Prototype and description of the function getellsys() (Function of the unlock requiring group "Parameter determination") |
getellsys() Determination of the designations and parameters of the geodetic ellipsoids used in a geodetic System. Prototype of the DLL function in C++ syntax (attend lower case!): extern "C" __declspec(dllimport) unsigned long __stdcall getellsys( unsigned short wRefSysQ, unsigned short wRefSysZ, unsigned short wCoordSysQ, unsigned short wCoordSysZ, char **pszEllSys); Prototype of the DLL function in Visual Objects syntax: _DLL function getellsys(; wRefSysQ as word,; // 2 Byte wRefSysZ as word,; // 2 Byte wCoordSysQ as word,; // 2 Byte wCoordSysZ as word,; // 2 Byte pszEllSys ref psz); // 4 Byte, char**, 600 alloc. as logic pascal:geodll32.getellsys // 4 Byte The allocation of memory for "ref psz" / "char**" is necessary only if setstringallocate(FALSE) is called before. The function returns the designations and earth semi axes parameters and the inverse flattenings of the ellipsoids fitting to the source and target systems passed in wRefSysQ, wRefSysZ, wCoordSysQ and wCoordSysZ as formatted text in the parameter pszEllSys. The text is returned in the language set by the function setLanguage() before. The parameters are passed and/or returned as follows: wRefSysQ Geodetic source Reference System. The available reference systems are specified in the list "Coordinate and Reference systems". wRefSysZ Geodetic target Reference System to which coordinates of the source Reference System has to be transformed. The available Reference Systems are specified in the list "Coordinate Reference Systems". wCoordSysQ Source Coordinate System. It is needed only if for the source or target Reference Systems the flags 1100, 1150 or 1200 (no Reference System Transition) or the flag 0 (standard reference system) are set, in order to indicate the standard ellipsoid used in that case. The available Coordinate Systems are specified in the list "Coordinate Reference Systems". wCoordSysZ Target Coordinate System. It is needed only if for the source or target Reference Systems the flags 1100, 1150 or 1200 (no Reference System Transition) or the flag 0 (standard reference system) are set, in order to indicate the standard ellipsoid used in that case. The available Coordinate Systems are specified in the list "Coordinate Reference Systems". pszEllSys The ellipsoid parameters will be provided together with their (ref) description in a formatted text and returned by reference. The lines of the text are separated with "Return and Linefeed". Note: "ref pszEllSys" corresponds to "char**" in C. 600 bytes of memory for the zero terminated string must be allocated with dependence to the call of the function setstringallocate(). Please consider the notes in the description of the function setstringallocate(). returnVal In case of an error the function returns FALSE, otherwise TRUE. The returned text looks dependently of the geodetic source and target systems e.g. like this: Ellipsoid of the source system: GRS80 (1980) 6378137.0000000 Semi-major axis [meter] 6356752.3141403 Semi-minor axis [meter] 00298.257222100 Inverse flattening [1/f] Ellipsoid of the target system: Hayford (1909)/Intern. (1924) 6378388.0000000 Semi-major axis [meter] 6356911.9461300 Semi-minor axis [meter] 00297.000000000 Inverse flattening [1/f] Unlocking: This function is a component of the unlock requiring function group "parameter determination". It is unlocked for unrestricted use together with the other functions of the group by passing the unlock parameters, acquired from the software distribution company, trough the function setunlockcode(). Without unlocking only a few function calls for test purposes (shareware principle) are possible. |