GDALWarp/RasterIO write to file

[mdsumner]

All that's needed is

inline List gdal_warp_in_memory(CharacterVector source_filename,
                     CharacterVector source_WKT,
                     CharacterVector target_WKT,
                     NumericVector target_geotransform,
                     IntegerVector target_dim,
                     IntegerVector band,
                     CharacterVector output_filename = "",
                     CharacterVector driver_shortname = "") {


// ...
// ............................................................
// ...


  if (strlen(output_filename[0]) < 1) {
    driver_shortname[0] = "MEM";

  }
  // Get output driver
  hDriver = GDALGetDriverByName( driver_shortname[0] );

  // Create the output data set.
  hDstDS = GDALCreate( hDriver, output_filename[0], target_dim[0], target_dim[1],
                       GDALGetRasterCount(po_SrcDS[0]), eDT, NULL );

// ...
// ............................................................
// ...


  Rcpp::List outlist(band.size());

  if (strlen(output_filename[0]) > 0) {
    GDALClose( hDstDS );
    for (int i = 0; i < source_filename.size(); i++) {
      GDALClose( po_SrcDS[i] );
    }
    return outlist;
  }

// else continue onto reading the band values out of MEM

but, it's a bit weird returning empty list or filename, so probably do a bit of work on modularizing first