Le 24/10/2025 à 13:33, Momtchil Momtchev a écrit :
Is there any way to know whether this is a GDALComputedDataset if
everything I have is a GDALDataset pointer?
ds->GetRasterCount() > 0 &&
dynamic_cast<GDALComputedRasterBand*>(ds->GetRasterBand(1)) != nullptr
maybe ?
but that assumes that the dataset is still alive If you do :
GDALDataset *dh = graylevel->GetDataset();
delete graylevel;
then dh is no longer valid after delete graylevel
There are other situations where the dataset returned by a band belongs
to something else.
For example if you do
ds->GetRasterBand(1)->GetOverview(0)->GetDataset(), this overview
dataset is owned by ds and shouldn't be manually destroyed.
Only datasets returned by GDALDataset::Open() / GDALOpen() /
GDALCreate() / GDALCreateCopy() should be manually destroyed.
On 24/10/2025 12:55, Even Rouault wrote:
Hi,
you should not destroy the dataset of a GDALComputedRasterBand. The
GDALComputedRasterBand destructor does that automatically.
Even
Le 24/10/2025 à 12:40, Momtchil Momtchev via gdal-dev a écrit :
I have modified one of the algebra examples as follows:
#include<gdal_priv.h>
intmain() {
GDALAllRegister();
autopoDS=std::unique_ptr<GDALDataset>(GDALDataset::Open("test/data/a39se10.jpg"));
auto&R=*(poDS->GetRasterBand(1));
auto&G=*(poDS->GetRasterBand(2));
auto&B=*(poDS->GetRasterBand(3));
GDALRasterBand*graylevel=newGDALComputedRasterBand((0.299*R+0.587*G+0.114*B).AsType(GDT_Byte));
autopoGTiffDrv=GetGDALDriverManager()->GetDriverByName("GTiff");
std::unique_ptr<GDALDataset>(
poGTiffDrv->CreateCopy("graylevel.tif", graylevel->GetDataset(),
false, nullptr, nullptr, nullptr))
.reset();
GDALDataset*dh=graylevel->GetDataset();
deletegraylevel;
dh->Close();
return0;
}
I allocate graylevel on the heap, I obtain a pointer to the
GDALComputedDataset and I attempt to destroy first the
GDALComputedRasterBand then the GDALComputedDataset. This fails with
a crash in Close. Is this a bug or am I not supposed to do this? I
am doing it, because this is the usual chain of destruction events
for objects returned to JS. RasterBands hold a reference to their
Dataset in order to prevent the object from being GCed.
--
Momtchil Momtchev<[email protected]>
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My software is free, but my time generally not.
--
Momtchil Momtchev<[email protected]>
--
http://www.spatialys.com
My software is free, but my time generally not.
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