[geos-devel] Proposal to add Coordinate class to c api

Charlie Savage cfis at savagexi.com
Wed Aug 29 15:00:52 EDT 2007

> Could you draw some requirements necessary to fulfill by an object
> exposed to ruby?
> I believe there should be no problem, if it won't break simplicity and
> C-nature of the GEOS C API.

First, expose the coordinate class (I've removed extern and GEOS_DLL for 

  GEOSCoordinate  *GEOSCoordinate_create(double x, double y, double z);
  GEOSCoordinate  *GEOSCoordinate_clone(const GEOSCoordinate* s);
  void  GEOSCoordinate_destroy(GEOSCoordinate* s);

  char  GEOSCoordinate_equals(GEOSCoordinate* s);

  int  GEOSCoordinate_setX(GEOSCoordinate* s, double val);
  int  GEOSCoordinate_setY(GEOSCoordinate* s, double val);
  int  GEOSCoordinate_setZ(GEOSCoordinate* s, double val);

  int  GEOSCoordinate_getX(const GEOSCoordinate* s, double *val);
  int  GEOSCoordinate_getY(const GEOSCoordinate* s, double *val);
  int  GEOSCoordinate_getZ(const GEOSCoordinate* s, double *val);

Next, update coordinate sequence so that you can:

* Add a coordinate to a coordinate sequence.  Right now there is no way 
to expand a coordinate sequence in the c api which is an extreme limitation.

* Add a getter to coordinate sequence "getCoordinate(size_t index)" that 
returns a coordiante

* Add a getter to point ("getCoordinate()") that returns its coordinate

* Add a method that lets you create a coordinate sequence from a 
coordinate (see next bullet).

* I'd like to change GEOSGeom_createPoint to take a coordinate, not a 
coordinate sequence.  But that would break backward compatibility - so 
maybe a new API?  Or maybe the constructor to create a coordinate 
sequence from a coordinate is good enough.

That should do the trick.

And while on the subject - exposing the envelope class would be helpful 
for working with boundings boxes.  I find it nicer to work with than a 
polygon acting as a bounding box.  Envelope provides niceties like minX, 
minY, expandBy, expandToInclude, etc.



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