One common class for labeling configurations (QgsAbstractVectorLayerLabeling)

This is +/- equivalent of QgsFeatureRendererV2 for vector layer labels

This code has been funded by Tuscany Region (Italy) - SITA (CIG: 63526840AE) and commissioned to Gis3W s.a.s.

src/core/qgspallabeling.cpp

@@ -43,6 +43,7 @@
 #include "qgsexpression.h"
 #include "qgsdatadefined.h"
 #include "qgslabelingenginev2.h"
+#include "qgsvectorlayerlabeling.h"
 
 #include <qgslogger.h>
 #include <qgsvectorlayer.h>
@@ -3610,7 +3611,6 @@ void QgsPalLabeling::clearActiveLayer( const QString &layerID )
   Q_UNUSED( layerID );
 }
 
-#include "qgsvectorlayerlabeling.h"
 
 int QgsPalLabeling::prepareLayer( QgsVectorLayer* layer, QStringList& attrNames, QgsRenderContext& ctx )
 {
@@ -3619,7 +3619,10 @@ int QgsPalLabeling::prepareLayer( QgsVectorLayer* layer, QStringList& attrNames,
     return 0;
   }
 
-  QgsVectorLayerLabelProvider* lp = layer->labeling().provider( layer );
+  if ( !layer->labeling() )
+    return 0;
+
+  QgsVectorLayerLabelProvider* lp = layer->labeling()->provider( layer );
   if ( !lp )
     return 0;
 

src/core/qgsrulebasedlabeling.cpp

@@ -139,7 +139,7 @@ QgsRuleBasedLabeling::Rule*QgsRuleBasedLabeling::Rule::create( QDomElement& rule
   return rule;
 }
 
-QDomElement QgsRuleBasedLabeling::Rule::save( QDomDocument& doc )
+QDomElement QgsRuleBasedLabeling::Rule::save( QDomDocument& doc ) const
 {
   QDomElement ruleElem = doc.createElement( "rule" );
 
@@ -161,7 +161,7 @@ QDomElement QgsRuleBasedLabeling::Rule::save( QDomDocument& doc )
   //  ruleElem.setAttribute( "checkstate", 0 );
   //ruleElem.setAttribute( "key", mRuleKey );
 
-  for ( RuleList::iterator it = mChildren.begin(); it != mChildren.end(); ++it )
+  for ( RuleList::const_iterator it = mChildren.constBegin(); it != mChildren.constEnd(); ++it )
   {
     Rule* rule = *it;
     ruleElem.appendChild( rule->save( doc ) );
@@ -265,7 +265,12 @@ QgsRuleBasedLabeling*QgsRuleBasedLabeling::create( QDomElement& element )
   return rl;
 }
 
-QDomElement QgsRuleBasedLabeling::save( QDomDocument& doc )
+QString QgsRuleBasedLabeling::type() const
+{
+  return "rule-based";
+}
+
+QDomElement QgsRuleBasedLabeling::save( QDomDocument& doc ) const
 {
   QDomElement elem = doc.createElement( "labeling" );
   elem.setAttribute( "type", "rule-based" );
@@ -276,3 +281,8 @@ QDomElement QgsRuleBasedLabeling::save( QDomDocument& doc )
 
   return elem;
 }
+
+QgsVectorLayerLabelProvider* QgsRuleBasedLabeling::provider( QgsVectorLayer* layer ) const
+{
+  return new QgsRuleBasedLabelProvider( *this, layer, false );
+}

src/core/qgsrulebasedlabeling.h

@@ -3,6 +3,8 @@
 
 #include <QStringList>
 
+#include "qgsvectorlayerlabeling.h"
+
 class QDomDocument;
 class QDomElement;
 
@@ -10,11 +12,9 @@ class QgsExpression;
 class QgsFeature;
 class QgsPalLayerSettings;
 class QgsRenderContext;
-class QgsVectorLayer;
-class QgsVectorLayerLabelProvider;
 
 
-class CORE_EXPORT QgsRuleBasedLabeling
+class CORE_EXPORT QgsRuleBasedLabeling : public QgsAbstractVectorLayerLabeling
 {
   public:
     class Rule;
@@ -49,7 +49,7 @@ class CORE_EXPORT QgsRuleBasedLabeling
          *
          * @return True if this rule is an else rule
          */
-        bool isElse() { return mElseRule; }
+        bool isElse() const { return mElseRule; }
 
         void setLabel( QString label ) { mLabel = label; }
         /**
@@ -93,13 +93,13 @@ class CORE_EXPORT QgsRuleBasedLabeling
          *
          * @return A list of rules
          */
-        RuleList& children() { return mChildren; }
+        const RuleList& children() const { return mChildren; }
         /**
          * The parent rule
          *
          * @return Parent rule
          */
-        Rule* parent() { return mParent; }
+        const Rule* parent() const { return mParent; }
 
         //! add child rule, take ownership, sets this as parent
         void appendChild( Rule* rule );
@@ -117,7 +117,7 @@ class CORE_EXPORT QgsRuleBasedLabeling
         static Rule* create( QDomElement& ruleElem );
 
         //! store labeling info to XML element
-        QDomElement save( QDomDocument& doc );
+        QDomElement save( QDomDocument& doc ) const;
 
         // evaluation
 
@@ -162,13 +162,16 @@ class CORE_EXPORT QgsRuleBasedLabeling
     ~QgsRuleBasedLabeling();
 
     Rule* rootRule() { return mRootRule; }
+    const Rule* rootRule() const { return mRootRule; }
 
     //! Create the instance from a DOM element with saved configuration
     static QgsRuleBasedLabeling* create( QDomElement& element );
 
-    //! Save configuration into a DOM element
-    QDomElement save( QDomDocument& doc );
+    // implementation of parent interface
 
+    virtual QString type() const override;
+    virtual QDomElement save( QDomDocument& doc ) const override;
+    virtual QgsVectorLayerLabelProvider* provider( QgsVectorLayer* layer ) const override;
 
   protected:
     Rule* mRootRule;

src/core/qgsvectorlayer.cpp

@@ -132,7 +132,7 @@ QgsVectorLayer::QgsVectorLayer( QString vectorLayerPath,
     , mRendererV2( NULL )
     , mLabel( 0 )
     , mLabelOn( false )
-    , mLabeling( new QgsVectorLayerLabeling )
+    , mLabeling( new QgsVectorLayerSimpleLabeling )
     , mLabelFontNotFoundNotified( false )
     , mFeatureBlendMode( QPainter::CompositionMode_SourceOver ) // Default to normal feature blending
     , mLayerTransparency( 0 )
@@ -1234,6 +1234,15 @@ bool QgsVectorLayer::hasLabelsEnabled( void ) const
   return mLabelOn;
 }
 
+void QgsVectorLayer::setLabeling( QgsAbstractVectorLayerLabeling* labeling )
+{
+  if ( mLabeling == labeling )
+    return;
+
+  delete mLabeling;
+  mLabeling = labeling;
+}
+
 bool QgsVectorLayer::startEditing()
 {
   if ( !mDataProvider )

src/core/qgsvectorlayer.h

@@ -63,7 +63,7 @@ class QgsSymbolV2;
 class QgsVectorDataProvider;
 class QgsVectorLayerEditBuffer;
 class QgsVectorLayerJoinBuffer;
-class QgsVectorLayerLabeling;
+class QgsAbstractVectorLayerLabeling;
 class QgsPointV2;
 
 typedef QList<int> QgsAttributeList;
@@ -1262,10 +1262,15 @@ class CORE_EXPORT QgsVectorLayer : public QgsMapLayer
     */
     Q_DECL_DEPRECATED bool hasLabelsEnabled() const;
 
-    /** Access to labeling configuration
+    /** Access to labeling configuration.
      * @note added in 2.12
      */
-    QgsVectorLayerLabeling& labeling() { return *mLabeling; }
+    const QgsAbstractVectorLayerLabeling* labeling() const { return mLabeling; }
+
+    /** Set labeling configuration. Takes ownership of the object.
+     * @note added in 2.12
+     */
+    void setLabeling( QgsAbstractVectorLayerLabeling* labeling );
 
     /** Returns true if the provider is in editing mode */
     virtual bool isEditable() const override;
@@ -2092,7 +2097,7 @@ class CORE_EXPORT QgsVectorLayer : public QgsMapLayer
     bool mLabelOn;
 
     /** Labeling configuration */
-    QgsVectorLayerLabeling* mLabeling;
+    QgsAbstractVectorLayerLabeling* mLabeling;
 
     /** Whether 'labeling font not found' has be shown for this layer (only show once in QgsMessageBar, on first rendering) */
     bool mLabelFontNotFoundNotified;

src/core/qgsvectorlayerlabeling.cpp

@@ -4,72 +4,28 @@
 #include "qgsrulebasedlabeling.h"
 #include "qgsvectorlayer.h"
 
-QgsVectorLayerLabeling::QgsVectorLayerLabeling()
-    : mMode( SimpleLabels )
-    //, mSimpleLabeling( 0 )
-    , mRuleBasedLabeling( 0 )
-{
 
+QgsAbstractVectorLayerLabeling::~QgsAbstractVectorLayerLabeling()
+{
 }
 
-QgsVectorLayerLabeling::~QgsVectorLayerLabeling()
+QgsVectorLayerLabelProvider* QgsVectorLayerSimpleLabeling::provider( QgsVectorLayer* layer ) const
 {
-  //delete mSimpleLabeling;
-  delete mRuleBasedLabeling;
-}
+  if ( layer->customProperty( "labeling" ).toString() == QString( "pal" ) && layer->labelsEnabled() )
+    return new QgsVectorLayerLabelProvider( layer, false );
 
-//QgsPalLayerSettings QgsVectorLayerLabeling::simpleLabeling()
-//{
-//}
-
-//void QgsVectorLayerLabeling::setSimpleLabeling(QgsPalLayerSettings* settings)
-//{
-//  delete mSimpleLabeling;
-//  mSimpleLabeling = settings;
-//}
-
-void QgsVectorLayerLabeling::setRuleBasedLabeling( QgsRuleBasedLabeling* settings )
-{
-  delete mRuleBasedLabeling;
-  mRuleBasedLabeling = settings;
-}
-
-QgsVectorLayerLabelProvider* QgsVectorLayerLabeling::provider( QgsVectorLayer* layer )
-{
-  if ( mMode == SimpleLabels )
-  {
-    if ( layer->customProperty( "labeling" ).toString() == QString( "pal" ) && layer->labelsEnabled() )
-      return new QgsVectorLayerLabelProvider( layer, false );
-  }
-  else // rule-based
-  {
-    if ( mRuleBasedLabeling )
-      return new QgsRuleBasedLabelProvider( *mRuleBasedLabeling, layer, false );
-  }
   return 0;
 }
 
-/*
-QgsAbstractLabelProvider* QgsVectorLayerLabeling::addProviderToEngine( QgsVectorLayer* layer, QgsLabelingEngineV2* engine, QgsRenderContext& context )
+QString QgsVectorLayerSimpleLabeling::type() const
 {
-  if ( mMode == SimpleLabels )
-  {
-    QgsVectorLayerLabelProvider* provider = 0;
-    if ( layer->labelsEnabled() )
-    {
-      provider = new QgsVectorLayerLabelProvider( layer, false );
-      engine->addProvider( provider );
-      if ( !provider->prepare( context, attributeNames ) )
-      {
-        engine->removeProvider( provider );
-        provider = 0; // deleted by engine
-      }
-    }
-  }
-  else // rule-based
-  {
-    return 0; // TODO
-  }
-
+  return "simple";
+}
+
+QDomElement QgsVectorLayerSimpleLabeling::save( QDomDocument& doc ) const
+{
+  // all configuration is kept in layer custom properties (for compatibility)
+  QDomElement elem = doc.createElement( "labeling" );
+  elem.setAttribute( "type", "simple" );
+  return elem;
 }
-*/

src/core/qgsvectorlayerlabeling.h

@@ -1,49 +1,48 @@
 #ifndef QGSVECTORLAYERLABELING_H
 #define QGSVECTORLAYERLABELING_H
 
+class QDomDocument;
+class QDomElement;
+class QString;
 
-class QgsPalLayerSettings;
-class QgsRuleBasedLabeling;
 class QgsVectorLayer;
 class QgsVectorLayerLabelProvider;
 
-class CORE_EXPORT QgsVectorLayerLabeling
+/**
+ * Abstract base class - its implementations define different approaches to the labeling of a vector layer.
+ *
+ * @note added in 2.12
+ */
+class CORE_EXPORT QgsAbstractVectorLayerLabeling
 {
   public:
-    enum Mode
-    {
-      //NoLabels,         //!< the layer does not participate in labeling
-      //Obstacles,        //!< no labels are shown, but layer's features act as obstacles for other labels
-      SimpleLabels,     //!< the layer is labelled with one style
-      RuleBasedLabels   //!< the layer is labelled with multiple styles defined with rules
-    };
 
-    //! Defaults to no labels
-    QgsVectorLayerLabeling();
-    ~QgsVectorLayerLabeling();
+    virtual ~QgsAbstractVectorLayerLabeling();
 
-    Mode mode() const { return mMode; }
-    void setMode( Mode m ) { mMode = m; }
+    //! Unique type string of the labeling configuration implementation
+    virtual QString type() const = 0;
 
-    //QgsPalLayerSettings simpleLabeling();
-
-    //QgsPalLayerSettings* simpleLabeling() const { return mSimpleLabeling; }
-    //! Assign simple labeling configuration (takes ownership)
-    //void setSimpleLabeling( QgsPalLayerSettings* settings );
-
-    QgsRuleBasedLabeling* ruleBasedLabeling() const { return mRuleBasedLabeling; }
-    //! Assign rule-based labeling configuration (takes ownership)
-    void setRuleBasedLabeling( QgsRuleBasedLabeling* settings );
-
-    //! Factory for label provider implementation - according to the current mode
-    QgsVectorLayerLabelProvider* provider( QgsVectorLayer* layer );
-
-  protected:
-    Mode mMode;
-    //QgsPalLayerSettings* mSimpleLabeling;
-    QgsRuleBasedLabeling* mRuleBasedLabeling;
+    //! Factory for label provider implementation
+    virtual QgsVectorLayerLabelProvider* provider( QgsVectorLayer* layer ) const = 0;
 
+    //! Return labeling configuration as XML element
+    virtual QDomElement save( QDomDocument& doc ) const = 0;
 };
 
+/**
+ * Basic implementation of the labeling interface.
+ *
+ * The configuration is kept in layer's custom properties for backward compatibility.
+ *
+ * @note added in 2.12
+ */
+class CORE_EXPORT QgsVectorLayerSimpleLabeling : public QgsAbstractVectorLayerLabeling
+{
+  public:
+
+    virtual QString type() const override;
+    virtual QgsVectorLayerLabelProvider* provider( QgsVectorLayer* layer ) const override;
+    virtual QDomElement save( QDomDocument& doc ) const override;
+};
 
 #endif // QGSVECTORLAYERLABELING_H

src/core/qgsvectorlayerlabelprovider.h

@@ -23,7 +23,7 @@ class QgsAbstractFeatureSource;
 /**
  * @brief The QgsVectorLayerLabelProvider class implements a label provider
  * for vector layers. Parameters for the labeling are taken from the layer's
- * custom properties.
+ * custom properties or from the given settings.
  *
  * @note added in QGIS 2.12
  */

src/core/qgsvectorlayerrenderer.cpp

@@ -495,28 +495,19 @@ void QgsVectorLayerRenderer::prepareLabeling( QgsVectorLayer* layer, QStringList
   {
     if ( QgsLabelingEngineV2* engine2 = mContext.labelingEngineV2() )
     {
-      mLabelProvider = layer->labeling().provider( layer );
-      if ( mLabelProvider )
+      if ( layer->labeling() )
       {
-        engine2->addProvider( mLabelProvider );
-        if ( !mLabelProvider->prepare( mContext, attributeNames ) )
+        mLabelProvider = layer->labeling()->provider( layer );
+        if ( mLabelProvider )
         {
-          engine2->removeProvider( mLabelProvider );
-          mLabelProvider = 0; // deleted by engine
+          engine2->addProvider( mLabelProvider );
+          if ( !mLabelProvider->prepare( mContext, attributeNames ) )
+          {
+            engine2->removeProvider( mLabelProvider );
+            mLabelProvider = 0; // deleted by engine
+          }
         }
       }
-
-      //mLabelProvider = layer->labeling().addProviderToEngine( layer, engine2, mContext );
-      /*if ( layer->labelsEnabled() )
-      {
-        mLabelProvider = new QgsVectorLayerLabelProvider( layer, false );
-        engine2->addProvider( mLabelProvider );
-        if ( !mLabelProvider->prepare( mContext, attributeNames ) )
-        {
-          engine2->removeProvider( mLabelProvider );
-          mLabelProvider = 0; // deleted by engine
-        }
-      }*/
     }
     return;
   }

tests/src/core/testqgslabelingenginev2.cpp

@@ -19,8 +19,10 @@
 #include <qgslabelingenginev2.h>
 #include <qgsmaplayerregistry.h>
 #include <qgsmaprenderersequentialjob.h>
+#include <qgsrulebasedlabeling.h>
 #include <qgsvectorlayer.h>
 #include <qgsvectorlayerdiagramprovider.h>
+#include <qgsvectorlayerlabeling.h>
 #include <qgsvectorlayerlabelprovider.h>
 
 class TestQgsLabelingEngineV2 : public QObject
@@ -140,8 +142,6 @@ void TestQgsLabelingEngineV2::testDiagrams()
   vl->loadDefaultStyle( res );
 }
 
-#include "qgsvectorlayerlabeling.h"
-#include "qgsrulebasedlabeling.h"
 
 void TestQgsLabelingEngineV2::testRuleBased()
 {
@@ -170,8 +170,7 @@ void TestQgsLabelingEngineV2::testRuleBased()
   s2.textColor = Qt::red;
   root->appendChild( new QgsRuleBasedLabeling::Rule( new QgsPalLayerSettings( s2 ), 0, 0, "Class = 'Jet'" ) );
 
-  vl->labeling().setMode( QgsVectorLayerLabeling::RuleBasedLabels );
-  vl->labeling().setRuleBasedLabeling( new QgsRuleBasedLabeling( root ) );
+  vl->setLabeling( new QgsRuleBasedLabeling( root ) );
 
   QgsMapRendererSequentialJob job( mapSettings );
   job.start();
@@ -182,7 +181,7 @@ void TestQgsLabelingEngineV2::testRuleBased()
 
   // test read/write rules
   QDomDocument doc, doc2, doc3;
-  QDomElement e = vl->labeling().ruleBasedLabeling()->save( doc );
+  QDomElement e = vl->labeling()->save( doc );
   doc.appendChild( e );
   // read saved rules
   doc2.setContent( doc.toString() );
@@ -194,7 +193,7 @@ void TestQgsLabelingEngineV2::testRuleBased()
   doc3.appendChild( e3 );
   QCOMPARE( doc.toString(), doc3.toString() );
 
-  vl->labeling().setMode( QgsVectorLayerLabeling::SimpleLabels );
+  vl->setLabeling( new QgsVectorLayerSimpleLabeling );
 
   /*
   QPainter p( &img );