Prototype and description of the function setntvbinaryfile()

(Function of the unlock requiring group "NTv2 Transformations")

setntvbinaryfile()
Set or reset an NTv2 grid data binary file for Reference System Transition.

Prototype of the DLL function in C++ syntax (attend lower case!):
extern "C" __declspec(dllimport) unsigned long __stdcall setntvbinaryfile(
     char *pszFileBinary);

Prototype of the DLL function in Visual Objects syntax:
_DLL function setntvbinaryfile(;
     pszFileBinary as psz);                 // 4 Byte, char*
as logic pascal:geodll32.setntvbinaryfile   // 4 Byte


The function tests and initializes an NTv2 grid data binary file containing
grid data for NTv2 Reference System Transitions. The grid data are used,
when one of the functions coordtrans???() has set the Reference System flags
for an NTv2 Reference System Transition. The memory space required for NTv2
Reference System Transitions is allocated regardless of the actual execution
of NTv2 Reference System Transitions. The testing of the file content is
made directly with the function call and any error messages are directly
initialized by the function setntvbinaryfile().

For geodetic calculations with NTv2 grid files GeoDLL can make aware of the
paths of the files with further functions:

The function setntvbinautofile() can be used to store the NTv2 file
path only in a waiting position. Testing and the allocation of memory
space takes place primary with the first NTv2 Reference System Transition.

With the function setntvbinautodir() an automatically selection and
initializtion of the required NTv2 file can be realized. For this purpose,
the required NTv2 files must be stored in a common directory with up to
three subdirectories. When changing to an NTv2-based Reference System, the
required NTv2 file is searched there. If the file is present in the common
directory, it is initialized automatically.

To close an already opened NTv2-grid file and to release the corresponding
NTv2 instance in GeoDLL, the function closentvbinaryfile() can be used. But
this is only necessary in special cases. Please read the function description.
Alternatively the NTv2 grid file can be reseted by calling this function with
a null string as a parameter.

You can download the NTv2 files supported by GeoDLL directly from the
KilletSoft website http://www.killetsoft.de/p_gdln_e.htm#download or use the
download links to the original sources there. On that Internet site you also
find a detailed description of the NTv2 standard.

The file name may contain a drive letter, a directory path and a file name
extension. The file name extension for NTv2 binary files is by standard "gsb".
Example: "c:\calculations\ntv2_files\beta2007.gsb".
Attention, in C syntax double backslashes must be used!

With the functions getntvbinaryfile() and setntvbinaryfile() an
automatically selection and initializtion of the required NTv2 file can be
realized. For this purpose, the required NTv2 files must be stored in a
common directory. When changing to an NTv2-based Reference System, the name of
the required NTv2 file is determined by the function getntvbinaryfile(). If
the file is present in the common directory, it is initialized there with the
function setntvbinaryfile().


The parameters are passed and/or returned as follows:
pszFileBinary File name of an NTv2 binary file.
              The file name may contain a drive letter, a directory path
              and a file name extension.

returnVal     In case of an error the function returns FALSE, otherwise TRUE.


Unlocking:
This function is a component of the unlock requiring function group
"NTv2 Transformations". 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. It should be noted that in addition the function
group "Coordinate Transformations" must be unlocked.