Generate more descriptive legends for raster layers

- include band name details where its useful - create a legend for multiband raster renderer
qgis · Dec 16, 2020 · 0d7b95f · 0d7b95f
1 parent d76ec1c
commit 0d7b95f
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Showing 16 changed files with 156 additions and 24 deletions.
diff --git a/python/core/auto_generated/raster/qgsmultibandcolorrenderer.sip.in b/python/core/auto_generated/raster/qgsmultibandcolorrenderer.sip.in
@@ -121,6 +121,8 @@ Ownership of the enhancement is transferred.
 
     virtual QList<int> usesBands() const;
 
+    virtual QList<QgsLayerTreeModelLegendNode *> createLegendNodes( QgsLayerTreeLayer *nodeLayer ) /Factory/;
+
 
     virtual void toSld( QDomDocument &doc, QDomElement &element, const QgsStringMap &props = QgsStringMap() ) const;
 

diff --git a/python/core/auto_generated/raster/qgspalettedrasterrenderer.sip.in b/python/core/auto_generated/raster/qgspalettedrasterrenderer.sip.in
@@ -88,6 +88,8 @@ Returns the raster band used for rendering the raster.
 
     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;

diff --git a/python/core/auto_generated/raster/qgsrasterdataprovider.sip.in b/python/core/auto_generated/raster/qgsrasterdataprovider.sip.in
@@ -148,6 +148,7 @@ Reload data (data could change)
 
     virtual QString colorInterpretationName( int bandNo ) const;
 
+
     virtual double bandScale( int bandNo ) const;
 %Docstring
 Read band scale for raster value

diff --git a/python/core/auto_generated/raster/qgsrasterinterface.sip.in b/python/core/auto_generated/raster/qgsrasterinterface.sip.in
@@ -223,6 +223,20 @@ Gets raster size
     virtual QString generateBandName( int bandNumber ) const;
 %Docstring
 helper function to create zero padded band names
+%End
+
+    virtual QString colorInterpretationName( int bandNumber ) const;
+%Docstring
+Returns the name of the color interpretation for the specified ``bandNumber``.
+
+.. versionadded:: 3.18
+%End
+
+    QString displayBandName( int bandNumber ) const;
+%Docstring
+Generates a friendly, descriptive name for the specified ``bandNumber``.
+
+.. versionadded:: 3.18
 %End
 
     virtual QgsRasterBlock *block( int bandNo, const QgsRectangle &extent, int width, int height, QgsRasterBlockFeedback *feedback = 0 ) = 0 /Factory/;

diff --git a/src/core/raster/qgsmultibandcolorrenderer.cpp b/src/core/raster/qgsmultibandcolorrenderer.cpp
@@ -19,6 +19,7 @@
 #include "qgscontrastenhancement.h"
 #include "qgsrastertransparency.h"
 #include "qgsrasterviewport.h"
+#include "qgslayertreemodellegendnode.h"
 
 #include <QDomDocument>
 #include <QDomElement>
@@ -418,6 +419,25 @@ QList<int> QgsMultiBandColorRenderer::usesBands() const
   return bandList;
 }
 
+QList<QgsLayerTreeModelLegendNode *> QgsMultiBandColorRenderer::createLegendNodes( QgsLayerTreeLayer *nodeLayer )
+{
+  QList<QgsLayerTreeModelLegendNode *> res;
+  if ( mRedBand != -1 )
+  {
+    res << new QgsRasterSymbolLegendNode( nodeLayer, QColor( 255, 0, 0 ), displayBandName( mRedBand ) );
+  }
+  if ( mGreenBand != -1 )
+  {
+    res << new QgsRasterSymbolLegendNode( nodeLayer, QColor( 0, 255, 0 ), displayBandName( mGreenBand ) );
+  }
+  if ( mBlueBand != -1 )
+  {
+    res << new QgsRasterSymbolLegendNode( nodeLayer, QColor( 0, 0, 255 ), displayBandName( mBlueBand ) );
+  }
+
+  return res;
+}
+
 void QgsMultiBandColorRenderer::toSld( QDomDocument &doc, QDomElement &element, const QgsStringMap &props ) const
 {
   // create base structure

diff --git a/src/core/raster/qgsmultibandcolorrenderer.h b/src/core/raster/qgsmultibandcolorrenderer.h
@@ -118,6 +118,7 @@ class CORE_EXPORT QgsMultiBandColorRenderer: public QgsRasterRenderer
     void writeXml( QDomDocument &doc, QDomElement &parentElem ) const override;
 
     QList<int> usesBands() const override;
+    QList<QgsLayerTreeModelLegendNode *> createLegendNodes( QgsLayerTreeLayer *nodeLayer ) SIP_FACTORY override;
 
     void toSld( QDomDocument &doc, QDomElement &element, const QgsStringMap &props = QgsStringMap() ) const override;
 

diff --git a/src/core/raster/qgspalettedrasterrenderer.cpp b/src/core/raster/qgspalettedrasterrenderer.cpp
@@ -22,6 +22,7 @@
 #include "qgsstyleentityvisitor.h"
 #include "qgsmessagelog.h"
 #include "qgsrasteriterator.h"
+#include "qgslayertreemodellegendnode.h"
 
 #include <QColor>
 #include <QDomDocument>
@@ -328,6 +329,28 @@ QList< QPair< QString, QColor > > QgsPalettedRasterRenderer::legendSymbologyItem
   return symbolItems;
 }
 
+
+QList<QgsLayerTreeModelLegendNode *> QgsPalettedRasterRenderer::createLegendNodes( QgsLayerTreeLayer *nodeLayer )
+{
+  QList<QgsLayerTreeModelLegendNode *> res;
+
+  const QString name = displayBandName( mBand );
+  if ( !name.isEmpty() )
+  {
+    res << new QgsSimpleLegendNode( nodeLayer, name );
+  }
+
+  const QList< QPair< QString, QColor > > items = legendSymbologyItems();
+  res.reserve( res.size() + items.size() );
+  for ( const QPair< QString, QColor > &item : items )
+  {
+    res << new QgsRasterSymbolLegendNode( nodeLayer, item.second, item.first );
+  }
+
+  return res;
+}
+
+
 QList<int> QgsPalettedRasterRenderer::usesBands() const
 {
   QList<int> bandList;

diff --git a/src/core/raster/qgspalettedrasterrenderer.h b/src/core/raster/qgspalettedrasterrenderer.h
@@ -101,6 +101,7 @@ class CORE_EXPORT QgsPalettedRasterRenderer: 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;

diff --git a/src/core/raster/qgsrasterdataprovider.cpp b/src/core/raster/qgsrasterdataprovider.cpp
@@ -247,6 +247,12 @@ QgsRasterDataProvider::ProviderCapabilities QgsRasterDataProvider::providerCapab
   return QgsRasterDataProvider::NoProviderCapabilities;
 }
 
+int QgsRasterDataProvider::colorInterpretation( int bandNo ) const
+{
+  Q_UNUSED( bandNo )
+  return QgsRaster::UndefinedColorInterpretation;
+}
+
 //
 //Random Static convenience function
 //
@@ -624,5 +630,7 @@ void QgsRasterDataProvider::writeXml( QDomDocument &doc, QDomElement &parentElem
                                   QString::number( mMaxOversampling ) );
 }
 
-
-// ENDS
+QString QgsRasterDataProvider::colorInterpretationName( int bandNo ) const
+{
+  return colorName( colorInterpretation( bandNo ) );
+}
diff --git a/src/core/raster/qgsrasterdataprovider.h b/src/core/raster/qgsrasterdataprovider.h
@@ -152,11 +152,7 @@ class CORE_EXPORT QgsRasterDataProvider : public QgsDataProvider, public QgsRast
     Qgis::DataType sourceDataType( int bandNo ) const override = 0;
 
     //! Returns data type for the band specified by number
-    virtual int colorInterpretation( int bandNo ) const
-    {
-      Q_UNUSED( bandNo )
-      return QgsRaster::UndefinedColorInterpretation;
-    }
+    virtual int colorInterpretation( int bandNo ) const;
 
     QString colorName( int colorInterpretation ) const
     {
@@ -221,10 +217,7 @@ class CORE_EXPORT QgsRasterDataProvider : public QgsDataProvider, public QgsRast
     //! Reload data (data could change)
     virtual bool reload() { return true; }
 
-    virtual QString colorInterpretationName( int bandNo ) const
-    {
-      return colorName( colorInterpretation( bandNo ) );
-    }
+    QString colorInterpretationName( int bandNo ) const override;
 
     /**
      * Read band scale for raster value

diff --git a/src/core/raster/qgsrasterinterface.cpp b/src/core/raster/qgsrasterinterface.cpp
@@ -616,3 +616,30 @@ QString QgsRasterInterface::capabilitiesString() const
 
   return abilitiesList.join( QLatin1String( ", " ) );
 }
+
+QString QgsRasterInterface::generateBandName( int bandNumber ) const
+{
+  if ( mInput )
+    return mInput->generateBandName( bandNumber );
+
+  return tr( "Band" ) + QStringLiteral( " %1" ) .arg( bandNumber, 1 + static_cast< int >( std::log10( static_cast< double >( bandCount() ) ) ), 10, QChar( '0' ) );
+}
+
+QString QgsRasterInterface::colorInterpretationName( int bandNo ) const
+{
+  if ( mInput )
+    return mInput->colorInterpretationName( bandNo );
+
+  return QString();
+}
+
+QString QgsRasterInterface::displayBandName( int bandNumber ) const
+{
+  QString name = generateBandName( bandNumber );
+  QString colorInterp = colorInterpretationName( bandNumber );
+  if ( colorInterp != QLatin1String( "Undefined" ) )
+  {
+    name.append( QStringLiteral( " (%1)" ).arg( colorInterp ) );
+  }
+  return name;
+}
diff --git a/src/core/raster/qgsrasterinterface.h b/src/core/raster/qgsrasterinterface.h
@@ -242,10 +242,21 @@ class CORE_EXPORT QgsRasterInterface
     virtual int ySize() const { return mInput ? mInput->ySize() : 0; }
 
     //! \brief helper function to create zero padded band names
-    virtual QString generateBandName( int bandNumber ) const
-    {
-      return tr( "Band" ) + QStringLiteral( " %1" ) .arg( bandNumber, 1 + static_cast< int >( std::log10( static_cast< double >( bandCount() ) ) ), 10, QChar( '0' ) );
-    }
+    virtual QString generateBandName( int bandNumber ) const;
+
+    /**
+     * Returns the name of the color interpretation for the specified \a bandNumber.
+     *
+     * \since QGIS 3.18
+     */
+    virtual QString colorInterpretationName( int bandNumber ) const;
+
+    /**
+     * Generates a friendly, descriptive name for the specified \a bandNumber.
+     *
+     * \since QGIS 3.18
+     */
+    QString displayBandName( int bandNumber ) const;
 
     /**
      * Read block of data using given extent and size.

diff --git a/src/core/raster/qgssinglebandgrayrenderer.cpp b/src/core/raster/qgssinglebandgrayrenderer.cpp
@@ -217,6 +217,12 @@ QList<QgsLayerTreeModelLegendNode *> QgsSingleBandGrayRenderer::createLegendNode
   QList<QgsLayerTreeModelLegendNode *> res;
   if ( mContrastEnhancement && mContrastEnhancement->contrastEnhancementAlgorithm() != QgsContrastEnhancement::NoEnhancement )
   {
+    const QString name = displayBandName( mGrayBand );
+    if ( !name.isEmpty() )
+    {
+      res << new QgsSimpleLegendNode( nodeLayer, name );
+    }
+
     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 ),

diff --git a/src/core/raster/qgssinglebandpseudocolorrenderer.cpp b/src/core/raster/qgssinglebandpseudocolorrenderer.cpp
@@ -431,6 +431,13 @@ QList<QgsLayerTreeModelLegendNode *> QgsSingleBandPseudoColorRenderer::createLeg
     return QList<QgsLayerTreeModelLegendNode *>();
 
   QList<QgsLayerTreeModelLegendNode *> res;
+
+  const QString name = displayBandName( mBand );
+  if ( !name.isEmpty() )
+  {
+    res << new QgsSimpleLegendNode( nodeLayer, name );
+  }
+
   switch ( rampShader->colorRampType() )
   {
     case QgsColorRampShader::Interpolated:

diff --git a/src/gui/raster/qgsrasterbandcombobox.cpp b/src/gui/raster/qgsrasterbandcombobox.cpp
@@ -166,12 +166,5 @@ QString QgsRasterBandComboBox::displayBandName( QgsRasterDataProvider *provider,
   if ( !provider )
     return QString();
 
-  QString name = provider->generateBandName( band );
-
-  QString colorInterp = provider->colorInterpretationName( band );
-  if ( colorInterp != QLatin1String( "Undefined" ) )
-  {
-    name.append( QStringLiteral( " (%1)" ).arg( colorInterp ) );
-  }
-  return name;
+  return provider->displayBandName( band );
 }
diff --git a/tests/src/core/testqgslegendrenderer.cpp b/tests/src/core/testqgslegendrenderer.cpp
@@ -119,7 +119,30 @@ static bool _verifyImage( const QString &testName, QString &report, int diff = 3
   return equal;
 }
 
+class TestRasterRenderer : public QgsPalettedRasterRenderer
+{
+  public:
+
+    TestRasterRenderer( QgsRasterInterface *input, int bandNumber, const ClassData &classes )
+      : QgsPalettedRasterRenderer( input, bandNumber, classes )
+    {}
+
+    // don't create the default legend nodes for this layer!
+    QList<QgsLayerTreeModelLegendNode *> createLegendNodes( QgsLayerTreeLayer *nodeLayer ) override
+    {
+      QList<QgsLayerTreeModelLegendNode *> res;
 
+      const QList< QPair< QString, QColor > > items = legendSymbologyItems();
+      res.reserve( res.size() + items.size() );
+      for ( const QPair< QString, QColor > &item : items )
+      {
+        res << new QgsRasterSymbolLegendNode( nodeLayer, item.second, item.first );
+      }
+
+      return res;
+    }
+
+};
 
 class TestQgsLegendRenderer : public QObject
 {
@@ -263,7 +286,7 @@ void TestQgsLegendRenderer::init()
   QString rasterUri = QStringLiteral( "MEM:::DATAPOINTER=%1,PIXELS=2,LINES=2" ).arg( ( qulonglong ) RASTER_ARRAY );
   mRL = new QgsRasterLayer( rasterUri, QStringLiteral( "Raster Layer" ), QStringLiteral( "gdal" ) );
 
-  std::unique_ptr< QgsPalettedRasterRenderer > rasterRenderer( new  QgsPalettedRasterRenderer( mRL->dataProvider(), 1,
+  std::unique_ptr< TestRasterRenderer > rasterRenderer( new  TestRasterRenderer( mRL->dataProvider(), 1,
   {
     QgsPalettedRasterRenderer::Class( 1, QColor( 0, 0, 0 ), QStringLiteral( "1" ) ),
     QgsPalettedRasterRenderer::Class( 2, QColor( 255, 255, 255 ), QStringLiteral( "2" ) )