Prototype and description of the function setntvbinautodir()

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


Set or reset a directory for the automatically use of NTv2 binary files.

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

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

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 a NTv2-based Reference System, the
required NTv2 file is searched there. If the file is present in the common
directory, it is initialized automatically.

When calling setntvbinautodir() a still existing NTv2 class instance is
destroyed. When doing the first NTv2 Reference System Transition, GeoDLL
automatically creates a new NTv2 instance using the automatically found NTv2
file. The NTv2 instance remains for further NTv2 calculations until the
another NTv2 Reference System is adjusted. Thereby a new NTv2 instance
useing the required NTv2 file will be created. With calls of the functions
setntvbinaryfile() and setntvbinautofile() also the existing NTv2 instance
will be destroyed and replaced with a new one.

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

With the function setntvbinaryfile(), a particular NTv2 file can be
initialized specifically in any directory. That is, for example, necessary
if with the GeoDLL Reference Systems 208 and 209 any, not implicitly by
GeoDLL supported NTv2 file must be initialized. However, the function also
works with all implicitly by GeoDLL supported NTv2 files.

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.

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 search directory 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 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 path name may contain a drive letter and a directory path. The path name
should end with a backslash (\)
Example: "c:\calculations\ntv2_files\"
Attention, in C syntax double backslashes must be used!

Subdirectories are scanned to the third level for NTv2 binaries.

The parameters are passed and/or returned as follows:
pszBinaryDir  Path of a common directory for NTv2 binary file.
              The path may must contain a drive letter and a directory path
              with a trailing backslash.

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

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.