More labeling engine refactoring

- QgsPalLabeling now internally uses new engine
- label/diagram providers can hook into rendering loop to avoid extra feature loops
- map rendering uses the new engine instead of QgsPalLabeling

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

Author: wonder-sk

python/core/qgsmaprenderer.sip

@@ -47,9 +47,14 @@ class QgsLabelingEngineInterface
     //! called when starting rendering of a layer
     virtual int prepareLayer( QgsVectorLayer* layer, QStringList& attrNames, QgsRenderContext& ctx ) = 0;
     //! returns PAL layer settings for a registered layer
-    virtual QgsPalLayerSettings& layer( const QString& layerName ) = 0;
+    //! @deprecated since 2.12 - if direct access to QgsPalLayerSettings is necessary, use QgsPalLayerSettings::fromLayer()
+    virtual QgsPalLayerSettings& layer( const QString& layerName ) = 0 /Deprecated/;
     //! adds a diagram layer to the labeling engine
-    virtual int addDiagramLayer( QgsVectorLayer* layer, const QgsDiagramLayerSettings* s );
+    //! @note added in QGIS 2.12
+    virtual int prepareDiagramLayer( QgsVectorLayer* layer, QStringList& attrNames, QgsRenderContext& ctx );
+    //! adds a diagram layer to the labeling engine
+    //! @deprecated since 2.12 - use prepareDiagramLayer()
+    virtual int addDiagramLayer( QgsVectorLayer* layer, const QgsDiagramLayerSettings* s ) /Deprecated/;
     //! called for every feature
     virtual void registerFeature( const QString& layerID, QgsFeature& feat, const QgsRenderContext& context = QgsRenderContext(), QString dxfLayer = QString::null ) = 0;
     //! called for every diagram feature

python/core/qgspallabeling.sip

@@ -699,7 +699,8 @@ class QgsPalLabeling : QgsLabelingEngineInterface
 
     bool isShowingCandidates() const;
     void setShowingCandidates( bool showing );
-    const QList<QgsLabelCandidate>& candidates();
+    //! @deprecated since 2.12
+    const QList<QgsLabelCandidate>& candidates() /Deprecated/;
 
     bool isShowingShadowRectangles() const;
     void setShowingShadowRectangles( bool showing );

src/core/qgslabelingenginev2.cpp

@@ -17,6 +17,7 @@
 
 #include "qgslogger.h"
 #include "qgspalgeometry.h"
+#include "qgsproject.h"
 
 #include "feature.h"
 #include "labelposition.h"
@@ -33,9 +34,8 @@ static bool _palIsCancelled( void* ctx )
 }
 
 
-QgsLabelingEngineV2::QgsLabelingEngineV2( const QgsMapSettings& mapSettings )
-    : mMapSettings( mapSettings )
-    , mFlags( RenderOutlineLabels | UsePartialCandidates )
+QgsLabelingEngineV2::QgsLabelingEngineV2()
+    : mFlags( RenderOutlineLabels | UsePartialCandidates )
     , mSearchMethod( QgsPalLabeling::Chain )
     , mCandPoint( 8 )
     , mCandLine( 8 )
@@ -57,6 +57,15 @@ void QgsLabelingEngineV2::addProvider( QgsAbstractLabelProvider* provider )
   mProviders << provider;
 }
 
+void QgsLabelingEngineV2::removeProvider( QgsAbstractLabelProvider* provider )
+{
+  int idx = mProviders.indexOf( provider );
+  if ( idx >= 0 )
+  {
+    delete mProviders.takeAt( idx );
+  }
+}
+
 void QgsLabelingEngineV2::run( QgsRenderContext& context )
 {
   pal::Pal p;
@@ -146,7 +155,7 @@ void QgsLabelingEngineV2::run( QgsRenderContext& context )
     l->setUpsidedownLabels( upsdnlabels );
 
 
-    QList<QgsLabelFeature*> features = provider->labelFeatures( mMapSettings, context );
+    QList<QgsLabelFeature*> features = provider->labelFeatures( context );
 
     foreach ( QgsLabelFeature* feature, features )
     {
@@ -286,6 +295,40 @@ QgsLabelingResults* QgsLabelingEngineV2::takeResults()
   return res;
 }
 
+
+void QgsLabelingEngineV2::readSettingsFromProject()
+{
+  bool saved = false;
+  QgsProject* prj = QgsProject::instance();
+  mSearchMethod = ( QgsPalLabeling::Search )( prj->readNumEntry( "PAL", "/SearchMethod", ( int ) QgsPalLabeling::Chain, &saved ) );
+  mCandPoint = prj->readNumEntry( "PAL", "/CandidatesPoint", 8, &saved );
+  mCandLine = prj->readNumEntry( "PAL", "/CandidatesLine", 8, &saved );
+  mCandPolygon = prj->readNumEntry( "PAL", "/CandidatesPolygon", 8, &saved );
+
+  mFlags = 0;
+  if ( prj->readBoolEntry( "PAL", "/ShowingCandidates", false, &saved ) ) mFlags |= DrawCandidates;
+  if ( prj->readBoolEntry( "PAL", "/DrawRectOnly", false, &saved ) ) mFlags |= DrawLabelRectOnly;
+  if ( prj->readBoolEntry( "PAL", "/ShowingShadowRects", false, &saved ) ) mFlags |= DrawShadowRects;
+  if ( prj->readBoolEntry( "PAL", "/ShowingAllLabels", false, &saved ) ) mFlags |= UseAllLabels;
+  if ( prj->readBoolEntry( "PAL", "/ShowingPartialsLabels", true, &saved ) ) mFlags |= UsePartialCandidates;
+  if ( prj->readBoolEntry( "PAL", "/DrawOutlineLabels", true, &saved ) ) mFlags |= RenderOutlineLabels;
+}
+
+void QgsLabelingEngineV2::writeSettingsToProject()
+{
+  QgsProject::instance()->writeEntry( "PAL", "/SearchMethod", ( int )mSearchMethod );
+  QgsProject::instance()->writeEntry( "PAL", "/CandidatesPoint", mCandPoint );
+  QgsProject::instance()->writeEntry( "PAL", "/CandidatesLine", mCandLine );
+  QgsProject::instance()->writeEntry( "PAL", "/CandidatesPolygon", mCandPolygon );
+
+  QgsProject::instance()->writeEntry( "PAL", "/ShowingCandidates", mFlags.testFlag( DrawCandidates ) );
+  QgsProject::instance()->writeEntry( "PAL", "/DrawRectOnly", mFlags.testFlag( DrawLabelRectOnly ) );
+  QgsProject::instance()->writeEntry( "PAL", "/ShowingShadowRects", mFlags.testFlag( DrawShadowRects ) );
+  QgsProject::instance()->writeEntry( "PAL", "/ShowingAllLabels", mFlags.testFlag( UseAllLabels ) );
+  QgsProject::instance()->writeEntry( "PAL", "/ShowingPartialsLabels", mFlags.testFlag( UsePartialCandidates ) );
+  QgsProject::instance()->writeEntry( "PAL", "/DrawOutlineLabels", mFlags.testFlag( RenderOutlineLabels ) );
+}
+
 QgsAbstractLabelProvider* QgsLabelingEngineV2::providerById( const QString& id )
 {
   Q_FOREACH ( QgsAbstractLabelProvider* provider, mProviders )

src/core/qgslabelingenginev2.h

@@ -164,7 +164,7 @@ class CORE_EXPORT QgsAbstractLabelProvider
     virtual QString id() const = 0;
 
     //! Return list of labels
-    virtual QList<QgsLabelFeature*> labelFeatures( const QgsMapSettings& mapSettings, const QgsRenderContext& context ) = 0;
+    virtual QList<QgsLabelFeature*> labelFeatures( const QgsRenderContext& context ) = 0;
 
     //! draw this label at the position determined by the labeling engine
     virtual void drawLabel( QgsRenderContext& context, pal::LabelPosition* label ) const = 0;
@@ -210,7 +210,7 @@ Q_DECLARE_OPERATORS_FOR_FLAGS( QgsAbstractLabelProvider::Flags )
 class CORE_EXPORT QgsLabelingEngineV2
 {
   public:
-    QgsLabelingEngineV2( const QgsMapSettings& mapSettings );
+    QgsLabelingEngineV2();
     ~QgsLabelingEngineV2();
 
     enum Flag
@@ -224,9 +224,18 @@ class CORE_EXPORT QgsLabelingEngineV2
     };
     Q_DECLARE_FLAGS( Flags, Flag )
 
+    void setMapSettings( const QgsMapSettings& mapSettings ) { mMapSettings = mapSettings; }
+    const QgsMapSettings& mapSettings() const { return mMapSettings; }
+
     //! Add provider of label features. Takes ownership of the provider
     void addProvider( QgsAbstractLabelProvider* provider );
 
+    //! Remove provider if the provider's initialization failed. Provider instance is deleted.
+    void removeProvider( QgsAbstractLabelProvider* provider );
+
+    //! Lookup provider by its ID
+    QgsAbstractLabelProvider* providerById( const QString& id );
+
     //! compute the labeling with given map settings and providers
     void run( QgsRenderContext& context );
 
@@ -238,15 +247,17 @@ class CORE_EXPORT QgsLabelingEngineV2
 
     void setFlags( Flags flags ) { mFlags = flags; }
     Flags flags() const { return mFlags; }
+    bool testFlag( Flag f ) const { return mFlags.testFlag( f ); }
+    void setFlag( Flag f, bool enabled ) { if ( enabled ) mFlags |= f; else mFlags &= ~f; }
 
     void numCandidatePositions( int& candPoint, int& candLine, int& candPolygon ) { candPoint = mCandPoint; candLine = mCandLine; candPolygon = mCandPolygon; }
     void setNumCandidatePositions( int candPoint, int candLine, int candPolygon ) { mCandPoint = candPoint; mCandLine = candLine; mCandPolygon = candPolygon; }
 
     void setSearchMethod( QgsPalLabeling::Search s ) { mSearchMethod = s; }
     QgsPalLabeling::Search searchMethod() const { return mSearchMethod; }
 
-  protected:
-    QgsAbstractLabelProvider* providerById( const QString& id );
+    void readSettingsFromProject();
+    void writeSettingsToProject();
 
   protected:
     QgsMapSettings mMapSettings;

src/core/qgsmaprenderer.h

@@ -84,9 +84,15 @@ class CORE_EXPORT QgsLabelingEngineInterface
     //! called when starting rendering of a layer
     virtual int prepareLayer( QgsVectorLayer* layer, QStringList& attrNames, QgsRenderContext& ctx ) = 0;
     //! returns PAL layer settings for a registered layer
-    virtual QgsPalLayerSettings& layer( const QString& layerName ) = 0;
+    //! @deprecated since 2.12 - if direct access to QgsPalLayerSettings is necessary, use QgsPalLayerSettings::fromLayer()
+    Q_DECL_DEPRECATED virtual QgsPalLayerSettings& layer( const QString& layerName ) = 0;
     //! adds a diagram layer to the labeling engine
-    virtual int addDiagramLayer( QgsVectorLayer* layer, const QgsDiagramLayerSettings* s )
+    //! @note added in QGIS 2.12
+    virtual int prepareDiagramLayer( QgsVectorLayer* layer, QStringList& attrNames, QgsRenderContext& ctx )
+    { Q_UNUSED( layer ); Q_UNUSED( attrNames ); Q_UNUSED( ctx ); return 0; }
+    //! adds a diagram layer to the labeling engine
+    //! @deprecated since 2.12 - use prepareDiagramLayer()
+    Q_DECL_DEPRECATED virtual int addDiagramLayer( QgsVectorLayer* layer, const QgsDiagramLayerSettings* s )
     { Q_UNUSED( layer ); Q_UNUSED( s ); return 0; }
     //! called for every feature
     virtual void registerFeature( const QString& layerID, QgsFeature& feat, const QgsRenderContext& context = QgsRenderContext(), QString dxfLayer = QString::null ) = 0;

src/core/qgsmaprenderercustompainterjob.cpp

@@ -85,7 +85,9 @@ void QgsMapRendererCustomPainterJob::start()
   if ( mSettings.testFlag( QgsMapSettings::DrawLabeling ) )
   {
 #ifdef LABELING_V2
-    mLabelingEngineV2 = new QgsLabelingEngineV2( mSettings );
+    mLabelingEngineV2 = new QgsLabelingEngineV2();
+    mLabelingEngineV2->readSettingsFromProject();
+    mLabelingEngineV2->setMapSettings( mSettings );
 #else
     mLabelingEngine = new QgsPalLabeling;
     mLabelingEngine->loadEngineSettings();

src/core/qgsmaprendererparalleljob.cpp

@@ -64,7 +64,9 @@ void QgsMapRendererParallelJob::start()
   if ( mSettings.testFlag( QgsMapSettings::DrawLabeling ) )
   {
 #ifdef LABELING_V2
-    mLabelingEngineV2 = new QgsLabelingEngineV2( mSettings );
+    mLabelingEngineV2 = new QgsLabelingEngineV2();
+    mLabelingEngineV2->readSettingsFromProject();
+    mLabelingEngineV2->setMapSettings( mSettings );
 #else
     mLabelingEngine = new QgsPalLabeling;
     mLabelingEngine->loadEngineSettings();