Le 16/10/2023 à 15:15, Javier Jimenez Shaw via gdal-dev a écrit :
Do you mean a MultiLineString?
This piece of code is working for me (I hope without any bug).
if (wkbFlatten(poGeometry->getGeometryType()) == wkbMultiLineString)
multiLineStringGeometry(poGeometry);
...
multiLineStringGeometry(OGRGeometry* poGeometry)
{
OGRMultiLineString* multiLine =
dynamic_cast<OGRMultiLineString*>(poGeometry);
int numGeometries = multiLine->getNumGeometries();
for (int i = 0; i < numGeometries; i++)
{
OGRGeometry* eachGeometry =
multiLine->getGeometryRef(i);
OGRLineString* line =
dynamic_cast<OGRLineString*>(eachGeometry);
// do whatever with that LineString
}
}
Can further be simplified to something like:
multiLineStringGeometry(const OGRGeometry* poGeometry)
{
for (const OGRLineString* line:
poGeometry->toMultiLineString())
{
// do whatever with that LineString
}
}
On Mon, 16 Oct 2023 at 12:14, Roland Baviere via gdal-dev
<gdal-dev@lists.osgeo.org> wrote:
Hi all,
I hope this e-mel finds you well.
I am trying to read a shapefile layer from OGR from a C++
application following the tutorial found here:
https://gdal.org/tutorials/vector_api_tut.html#reading-from-ogr
We have difficulties with a layer containing PolyLines with
several parts.
The pre-existing code works fine for polylines having a unique part.
Do you have any example or advice to help me implement a version
that works for polylines containing several parts. My intention is
to display each shape on a map, so I need to retrieve the
coordinates of points and draw segment between points when relevant.
Thanks a lot for your help.
Kind regards,
Roland
//// CODE THAT WORKS for "simple" polylines but fails when
dealiing with a polyline containing several parts
int o = 0;
for(auto y : poGeometry->toLineString()) {
if (o == 0) {
line.mInCoord =
QGeoCoordinate(y.getX(), y.getY());
} else if (o ==
(poGeometry->toLineString()->getNumPoints() - 1)) {
line.mOutCoord =
QGeoCoordinate(y.getX(), y.getY());
} else {
line.mPath.addCoordinate(QGeoCoordinate(y.getX(), y.getY()));
}
qDebug() << o;
o++;
}
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