[labeling] Move settings related to removing labels (e.g. max no

of labels, min size for labels) to a new class QgsLabelThinningSettings This new class is designed to contain settings related to how the label engine removes candidate label positions and reduces the number of displayed labels.
qgis · Dec 11, 2019 · b1bbc85 · b1bbc85
1 parent 2e25151
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diff --git a/python/core/auto_generated/labeling/qgslabelthinningsettings.sip.in b/python/core/auto_generated/labeling/qgslabelthinningsettings.sip.in
@@ -0,0 +1,93 @@
+/************************************************************************
+ * This file has been generated automatically from                      *
+ *                                                                      *
+ * src/core/labeling/qgslabelthinningsettings.h                         *
+ *                                                                      *
+ * Do not edit manually ! Edit header and run scripts/sipify.pl again   *
+ ************************************************************************/
+
+
+
+
+class QgsLabelThinningSettings
+{
+%Docstring
+
+Contains settings related to how the label engine removes candidate label positions and reduces the number
+of displayed labels.
+
+.. versionadded:: 3.10.2
+%End
+
+%TypeHeaderCode
+#include "qgslabelthinningsettings.h"
+%End
+  public:
+
+    bool limitNumberOfLabelsEnabled() const;
+%Docstring
+Returns ``True`` if the number of labels drawn for the layer should be limited.
+
+.. seealso:: :py:func:`maximumNumberLabels`
+
+.. seealso:: :py:func:`setLimitNumberLabelsEnabled`
+%End
+
+    void setLimitNumberLabelsEnabled( bool enabled );
+%Docstring
+Sets wheter the the number of labels drawn for the layer should be limited.
+
+.. seealso:: :py:func:`setMaximumNumberLabels`
+
+.. seealso:: :py:func:`limitNumberOfLabelsEnabled`
+%End
+
+    int maximumNumberLabels() const;
+%Docstring
+Returns the maximum number of labels which should be drawn for this layer.
+This only has an effect if limitNumberOfLabelsEnabled() is ``True``.
+
+.. seealso:: :py:func:`limitNumberOfLabelsEnabled`
+
+.. seealso:: :py:func:`setMaximumNumberLabels`
+%End
+
+    void setMaximumNumberLabels( int number );
+%Docstring
+Sets the maximum ``number`` of labels which should be drawn for this layer.
+This only has an effect if limitNumberOfLabelsEnabled() is ``True``.
+
+.. seealso:: :py:func:`setLimitNumberLabelsEnabled`
+
+.. seealso:: :py:func:`maximumNumberLabels`
+%End
+
+    double minimumFeatureSize() const;
+%Docstring
+Returns the minimum feature size (in millimeters) for a feature to be labelled.
+
+.. seealso:: :py:func:`setMinimumFeatureSize`
+%End
+
+    void setMinimumFeatureSize( double size );
+%Docstring
+Sets the minimum feature ``size`` (in millimeters) for a feature to be labelled.
+
+.. seealso:: :py:func:`minimumFeatureSize`
+%End
+
+    void updateDataDefinedProperties( const QgsPropertyCollection &properties, QgsExpressionContext &context );
+%Docstring
+Updates the thinning settings to respect any data defined properties
+set within the specified ``properties`` collection.
+%End
+
+};
+
+/************************************************************************
+ * This file has been generated automatically from                      *
+ *                                                                      *
+ * src/core/labeling/qgslabelthinningsettings.h                         *
+ *                                                                      *
+ * Do not edit manually ! Edit header and run scripts/sipify.pl again   *
+ ************************************************************************/
diff --git a/python/core/auto_generated/labeling/qgspallabeling.sip.in b/python/core/auto_generated/labeling/qgspallabeling.sip.in
@@ -462,17 +462,20 @@ Returns the QgsExpression for this label settings. May be ``None`` if isExpressi
 
     bool mergeLines;
 
-    bool limitNumLabels;
-
-    int maxNumLabels;
-
-    double minFeatureSize;
-
 
+%Property( name = limitNumLabels, get = _limitNumLabels, set = _setLimitNumLabels )
+%Property( name = maxNumLabels, get = _maxNumLabels, set = _setMaxNumLabels )
+%Property( name = minFeatureSize, get = _minFeatureSize, set = _setMinFeatureSize )
 %Property( name = obstacle, get = _getIsObstacle, set = _setIsObstacle )
 %Property( name = obstacleFactor, get = _getObstacleFactor, set = _setObstacleFactor )
 %Property( name = obstacleType, get = _getObstacleType, set = _setObstacleType )
 
+    bool _limitNumLabels() const;
+    void _setLimitNumLabels( bool limit );
+    int _maxNumLabels() const;
+    void _setMaxNumLabels( int max );
+    double _minFeatureSize() const;
+    void _setMinFeatureSize( double size );
     bool _getIsObstacle() const;
     void _setIsObstacle( bool obstacle );
     double _getObstacleFactor() const;
@@ -610,6 +613,25 @@ Sets the label obstacle ``settings``.
 .. versionadded:: 3.10.2
 %End
 
+
+    QgsLabelThinningSettings &thinningSettings();
+%Docstring
+Returns the label thinning settings.
+
+.. seealso:: :py:func:`setThinningSettings`
+
+.. versionadded:: 3.12
+%End
+
+    void setThinningSettings( const QgsLabelThinningSettings &settings );
+%Docstring
+Sets the label thinning ``settings``.
+
+.. seealso:: :py:func:`thinningSettings`
+
+.. versionadded:: 3.12
+%End
+
     static QPixmap labelSettingsPreviewPixmap( const QgsPalLayerSettings &settings, QSize size, const QString &previewText = QString(), int padding = 0 );
 %Docstring
 Returns a pixmap preview for label ``settings``.

diff --git a/python/core/core_auto.sip b/python/core/core_auto.sip
@@ -311,6 +311,7 @@
 %Include auto_generated/labeling/qgslabelingenginesettings.sip
 %Include auto_generated/labeling/qgslabelobstaclesettings.sip
 %Include auto_generated/labeling/qgslabelsearchtree.sip
+%Include auto_generated/labeling/qgslabelthinningsettings.sip
 %Include auto_generated/labeling/qgspallabeling.sip
 %Include auto_generated/labeling/qgsrulebasedlabeling.sip
 %Include auto_generated/labeling/qgsvectorlayerlabeling.sip

diff --git a/src/core/CMakeLists.txt b/src/core/CMakeLists.txt
@@ -538,6 +538,7 @@ SET(QGIS_CORE_SRCS
   labeling/qgslabelingenginesettings.cpp
   labeling/qgslabelobstaclesettings.cpp
   labeling/qgslabelsearchtree.cpp
+  labeling/qgslabelthinningsettings.cpp
   labeling/qgspallabeling.cpp
   labeling/qgsrulebasedlabeling.cpp
   labeling/qgstextlabelfeature.cpp
@@ -1021,6 +1022,7 @@ SET(QGIS_CORE_HDRS
   labeling/qgslabelingenginesettings.h
   labeling/qgslabelobstaclesettings.h
   labeling/qgslabelsearchtree.h
+  labeling/qgslabelthinningsettings.h
   labeling/qgspallabeling.h
   labeling/qgsrulebasedlabeling.h
   labeling/qgstextlabelfeature.h

diff --git a/src/core/labeling/qgslabelobstaclesettings.h b/src/core/labeling/qgslabelobstaclesettings.h
@@ -18,7 +18,7 @@
 
 #include "qgis_core.h"
 #include "qgis_sip.h"
-#include "qgsgeos.h"
+#include "qgsgeometry.h"
 
 class QgsPropertyCollection;
 class QgsExpressionContext;

diff --git a/src/core/labeling/qgslabelthinningsettings.cpp b/src/core/labeling/qgslabelthinningsettings.cpp
@@ -0,0 +1,30 @@
+/***************************************************************************
+  qgslabelthinningsettings.cpp
+  ----------------------------
+  Date                 : December 2019
+  Copyright            : (C) 2019 by Nyall Dawson
+  Email                : nyall dot dawson at gmail dot com
+ ***************************************************************************
+ *                                                                         *
+ *   This program is free software; you can redistribute it and/or modify  *
+ *   it under the terms of the GNU General Public License as published by  *
+ *   the Free Software Foundation; either version 2 of the License, or     *
+ *   (at your option) any later version.                                   *
+ *                                                                         *
+ ***************************************************************************/
+
+#include "qgslabelthinningsettings.h"
+#include "qgspropertycollection.h"
+#include "qgsexpressioncontext.h"
+#include "qgspallabeling.h"
+
+
+void QgsLabelThinningSettings::updateDataDefinedProperties( const QgsPropertyCollection &properties, QgsExpressionContext &context )
+{
+  Q_UNUSED( properties )
+  Q_UNUSED( context )
+
+  // temporarily avoid warnings
+  int unused = 1;
+  ( void )unused;
+}
diff --git a/src/core/labeling/qgslabelthinningsettings.h b/src/core/labeling/qgslabelthinningsettings.h
@@ -0,0 +1,93 @@
+/***************************************************************************
+  qgslabelthinningsettings.h
+  --------------------------
+  Date                 : December 2019
+  Copyright            : (C) 2019 by Nyall Dawson
+  Email                : nyall dot dawson at gmail dot com
+ ***************************************************************************
+ *                                                                         *
+ *   This program is free software; you can redistribute it and/or modify  *
+ *   it under the terms of the GNU General Public License as published by  *
+ *   the Free Software Foundation; either version 2 of the License, or     *
+ *   (at your option) any later version.                                   *
+ *                                                                         *
+ ***************************************************************************/
+
+#ifndef QGSLABELTHINNINGSETTINGS_H
+#define QGSLABELTHINNINGSETTINGS_H
+
+#include "qgis_core.h"
+#include "qgis_sip.h"
+
+class QgsPropertyCollection;
+class QgsExpressionContext;
+
+/**
+ * \ingroup core
+ * \class QgsLabelThinningSettings
+ *
+ * Contains settings related to how the label engine removes candidate label positions and reduces the number
+ * of displayed labels.
+ *
+ * \since QGIS 3.10.2
+ */
+class CORE_EXPORT QgsLabelThinningSettings
+{
+  public:
+
+    /**
+     * Returns TRUE if the number of labels drawn for the layer should be limited.
+     * \see maximumNumberLabels()
+     * \see setLimitNumberLabelsEnabled()
+     */
+    bool limitNumberOfLabelsEnabled() const { return mLimitNumLabels; }
+
+    /**
+     * Sets wheter the the number of labels drawn for the layer should be limited.
+     * \see setMaximumNumberLabels()
+     * \see limitNumberOfLabelsEnabled()
+     */
+    void setLimitNumberLabelsEnabled( bool enabled ) { mLimitNumLabels = enabled; }
+
+    /**
+     * Returns the maximum number of labels which should be drawn for this layer.
+     * This only has an effect if limitNumberOfLabelsEnabled() is TRUE.
+     * \see limitNumberOfLabelsEnabled()
+     * \see setMaximumNumberLabels()
+     */
+    int maximumNumberLabels() const { return mMaxNumLabels; }
+
+    /**
+     * Sets the maximum \a number of labels which should be drawn for this layer.
+     * This only has an effect if limitNumberOfLabelsEnabled() is TRUE.
+     * \see setLimitNumberLabelsEnabled()
+     * \see maximumNumberLabels()
+     */
+    void setMaximumNumberLabels( int number ) { mMaxNumLabels = number; }
+
+    /**
+     * Returns the minimum feature size (in millimeters) for a feature to be labelled.
+     * \see setMinimumFeatureSize()
+     */
+    double minimumFeatureSize() const { return mMinFeatureSize; }
+
+    /**
+     * Sets the minimum feature \a size (in millimeters) for a feature to be labelled.
+     * \see minimumFeatureSize()
+     */
+    void setMinimumFeatureSize( double size ) { mMinFeatureSize = size; }
+
+    /**
+     * Updates the thinning settings to respect any data defined properties
+     * set within the specified \a properties collection.
+     */
+    void updateDataDefinedProperties( const QgsPropertyCollection &properties, QgsExpressionContext &context );
+
+  private:
+
+    bool mLimitNumLabels = false;
+    int mMaxNumLabels = 2000;
+    double mMinFeatureSize = 0;
+};
+
+#endif // QGSLABELTHINNINGSETTINGS_H
diff --git a/src/core/labeling/qgspallabeling.cpp b/src/core/labeling/qgspallabeling.cpp
@@ -344,9 +344,6 @@ QgsPalLayerSettings &QgsPalLayerSettings::operator=( const QgsPalLayerSettings &
 
   labelPerPart = s.labelPerPart;
   mergeLines = s.mergeLines && !s.addDirectionSymbol;
-  minFeatureSize = s.minFeatureSize;
-  limitNumLabels = s.limitNumLabels;
-  maxNumLabels = s.maxNumLabels;
   zIndex = s.zIndex;
 
   mFormat = s.mFormat;
@@ -355,6 +352,7 @@ QgsPalLayerSettings &QgsPalLayerSettings::operator=( const QgsPalLayerSettings &
   mCallout.reset( s.mCallout ? s.mCallout->clone() : nullptr );
 
   mObstacleSettings = s.mObstacleSettings;
+  mThinningSettings = s.mThinningSettings;
 
   geometryGenerator = s.geometryGenerator;
   geometryGeneratorEnabled = s.geometryGeneratorEnabled;
@@ -808,9 +806,9 @@ void QgsPalLayerSettings::readFromLayerCustomProperties( QgsVectorLayer *layer )
 
   labelPerPart = layer->customProperty( QStringLiteral( "labeling/labelPerPart" ) ).toBool();
   mergeLines = layer->customProperty( QStringLiteral( "labeling/mergeLines" ) ).toBool();
-  minFeatureSize = layer->customProperty( QStringLiteral( "labeling/minFeatureSize" ) ).toDouble();
-  limitNumLabels = layer->customProperty( QStringLiteral( "labeling/limitNumLabels" ), QVariant( false ) ).toBool();
-  maxNumLabels = layer->customProperty( QStringLiteral( "labeling/maxNumLabels" ), QVariant( 2000 ) ).toInt();
+  mThinningSettings.setMinimumFeatureSize( layer->customProperty( QStringLiteral( "labeling/minFeatureSize" ) ).toDouble() );
+  mThinningSettings.setLimitNumberLabelsEnabled( layer->customProperty( QStringLiteral( "labeling/limitNumLabels" ), QVariant( false ) ).toBool() );
+  mThinningSettings.setMaximumNumberLabels( layer->customProperty( QStringLiteral( "labeling/maxNumLabels" ), QVariant( 2000 ) ).toInt() );
   mObstacleSettings.setIsObstacle( layer->customProperty( QStringLiteral( "labeling/obstacle" ), QVariant( true ) ).toBool() );
   mObstacleSettings.setFactor( layer->customProperty( QStringLiteral( "labeling/obstacleFactor" ), QVariant( 1.0 ) ).toDouble() );
   mObstacleSettings.setType( static_cast< QgsLabelObstacleSettings::ObstacleType >( layer->customProperty( QStringLiteral( "labeling/obstacleType" ), QVariant( PolygonInterior ) ).toUInt() ) );
@@ -1034,9 +1032,9 @@ void QgsPalLayerSettings::readXml( const QDomElement &elem, const QgsReadWriteCo
 
   labelPerPart = renderingElem.attribute( QStringLiteral( "labelPerPart" ) ).toInt();
   mergeLines = renderingElem.attribute( QStringLiteral( "mergeLines" ) ).toInt();
-  minFeatureSize = renderingElem.attribute( QStringLiteral( "minFeatureSize" ) ).toDouble();
-  limitNumLabels = renderingElem.attribute( QStringLiteral( "limitNumLabels" ), QStringLiteral( "0" ) ).toInt();
-  maxNumLabels = renderingElem.attribute( QStringLiteral( "maxNumLabels" ), QStringLiteral( "2000" ) ).toInt();
+  mThinningSettings.setMinimumFeatureSize( renderingElem.attribute( QStringLiteral( "minFeatureSize" ) ).toDouble() );
+  mThinningSettings.setLimitNumberLabelsEnabled( renderingElem.attribute( QStringLiteral( "limitNumLabels" ), QStringLiteral( "0" ) ).toInt() );
+  mThinningSettings.setMaximumNumberLabels( renderingElem.attribute( QStringLiteral( "maxNumLabels" ), QStringLiteral( "2000" ) ).toInt() );
   mObstacleSettings.setIsObstacle( renderingElem.attribute( QStringLiteral( "obstacle" ), QStringLiteral( "1" ) ).toInt() );
   mObstacleSettings.setFactor( renderingElem.attribute( QStringLiteral( "obstacleFactor" ), QStringLiteral( "1" ) ).toDouble() );
   mObstacleSettings.setType( static_cast< QgsLabelObstacleSettings::ObstacleType >( renderingElem.attribute( QStringLiteral( "obstacleType" ), QString::number( PolygonInterior ) ).toUInt() ) );
@@ -1181,9 +1179,9 @@ QDomElement QgsPalLayerSettings::writeXml( QDomDocument &doc, const QgsReadWrite
 
   renderingElem.setAttribute( QStringLiteral( "labelPerPart" ), labelPerPart );
   renderingElem.setAttribute( QStringLiteral( "mergeLines" ), mergeLines );
-  renderingElem.setAttribute( QStringLiteral( "minFeatureSize" ), minFeatureSize );
-  renderingElem.setAttribute( QStringLiteral( "limitNumLabels" ), limitNumLabels );
-  renderingElem.setAttribute( QStringLiteral( "maxNumLabels" ), maxNumLabels );
+  renderingElem.setAttribute( QStringLiteral( "minFeatureSize" ), mThinningSettings.minimumFeatureSize() );
+  renderingElem.setAttribute( QStringLiteral( "limitNumLabels" ), mThinningSettings.limitNumberOfLabelsEnabled() );
+  renderingElem.setAttribute( QStringLiteral( "maxNumLabels" ), mThinningSettings.maximumNumberLabels() );
   renderingElem.setAttribute( QStringLiteral( "obstacle" ), mObstacleSettings.isObstacle() );
   renderingElem.setAttribute( QStringLiteral( "obstacleFactor" ), mObstacleSettings.factor() );
   renderingElem.setAttribute( QStringLiteral( "obstacleType" ), static_cast< unsigned int >( mObstacleSettings.type() ) );
@@ -1972,7 +1970,10 @@ void QgsPalLayerSettings::registerFeature( const QgsFeature &f, QgsRenderContext
     }
   }
 
-  if ( minFeatureSize > 0 && !checkMinimumSizeMM( context, geom, minFeatureSize ) )
+  QgsLabelThinningSettings featureThinningSettings = mThinningSettings;
+  featureThinningSettings.updateDataDefinedProperties( mDataDefinedProperties, context.expressionContext() );
+
+  if ( featureThinningSettings.minimumFeatureSize() > 0 && !checkMinimumSizeMM( context, geom, featureThinningSettings.minimumFeatureSize() ) )
     return;
 
   if ( !geos_geom_clone )
@@ -1981,18 +1982,18 @@ void QgsPalLayerSettings::registerFeature( const QgsFeature &f, QgsRenderContext
   // likelihood exists label will be registered with PAL and may be drawn
   // check if max number of features to label (already registered with PAL) has been reached
   // Debug output at end of QgsPalLabeling::drawLabeling(), when deleting temp geometries
-  if ( limitNumLabels )
+  if ( featureThinningSettings.limitNumberOfLabelsEnabled() )
   {
-    if ( !maxNumLabels )
+    if ( !featureThinningSettings.maximumNumberLabels() )
     {
       return;
     }
-    if ( mFeatsRegPal >= maxNumLabels )
+    if ( mFeatsRegPal >= featureThinningSettings.maximumNumberLabels() )
     {
       return;
     }
 
-    int divNum = static_cast< int >( ( static_cast< double >( mFeaturesToLabel ) / maxNumLabels ) + 0.5 ); // NOLINT
+    int divNum = static_cast< int >( ( static_cast< double >( mFeaturesToLabel ) / featureThinningSettings.maximumNumberLabels() ) + 0.5 ); // NOLINT
     if ( divNum && ( mFeatsRegPal == static_cast< int >( mFeatsSendingToPal / divNum ) ) )
     {
       mFeatsSendingToPal += 1;