Merge pull request #60212 from alexbruy/processing-zonal-histogram-pr…

…ecision show warning if float raster is used as input in zonal histogram algorithm (fix #30822)
qgis · Jan 23, 2025 · 836a197 · 836a197
2 parents 510ef31 + 69f7317
commit 836a197
Showing 1 changed file with 16 additions and 1 deletion.
diff --git a/src/analysis/processing/qgsalgorithmzonalhistogram.cpp b/src/analysis/processing/qgsalgorithmzonalhistogram.cpp
@@ -68,7 +68,7 @@ QgsZonalHistogramAlgorithm *QgsZonalHistogramAlgorithm::createInstance() const
   return new QgsZonalHistogramAlgorithm();
 }
 
-bool QgsZonalHistogramAlgorithm::prepareAlgorithm( const QVariantMap &parameters, QgsProcessingContext &context, QgsProcessingFeedback * )
+bool QgsZonalHistogramAlgorithm::prepareAlgorithm( const QVariantMap &parameters, QgsProcessingContext &context, QgsProcessingFeedback *feedback )
 {
   QgsRasterLayer *layer = parameterAsRasterLayer( parameters, QStringLiteral( "INPUT_RASTER" ), context );
   if ( !layer )
@@ -84,6 +84,21 @@ bool QgsZonalHistogramAlgorithm::prepareAlgorithm( const QVariantMap &parameters
   mCellSizeY = std::abs( layer->rasterUnitsPerPixelX() );
   mNbCellsXProvider = mRasterInterface->xSize();
   mNbCellsYProvider = mRasterInterface->ySize();
+  Qgis::DataType dataType = mRasterInterface->dataType( mRasterBand );
+
+  switch ( dataType )
+  {
+    case Qgis::DataType::Byte:
+    case Qgis::DataType::Int16:
+    case Qgis::DataType::UInt16:
+    case Qgis::DataType::Int32:
+    case Qgis::DataType::UInt32:
+      break;
+    default:
+      feedback->pushWarning( QObject::tr( "The input raster is a floating-point raster. Such rasters are not suitable for use with zonal histogram algorithm.\n"
+                                          "Please use Round raster or Reclassify by table tools to reduce number of decimal places or define histogram bins." ) );
+      break;
+  }
 
   return true;
 }