qgsrastervectorfieldvaluesource.h

Go to the documentation of this file.

/***************************************************************************
                         qgsrastervectorfieldvaluesource.h
                         ---------------------------------
    begin                : September 2026
    copyright            : (C) 2026 by Stefanos Natsis
    email                : uclaros 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 QGSRASTERVECTORFIELDVALUESOURCE_H
#define QGSRASTERVECTORFIELDVALUESOURCE_H
 
#include <memory>
 
#include "qgis.h"
#include "qgsrasterinterface.h"
#include "qgsrectangle.h"
#include "qgsvectorfieldvaluesource.h"
 
#define SIP_NO_FILE
 
class QgsRasterBlock;


class QgsRasterVectorFieldValueSourceBase : public QgsVectorFieldValueSource
{
  public:
    QgsRasterVectorFieldValueSourceBase( const QgsRectangle &blockExtent, const QgsRectangle &dataExtent, int columns, int rows );
 
    QgsRectangle extent() const override;
    QVector<QgsPointXY> seedPoints( const QgsRectangle &extent ) const override;

    bool nativeLayout( QgsPointXY &origin, double &spacingX, double &spacingY ) const override;

    static constexpr int MAXIMUM_SEED_POINTS = 100'000;
 
  protected:
    bool isValid() const;

    virtual bool cellHasValue( int row, int column ) const = 0;
 
    QgsRectangle mBlockExtent;
    QgsRectangle mDataExtent;
 
    int mColumns = 0;
    int mRows = 0;
    double mXResolution = 0;
    double mYResolution = 0;
};

class QgsRasterVectorFieldValueSource : public QgsRasterVectorFieldValueSourceBase
{
  public:
    QgsRasterVectorFieldValueSource(
      std::shared_ptr<const QgsRasterBlock> xValues, std::shared_ptr<const QgsRasterBlock> yValues, const QgsRectangle &blockExtent, const QgsRectangle &dataExtent, double maximumMagnitude
    );
 
    QgsRasterVectorFieldValueSource *clone() const override;
    QgsVector vectorValue( const QgsPointXY &point ) const override;
    double maximumMagnitude() const override;
    std::unique_ptr<QgsRasterInterface> magnitudeSource( const QgsRenderContext &context, QSize size ) const override;
 
  private:
    double sampledValue( const QgsRasterBlock *block, const QgsPointXY &point ) const;
 
    bool cellHasValue( int row, int column ) const override;
 
    std::shared_ptr<const QgsRasterBlock> mXValues;
    std::shared_ptr<const QgsRasterBlock> mYValues;
    double mMaximumMagnitude = 0;
};

class CORE_EXPORT QgsRasterVectorFieldEncodedDirectionValueSource : public QgsRasterVectorFieldValueSourceBase
{
  public:
    QgsRasterVectorFieldEncodedDirectionValueSource( std::shared_ptr<const QgsRasterBlock> values, Qgis::RasterDirectionEncoding encoding, const QgsRectangle &blockExtent, const QgsRectangle &dataExtent );
 
    QgsRasterVectorFieldEncodedDirectionValueSource *clone() const override;
    QgsVector vectorValue( const QgsPointXY &point ) const override;

    double maximumMagnitude() const override;

    void setSamplingWindow( double width, double height ) override;

    static int directionOrdinal( Qgis::RasterDirectionEncoding encoding, double value );

    static QgsVector ordinalVector( int ordinal );
 
  private:
    int nearestOrdinal( const QgsPointXY &point ) const;

    int majorityOrdinal( const QgsPointXY &point ) const;
 
    bool cellHasValue( int row, int column ) const override;
 
    std::shared_ptr<const QgsRasterBlock> mValues;
    Qgis::RasterDirectionEncoding mEncoding = Qgis::RasterDirectionEncoding::Esri;
    double mWindowWidth = 0;
    double mWindowHeight = 0;
};

class QgsRasterVectorFieldMagnitudeInterface : public QgsRasterInterface
{
  public:
    QgsRasterVectorFieldMagnitudeInterface( std::shared_ptr<const QgsRasterBlock> xValues, std::shared_ptr<const QgsRasterBlock> yValues, const QgsRectangle &blockExtent );
 
    QgsRasterInterface *clone() const override;
    Qgis::DataType dataType( int bandNo ) const override;
    int bandCount() const override;
    QgsRectangle extent() const override;
    QgsRasterBlock *block( int bandNo, const QgsRectangle &extent, int width, int height, QgsRasterBlockFeedback *feedback = nullptr ) override;
 
  private:
    std::shared_ptr<const QgsRasterBlock> mXValues;
    std::shared_ptr<const QgsRasterBlock> mYValues;
    QgsRectangle mBlockExtent;
};

 
#endif // QGSRASTERVECTORFIELDVALUESOURCE_H