Abel,
At the minimum for the reading side of a vector driver, you need to
implement GetNextFeature().
If there is an efficient way of knowing the number of features without
iterating over the whole file (typically a field in a header giving that
number), you may implement GetFeatureCount(). If you don't implement it,
and code using your driver needs the feature count, the generic
implementation of OGRLayer::GetFeatureCount() will call GetNextFeature()
repeatdly until it returns NULL.
Not totally sure to understand your question about multielements. If you
have an instance of OGRGeometryCollection or any deriving class, there's
a getNumGeometries() method to get the number of parts
Even
Le 07/07/2023 à 11:33, Abel Pau a écrit :
Hi,
I would like to know if when we use the code of GDAL to program a
driver (or whatever) in vectors (so, ogr) we can assume that we can
know the number of elements we are going to import in any way or it
would be possible not knowing that until NextFeature is empty (or
something like that). So, there is any way to obtain this number of
elements without doing a while? And in case of multielements its
possible to know how many parts are there in total?
I need that to write my format (I don’t explain the details cause I
don’t get you bored :) )
If anyone know that I’d appreciate an answer. Thanks in advance.
Abel.
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