On 13.11.2015 15:58, Even Rouault wrote:
Le vendredi 13 novembre 2015 14:48:02, Ari Jolma a écrit :
OGR_Dr_Open became deprecated in 2.0 but it is still the main method to
open vector datasets in the bindings.
I just realized that I would need one method to open all data sets.
OpenEx seems to be it but I would still need to cast the object into a
Dataset or a DataSource.
Just don't cast. You can use a Dataset for all purposes since the OGR_DS_XXXX
API has been transposed to GDALDatasetXXXX and is already available in
GDALDatasetShadow
Swig imposes typechecks that prevent that. It is like with the GDALGrid,
which takes a vector dataset. I had to write an explicit cast function
for DataSource object into a Dataset object. Which I now realize is
probably not safe since there is an explicit warning against that in the
docs.
Maybe OpenEx should be the preferred way to
open any data set also with the bindings.
However, I don't seem to find good way to tell whether the data set
object OpenEx gives me is a raster or a vector. Is there such?
If you open with OpenEx(filename, OF_VECTOR), so read-only + vector, then the
few drivers that support vector and raster will return NULL if the dataset has
no vector data and just raster. If you open with OpenEx(filename, OF_VECTOR |
OF_UPDATE) and they support update mode, then they will return non-NULL even
if the dataset has no vector data. A robust way of checking if there's vector
data is to check GetLayerCount() != 0.
Thanks.
I have so far ignored the OpenEx method. I'll develop it so in the Perl
bindings that it will return a raster dataset object or a vector data
set object depending whether the returned handle is raster or vector.
I'll also deprecate the old Open methods in the Perl bindings.
Ari
Even
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