I can't say why QGIS handles Shapefiles so quickly but I do have experience of
reading and writing them for myself.
I didn't want to use Shapelib - too big and cumbersome so I just added
read/write functions to my application and used the ESRI document for
reference. It is quite easy to follow but you have to be careful with the
endian-ness of the different fields.
Just search for 'ESRI Shapefile format' and you should find their document.
> On 28/03/2023 02:00 +07 qgis-developer-requ...@lists.osgeo.org wrote:
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> Today's Topics:
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>1. How does QGIS parses the shapefile so quickly (? ??)
>2. Re: How does QGIS parses the shapefile so quickly
> (Alessandro Pasotti)
>3. Re: How does QGIS parses the shapefile so quickly (Even Rouault)
>4. Re: How does QGIS parses the shapefile so quickly (Werner Macho)
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> Dear All,
> Sorry to interrupt, I'm newer to QGIS, whe I use QIGS, I find that it is so
> quick for QGIS to parse shapefile even it is a very big file, I try to decode
> the file by my own with shapelib library, but the result is disappointed, I
> try to learn it by myself with QGIS source code but failed, so anyone can
> help point the entry of decoding process?
>
> Thanks.Hi,
>
> QGIS is using the GDAL/OGR library to read the shapefiles.
>
> On Mon, Mar 27, 2023 at 9:51 AM 余 绍健 via QGIS-Developer
> wrote:
> >
> > Dear All,
> > Sorry to interrupt, I'm newer to QGIS, whe I use QIGS, I find that it is
> > so quick for QGIS to parse shapefile even it is a very big file, I try to
> > decode the file by my own with shapelib library, but the result is
> > disappointed, I try to learn it by myself with QGIS source code but failed,
> > so anyone can help point the entry of decoding process?
> >
> > Thanks.
> > ___
> > QGIS-Developer mailing list
> > QGIS-Developer@lists.osgeo.org
> > List info: https://lists.osgeo.org/mailman/listinfo/qgis-developer
> > Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-developer
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>
>
> --
> Alessandro Pasotti
> QCooperative: www.qcooperative.net
> ItOpen: www.itopen.it
>
>
> Le 27/03/2023 à 10:06, Alessandro Pasotti via QGIS-Developer a écrit :
> > Hi,
> >
> > QGIS is using the GDAL/OGR library to read the shapefiles.
> which uses shapelib
> >
> > On Mon, Mar 27, 2023 at 9:51 AM 余 绍健 via QGIS-Developer
> > wrote:
> >> Dear All,
> >>Sorry to interrupt, I'm newer to QGIS, whe I use QIGS, I find that it
> >> is so quick for QGIS to parse shapefile even it is a very big file, I try
> >> to decode the file by my own with shapelib library, but the result is
> >> disappointed, I try to learn it by myself with QGIS source code but
> >> failed, so anyone can help point the entry of decoding process?
> >>
> >> Thanks.
> >> ___
> >> QGIS-Developer mailing list
> >> QGIS-Developer@lists.osgeo.org
> >> List info: https://lists.osgeo.org/mailman/listinfo/qgis-developer
> >> Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-developer
> >
> >
> --
> http://www.spatialys.com
> My software is free, but my time generally not.
>
>
> Hi!
> Just to add some side information regarding Shapefiles:
> (ignore it if understanding shapefiles ist a must in your case)
>
> http://switchfromshapefile.org/
>
> ;)
> regards
> Werner
>
> On Mon, Mar 27, 2023 at 5:16 PM Even Rouault via QGIS-Developer
> wrote:
> > Le 27/03/2023 à 10:06, Alessandro Pasotti via QGIS-Developer a écrit :
> > > Hi,
> > >
> > > QGIS is using the GDAL/OGR library to read the shapefiles.
> > which uses shapelib
> > >
> > > On Mon, Mar 27, 2023 at 9:51 AM 余 绍健 via QGIS-Developer
> > > wrote:
> > >> Dear All,
> > >> Sorry to interrupt, I'm newer to QGIS, whe I use QIGS, I find that it
> > >>is so quick for QGIS to parse shapefile even it is a very big file, I try
> > >>to decode the file by my own with shapelib library, but the result is
> > >>disappointed, I try to learn it by myself with QGIS source code but
> > >>failed, so anyone can help point the entry of decoding process?
> > >>
> > >> Thanks.
> > >> ___
> > >>
