Merge pull request #8438 from wonder-sk/fix-block-outside-raster-extent

Fix raster block output when block extent is outside of valid area

Author: wonder-sk

src/providers/gdal/qgsgdalprovider.cpp

@@ -640,6 +640,13 @@ QgsRasterBlock *QgsGdalProvider::block( int bandNo, const QgsRectangle &extent,
     return block;
   }
 
+  if ( !mExtent.intersects( extent ) )
+  {
+    // the requested extent is completely outside of the raster's extent - nothing to do
+    block->setIsNoData();
+    return block;
+  }
+
   if ( !mExtent.contains( extent ) )
   {
     QRect subRect = QgsRasterBlock::subRect( extent, width, height, mExtent );

tests/src/providers/testqgsgdalprovider.cpp

@@ -48,6 +48,7 @@ class TestQgsGdalProvider : public QObject
     void scaleDataType(); //test resultant data types for int raster with float scale (#11573)
     void warpedVrt(); //test loading raster which requires a warped vrt
     void noData();
+    void noDataOutsideExtent();
     void invalidNoDataInSourceIgnored();
     void isRepresentableValue();
     void mask();
@@ -151,6 +152,30 @@ void TestQgsGdalProvider::noData()
   delete provider;
 }
 
+void TestQgsGdalProvider::noDataOutsideExtent()
+{
+  QString raster = QStringLiteral( TEST_DATA_DIR ) + "/raster/band1_byte_ct_epsg4326.tif";
+  QgsDataProvider *provider = QgsProviderRegistry::instance()->createProvider( QStringLiteral( "gdal" ), raster, QgsDataProvider::ProviderOptions() );
+  QVERIFY( provider->isValid() );
+  QgsRasterDataProvider *rp = dynamic_cast< QgsRasterDataProvider * >( provider );
+  QVERIFY( rp );
+  if ( rp )
+  {
+    std::unique_ptr<QgsRasterBlock> block( rp->block( 1, QgsRectangle( 10, 10, 12, 12 ), 16, 16 ) );
+    QVERIFY( block );
+    QCOMPARE( block->width(), 16 );
+    QCOMPARE( block->height(), 16 );
+    for ( int y = 0; y < 16; ++y )
+    {
+      for ( int x = 0; x < 16; ++x )
+      {
+        QVERIFY( block->isNoData( y, x ) );
+      }
+    }
+  }
+  delete provider;
+}
+
 void TestQgsGdalProvider::invalidNoDataInSourceIgnored()
 {
   QString raster = QStringLiteral( TEST_DATA_DIR ) + "/raster/byte_with_nan_nodata.tif";