polygonize_polygonizer.h

/******************************************************************************
 * Project:  GDAL
 * Purpose:  Implements The Two-Arm Chains EdgeTracing Algorithm
 * Author:   kikitte.lee
 *
 ******************************************************************************
 * Copyright (c) 2023, kikitte.lee <kikitte.lee@gmail.com>
 *
 * SPDX-License-Identifier: MIT
 ****************************************************************************/
 
#ifndef POLYGONIZE_POLYGONIZER_H_INCLUDED
#define POLYGONIZE_POLYGONIZER_H_INCLUDED

 
// Implements Junhua Teng, Fahui Wang, Yu Liu: An Efficient Algorithm for
// Raster-to-Vector Data Conversion: https://doi.org/10.1080/10824000809480639
 
#include <array>
#include <cstdint>
#include <vector>
#include <limits>
#include <map>
 
#include "cpl_error.h"
#include "ogr_api.h"
#include "ogr_geometry.h"
#include "ogrsf_frmts.h"
 
namespace gdal
{
namespace polygonizer
{
 
using IndexType = std::uint32_t;
using Point = std::array<IndexType, 2>;
using Arc = std::vector<Point>;
 
struct IndexedArc
{
    Arc *poArc;
    std::size_t iIndex;
};

struct RPolygon
{
    IndexType iBottomRightRow{0};
    IndexType iBottomRightCol{0};
 
    struct ArcStruct
    {
        std::unique_ptr<Arc> poArc{};
        // each element is the next arc index of the current arc
        unsigned nConnection = 0;
        // does arc follows the right-hand rule with
        bool bFollowRighthand = false;
 
        ArcStruct(unsigned nConnectionIn, bool bFollowRighthandIn)
            : poArc(std::make_unique<Arc>()), nConnection(nConnectionIn),
              bFollowRighthand(bFollowRighthandIn)
        {
        }
    };
 
    // arc object list
    std::vector<ArcStruct> oArcs{};
 
    RPolygon() = default;
 
    RPolygon(const RPolygon &) = delete;
 
    RPolygon &operator=(const RPolygon &) = delete;

    IndexedArc newArc(bool bFollowRighthand);

    void setArcConnection(const IndexedArc &oArc, const IndexedArc &oNextArc);

    void updateBottomRightPos(IndexType iRow, IndexType iCol);
};

struct TwoArm
{
    IndexType iRow{0};
    IndexType iCol{0};
 
    RPolygon *poPolyInside{nullptr};
    RPolygon *poPolyAbove{nullptr};
    RPolygon *poPolyLeft{nullptr};
 
    IndexedArc oArcHorOuter{};
    IndexedArc oArcHorInner{};
    IndexedArc oArcVerInner{};
    IndexedArc oArcVerOuter{};
 
    bool bSolidHorizontal{false};
    bool bSolidVertical{false};
};
 
template <typename DataType> class PolygonReceiver
{
  public:
    PolygonReceiver() = default;
 
    PolygonReceiver(const PolygonReceiver<DataType> &) = delete;
 
    virtual ~PolygonReceiver() = default;
 
    PolygonReceiver<DataType> &
    operator=(const PolygonReceiver<DataType> &) = delete;
 
    virtual void receive(RPolygon *poPolygon, DataType nPolygonCellValue) = 0;
};

template <typename PolyIdType, typename DataType> class Polygonizer
{
  public:
    static constexpr PolyIdType THE_OUTER_POLYGON_ID =
        std::numeric_limits<PolyIdType>::max();
 
  private:
    using PolygonMap = std::map<PolyIdType, RPolygon *>;
    using PolygonMapEntry = typename PolygonMap::value_type;
 
    PolyIdType nInvalidPolyId_;
    RPolygon *poTheOuterPolygon_{nullptr};
    PolygonMap oPolygonMap_{};
 
    PolygonReceiver<DataType> *poPolygonReceiver_;
 
    RPolygon *getPolygon(PolyIdType nPolygonId);
 
    RPolygon *createPolygon(PolyIdType nPolygonId);
 
    void destroyPolygon(PolyIdType nPolygonId);
 
  public:
    explicit Polygonizer(PolyIdType nInvalidPolyId,
                         PolygonReceiver<DataType> *poPolygonReceiver);
 
    Polygonizer(const Polygonizer<PolyIdType, DataType> &) = delete;
 
    ~Polygonizer();
 
    Polygonizer<PolyIdType, DataType> &
    operator=(const Polygonizer<PolyIdType, DataType> &) = delete;
 
    RPolygon *getTheOuterPolygon() const
    {
        return poTheOuterPolygon_;
    }
 
    bool processLine(const PolyIdType *panThisLineId,
                     const DataType *panLastLineVal, TwoArm *poThisLineArm,
                     TwoArm *poLastLineArm, IndexType nCurrentRow,
                     IndexType nCols);
};

template <typename DataType>
class OGRPolygonWriter : public PolygonReceiver<DataType>
{
    OGRLayer *poOutLayer_ = nullptr;
    GDALDataset *poOutDS_ = nullptr;
    const int iPixValField_;
    const GDALGeoTransform gt_;
    int nCommitInterval_ = 0;
    GIntBig nFeaturesWrittenInTransaction_ = 0;
    std::unique_ptr<OGRFeature> poFeature_{};
    OGRPolygon *poPolygon_ =
        nullptr;  // = poFeature_->GetGeometryRef(), owned by poFeature
 
    CPLErr eErr_{CE_None};
 
  public:
    OGRPolygonWriter(OGRLayerH hOutLayer, int iPixValField,
                     const GDALGeoTransform &gt, int nCommitInterval);
    ~OGRPolygonWriter() override;
 
    OGRPolygonWriter(const OGRPolygonWriter<DataType> &) = delete;
 
    OGRPolygonWriter<DataType> &
    operator=(const OGRPolygonWriter<DataType> &) = delete;
 
    bool Finalize();
 
    void receive(RPolygon *poPolygon, DataType nPolygonCellValue) override;
 
    inline CPLErr getErr()
    {
        return eErr_;
    }
};
 
}  // namespace polygonizer
}  // namespace gdal

 
#endif /* POLYGONIZE_POLYGONIZER_H_INCLUDED */