[gdal-dev] gdal & WMS
even.rouault at spatialys.com
Thu Jun 17 08:47:08 PDT 2021
A OGRLayer is a *vector* layer, not a raster one. So you should rather
look at the raster API: https://gdal.org/tutorials/raster_api_tut.html
Depending on the kind of URL you provide to GDAL, you may get directly a
workable dataset, or just a placeholder that links to real datasets with
the subdataset (which can be seen as a king of raster layer) mechanism,
using GDALDataset::GetMetadata("SUBDATASETS") to get the list of
subdatasets, and then pass to GDALOpen() the value of one of the
Le 17/06/2021 à 17:41, Ming Chin a écrit :
> Hello GDAL devs,
> I am a GDAL rookie, and I am trying to add WMS support to an
> existing GDAL (2.2.4) implementation.
> I saw in this example:
> that its possible to provide OGRSFDriverRegistrar::Open(sURL, FALSE );
> with a url and use it to open an OGRDataSource.
> And in other examples I see that OGRSFDriverRegistrar::Open() has been
> deprecated and that GDALOpen() should be used instead.
> So I did that, adding cURL to our GDAL build, and then in my
> implementation, I provided GDALOpen() with a URL like this:
> GDALDataset *pDataset = (GDALDataset*)::GDALOpen(sURL, GA_ReadOnly);
> if( pDataset )
> int nLayers = pDataset->GetLayerCount();
> OGRLayer *pLayer = pDataset->GetLayerByName(sLayerName);
> This seems to partially work, in the sense that the GDALOpen function
> returns a non-NULL pointer to a GDALDataset, but when I try to call
> the member functions of the resulting GDALDataset, everything seems to
> return zeros or nulls;
> The above call returns nLayers = 0, and pLayer=NULL
> but if I feed the same sURL into my web browser (Chrome), the browser
> receives a properly formatted xml file that clearly has <Layer>(s)
> defined in it.
> What am I missing? Why am I unable to retrieve useful data from the
> gdal-dev mailing list
> gdal-dev at lists.osgeo.org
My software is free, but my time generally not.
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