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       1                 :            : /***************************************************************************
       2                 :            :   qgslabelingengine.h
       3                 :            :   --------------------------------------
       4                 :            :   Date                 : September 2015
       5                 :            :   Copyright            : (C) 2015 by Martin Dobias
       6                 :            :   Email                : wonder dot sk at gmail dot com
       7                 :            :  ***************************************************************************
       8                 :            :  *                                                                         *
       9                 :            :  *   This program is free software; you can redistribute it and/or modify  *
      10                 :            :  *   it under the terms of the GNU General Public License as published by  *
      11                 :            :  *   the Free Software Foundation; either version 2 of the License, or     *
      12                 :            :  *   (at your option) any later version.                                   *
      13                 :            :  *                                                                         *
      14                 :            :  ***************************************************************************/
      15                 :            : 
      16                 :            : #ifndef QGSLABELINGENGINE_H
      17                 :            : #define QGSLABELINGENGINE_H
      18                 :            : 
      19                 :            : #define SIP_NO_FILE
      20                 :            : 
      21                 :            : #include "qgis_core.h"
      22                 :            : #include "qgsmapsettings.h"
      23                 :            : 
      24                 :            : #include "qgspallabeling.h"
      25                 :            : #include "qgslabelingenginesettings.h"
      26                 :            : #include "qgslabeling.h"
      27                 :            : 
      28                 :            : class QgsLabelingEngine;
      29                 :            : class QgsLabelingResults;
      30                 :            : 
      31                 :            : namespace pal
      32                 :            : {
      33                 :            :   class Problem;
      34                 :            : }
      35                 :            : 
      36                 :            : /**
      37                 :            :  * \ingroup core
      38                 :            :  * \brief The QgsAbstractLabelProvider class is an interface class. Implementations
      39                 :            :  * return list of labels and their associated geometries - these are used by
      40                 :            :  * QgsLabelingEngine to compute the final layout of labels.
      41                 :            :  *
      42                 :            :  * Implementations also take care of drawing the returned final label positions.
      43                 :            :  *
      44                 :            :  * \note this class is not a part of public API yet. See notes in QgsLabelingEngine
      45                 :            :  * \note not available in Python bindings
      46                 :            :  * \since QGIS 2.12
      47                 :            :  */
      48                 :            : class CORE_EXPORT QgsAbstractLabelProvider
      49                 :            : {
      50                 :            : 
      51                 :            :   public:
      52                 :            :     //! Construct the provider with default values
      53                 :            :     QgsAbstractLabelProvider( QgsMapLayer *layer, const QString &providerId = QString() );
      54                 :            : 
      55                 :          0 :     virtual ~QgsAbstractLabelProvider() = default;
      56                 :            : 
      57                 :            :     //! Associate provider with a labeling engine (should be only called internally from QgsLabelingEngine)
      58                 :          0 :     void setEngine( const QgsLabelingEngine *engine ) { mEngine = engine; }
      59                 :            : 
      60                 :            :     enum Flag
      61                 :            :     {
      62                 :            :       DrawLabels              = 1 << 1,  //!< Whether the labels should be rendered
      63                 :            :       DrawAllLabels           = 1 << 2,  //!< Whether all features will be labelled even though overlaps occur
      64                 :            :       MergeConnectedLines     = 1 << 3,  //!< Whether adjacent lines (with the same label text) should be merged
      65                 :            :       CentroidMustBeInside    = 1 << 4,  //!< Whether location of centroid must be inside of polygons
      66                 :            :     };
      67                 :            :     Q_DECLARE_FLAGS( Flags, Flag )
      68                 :            : 
      69                 :            :     //! Returns list of label features (they are owned by the provider and thus deleted on its destruction)
      70                 :            :     virtual QList<QgsLabelFeature *> labelFeatures( QgsRenderContext &context ) = 0;
      71                 :            : 
      72                 :            :     /**
      73                 :            :      * Draw this label at the position determined by the labeling engine.
      74                 :            :      *
      75                 :            :      * Before any calls to drawLabel(), a provider should be prepared for rendering by a call to
      76                 :            :      * startRender() and a corresponding call to stopRender().
      77                 :            :      */
      78                 :            :     virtual void drawLabel( QgsRenderContext &context, pal::LabelPosition *label ) const = 0;
      79                 :            : 
      80                 :            :     /**
      81                 :            :      * Draw an unplaced label. These correspond to features which were registered for labeling,
      82                 :            :      * but which could not be labeled (e.g. due to conflicting labels).
      83                 :            :      *
      84                 :            :      * The default behavior is to draw nothing for these labels.
      85                 :            :      *
      86                 :            :      * \note This method is only used if the QgsLabelingEngineSettings::DrawUnplacedLabels flag
      87                 :            :      * is set on the labeling engine.
      88                 :            :      *
      89                 :            :      * \since QGIS 3.10
      90                 :            :      */
      91                 :            :     virtual void drawUnplacedLabel( QgsRenderContext &context, pal::LabelPosition *label ) const;
      92                 :            : 
      93                 :            :     /**
      94                 :            :      * Draw the background for the specified \a label.
      95                 :            :      *
      96                 :            :      * This is called in turn for each label provider before any actual labels are rendered,
      97                 :            :      * and allows the provider to render content which should be drawn below ALL map labels
      98                 :            :      * (such as background rectangles or callout lines).
      99                 :            :      *
     100                 :            :      * Before any calls to drawLabelBackground(), a provider should be prepared for rendering by a call to
     101                 :            :      * startRender() and a corresponding call to stopRender().
     102                 :            :      *
     103                 :            :      * \since QGIS 3.10
     104                 :            :      */
     105                 :            :     virtual void drawLabelBackground( QgsRenderContext &context, pal::LabelPosition *label ) const;
     106                 :            : 
     107                 :            :     /**
     108                 :            :      * To be called before rendering of labels begins. Must be accompanied by
     109                 :            :      * a corresponding call to stopRender()
     110                 :            :      * \since QGIS 3.10
     111                 :            :      */
     112                 :            :     virtual void startRender( QgsRenderContext &context );
     113                 :            : 
     114                 :            :     /**
     115                 :            :      * To be called after rendering is complete.
     116                 :            :      * \see startRender()
     117                 :            :      * \since QGIS 3.10
     118                 :            :      */
     119                 :            :     virtual void stopRender( QgsRenderContext &context );
     120                 :            : 
     121                 :            :     //! Returns list of child providers - useful if the provider needs to put labels into more layers with different configuration
     122                 :          0 :     virtual QList<QgsAbstractLabelProvider *> subProviders() { return QList<QgsAbstractLabelProvider *>(); }
     123                 :            : 
     124                 :            :     //! Name of the layer (for statistics, debugging etc.) - does not need to be unique
     125                 :          0 :     QString name() const { return mName; }
     126                 :            : 
     127                 :            :     //! Returns ID of associated layer, or empty string if no layer is associated with the provider.
     128                 :          0 :     QString layerId() const { return mLayerId; }
     129                 :            : 
     130                 :            :     //! Returns the associated layer, or NULLPTR if no layer is associated with the provider.
     131                 :          0 :     QgsMapLayer *layer() const { return mLayer.data(); }
     132                 :            : 
     133                 :            :     /**
     134                 :            :      * Returns provider ID - useful in case there is more than one label provider within a layer
     135                 :            :      * (e.g. in case of rule-based labeling - provider ID = rule's key). May be empty string if
     136                 :            :      * layer ID is sufficient for identification of provider's configuration.
     137                 :            :      */
     138                 :          0 :     QString providerId() const { return mProviderId; }
     139                 :            : 
     140                 :            :     //! Flags associated with the provider
     141                 :          0 :     Flags flags() const { return mFlags; }
     142                 :            : 
     143                 :            :     //! What placement strategy to use for the labels
     144                 :          0 :     QgsPalLayerSettings::Placement placement() const { return mPlacement; }
     145                 :            : 
     146                 :            :     //! Default priority of labels (may be overridden by individual labels)
     147                 :          0 :     double priority() const { return mPriority; }
     148                 :            : 
     149                 :            :     //! How the feature geometries will work as obstacles
     150                 :          0 :     QgsLabelObstacleSettings::ObstacleType obstacleType() const { return mObstacleType; }
     151                 :            : 
     152                 :            :     //! How to handle labels that would be upside down
     153                 :          0 :     QgsPalLayerSettings::UpsideDownLabels upsidedownLabels() const { return mUpsidedownLabels; }
     154                 :            : 
     155                 :            :   protected:
     156                 :            :     //! Associated labeling engine
     157                 :            :     const QgsLabelingEngine *mEngine = nullptr;
     158                 :            : 
     159                 :            :     //! Name of the layer
     160                 :            :     QString mName;
     161                 :            :     //! Associated layer's ID, if applicable
     162                 :            :     QString mLayerId;
     163                 :            :     //! Weak pointer to source layer
     164                 :            :     QgsWeakMapLayerPointer mLayer;
     165                 :            :     //! Associated provider ID (one layer may have multiple providers, e.g. in rule-based labeling)
     166                 :            :     QString mProviderId;
     167                 :            :     //! Flags altering drawing and registration of features
     168                 :            :     Flags mFlags;
     169                 :            :     //! Placement strategy
     170                 :            :     QgsPalLayerSettings::Placement mPlacement;
     171                 :            :     //! Default priority of labels
     172                 :            :     double mPriority;
     173                 :            :     //! Type of the obstacle of feature geometries
     174                 :            :     QgsLabelObstacleSettings::ObstacleType mObstacleType = QgsLabelObstacleSettings::PolygonBoundary;
     175                 :            :     //! How to handle labels that would be upside down
     176                 :            :     QgsPalLayerSettings::UpsideDownLabels mUpsidedownLabels;
     177                 :            : };
     178                 :            : 
     179                 :            : Q_DECLARE_OPERATORS_FOR_FLAGS( QgsAbstractLabelProvider::Flags )
     180                 :            : 
     181                 :            : 
     182                 :            : /**
     183                 :            :  * \ingroup core
     184                 :            :  * \brief The QgsLabelingEngine class provides map labeling functionality.
     185                 :            :  * The input for the engine is a list of label provider objects and map settings.
     186                 :            :  * Based on the input, the engine computes layout of labels for the given map view
     187                 :            :  * with no collisions between the labels. Drawing of resulting labels is done
     188                 :            :  * again by label providers.
     189                 :            :  *
     190                 :            :  * The labeling engine is used for the map rendering in QgsMapRendererJob instances,
     191                 :            :  * individual map layer renderers may add label providers - for example,
     192                 :            :  * QgsVectorLayerRenderer may add text label provider and diagram provider
     193                 :            :  * (if labeling / diagrams were configured for such vector layer).
     194                 :            :  *
     195                 :            :  * The labeling engine may also be used independently from map rendering loop:
     196                 :            :  * \code{.cpp}
     197                 :            :  *   QgsLabelingEngine engine;
     198                 :            :  *   engine.setMapSettings( mapSettings );
     199                 :            :  *   // add one or more providers
     200                 :            :  *   engine.addProvider( ... );
     201                 :            :  *   // compute the labeling and draw labels (using painter from the context)
     202                 :            :  *   engine.run( context );
     203                 :            :  * \endcode
     204                 :            :  *
     205                 :            :  * \note this class is not a part of public API yet. The provider's interface still
     206                 :            :  * uses pal::LabelPosition as an argument in drawLabels() method - this should be
     207                 :            :  * sorted out first (a class common to API and pal?). Also, the API may need more
     208                 :            :  * polishing to be easy to use - e.g. use concept of labeling layers in API
     209                 :            :  * (equivalent of pal::Layer) instead of subProviders(), label providers integrated
     210                 :            :  * into feature loop vs providers with independent feature loop), split labeling
     211                 :            :  * computation from drawing of labels, improved results class with label iterator).
     212                 :            :  * \note not available in Python bindings
     213                 :            :  * \since QGIS 2.12
     214                 :            :  */
     215                 :            : class CORE_EXPORT QgsLabelingEngine
     216                 :            : {
     217                 :            :   public:
     218                 :            :     //! Construct the labeling engine with default settings
     219                 :            :     QgsLabelingEngine();
     220                 :            :     //! Clean up everything (especially the registered providers)
     221                 :            :     virtual ~QgsLabelingEngine();
     222                 :            : 
     223                 :            :     //! QgsLabelingEngine cannot be copied.
     224                 :            :     QgsLabelingEngine( const QgsLabelingEngine &rh ) = delete;
     225                 :            :     //! QgsLabelingEngine cannot be copied.
     226                 :            :     QgsLabelingEngine &operator=( const QgsLabelingEngine &rh ) = delete;
     227                 :            : 
     228                 :            :     //! Associate map settings instance
     229                 :            :     void setMapSettings( const QgsMapSettings &mapSettings );
     230                 :            :     //! Gets associated map settings
     231                 :          0 :     const QgsMapSettings &mapSettings() const { return mMapSettings; }
     232                 :            : 
     233                 :            :     //! Gets associated labeling engine settings
     234                 :          0 :     const QgsLabelingEngineSettings &engineSettings() const { return mMapSettings.labelingEngineSettings(); }
     235                 :            : 
     236                 :            :     /**
     237                 :            :      * Returns a list of layers with providers in the engine.
     238                 :            :      * \since QGIS 3.0
     239                 :            :      */
     240                 :            :     QList< QgsMapLayer * > participatingLayers() const;
     241                 :            : 
     242                 :            :     /**
     243                 :            :      * Returns a list of layer IDs for layers with providers in the engine.
     244                 :            :      * \since QGIS 3.10
     245                 :            :      */
     246                 :            :     QStringList participatingLayerIds() const;
     247                 :            : 
     248                 :            :     //! Add provider of label features. Takes ownership of the provider
     249                 :            :     void addProvider( QgsAbstractLabelProvider *provider );
     250                 :            : 
     251                 :            :     //! Remove provider if the provider's initialization failed. Provider instance is deleted.
     252                 :            :     void removeProvider( QgsAbstractLabelProvider *provider );
     253                 :            : 
     254                 :            :     /**
     255                 :            :      * Runs the labeling job.
     256                 :            :      *
     257                 :            :      * Depending on the concrete labeling engine class, this will either run the whole
     258                 :            :      * labeling job, including rendering the labels themselves, OR possibly just run the labeling
     259                 :            :      * job but leave the rendering to a future, deferred stage.
     260                 :            :      */
     261                 :            :     virtual void run( QgsRenderContext &context ) = 0;
     262                 :            : 
     263                 :            :     //! Returns pointer to recently computed results and pass the ownership of results to the caller
     264                 :            :     QgsLabelingResults *takeResults();
     265                 :            : 
     266                 :            :     //! For internal use by the providers
     267                 :          0 :     QgsLabelingResults *results() const { return mResults.get(); }
     268                 :            : 
     269                 :            :   protected:
     270                 :            :     void processProvider( QgsAbstractLabelProvider *provider, QgsRenderContext &context, pal::Pal &p );
     271                 :            : 
     272                 :            :   protected:
     273                 :            : 
     274                 :            :     /**
     275                 :            :      * Runs the label registration step.
     276                 :            :      *
     277                 :            :      * Must be called by subclasses prior to solve() and drawLabels()
     278                 :            :      *
     279                 :            :      * \since QGIS 3.10
     280                 :            :      */
     281                 :            :     void registerLabels( QgsRenderContext &context );
     282                 :            : 
     283                 :            :     /**
     284                 :            :      * Solves the label problem.
     285                 :            :      *
     286                 :            :      * Must be called by subclasses prior to drawLabels(), and must be
     287                 :            :      * preceded by a call to registerLabels()
     288                 :            :      *
     289                 :            :      * \since QGIS 3.10
     290                 :            :      */
     291                 :            :     void solve( QgsRenderContext &context );
     292                 :            : 
     293                 :            :     /**
     294                 :            :      * Draws labels to the specified render \a context.
     295                 :            :      *
     296                 :            :      * If \a layerId is specified, only labels from the matching layer will
     297                 :            :      * be rendered.
     298                 :            :      *
     299                 :            :      * Must be preceded by a call to registerLabels() and solve()
     300                 :            :      *
     301                 :            :      * \since QGIS 3.10
     302                 :            :      */
     303                 :            :     void drawLabels( QgsRenderContext &context, const QString &layerId = QString() );
     304                 :            : 
     305                 :            :     /**
     306                 :            :      * Cleans up the engine following a call to registerLabels() or solve().
     307                 :            :      * \since QGIS 3.10
     308                 :            :      */
     309                 :            :     void cleanup();
     310                 :            : 
     311                 :            :     //! Associated map settings instance
     312                 :            :     QgsMapSettings mMapSettings;
     313                 :            : 
     314                 :            :     //! List of providers (the are owned by the labeling engine)
     315                 :            :     QList<QgsAbstractLabelProvider *> mProviders;
     316                 :            :     QList<QgsAbstractLabelProvider *> mSubProviders;
     317                 :            : 
     318                 :            :     //! Resulting labeling layout
     319                 :            :     std::unique_ptr< QgsLabelingResults > mResults;
     320                 :            : 
     321                 :            :     std::unique_ptr< pal::Pal > mPal;
     322                 :            :     std::unique_ptr< pal::Problem > mProblem;
     323                 :            :     QList<pal::LabelPosition *> mUnlabeled;
     324                 :            :     QList<pal::LabelPosition *> mLabels;
     325                 :            : 
     326                 :            : };
     327                 :            : 
     328                 :            : /**
     329                 :            :  * \ingroup core
     330                 :            :  * \class QgsDefaultLabelingEngine
     331                 :            :  * \brief Default QgsLabelingEngine implementation, which completes the whole
     332                 :            :  * labeling operation (including label rendering) in the run() method.
     333                 :            :  * \note this class is not a part of public API yet. See notes in QgsLabelingEngine
     334                 :            :  * \note not available in Python bindings
     335                 :            :  * \since QGIS 3.10
     336                 :            :  */
     337                 :          0 : class CORE_EXPORT QgsDefaultLabelingEngine : public QgsLabelingEngine
     338                 :            : {
     339                 :            :   public:
     340                 :            :     //! Construct the labeling engine with default settings
     341                 :            :     QgsDefaultLabelingEngine();
     342                 :            : 
     343                 :            :     //! QgsDefaultLabelingEngine cannot be copied.
     344                 :            :     QgsDefaultLabelingEngine( const QgsDefaultLabelingEngine &rh ) = delete;
     345                 :            :     //! QgsDefaultLabelingEngine cannot be copied.
     346                 :            :     QgsDefaultLabelingEngine &operator=( const QgsDefaultLabelingEngine &rh ) = delete;
     347                 :            : 
     348                 :            :     void run( QgsRenderContext &context ) override;
     349                 :            : 
     350                 :            : };
     351                 :            : 
     352                 :            : /**
     353                 :            :  * \ingroup core
     354                 :            :  * \class QgsStagedRenderLabelingEngine
     355                 :            :  * \brief A QgsLabelingEngine implementation, which only calculates
     356                 :            :  * the labeling solution during its run() method. The actual rendering
     357                 :            :  * of labels themselves is deferred to follow up calls to ....
     358                 :            :  *
     359                 :            :  * \note this class is not a part of public API yet. See notes in QgsLabelingEngine
     360                 :            :  * \note not available in Python bindings
     361                 :            :  * \since QGIS 3.10
     362                 :            :  */
     363                 :          0 : class CORE_EXPORT QgsStagedRenderLabelingEngine : public QgsLabelingEngine
     364                 :            : {
     365                 :            :   public:
     366                 :            :     //! Construct the labeling engine with default settings
     367                 :            :     QgsStagedRenderLabelingEngine();
     368                 :            : 
     369                 :            :     //! QgsStagedRenderLabelingEngine cannot be copied.
     370                 :            :     QgsStagedRenderLabelingEngine( const QgsStagedRenderLabelingEngine &rh ) = delete;
     371                 :            :     //! QgsStagedRenderLabelingEngine cannot be copied.
     372                 :            :     QgsStagedRenderLabelingEngine &operator=( const QgsStagedRenderLabelingEngine &rh ) = delete;
     373                 :            : 
     374                 :            :     void run( QgsRenderContext &context ) override;
     375                 :            : 
     376                 :            :     /**
     377                 :            :      * Renders all the labels which belong only to the layer with matching \a layerId
     378                 :            :      * to the specified render \a context.
     379                 :            :      */
     380                 :            :     void renderLabelsForLayer( QgsRenderContext &context, const QString &layerId );
     381                 :            : 
     382                 :            :     /**
     383                 :            :      * Finalizes and cleans up the engine following the rendering of labels for the last layer
     384                 :            :      * to be labeled (via renderLabelsForLayer() ).
     385                 :            :      */
     386                 :            :     void finalize();
     387                 :            : };
     388                 :            : 
     389                 :            : 
     390                 :            : /**
     391                 :            :  * \ingroup core
     392                 :            :  * \class QgsLabelingUtils
     393                 :            :  * \brief Contains helper utilities for working with QGIS' labeling engine.
     394                 :            :  * \note this class is not a part of public API yet. See notes in QgsLabelingEngine
     395                 :            :  * \note not available in Python bindings
     396                 :            :  * \since QGIS 2.14
     397                 :            :  */
     398                 :            : class CORE_EXPORT QgsLabelingUtils
     399                 :            : {
     400                 :            :   public:
     401                 :            : 
     402                 :            :     /**
     403                 :            :      * Encodes an ordered list of predefined point label positions to a string.
     404                 :            :      * \param positions order list of positions
     405                 :            :      * \returns list encoded to string
     406                 :            :      * \see decodePredefinedPositionOrder()
     407                 :            :      */
     408                 :            :     static QString encodePredefinedPositionOrder( const QVector< QgsPalLayerSettings::PredefinedPointPosition > &positions );
     409                 :            : 
     410                 :            :     /**
     411                 :            :      * Decodes a string to an ordered list of predefined point label positions.
     412                 :            :      * \param positionString encoded string of positions
     413                 :            :      * \returns decoded list
     414                 :            :      * \see encodePredefinedPositionOrder()
     415                 :            :      */
     416                 :            :     static QVector< QgsPalLayerSettings::PredefinedPointPosition > decodePredefinedPositionOrder( const QString &positionString );
     417                 :            : 
     418                 :            :     /**
     419                 :            :      * Encodes line placement \a flags to a string.
     420                 :            :      * \see decodeLinePlacementFlags()
     421                 :            :      */
     422                 :            :     static QString encodeLinePlacementFlags( QgsLabeling::LinePlacementFlags flags );
     423                 :            : 
     424                 :            :     /**
     425                 :            :      * Decodes a \a string to set of line placement flags.
     426                 :            :      * \see encodeLinePlacementFlags()
     427                 :            :      */
     428                 :            :     static QgsLabeling::LinePlacementFlags decodeLinePlacementFlags( const QString &string );
     429                 :            : 
     430                 :            : };
     431                 :            : 
     432                 :            : #endif // QGSLABELINGENGINE_H