qgsvectorfieldengine.h

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/***************************************************************************
    qgsvectorfieldengine.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 QGSVECTORFIELDENGINE_H
#define QGSVECTORFIELDENGINE_H
 
#include <memory>
 
#include "qgsinterpolatedlinerenderer.h"
#include "qgsvectorfieldsettings.h"
 
#include <QSize>
 
#define SIP_NO_FILE
 
class QgsCoordinateTransform;
class QgsPointXY;
class QgsRasterBlockFeedback;
class QgsRenderContext;
class QgsScopedQPainterState;
class QgsVectorFieldValueSource;

class QgsVectorFieldEngine
{
  public:
    QgsVectorFieldEngine( double datasetMagMaximumValue, double datasetMagMinimumValue, const QgsVectorFieldSettings &settings, QgsRenderContext &context, QSize size );
    ~QgsVectorFieldEngine();
 
    QgsVectorFieldEngine( const QgsVectorFieldEngine & ) = delete;
    QgsVectorFieldEngine &operator=( const QgsVectorFieldEngine & ) = delete;

    void drawGlyph( const QgsPointXY &lineStart, double xVal, double yVal, double magnitude );

    void drawStreamlines( std::unique_ptr<QgsVectorFieldValueSource> source, QgsRasterBlockFeedback *feedback = nullptr );

    void drawTraces( std::unique_ptr<QgsVectorFieldValueSource> source );
 
  private:
    void drawArrow( const QgsPointXY &lineStart, double xVal, double yVal, double magnitude );

    void drawWindBarb( const QgsPointXY &lineStart, double xVal, double yVal, double magnitude );

    bool calcVectorLineEnd(
      QgsPointXY &lineEnd,
      double &vectorLength,
      double &cosAlpha,
      double &sinAlpha, //out
      const QgsPointXY &lineStart,
      double xVal,
      double yVal,
      double magnitude //in
    );
 
    double mMinMag = 0.0;
    double mMaxMag = 0.0;
 
    QgsRenderContext &mContext;
    const QgsVectorFieldSettings mCfg;
    QgsInterpolatedLineColor mVectorColoring;
 
    QSize mOutputSize;
 
    std::unique_ptr<QgsCoordinateTransform> mGeographicTransform;
    std::unique_ptr<QgsScopedQPainterState> mScopedPainterState;
};
 
#endif // QGSVECTORFIELDENGINE_H