[PROJ] function to get grid transformation data

[Javier Jimenez Shaw]

*HiI have a problem determining if a (gravity related height) vertical CRS
has a corresponding geoid model grid-file in the system or not. In other
words, if I can expect an actual transformation to that VCRS or not. (All
this is not using the “PROJ_NETWORK” mechanism to use a remote location,
but assuming that any file is already in the computer I am running).I am
thinking about developing a PR for C++ that returns some useful information
about the grid transformations for a given CRS code (doing some SQL
queries). That will allow the user/developer to know the grid files
involved for that CRS, and check if they are available on the
filesystem.The API would be something like this:struct
GridTransformationData {    std::string auth_name;    std::string
code;    std::string source_crs_auth_name;    std::string
source_crs_code;    std::string accuracy;    std::string
param_auth_name;    std::string param_code;    std::string
grid_name;    Extent
extent;};std::list<GridTransformationData>AuthorityFactory::getGridTransformationData(const
std::string &code) const;To find if the file is in the system, this other
function will help to search among the tiff files from PROJ-datastd::string
getGridAlternative(const std::string& original_grid_name) const;Is there
already a way to do it?Which fields (mainly from grid_transformation table)
should I return?Probably there are other use cases (maybe not only for
vertical CRSs) that can take advantage of these functions.Thanks.*
.___ ._ ..._ .. . ._.  .___ .. __ . _. . __..  ... .... ._ .__
Entre dos pensamientos racionales
hay infinitos pensamientos irracionales.
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