Michael,
This is likely a design decision from 20 years ago when the "new"
bindings have been added. I wasn't involved, but I can imagine at least
2 reasons to prefer binding C functions rather than C++ classes:
- make sure that the bindings generated against GDAL X still run against
libgdal Y where Y >= X without being rebuilt, since the C ABI is
backwards compatible. But that doesn't seem to be a very
realistic/common scenario
- avoid exposing to SWIG things that haven't been considered stable
enough to be exposed to C
Maybe other GDAL users, such as people doing Rust or R bindings, could
give us some hints if they'd be interested in binding the
GDALGeoTransform class to their language. If so, making C bindings would
serve everybody.
Even
Le 31/08/2026 à 21:50, Michael via gdal-dev a écrit :
I want to expose the GDALGeoTransform class. It doesn't have a C
struct representation (like OGREnvelope) or an opaque C handle type. I
could add C interfaces to GDALGeoTransfor, but that seems absurd since
GDALGeoTransfor is mostly a C++ wrapper of the C routines.
However, using the GDALGeoTransfor class directly from the SWIG
interfaces works surprisingly well (See below). What doesn't work is
the 'Apply' overloads which accept a `GDALRasterWindow` type, because
SWIG can't include gdal_rasterband.h while CPL_SUPRESS_CPLUSPLUS is
defined.
So my questions are: can I use the GDALGeoTransfor c++ class directly
from SWIG and, if not, why?
-------------
%{
#include "gdal_geotransform.h"
%}
class GDALGeoTransform {
private:
const double *data() const;
~GDALGeoTransform();
public:
%mutable;
GDALGeoTransform();
GDALGeoTransform(const double coeffs[6]);
GDALGeoTransform(double xorigIn, double xscaleIn, double xrotIn,
double yorigIn, double yrotIn, double yscaleIn);
void Rescale(double dfXRatio, double dfYRatio);
%immutable;
void Apply(double dfPixel, double dfLine, double *pdfGeoX, double
*pdfGeoY) const;
bool GetInverse(GDALGeoTransform &inverse) const;
bool IsAxisAligned() const;
};
--
Michael Bucari
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