Create color ramp legend nodes for pseudocolor or grayscale rasters or

point clouds using a Linear color ramp based renderer

python/core/auto_generated/raster/qgssinglebandgrayrenderer.sip.in

@@ -56,6 +56,8 @@ Takes ownership
 
     virtual QList< QPair< QString, QColor > > legendSymbologyItems() const;
 
+    virtual QList<QgsLayerTreeModelLegendNode *> createLegendNodes( QgsLayerTreeLayer *nodeLayer ) /Factory/;
+
 
     virtual QList<int> usesBands() const;
 

python/core/auto_generated/raster/qgssinglebandpseudocolorrenderer.sip.in

@@ -77,6 +77,8 @@ Creates a color ramp shader
 
     virtual QList< QPair< QString, QColor > > legendSymbologyItems() const;
 
+    virtual QList<QgsLayerTreeModelLegendNode *> createLegendNodes( QgsLayerTreeLayer *nodeLayer ) /Factory/;
+
     virtual QList<int> usesBands() const;
 
     virtual void toSld( QDomDocument &doc, QDomElement &element, const QgsStringMap &props = QgsStringMap() ) const;

src/core/pointcloud/qgspointcloudattributebyramprenderer.cpp

@@ -21,6 +21,7 @@
 #include "qgscolorramp.h"
 #include "qgssymbollayerutils.h"
 #include "qgslayertreemodellegendnode.h"
+#include "qgscolorramplegendnode.h"
 
 QgsPointCloudAttributeByRampRenderer::QgsPointCloudAttributeByRampRenderer()
 {
@@ -167,16 +168,31 @@ QSet<QString> QgsPointCloudAttributeByRampRenderer::usedAttributes( const QgsPoi
 
 QList<QgsLayerTreeModelLegendNode *> QgsPointCloudAttributeByRampRenderer::createLegendNodes( QgsLayerTreeLayer *nodeLayer )
 {
-  QList<QgsLayerTreeModelLegendNode *> nodes;
-
-  QList< QPair< QString, QColor > > items;
-  mColorRampShader.legendSymbologyItems( items );
-  for ( const QPair< QString, QColor > &item : qgis::as_const( items ) )
+  QList<QgsLayerTreeModelLegendNode *> res;
+  switch ( mColorRampShader.colorRampType() )
   {
-    nodes << new QgsRasterSymbolLegendNode( nodeLayer, item.second, item.first );
+    case QgsColorRampShader::Interpolated:
+      // for interpolated shaders we use a ramp legend node
+      res << new QgsColorRampLegendNode( nodeLayer, mColorRampShader.sourceColorRamp()->clone(),
+                                         QString::number( mColorRampShader.minimumValue() ),
+                                         QString::number( mColorRampShader.maximumValue() ) );
+      break;
+
+    case QgsColorRampShader::Discrete:
+    case QgsColorRampShader::Exact:
+    {
+      // for all others we use itemised lists
+      QList< QPair< QString, QColor > > items;
+      mColorRampShader.legendSymbologyItems( items );
+      res.reserve( items.size() );
+      for ( const QPair< QString, QColor > &item : qgis::as_const( items ) )
+      {
+        res << new QgsRasterSymbolLegendNode( nodeLayer, item.second, item.first );
+      }
+      break;
+    }
   }
-
-  return nodes;
+  return res;
 }
 
 QString QgsPointCloudAttributeByRampRenderer::attribute() const

src/core/raster/qgssinglebandgrayrenderer.cpp

@@ -18,6 +18,7 @@
 #include "qgssinglebandgrayrenderer.h"
 #include "qgscontrastenhancement.h"
 #include "qgsrastertransparency.h"
+#include "qgscolorramplegendnode.h"
 #include <QDomDocument>
 #include <QDomElement>
 #include <QImage>
@@ -211,6 +212,20 @@ QList<QPair<QString, QColor> > QgsSingleBandGrayRenderer::legendSymbologyItems()
   return symbolItems;
 }
 
+QList<QgsLayerTreeModelLegendNode *> QgsSingleBandGrayRenderer::createLegendNodes( QgsLayerTreeLayer *nodeLayer )
+{
+  QList<QgsLayerTreeModelLegendNode *> res;
+  if ( mContrastEnhancement && mContrastEnhancement->contrastEnhancementAlgorithm() != QgsContrastEnhancement::NoEnhancement )
+  {
+    const QColor minColor = ( mGradient == BlackToWhite ) ? Qt::black : Qt::white;
+    const QColor maxColor = ( mGradient == BlackToWhite ) ? Qt::white : Qt::black;
+    res << new QgsColorRampLegendNode( nodeLayer, new QgsGradientColorRamp( minColor, maxColor ),
+                                       QString::number( mContrastEnhancement->minimumValue() ),
+                                       QString::number( mContrastEnhancement->maximumValue() ) );
+  }
+  return res;
+}
+
 QList<int> QgsSingleBandGrayRenderer::usesBands() const
 {
   QList<int> bandList;

src/core/raster/qgssinglebandgrayrenderer.h

@@ -64,6 +64,7 @@ class CORE_EXPORT QgsSingleBandGrayRenderer: public QgsRasterRenderer
     void writeXml( QDomDocument &doc, QDomElement &parentElem ) const override;
 
     QList< QPair< QString, QColor > > legendSymbologyItems() const override;
+    QList<QgsLayerTreeModelLegendNode *> createLegendNodes( QgsLayerTreeLayer *nodeLayer ) SIP_FACTORY override;
 
     QList<int> usesBands() const override;
 

src/core/raster/qgssinglebandpseudocolorrenderer.cpp

@@ -22,6 +22,7 @@
 #include "qgsrastertransparency.h"
 #include "qgsrasterviewport.h"
 #include "qgsstyleentityvisitor.h"
+#include "qgscolorramplegendnode.h"
 
 #include <QDomDocument>
 #include <QDomElement>
@@ -422,3 +423,35 @@ bool QgsSingleBandPseudoColorRenderer::accept( QgsStyleEntityVisitorInterface *v
 
   return true;
 }
+
+QList<QgsLayerTreeModelLegendNode *> QgsSingleBandPseudoColorRenderer::createLegendNodes( QgsLayerTreeLayer *nodeLayer )
+{
+  const QgsColorRampShader *rampShader = dynamic_cast<const QgsColorRampShader *>( mShader->rasterShaderFunction() );
+  if ( !rampShader )
+    return QList<QgsLayerTreeModelLegendNode *>();
+
+  QList<QgsLayerTreeModelLegendNode *> res;
+  switch ( rampShader->colorRampType() )
+  {
+    case QgsColorRampShader::Interpolated:
+      // for interpolated shaders we use a ramp legend node
+      res << new QgsColorRampLegendNode( nodeLayer, rampShader->sourceColorRamp()->clone(),
+                                         QString::number( rampShader->minimumValue() ),
+                                         QString::number( rampShader->maximumValue() ) );
+      break;
+
+    case QgsColorRampShader::Discrete:
+    case QgsColorRampShader::Exact:
+    {
+      // for all others we use itemised lists
+      const QList< QPair< QString, QColor > > items = legendSymbologyItems();
+      res.reserve( items.size() );
+      for ( const QPair< QString, QColor > &item : items )
+      {
+        res << new QgsRasterSymbolLegendNode( nodeLayer, item.second, item.first );
+      }
+      break;
+    }
+  }
+  return res;
+}

src/core/raster/qgssinglebandpseudocolorrenderer.h

@@ -78,6 +78,7 @@ class CORE_EXPORT QgsSingleBandPseudoColorRenderer: public QgsRasterRenderer
 
     void writeXml( QDomDocument &doc, QDomElement &parentElem ) const override;
     QList< QPair< QString, QColor > > legendSymbologyItems() const override;
+    QList<QgsLayerTreeModelLegendNode *> createLegendNodes( QgsLayerTreeLayer *nodeLayer ) SIP_FACTORY override;
     QList<int> usesBands() const override;
     void toSld( QDomDocument &doc, QDomElement &element, const QgsStringMap &props = QgsStringMap() ) const override;
     bool accept( QgsStyleEntityVisitorInterface *visitor ) const override;