From 5b3f5b9a9c781cc35b0e6ab90895e5495b59e0f2 Mon Sep 17 00:00:00 2001
From: Alessandro Pasotti <elpaso@itopen.it>
Date: Thu, 18 Sep 2025 18:21:32 +0200
Subject: [PATCH 1/2] [pg][raster] Fix nodata ignored

Fix #63171

TODO: test
---
 src/core/qgsgdalutils.cpp | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/core/qgsgdalutils.cpp b/src/core/qgsgdalutils.cpp
index 5441fe688cd..419a7d9ae0a 100644
--- a/src/core/qgsgdalutils.cpp
+++ b/src/core/qgsgdalutils.cpp
@@ -386,6 +386,8 @@ static bool resampleSingleBandRasterStatic( GDALDatasetH hSrcDS, GDALDatasetH hD
   double noDataValue = GDALGetRasterNoDataValue( GDALGetRasterBand( hDstDS, 1 ), nullptr );
   psWarpOptions->padfDstNoDataReal = reinterpret_cast< double * >( CPLMalloc( sizeof( double ) * 1 ) );
   psWarpOptions->padfDstNoDataReal[0] = noDataValue;
+  psWarpOptions->padfSrcNoDataReal = reinterpret_cast< double * >( CPLMalloc( sizeof( double ) * 1 ) );
+  psWarpOptions->padfSrcNoDataReal[0] = noDataValue;
   psWarpOptions->eResampleAlg = resampleAlg;
 
   // Establish reprojection transformer.

From 9ba381bc0325154c33d8eae725ec2c989262d094 Mon Sep 17 00:00:00 2001
From: Alessandro Pasotti <elpaso@itopen.it>
Date: Fri, 19 Sep 2025 09:06:25 +0200
Subject: [PATCH 2/2] Tests for issue #63171

---
 tests/src/core/testqgsgdalutils.cpp | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/tests/src/core/testqgsgdalutils.cpp b/tests/src/core/testqgsgdalutils.cpp
index b008214855e..2d3a4a9616b 100644
--- a/tests/src/core/testqgsgdalutils.cpp
+++ b/tests/src/core/testqgsgdalutils.cpp
@@ -44,6 +44,7 @@ class TestQgsGdalUtils : public QObject
     void testPathIsCheapToOpen();
     void testVrtMatchesLayerType();
     void testMultilayerExtensions();
+    void testResampleSingleBandRasterNoData();
 
   private:
     double identify( GDALDatasetH dataset, int band, int px, int py );
@@ -322,5 +323,32 @@ double TestQgsGdalUtils::identify( GDALDatasetH dataset, int band, int px, int p
   return value;
 }
 
+void TestQgsGdalUtils::testResampleSingleBandRasterNoData()
+{
+  // Create 2x2 integer raster with values 1, 65535, 65535, 65535 and nodata=65535
+  QTemporaryDir tempDir;
+  const QString tempPath = tempDir.path();
+  const QString inputFilename = tempPath + "/input.tif";
+
+  gdal::dataset_unique_ptr ds1 = QgsGdalUtils::createSingleBandTiffDataset( inputFilename, GDT_UInt16, QgsRectangle( 1, 1, 3, 3 ), 2, 2, QgsCoordinateReferenceSystem( "EPSG:4326" ) );
+  QVERIFY( ds1 );
+
+  GDALRasterBandH band = GDALGetRasterBand( ds1.get(), 1 );
+  GDALSetRasterNoDataValue( band, 65535 );
+  GUInt16 buffer[4] = { 1, 65535, 65535, 65535 };
+  const CPLErr err = GDALRasterIO( band, GF_Write, 0, 0, 2, 2, buffer, 2, 2, GDT_UInt16, 0, 0 );
+  QCOMPARE( err, CE_None );
+
+  // Create destination GDAL DS
+  std::unique_ptr<QgsRasterBlock> dstBlock = std::make_unique<QgsRasterBlock>( Qgis::DataType::UInt16, 4, 4 );
+  dstBlock->setNoDataValue( 65535.0 );
+  gdal::dataset_unique_ptr gdalDsOutput = QgsGdalUtils::blockToSingleBandMemoryDataset( QgsRectangle( 1, 1, 3, 3 ), dstBlock.get() );
+
+  QVERIFY( QgsGdalUtils::resampleSingleBandRaster( ds1.get(), gdalDsOutput.get(), GRA_NearestNeighbour, nullptr ) );
+  QCOMPARE( identify( gdalDsOutput.get(), 1, 0, 0 ), 1.0 );
+  QCOMPARE( identify( gdalDsOutput.get(), 1, 2, 2 ), 65535.0 );
+}
+
+
 QGSTEST_MAIN( TestQgsGdalUtils )
 #include "testqgsgdalutils.moc"