Also add variant which takes a list of layers

python/PyQt6/core/auto_generated/qgselevationutils.sip.in

@@ -37,6 +37,15 @@ the values from layers contained by the project.
 
 These values will be highlighted in elevation related widgets for the project.
 
+.. versionadded:: 3.38
+%End
+
+    static QList< double > significantZValuesForLayers( const QList< QgsMapLayer * > &layers );
+%Docstring
+Returns a list of significant elevation/z-values for the specified ``layers``.
+
+These values will be highlighted in elevation related widgets for the project.
+
 .. versionadded:: 3.38
 %End
 

python/core/auto_generated/qgselevationutils.sip.in

@@ -37,6 +37,15 @@ the values from layers contained by the project.
 
 These values will be highlighted in elevation related widgets for the project.
 
+.. versionadded:: 3.38
+%End
+
+    static QList< double > significantZValuesForLayers( const QList< QgsMapLayer * > &layers );
+%Docstring
+Returns a list of significant elevation/z-values for the specified ``layers``.
+
+These values will be highlighted in elevation related widgets for the project.
+
 .. versionadded:: 3.38
 %End
 

src/core/qgselevationutils.cpp

@@ -57,13 +57,22 @@ QgsDoubleRange QgsElevationUtils::calculateZRangeForProject( QgsProject *project
 QList<double> QgsElevationUtils::significantZValuesForProject( QgsProject *project )
 {
   const QMap<QString, QgsMapLayer *> &mapLayers = project->mapLayers();
-  QSet< double > values;
+  QList< QgsMapLayer * > layers;
-
-  QgsMapLayer *currentLayer = nullptr;
   for ( QMap<QString, QgsMapLayer *>::const_iterator it = mapLayers.constBegin(); it != mapLayers.constEnd(); ++it )
   {
-    currentLayer = it.value();
+    if ( it.value() )
+      layers << it.value();
+  }
 
+  return significantZValuesForLayers( layers );
+}
+
+QList<double> QgsElevationUtils::significantZValuesForLayers( const QList<QgsMapLayer *> &layers )
+{
+  QSet< double > values;
+
+  for ( QgsMapLayer *currentLayer  : layers )
+  {
     if ( !currentLayer->elevationProperties() || !currentLayer->elevationProperties()->hasElevation() )
       continue;
 

src/core/qgselevationutils.h

@@ -51,6 +51,15 @@ class CORE_EXPORT QgsElevationUtils
      */
     static QList< double > significantZValuesForProject( QgsProject *project );
 
+    /**
+     * Returns a list of significant elevation/z-values for the specified \a layers.
+     *
+     * These values will be highlighted in elevation related widgets for the project.
+     *
+     * \since QGIS 3.38
+     */
+    static QList< double > significantZValuesForLayers( const QList< QgsMapLayer * > &layers );
+
     /**
      * Returns TRUE if elevation can be enabled for a map \a layer.
      *

tests/src/python/test_qgselevationutils.py

@@ -78,12 +78,16 @@ class TestQgsElevationUtils(QgisTestCase):
         project = QgsProject()
         self.assertFalse(
             QgsElevationUtils.significantZValuesForProject(project))
+        self.assertFalse(
+            QgsElevationUtils.significantZValuesForLayers([]))
 
         raster_layer = QgsRasterLayer(os.path.join(unitTestDataPath(), 'landsat_4326.tif'))
         self.assertTrue(raster_layer.isValid())
         project.addMapLayer(raster_layer)
         self.assertFalse(
             QgsElevationUtils.significantZValuesForProject(project))
+        self.assertFalse(
+            QgsElevationUtils.significantZValuesForLayers([raster_layer]))
 
         props = raster_layer.elevationProperties()
         props.setEnabled(True)
@@ -94,6 +98,9 @@ class TestQgsElevationUtils(QgisTestCase):
         self.assertEqual(
             QgsElevationUtils.significantZValuesForProject(project),
             [103.1, 106.8, 116.8, 126.8])
+        self.assertEqual(
+            QgsElevationUtils.significantZValuesForLayers([raster_layer]),
+            [103.1, 106.8, 116.8, 126.8])
 
         raster_layer2 = QgsRasterLayer(os.path.join(unitTestDataPath(), 'landsat_4326.tif'))
         self.assertTrue(raster_layer2.isValid())
@@ -101,6 +108,10 @@ class TestQgsElevationUtils(QgisTestCase):
         self.assertEqual(
             QgsElevationUtils.significantZValuesForProject(project),
             [103.1, 106.8, 116.8, 126.8])
+        self.assertEqual(
+            QgsElevationUtils.significantZValuesForLayers([raster_layer,
+                                                           raster_layer2]),
+            [103.1, 106.8, 116.8, 126.8])
 
         props = raster_layer2.elevationProperties()
         props.setEnabled(True)
@@ -111,6 +122,10 @@ class TestQgsElevationUtils(QgisTestCase):
         self.assertEqual(
             QgsElevationUtils.significantZValuesForProject(project),
             [103.1, 106.8, 116.8, 126.8, 136.8])
+        self.assertEqual(
+            QgsElevationUtils.significantZValuesForLayers([raster_layer,
+                                                           raster_layer2]),
+            [103.1, 106.8, 116.8, 126.8, 136.8])
 
 
 if __name__ == '__main__':