Prototype and description of the function setntvbinautofile() (Function of the unlock requiring group "NTv2 Transformations")
 setntvbinautofile() Sets a NTv2 grid binary file for automatically call in a wait position. Prototype of the DLL function in C++ syntax (attend lower case!): extern "C" __declspec(dllimport) unsigned long __stdcall setntvbinautofile( const char *pszFileBinary); Prototype of the DLL function in Visual Objects syntax: _DLL function setntvbinautofile(; pszFileBinary as psz); // 4 Byte, char* as logic pascal:geodll32.setntvbinautofile // 4 Byte The function passes the path and the name of a NTv2 grid data binary file to the DLL. The file is automatically checked, opened and used with the first NTv2 Reference System Transition. It is located so far in a waiting position. This approach makes sense, because the use of NTv2 binary data is memory intensive and the memory space only will be allocated, if NTv2 Reference System Transitions are executed. In the NTv2 binary file the grid data for NTv2 Reference System Transitions are contained. The grid data are used, when one of the functions coordtrans???() has set the reference system flags for a NTv2 Reference System Transition. The testing of the file content takes place primary with the first NTv2 Reference System Transition, then the possible error messages are initialized by the later used function coordtrans???(). When calling setntvbinautofile() at first 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 specified NTv2 file. The NTv2 instance remains for further NTv2 calculations until another call of setntvbinaryfile(), setntvbinautofile() or setntvbinautodir() occurs. 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. 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. 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! The parameters are passed and/or returned as follows: pszFileBinary File name of a 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.