gdalalg_vector_geom.h

/******************************************************************************
 *
 * Project:  GDAL
 * Purpose:  Base classes for some geometry-related vector algorithms
 * Author:   Even Rouault <even dot rouault at spatialys.com>
 *
 ******************************************************************************
 * Copyright (c) 2025, Even Rouault <even dot rouault at spatialys.com>
 *
 * SPDX-License-Identifier: MIT
 ****************************************************************************/
 
#ifndef GDALALG_VECTOR_GEOM_INCLUDED
#define GDALALG_VECTOR_GEOM_INCLUDED
 
#include "gdalalg_vector_pipeline.h"
#include "ogr_geos.h"
 
 
/************************************************************************/
/*                   GDALVectorGeomAbstractAlgorithm                    */
/************************************************************************/
 
class GDALVectorGeomAbstractAlgorithm /* non final */
    : public GDALVectorPipelineStepAlgorithm
{
  protected:
    struct OptionsBase
    {
        std::string m_activeLayer{};
        std::string m_geomField{};
    };
 
    virtual std::unique_ptr<OGRLayerWithTranslateFeature>
    CreateAlgLayer(OGRLayer &srcLayer) = 0;
 
    GDALVectorGeomAbstractAlgorithm(const std::string &name,
                                    const std::string &description,
                                    const std::string &helpURL,
                                    bool standaloneStep, OptionsBase &opts);
 
    bool RunStep(GDALPipelineStepRunContext &ctxt) override;
 
  private:
    std::string &m_activeLayer;
};
 
/************************************************************************/
/*                 GDALVectorGeomOneToOneAlgorithmLayer                 */
/************************************************************************/
 
template <class T>
class GDALVectorGeomOneToOneAlgorithmLayer /* non final */
    : public GDALVectorPipelineOutputLayer
{
  public:
    const OGRFeatureDefn *GetLayerDefn() const override
    {
        return m_srcLayer.GetLayerDefn();
    }
 
    GIntBig GetFeatureCount(int bForce) override
    {
        if (!m_poAttrQuery && !m_poFilterGeom)
            return m_srcLayer.GetFeatureCount(bForce);
        return OGRLayer::GetFeatureCount(bForce);
    }
 
    OGRErr IGetExtent(int iGeomField, OGREnvelope *psExtent,
                      bool bForce) override
    {
        return m_srcLayer.GetExtent(iGeomField, psExtent, bForce);
    }
 
    OGRFeature *GetFeature(GIntBig nFID) override
    {
        auto poSrcFeature =
            std::unique_ptr<OGRFeature>(m_srcLayer.GetFeature(nFID));
        if (!poSrcFeature)
            return nullptr;
        return TranslateFeature(std::move(poSrcFeature)).release();
    }
 
    int TestCapability(const char *pszCap) const override
    {
        if (EQUAL(pszCap, OLCRandomRead) || EQUAL(pszCap, OLCCurveGeometries) ||
            EQUAL(pszCap, OLCMeasuredGeometries) ||
            EQUAL(pszCap, OLCZGeometries) || EQUAL(pszCap, OLCFastGetExtent) ||
            (EQUAL(pszCap, OLCFastFeatureCount) && !m_poAttrQuery &&
             !m_poFilterGeom) ||
            EQUAL(pszCap, OLCStringsAsUTF8))
        {
            return m_srcLayer.TestCapability(pszCap);
        }
        return false;
    }
 
  protected:
    const typename T::Options m_opts;
 
    GDALVectorGeomOneToOneAlgorithmLayer(OGRLayer &oSrcLayer,
                                         const typename T::Options &opts)
        : GDALVectorPipelineOutputLayer(oSrcLayer), m_opts(opts)
    {
        SetDescription(oSrcLayer.GetDescription());
        SetMetadata(oSrcLayer.GetMetadata());
        if (!m_opts.m_geomField.empty())
        {
            const int nIdx = oSrcLayer.GetLayerDefn()->GetGeomFieldIndex(
                m_opts.m_geomField.c_str());
            if (nIdx >= 0)
                m_iGeomIdx = nIdx;
            else
                m_iGeomIdx = INT_MAX;
        }
    }
 
    bool IsSelectedGeomField(int idx) const
    {
        return m_iGeomIdx < 0 || idx == m_iGeomIdx;
    }
 
    virtual std::unique_ptr<OGRFeature>
    TranslateFeature(std::unique_ptr<OGRFeature> poSrcFeature) const = 0;
 
    void TranslateFeature(
        std::unique_ptr<OGRFeature> poSrcFeature,
        std::vector<std::unique_ptr<OGRFeature>> &apoOutFeatures) override
    {
        auto poDstFeature = TranslateFeature(std::move(poSrcFeature));
        if (poDstFeature)
            apoOutFeatures.push_back(std::move(poDstFeature));
    }
 
  private:
    int m_iGeomIdx = -1;
};
 
#ifdef HAVE_GEOS
 
/************************************************************************/
/*                  GDALGeosNonStreamingAlgorithmLayer                  */
/************************************************************************/
 
class GDALGeosNonStreamingAlgorithmLayer
    : public GDALVectorNonStreamingAlgorithmLayer
{
  public:
    GDALGeosNonStreamingAlgorithmLayer(OGRLayer &srcLayer, int geomFieldIndex);
 
    ~GDALGeosNonStreamingAlgorithmLayer() override;
 
    void ResetReading() override;
 
    CPL_DISALLOW_COPY_ASSIGN(GDALGeosNonStreamingAlgorithmLayer)
 
    bool Process(GDALProgressFunc pfnProgress, void *pProgressData) override;
 
    std::unique_ptr<OGRFeature> GetNextProcessedFeature() override;
 
    virtual bool ProcessGeos() = 0;
 
    virtual bool PolygonsOnly() const = 0;
 
    virtual bool SkipEmpty() const = 0;
 
  protected:
    GEOSContextHandle_t m_poGeosContext{nullptr};
    std::vector<GEOSGeometry *> m_apoGeosInputs{};
    GEOSGeometry *m_poGeosResultAsCollection{nullptr};
    GEOSGeometry **m_papoGeosResults{nullptr};
 
  private:
    bool ConvertInputsToGeos(OGRLayer &srcLayer, int geomFieldIndex,
                             GDALProgressFunc pfnProgress, void *pProgressData);
 
    void Cleanup();
 
    std::vector<std::unique_ptr<OGRFeature>> m_apoFeatures{};
    unsigned int m_nGeosResultSize{0};
    unsigned int m_readPos{0};
};
 
#endif
 
 
#endif /* GDALALG_VECTOR_GEOM_INCLUDED */