qgslabelingengine.h

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/***************************************************************************
  qgslabelingengine.h
  --------------------------------------
  Date                 : September 2015
  Copyright            : (C) 2015 by Martin Dobias
  Email                : wonder dot sk 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 QGSLABELINGENGINE_H
#define QGSLABELINGENGINE_H

#define SIP_NO_FILE

#include "qgis_core.h"
#include "qgsmapsettings.h"

#include "qgspallabeling.h"
#include "qgslabelingenginesettings.h"
#include "qgslabeling.h"

class QgsLabelingEngine;

namespace pal
{
  class Problem;
}

class CORE_EXPORT QgsAbstractLabelProvider
{

  public:
    QgsAbstractLabelProvider( QgsMapLayer *layer, const QString &providerId = QString() );

    virtual ~QgsAbstractLabelProvider() = default;

    void setEngine( const QgsLabelingEngine *engine ) { mEngine = engine; }

    enum Flag
    {
      DrawLabels              = 1 << 1,  
      DrawAllLabels           = 1 << 2,  
      MergeConnectedLines     = 1 << 3,  
      CentroidMustBeInside    = 1 << 4,  
    };
    Q_DECLARE_FLAGS( Flags, Flag )

    
    virtual QList<QgsLabelFeature *> labelFeatures( QgsRenderContext &context ) = 0;

    virtual void drawLabel( QgsRenderContext &context, pal::LabelPosition *label ) const = 0;

    virtual void drawUnplacedLabel( QgsRenderContext &context, pal::LabelPosition *label ) const;

    virtual void drawLabelBackground( QgsRenderContext &context, pal::LabelPosition *label ) const;

    virtual void startRender( QgsRenderContext &context );

    virtual void stopRender( QgsRenderContext &context );

    virtual QList<QgsAbstractLabelProvider *> subProviders() { return QList<QgsAbstractLabelProvider *>(); }

    QString name() const { return mName; }

    QString layerId() const { return mLayerId; }

    QgsMapLayer *layer() const { return mLayer.data(); }

    QString providerId() const { return mProviderId; }

    Flags flags() const { return mFlags; }

    QgsPalLayerSettings::Placement placement() const { return mPlacement; }

    double priority() const { return mPriority; }

    QgsLabelObstacleSettings::ObstacleType obstacleType() const { return mObstacleType; }

    QgsPalLayerSettings::UpsideDownLabels upsidedownLabels() const { return mUpsidedownLabels; }

  protected:
    const QgsLabelingEngine *mEngine = nullptr;

    QString mName;
    QString mLayerId;
    QgsWeakMapLayerPointer mLayer;
    QString mProviderId;
    Flags mFlags;
    QgsPalLayerSettings::Placement mPlacement;
    double mPriority;
    QgsLabelObstacleSettings::ObstacleType mObstacleType = QgsLabelObstacleSettings::PolygonBoundary;
    QgsPalLayerSettings::UpsideDownLabels mUpsidedownLabels;
};

Q_DECLARE_OPERATORS_FOR_FLAGS( QgsAbstractLabelProvider::Flags )



class CORE_EXPORT QgsLabelingEngine
{
  public:
    QgsLabelingEngine();
    virtual ~QgsLabelingEngine();

    QgsLabelingEngine( const QgsLabelingEngine &rh ) = delete;
    QgsLabelingEngine &operator=( const QgsLabelingEngine &rh ) = delete;

    void setMapSettings( const QgsMapSettings &mapSettings );
    const QgsMapSettings &mapSettings() const { return mMapSettings; }

    const QgsLabelingEngineSettings &engineSettings() const { return mMapSettings.labelingEngineSettings(); }

    QList< QgsMapLayer * > participatingLayers() const;

    QStringList participatingLayerIds() const;

    void addProvider( QgsAbstractLabelProvider *provider );

    void removeProvider( QgsAbstractLabelProvider *provider );

    virtual void run( QgsRenderContext &context ) = 0;

    QgsLabelingResults *takeResults();

    QgsLabelingResults *results() const { return mResults.get(); }

  protected:
    void processProvider( QgsAbstractLabelProvider *provider, QgsRenderContext &context, pal::Pal &p );

  protected:

    void registerLabels( QgsRenderContext &context );

    void solve( QgsRenderContext &context );

    void drawLabels( QgsRenderContext &context, const QString &layerId = QString() );

    void cleanup();

    QgsMapSettings mMapSettings;

    QList<QgsAbstractLabelProvider *> mProviders;
    QList<QgsAbstractLabelProvider *> mSubProviders;

    std::unique_ptr< QgsLabelingResults > mResults;

    std::unique_ptr< pal::Pal > mPal;
    std::unique_ptr< pal::Problem > mProblem;
    QList<pal::LabelPosition *> mUnlabeled;
    QList<pal::LabelPosition *> mLabels;

};

class CORE_EXPORT QgsDefaultLabelingEngine : public QgsLabelingEngine
{
  public:
    QgsDefaultLabelingEngine();

    QgsDefaultLabelingEngine( const QgsDefaultLabelingEngine &rh ) = delete;
    QgsDefaultLabelingEngine &operator=( const QgsDefaultLabelingEngine &rh ) = delete;

    void run( QgsRenderContext &context ) override;

};

class CORE_EXPORT QgsStagedRenderLabelingEngine : public QgsLabelingEngine
{
  public:
    QgsStagedRenderLabelingEngine();

    QgsStagedRenderLabelingEngine( const QgsStagedRenderLabelingEngine &rh ) = delete;
    QgsStagedRenderLabelingEngine &operator=( const QgsStagedRenderLabelingEngine &rh ) = delete;

    void run( QgsRenderContext &context ) override;

    void renderLabelsForLayer( QgsRenderContext &context, const QString &layerId );

    void finalize();
};


class CORE_EXPORT QgsLabelingUtils
{
  public:

    static QString encodePredefinedPositionOrder( const QVector< QgsPalLayerSettings::PredefinedPointPosition > &positions );

    static QVector< QgsPalLayerSettings::PredefinedPointPosition > decodePredefinedPositionOrder( const QString &positionString );

    static QString encodeLinePlacementFlags( QgsLabeling::LinePlacementFlags flags );

    static QgsLabeling::LinePlacementFlags decodeLinePlacementFlags( const QString &string );

};

#endif // QGSLABELINGENGINE_H