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: > > > Send QGIS-Developer mailing list submissions to > qgis-developer@lists.osgeo.org > > To subscribe or unsubscribe via the World Wide Web, visit > https://lists.osgeo.org/mailman/listinfo/qgis-developer > or, via email, send a message with subject or body 'help' to > qgis-developer-requ...@lists.osgeo.org > > You can reach the person managing the list at > qgis-developer-ow...@lists.osgeo.org > > When replying, please edit your Subject line so it is more specific > than "Re: Contents of QGIS-Developer digest..." > Today's Topics: > > 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) > _______________________________________________ > 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 > 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 > <qgis-developer@lists.osgeo.org> 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 > > > > -- > 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 > > <qgis-developer@lists.osgeo.org> 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 > <qgis-developer@lists.osgeo.org> 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 > > > <qgis-developer@lists.osgeo.org> 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. > > > > _______________________________________________ > > 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 _______________________________________________ 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
Re: [QGIS-Developer] How does QGIS parses the shapefile so quickly (? ??)
Colin Sare-Soar via QGIS-Developer Mon, 27 Mar 2023 20:50:57 -0700