[gdal-dev] RE: Editing KML files using ogr_csharp.dll

[Even Rouault]

Selon Kyle Shannon <KShannon at gcs-research.com>:

> Can you report your gdal version and where you got it from?  Is it from
> gisinternals.com/sdk, or did you build it yourself?

The old KML driver only supports appending features to a file it has just
created. It can't work on an existing KML file that is re-opened afterwards,
since the driver only writes new lines at the end of the file (and you cannot
write after the ending </kml> marker ...)

The new LIBKML driver uses a in-memory DOM, so it is likely a better candidate
for updating KML files, but I haven't checked if it works indeed for that use
case.

>
> From: Pouliot, Christopher (DNR) [mailto:Christopher.Pouliot at state.mn.us]
> Sent: Monday, December 05, 2011 9:04 AM
> To: Kyle Shannon; gdal-dev at lists.osgeo.org
> Subject: RE: Editing KML files using ogr_csharp.dll
>
> Thanks for the response Kyle.
>
>   I do use the CreateDataSource() to create a new KML.  But am unable to open
> an existing KML for editing using the Open() code I specified below.
>
> Chris
>
> From: Kyle Shannon [mailto:KShannon at gcs-research.com]
> Sent: Monday, December 05, 2011 9:54 AM
> To: Pouliot, Christopher (DNR); gdal-dev at lists.osgeo.org
> Subject: RE: Editing KML files using ogr_csharp.dll
>
> Chris,
>
> I don' know OGR very well, but I see a few issues.  I also am not sure about
> the c# bindings, I believe they are pretty complete though.
>
> '''OSGeo.OGR.Driver drv = Ogr.GetDriverByName("KML");
> DataSource ds = drv.Open("c:\\temp\\mykml.kml", 1);'''
>
> Open() opens existing files, you need to use driver->CreateDatasource() to
> create datasets.  Open() opens files for editing.  If mykml.kml exists, use
> Open().
>
> see http://gdal.org/ogr/ogr_apitut.html for information on using OGR to
> read/write data
>
> '''Also, when creating a KML file from scratch is there a way to map the Name
> and Description fields to my existing fields so that the Name and Description
> appear in Google Earth?'''
>
> See http://gdal.org/ogr/drv_kml.html for this, it appears to be possible.
>
> There is also the libkml driver: http://gdal.org/ogr/drv_libkml.html
>
> kss
>
> From: gdal-dev-bounces at lists.osgeo.org
> [mailto:gdal-dev-bounces at lists.osgeo.org] On Behalf Of Pouliot, Christopher
> (DNR)
> Sent: Monday, December 05, 2011 7:51 AM
> To: gdal-dev at lists.osgeo.org
> Subject: [gdal-dev] Editing KML files using ogr_csharp.dll
>
> Hello All,
>
> I have a C# application that uses OGR_CSHARP.DLL to read/write KML files.
> I'm able to read from KML files fine.  I'm able to create a new KML file and
> write to it fine.  I am unable, however, to open a KML file to edit.  I'd
> like to be able to append a new layer (folder) onto an existing KML file.
> I've tried both of the following code snippets:
>
> //This returns NULL
> OSGeo.OGR.Driver drv = Ogr.GetDriverByName("KML");
> DataSource ds = drv.Open("c:\\temp\\mykml.kml", 1);
>
>
> //This returns NULL
> DataSource ds = Ogr.Open("c:\\temp\\mykml.kml", 1);
>
>
> I'm able to use this code to edit File Geodatabases and Shapefiles but not
> KML.
>
>
>
> Also, when creating a KML file from scratch is there a way to map the Name
> and Description fields to my existing fields so that the Name and Description
> appear in Google Earth?
>
>
> Thanks,
>
> Chris
>
> Chris Pouliot
> GIS Application Developer
> Minnesota Department of Natural Resources
> christopher.pouliot at state.mn.us<mailto:christopher.pouliot at state.mn.us>
> (651) 259-5491
>
>
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