[gdal-dev] Writing interior rings is not working

[Even Rouault]

Le vendredi 10 avril 2015 17:37:38, Heiko Thiel a écrit :
> Hello,
> 
> I currently trying to save Polygons in a ShapeFile with Gdal 1.11.2. It
> works so far - except interior rings are not stored. Anyone any idea?
> 
> My Code:
> 
> #include <ogrsf_frmts.h>
> #include <iostream>
> #include <vector>
> #include <cassert>
> 
> int main(int argc, char *argv[])
> {
>      OGRRegisterAll();
> 
>      OGRSFDriver *poDriver =
> OGRSFDriverRegistrar::GetRegistrar()->GetDriverByName("ESRI Shapefile");
>      if (poDriver == nullptr)
>      {
>          std::cout << "ESRI Shapefile driver not available." << std::endl;
>          return 0;
>      }
> 
>      OGRDataSource *poDS = poDriver->CreateDataSource("gdaltest.shp",
> nullptr);
>      if (poDS == nullptr)
>      {
>          std::cout << "Creation of output file failed." << std::endl;
>          return 0;
>      }
> 
>      OGRLayer *poLayer = poDS->CreateLayer("polygons", nullptr,
> wkbPolygon, nullptr);
>      if (poLayer == nullptr)
>      {
>          std::cout << "Layer creation failed." << std::endl;
>          OGRDataSource::DestroyDataSource(poDS);
>          return 0;
>      }
> 
>      //write 1 polygon with with 1 exterior and 2 exterior rings
> 
>      OGRFeature *poFeature =
> OGRFeature::CreateFeature(poLayer->GetLayerDefn());
> 
>      OGRPolygon polygon;
> 
>      auto outerRing = std::vector<std::pair<int, int>>({ { 0, 0 }, { 0,
> 5 }, { 5, 5 }, { 5, 0 } });
> 
>      OGRLinearRing ring;
>      for (auto &p : outerRing)
>      {
>          OGRPoint pt;
> 
>          pt.setX(p.first);
>          pt.setY(p.second);
>          ring.addPoint(&pt);
>      }
>      polygon.addRing(&ring);
> 
>      auto innerRingBase = std::vector<std::pair<int, int>>({ { 1, 1 }, {
> 1, 2 }, { 2, 2 }, { 2, 1 } });
>      //auto innerRingBase = std::vector<std::pair<int, int>>({ { 2, 1 },
> { 2, 2 }, { 1, 2 }, { 1, 1 } }); //reverse order don't work too
>      const int innerRingOffsetX = 2;
> 
>      for (int i = 0; i < 2; i++)
>      {
>          OGRLinearRing innerRing;
>          for (auto &p : innerRingBase)
>          {
>              OGRPoint pt;
> 
>              pt.setX(p.first + i*innerRingOffsetX);
>              pt.setY(p.second);
>              ring.addPoint(&pt);

==> Should be innerRing.addPoint(&pt) (took me sometime to realize that...)

>          }
> 
>          polygon.addRing(&innerRing);
>      }
>      assert(polygon.getNumInteriorRings() == 2); //this don't throw, so
> gdal detected interior rings
> 
>      polygon.closeRings();
>      poFeature->SetGeometry(&polygon);
> 
>      if (poLayer->CreateFeature(poFeature) != OGRERR_NONE)
>      {
>          std::cout << "Failed to create feature in shapefile." <<
> std::endl; }
> 
>      OGRFeature::DestroyFeature(poFeature);
> 
>      OGRDataSource::DestroyDataSource(poDS);
> 
>      return 0;
> }
> 
> Regards
> _______________________________________________
> gdal-dev mailing list
> gdal-dev at lists.osgeo.org
> http://lists.osgeo.org/mailman/listinfo/gdal-dev

-- 
Spatialys - Geospatial professional services
http://www.spatialys.com