QPolygonF& points, QgsSymbolV2Re
     return;
   }
 
+  context.renderContext().expressionContext().appendScope( mExpressionScope.data() );
+  mExpressionScope->setVariable( QgsExpressionContext::EXPR_GEOMETRY_POINT_COUNT, points.size() + 1 );
+  mExpressionScope->setVariable( QgsExpressionContext::EXPR_GEOMETRY_POINT_NUM, 1 );
   if ( isCurved() )
   {
     for ( int pIdx = 0; pIdx < points.size() - 1; pIdx += 2 )
     {
+      mExpressionScope->setVariable( QgsExpressionContext::EXPR_GEOMETRY_POINT_NUM, pIdx + 1 );
       _resolveDataDefined( context );
 
       if ( points.size() - pIdx >= 3 )
@@ -579,6 +584,7 @@ void QgsArrowSymbolLayer::renderPolyline( const QPolygonF& points, QgsSymbolV2Re
     // only straight arrows
     for ( int pIdx = 0; pIdx < points.size() - 1; pIdx++ )
     {
+      mExpressionScope->setVariable( QgsExpressionContext::EXPR_GEOMETRY_POINT_NUM, pIdx + 1 );
       _resolveDataDefined( context );
 
       // origin point
@@ -590,5 +596,6 @@ void QgsArrowSymbolLayer::renderPolyline( const QPolygonF& points, QgsSymbolV2Re
       mSymbol->renderPolygon( poly, /* rings */ nullptr, context.feature(), context.renderContext() );
     }
   }
+  context.renderContext().expressionContext().popScope();
 }
 

src/core/symbology-ng/qgsarrowsymbollayer.h

@@ -151,6 +151,8 @@ class CORE_EXPORT QgsArrowSymbolLayer : public QgsLineSymbolLayerV2
     double mScaledOffset;
     HeadType mComputedHeadType;
 
+    QScopedPointer<QgsExpressionContextScope> mExpressionScope;
+
     void _resolveDataDefined( QgsSymbolV2RenderContext& );
 };
 

src/gui/symbology-ng/qgssymbollayerv2widget.cpp

@@ -85,11 +85,14 @@ static QgsExpressionContext _getExpressionContext( const void* context )
   expContext << symbolScope;
   expContext.lastScope()->addVariable( QgsExpressionContextScope::StaticVariable( QgsExpressionContext::EXPR_GEOMETRY_PART_COUNT, 1, true ) );
   expContext.lastScope()->addVariable( QgsExpressionContextScope::StaticVariable( QgsExpressionContext::EXPR_GEOMETRY_PART_NUM, 1, true ) );
+  expContext.lastScope()->addVariable( QgsExpressionContextScope::StaticVariable( QgsExpressionContext::EXPR_GEOMETRY_POINT_COUNT, 1, true ) );
+  expContext.lastScope()->addVariable( QgsExpressionContextScope::StaticVariable( QgsExpressionContext::EXPR_GEOMETRY_POINT_NUM, 1, true ) );
 
   //TODO - show actual value
   expContext.setOriginalValueVariable( QVariant() );
   expContext.setHighlightedVariables( QStringList() << QgsExpressionContext::EXPR_ORIGINAL_VALUE << QgsExpressionContext::EXPR_SYMBOL_COLOR
-                                      << QgsExpressionContext::EXPR_GEOMETRY_PART_COUNT << QgsExpressionContext::EXPR_GEOMETRY_PART_NUM );
+                                      << QgsExpressionContext::EXPR_GEOMETRY_PART_COUNT << QgsExpressionContext::EXPR_GEOMETRY_PART_NUM
+                                      << QgsExpressionContext::EXPR_GEOMETRY_POINT_COUNT << QgsExpressionContext::EXPR_GEOMETRY_POINT_NUM );
 
   return expContext;
 }

tests/src/python/test_qgsarrowsymbollayer.py

@@ -39,7 +39,8 @@
     QgsRectangle,
     QgsArrowSymbolLayer,
     QgsSymbolV2,
-    QgsMultiRenderChecker
+    QgsMultiRenderChecker,
+    QgsDataDefined
 )
 
 from qgis.testing import start_app, unittest
@@ -76,7 +77,11 @@ def tearDown(self):
 
     def test_1(self):
         sym = self.lines_layer.rendererV2().symbol()
-        sym_layer = QgsArrowSymbolLayer.create({'arrow_width': '5', 'head_size': '6.5'})
+        sym_layer = QgsArrowSymbolLayer.create({'head_size': '6.5'})
+        dd = QgsDataDefined("(@geometry_point_num % 4) * 2")
+        sym_layer.setDataDefinedProperty("arrow_width", dd)
+        dd2 = QgsDataDefined("(@geometry_point_num % 4) * 2")
+        sym_layer.setDataDefinedProperty("head_size", dd2)
         fill_sym = QgsFillSymbolV2.createSimple({'color': '#8bcfff', 'outline_color': '#000000', 'outline_style': 'solid', 'outline_width': '1'})
         sym_layer.setSubSymbol(fill_sym)
         sym.changeSymbolLayer(0, sym_layer)