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SQLITE/GPKG: add a gdal_get_pixel_value() SQL function.
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Applies to both SQL SQLite dialect and GPKG

The ``gdal_get_pixel_value()`` function (added in GDAL 3.7) can be used to extract the value
of a pixel in a GDAL dataset. It requires the configuration option OGR_SQLITE_ALLOW_EXTERNAL_ACCESS
to be set to YES (for security reasons).

It takes 5 arguments:

* a string with the dataset name
* a band number (numbering starting at 1)
* a string being "georef" to indicate that subsequent values will be georeferenced
  coordinates, or "pixel" to indicate that subsequent values will be in column, line
  pixel space
* georeferenced X value or column number
* georeferenced Y value or line number

.. code-block::

    SELECT gdal_get_pixel_value('../gcore/data/byte.tif', 1, 'georef', 440720, 3751320)
    SELECT gdal_get_pixel_value('../gcore/data/byte.tif', 1, 'pixel', 0, 0)
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@rouault
rouault committed Dec 8, 2022
1 parent bc0948f commit bf9cd25
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Showing 9 changed files with 481 additions and 100 deletions.
124 changes: 124 additions & 0 deletions autotest/ogr/ogr_gpkg.py
View file
Expand Up @@ -8055,3 +8055,127 @@ def test_ogr_gpkg_read_generated_column():
ds = None

gdal.Unlink(filename)


###############################################################################
# Test gdal_get_pixel_value() function


def test_ogr_gpkg_sql_gdal_get_pixel_value():

filename = "/vsimem/test_ogr_gpkg_sql_gdal_get_pixel_value.gpkg"
ds = ogr.GetDriverByName("GPKG").CreateDataSource(filename)

with gdaltest.config_option("OGR_SQLITE_ALLOW_EXTERNAL_ACCESS", "YES"):
sql_lyr = ds.ExecuteSQL(
"select gdal_get_pixel_value('../gcore/data/byte.tif', 1, 'georef', 440780, 3751080)"
)
f = sql_lyr.GetNextFeature()
ds.ReleaseResultSet(sql_lyr)
assert f[0] == 156

with gdaltest.config_option("OGR_SQLITE_ALLOW_EXTERNAL_ACCESS", "YES"):
sql_lyr = ds.ExecuteSQL(
"select gdal_get_pixel_value('../gcore/data/byte.tif', 1, 'pixel', 1, 4)"
)
f = sql_lyr.GetNextFeature()
ds.ReleaseResultSet(sql_lyr)
assert f[0] == 156

with gdaltest.config_option("OGR_SQLITE_ALLOW_EXTERNAL_ACCESS", "YES"):
sql_lyr = ds.ExecuteSQL(
"select gdal_get_pixel_value('../gcore/data/float64.tif', 1, 'pixel', 0, 1)"
)
f = sql_lyr.GetNextFeature()
ds.ReleaseResultSet(sql_lyr)
assert f[0] == 115.0

# Invalid column
with gdaltest.config_option("OGR_SQLITE_ALLOW_EXTERNAL_ACCESS", "YES"):
sql_lyr = ds.ExecuteSQL(
"select gdal_get_pixel_value('../gcore/data/byte.tif', 1, 'pixel', -1, 0)"
)
f = sql_lyr.GetNextFeature()
ds.ReleaseResultSet(sql_lyr)
assert f[0] is None

# Missing OGR_SQLITE_ALLOW_EXTERNAL_ACCESS
with gdaltest.error_handler():
sql_lyr = ds.ExecuteSQL(
"select gdal_get_pixel_value('../gcore/data/byte.tif', 1, 'georef', 440720, 3751320)"
)
f = sql_lyr.GetNextFeature()
ds.ReleaseResultSet(sql_lyr)
assert f[0] is None

# NULL as 1st arg
with gdaltest.error_handler():
with gdaltest.config_option("OGR_SQLITE_ALLOW_EXTERNAL_ACCESS", "YES"):
sql_lyr = ds.ExecuteSQL(
"select gdal_get_pixel_value(NULL, 1, 'pixel', 0, 0)"
)
f = sql_lyr.GetNextFeature()
ds.ReleaseResultSet(sql_lyr)
assert f[0] is None

# NULL as 2nd arg
with gdaltest.error_handler():
with gdaltest.config_option("OGR_SQLITE_ALLOW_EXTERNAL_ACCESS", "YES"):
sql_lyr = ds.ExecuteSQL(
"select gdal_get_pixel_value('../gcore/data/byte.tif', NULL, 'pixel', 0, 0)"
)
f = sql_lyr.GetNextFeature()
ds.ReleaseResultSet(sql_lyr)
assert f[0] is None

# NULL as 3rd arg
with gdaltest.error_handler():
with gdaltest.config_option("OGR_SQLITE_ALLOW_EXTERNAL_ACCESS", "YES"):
sql_lyr = ds.ExecuteSQL(
"select gdal_get_pixel_value('../gcore/data/byte.tif', 1, NULL, 0, 0)"
)
f = sql_lyr.GetNextFeature()
ds.ReleaseResultSet(sql_lyr)
assert f[0] is None

# NULL as 4th arg
with gdaltest.error_handler():
with gdaltest.config_option("OGR_SQLITE_ALLOW_EXTERNAL_ACCESS", "YES"):
sql_lyr = ds.ExecuteSQL(
"select gdal_get_pixel_value('../gcore/data/byte.tif', 1, 'pixel', NULL, 0)"
)
f = sql_lyr.GetNextFeature()
ds.ReleaseResultSet(sql_lyr)
assert f[0] is None

# NULL as 5th arg
with gdaltest.error_handler():
with gdaltest.config_option("OGR_SQLITE_ALLOW_EXTERNAL_ACCESS", "YES"):
sql_lyr = ds.ExecuteSQL(
"select gdal_get_pixel_value('../gcore/data/byte.tif', 1, 'pixel', 0, NULL)"
)
f = sql_lyr.GetNextFeature()
ds.ReleaseResultSet(sql_lyr)
assert f[0] is None

# Invalid band number
with gdaltest.error_handler():
with gdaltest.config_option("OGR_SQLITE_ALLOW_EXTERNAL_ACCESS", "YES"):
sql_lyr = ds.ExecuteSQL(
"select gdal_get_pixel_value('../gcore/data/byte.tif', 0, 'pixel', 0, 0)"
)
f = sql_lyr.GetNextFeature()
ds.ReleaseResultSet(sql_lyr)
assert f[0] is None

# Invalid value for 3rd argument
with gdaltest.error_handler():
with gdaltest.config_option("OGR_SQLITE_ALLOW_EXTERNAL_ACCESS", "YES"):
sql_lyr = ds.ExecuteSQL(
"select gdal_get_pixel_value('../gcore/data/byte.tif', 1, 'invalid', 0, 0)"
)
f = sql_lyr.GetNextFeature()
ds.ReleaseResultSet(sql_lyr)
assert f[0] is None

gdal.Unlink(filename)
3 changes: 3 additions & 0 deletions doc/source/drivers/vector/gpkg.rst
View file
Expand Up @@ -124,6 +124,9 @@ Spatialite, are also available :
in gpkg_spatial_ref_sys, starting with GDAL 3.2, it will be interpreted as
a EPSG code.

The raster SQL functions mentioned at :ref:`sql_sqlite_dialect_raster_functions`
are also available.

Link with Spatialite
~~~~~~~~~~~~~~~~~~~~

Expand Down
25 changes: 25 additions & 0 deletions doc/source/user/sql_sqlite_dialect.rst
View file
Expand Up @@ -257,6 +257,31 @@ a value associate to a key from a HSTORE string, formatted like "key=>value,othe
SELECT hstore_get_value('a => b, "key with space"=> "value with space"', 'key with space') --> 'value with space'
.. _sql_sqlite_dialect_raster_functions:

Raster related functions
++++++++++++++++++++++++

The ``gdal_get_pixel_value()`` function (added in GDAL 3.7) can be used to extract the value
of a pixel in a GDAL dataset. It requires the configuration option OGR_SQLITE_ALLOW_EXTERNAL_ACCESS
to be set to YES (for security reasons).

It takes 5 arguments:

* a string with the dataset name
* a band number (numbering starting at 1)
* a string being "georef" to indicate that subsequent values will be georeferenced
coordinates, or "pixel" to indicate that subsequent values will be in column, line
pixel space
* georeferenced X value or column number
* georeferenced Y value or line number

.. code-block::
SELECT gdal_get_pixel_value('../gcore/data/byte.tif', 1, 'georef', 440720, 3751320)
SELECT gdal_get_pixel_value('../gcore/data/byte.tif', 1, 'pixel', 0, 0)
OGR geocoding functions
+++++++++++++++++++++++

Expand Down
3 changes: 3 additions & 0 deletions ogr/ogrsf_frmts/gpkg/ogr_geopackage.h
View file
Expand Up @@ -122,6 +122,7 @@ class GDALGeoPackageDataset final : public OGRSQLiteBaseDataSource, public GDALG
int argc,
sqlite3_value** argv);

void *m_pSQLFunctionData = nullptr;
GUInt32 m_nApplicationId = GPKG_APPLICATION_ID;
GUInt32 m_nUserVersion = GPKG_1_2_VERSION;
OGRGeoPackageTableLayer** m_papoLayers = nullptr;
Expand Down Expand Up @@ -272,6 +273,8 @@ class GDALGeoPackageDataset final : public OGRSQLiteBaseDataSource, public GDALG
bool m_bIsGeometryTypeAggregateInterrupted = false;
std::string m_osGeometryTypeAggregateResult{};

virtual void CloseDB() override;

CPL_DISALLOW_COPY_ASSIGN(GDALGeoPackageDataset)

public:
Expand Down
14 changes: 13 additions & 1 deletion ogr/ogrsf_frmts/gpkg/ogrgeopackagedatasource.cpp
View file
Expand Up @@ -45,6 +45,8 @@
#include <limits>
#include <sstream>

#define COMPILATION_ALLOWED
#include "ogrsqlitesqlfunctionscommon.cpp"

// Keep in sync prototype of those 2 functions between gdalopeninfo.cpp,
// ogrsqlitedatasource.cpp and ogrgeopackagedatasource.cpp
Expand Down Expand Up @@ -185,7 +187,6 @@ static std::unique_ptr<TilingSchemeDefinition> GetTilingScheme(const char* pszNa
return poTilingScheme;
}


static const char* pszCREATE_GPKG_GEOMETRY_COLUMNS =
"CREATE TABLE gpkg_geometry_columns ("
"table_name TEXT NOT NULL,"
Expand Down Expand Up @@ -259,6 +260,13 @@ OGRErr GDALGeoPackageDataset::SetApplicationAndUserVersionId()
#endif
}

void GDALGeoPackageDataset::CloseDB()
{
OGRSQLiteUnregisterSQLFunctions(m_pSQLFunctionData);
m_pSQLFunctionData = nullptr;
OGRSQLiteBaseDataSource::CloseDB();
}

bool GDALGeoPackageDataset::ReOpenDB()
{
CPLAssert( hDB != nullptr );
Expand Down Expand Up @@ -999,6 +1007,8 @@ GDALGeoPackageDataset::~GDALGeoPackageDataset()
if( poSRS )
poSRS->Release();
}

CloseDB();
}

/************************************************************************/
Expand Down Expand Up @@ -8203,6 +8213,8 @@ void GDALGeoPackageDataset::InstallSQLFunctions()
SQLITE_UTF8 | SQLITE_DETERMINISTIC, nullptr,
GPKG_GDAL_HasColorTable, nullptr, nullptr);
}

m_pSQLFunctionData = OGRSQLiteRegisterSQLFunctionsCommon(hDB);
}

/************************************************************************/
Expand Down
2 changes: 1 addition & 1 deletion ogr/ogrsf_frmts/sqlite/ogrsqlitebase.h
View file
Expand Up @@ -141,7 +141,7 @@ class OGRSQLiteBaseDataSource CPL_NON_FINAL: public GDALPamDataset
bool SetCacheSize();
void LoadExtensions();

void CloseDB();
virtual void CloseDB();

std::map<CPLString, OGREnvelope> oMapSQLEnvelope{};

Expand Down
2 changes: 1 addition & 1 deletion ogr/ogrsf_frmts/sqlite/ogrsqliteregexp.h
View file
Expand Up @@ -30,7 +30,7 @@
#ifndef OGR_SQLITE_REGEXP_INCLUDED
#define OGR_SQLITE_REGEXP_INCLUDED

#include "ogr_sqlite.h"
#include "sqlite3.h"

static void* OGRSQLiteRegisterRegExpFunction(sqlite3* hDB);
static void OGRSQLiteFreeRegExpCache(void* hRegExpCache);
Expand Down
101 changes: 4 additions & 97 deletions ogr/ogrsf_frmts/sqlite/ogrsqlitesqlfunctions.cpp
View file
Expand Up @@ -35,7 +35,6 @@
#include "ogrsqlitesqlfunctions.h"
#include "ogr_geocoding.h"

#include "ogrsqliteregexp.cpp" /* yes the .cpp file, to make it work on Windows with load_extension('gdalXX.dll') */
#include "ogr_swq.h"

#include <limits>
Expand All @@ -49,90 +48,11 @@
#define MINIMAL_SPATIAL_FUNCTIONS
#endif

class OGRSQLiteExtensionData
{
#ifdef DEBUG
void* pDummy; /* to track memory leaks */
#endif
std::map< std::pair<int,int>, OGRCoordinateTransformation*> oCachedTransformsMap;

void* hRegExpCache;

OGRGeocodingSessionH hGeocodingSession;

public:
explicit OGRSQLiteExtensionData(sqlite3* hDB);
~OGRSQLiteExtensionData();

OGRCoordinateTransformation* GetTransform(int nSrcSRSId, int nDstSRSId);

OGRGeocodingSessionH GetGeocodingSession() { return hGeocodingSession; }
void SetGeocodingSession(OGRGeocodingSessionH hGeocodingSessionIn) { hGeocodingSession = hGeocodingSessionIn; }

void SetRegExpCache(void* hRegExpCacheIn) { hRegExpCache = hRegExpCacheIn; }
};

/************************************************************************/
/* OGRSQLiteExtensionData() */
/************************************************************************/

OGRSQLiteExtensionData::OGRSQLiteExtensionData(CPL_UNUSED sqlite3* hDB) :
#ifdef DEBUG
pDummy(CPLMalloc(1)),
#endif
hRegExpCache(nullptr),
hGeocodingSession(nullptr)
{}

/************************************************************************/
/* ~OGRSQLiteExtensionData() */
/************************************************************************/

OGRSQLiteExtensionData::~OGRSQLiteExtensionData()
{
#ifdef DEBUG
CPLFree(pDummy);
#endif

std::map< std::pair<int,int>, OGRCoordinateTransformation*>::iterator oIter =
oCachedTransformsMap.begin();
for(; oIter != oCachedTransformsMap.end(); ++oIter)
delete oIter->second;

OGRSQLiteFreeRegExpCache(hRegExpCache);

OGRGeocodeDestroySession(hGeocodingSession);
}
#define DEFINE_OGRSQLiteExtensionData_GetTransform
#include "ogrsqlitesqlfunctionscommon.cpp"

/************************************************************************/
/* GetTransform() */
/************************************************************************/

OGRCoordinateTransformation* OGRSQLiteExtensionData::GetTransform(int nSrcSRSId,
int nDstSRSId)
{
std::map< std::pair<int,int>, OGRCoordinateTransformation*>::iterator oIter =
oCachedTransformsMap.find(std::pair<int,int>(nSrcSRSId, nDstSRSId));
if( oIter == oCachedTransformsMap.end() )
{
OGRCoordinateTransformation* poCT = nullptr;
OGRSpatialReference oSrcSRS, oDstSRS;
oSrcSRS.SetAxisMappingStrategy(OAMS_TRADITIONAL_GIS_ORDER);
oDstSRS.SetAxisMappingStrategy(OAMS_TRADITIONAL_GIS_ORDER);
if (oSrcSRS.importFromEPSG(nSrcSRSId) == OGRERR_NONE &&
oDstSRS.importFromEPSG(nDstSRSId) == OGRERR_NONE )
{
poCT = OGRCreateCoordinateTransformation( &oSrcSRS, &oDstSRS );
}
oCachedTransformsMap[std::pair<int,int>(nSrcSRSId, nDstSRSId)] = poCT;
return poCT;
}
else
return oIter->second;
}

/************************************************************************/
/* OGR2SQLITE_ogr_version() */
/* OGR2SQLITE_ogr_version() */
/************************************************************************/

static
Expand Down Expand Up @@ -1108,7 +1028,7 @@ void OGRSQLITE_hstore_get_value(sqlite3_context* pContext,
static
void* OGRSQLiteRegisterSQLFunctions(sqlite3* hDB)
{
OGRSQLiteExtensionData* pData = new OGRSQLiteExtensionData(hDB);
OGRSQLiteExtensionData* pData = OGRSQLiteRegisterSQLFunctionsCommon(hDB);

sqlite3_create_function(hDB, "ogr_version", 0,
SQLITE_UTF8 | SQLITE_DETERMINISTIC, nullptr,
Expand Down Expand Up @@ -1272,18 +1192,5 @@ void* OGRSQLiteRegisterSQLFunctions(sqlite3* hDB)
}
}

pData->SetRegExpCache(OGRSQLiteRegisterRegExpFunction(hDB));

return pData;
}

/************************************************************************/
/* OGRSQLiteUnregisterSQLFunctions() */
/************************************************************************/

static
void OGRSQLiteUnregisterSQLFunctions(void* hHandle)
{
OGRSQLiteExtensionData* pData = (OGRSQLiteExtensionData* )hHandle;
delete pData;
}

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