Edzer,
Le 14/09/2023 à 13:52, Edzer Pebesma a écrit :
This came up here: https://github.com/r-spatial/sf/issues/2166
It seems to me that GDAL queries PROJ's ability to access the network
for datum grids once, and remembers that. That means that applications
can't switch this on and off on demand and expect GDAL to follow. Is
this the case? If this is the case, is there a way applications can
ask GDAL what this state is?
The first time, per thread, GDAL uses PROJ it will inherit the network
settings from PROJ when creating its per-thread PROJ context.
The current status can be queried with OSRGetPROJEnableNetwork():
https://gdal.org/api/ogr_srs_api.html#_CPPv423OSRGetPROJEnableNetworkv
and changed with OSRSetPROJEnableNetwork():
https://gdal.org/api/ogr_srs_api.html#_CPPv423OSRSetPROJEnableNetworki
I see that sf_proj_network() calls CPL_enable_network()
(https://github.com/r-spatial/sf/blob/f36bd2f7273ace6d244e401b760291a3dc195c3c/src/proj.cpp#L193)
which calls proj_context_set_enable_network() on the default PROJ
context. If this is done before any GDAL use (or more exactly any use of
PROJ by GDAL), then it is OK. But if it is called afterwards, GDAL will
have created its own PROJ context, and later changes to the default PROJ
context will not affect it anymore. Presumably sf_proj_network() or
CPL_enable_network() should call OSRSetPROJEnableNetwork() as well if
the intent if that this affects both pure-PROJ and PROJ-through-GDAL uses.
Even
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