Add method to get QgsLayerItem::LayerType from a map layer

python/core/auto_generated/qgsdataitem.sip.in

@@ -433,6 +433,13 @@ Item that represents a layer that can be opened with one of the providers
     QgsMapLayer::LayerType mapLayerType() const;
 %Docstring
 Returns QgsMapLayer.LayerType
+%End
+
+    static LayerType typeFromMapLayer( QgsMapLayer *layer );
+%Docstring
+Returns the layer item type corresponding to a :py:class:`QgsMapLayer` ``layer``.
+
+.. versionadded:: 3.6
 %End
 
     QString uri() const;

src/core/qgsdataitem.cpp

@@ -45,6 +45,7 @@
 #include "qgssettings.h"
 #include "qgsanimatedicon.h"
 #include "qgsproject.h"
+#include "qgsvectorlayer.h"
 
 // use GDAL VSI mechanism
 #define CPL_SUPRESS_CPLUSPLUS  //#spellok
@@ -636,6 +637,43 @@ QgsMapLayer::LayerType QgsLayerItem::mapLayerType() const
   return QgsMapLayer::VectorLayer; // no warnings
 }
 
+QgsLayerItem::LayerType QgsLayerItem::typeFromMapLayer( QgsMapLayer *layer )
+{
+  switch ( layer->type() )
+  {
+    case QgsMapLayer::VectorLayer:
+    {
+      switch ( qobject_cast< QgsVectorLayer * >( layer )->geometryType() )
+      {
+        case QgsWkbTypes::PointGeometry:
+          return Point;
+
+        case QgsWkbTypes::LineGeometry:
+          return Line;
+
+        case QgsWkbTypes::PolygonGeometry:
+          return Polygon;
+
+        case QgsWkbTypes::NullGeometry:
+          return TableLayer;
+
+        case QgsWkbTypes::UnknownGeometry:
+          return Vector;
+      }
+
+      return Vector; // no warnings
+    }
+
+    case QgsMapLayer::RasterLayer:
+      return Raster;
+    case QgsMapLayer::PluginLayer:
+      return Plugin;
+    case QgsMapLayer::MeshLayer:
+      return Mesh;
+  }
+  return Vector; // no warnings
+}
+
 QString QgsLayerItem::layerTypeAsString( QgsLayerItem::LayerType layerType )
 {
   static int enumIdx = staticMetaObject.indexOfEnumerator( "LayerType" );

src/core/qgsdataitem.h

@@ -463,6 +463,12 @@ class CORE_EXPORT QgsLayerItem : public QgsDataItem
     //! Returns QgsMapLayer::LayerType
     QgsMapLayer::LayerType mapLayerType() const;
 
+    /**
+     * Returns the layer item type corresponding to a QgsMapLayer \a layer.
+     * \since QGIS 3.6
+     */
+    static LayerType typeFromMapLayer( QgsMapLayer *layer );
+
     //! Returns layer uri or empty string if layer cannot be created
     QString uri() const { return mUri; }
 

tests/src/core/testqgsdataitem.cpp

@@ -21,6 +21,8 @@
 //qgis includes...
 #include "qgsdataitem.h"
 #include "qgsvectorlayer.h"
+#include "qgsrasterlayer.h"
+#include "qgsmeshlayer.h"
 #include "qgsapplication.h"
 #include "qgslogger.h"
 #include "qgssettings.h"
@@ -44,10 +46,12 @@ class TestQgsDataItem : public QObject
 
     void testValid();
     void testDirItemChildren();
+    void testLayerItemType();
 
   private:
     QgsDirectoryItem *mDirItem = nullptr;
     QString mScanItemsSetting;
+    QString mTestDataDir;
     bool isValidDirItem( QgsDirectoryItem *item );
 };
 
@@ -63,6 +67,9 @@ void TestQgsDataItem::initTestCase()
   QgsApplication::initQgis();
   QgsApplication::showSettings();
 
+  QString dataDir( TEST_DATA_DIR ); //defined in CmakeLists.txt
+  mTestDataDir = dataDir + '/';
+
   // Set up the QgsSettings environment
   QCoreApplication::setOrganizationName( QStringLiteral( "QGIS" ) );
   QCoreApplication::setOrganizationDomain( QStringLiteral( "qgis.org" ) );
@@ -176,5 +183,44 @@ void TestQgsDataItem::testDirItemChildren()
   }
 }
 
+void TestQgsDataItem::testLayerItemType()
+{
+  std::unique_ptr< QgsMapLayer > layer = qgis::make_unique< QgsVectorLayer >( mTestDataDir + "polys.shp",
+                                         QString(), QStringLiteral( "ogr" ) );
+  QVERIFY( layer->isValid() );
+  QCOMPARE( QgsLayerItem::typeFromMapLayer( layer.get() ), QgsLayerItem::Polygon );
+
+  layer = qgis::make_unique< QgsVectorLayer >( mTestDataDir + "points.shp",
+          QString(), QStringLiteral( "ogr" ) );
+  QVERIFY( layer->isValid() );
+  QCOMPARE( QgsLayerItem::typeFromMapLayer( layer.get() ), QgsLayerItem::Point );
+
+  layer = qgis::make_unique< QgsVectorLayer >( mTestDataDir + "lines.shp",
+          QString(), QStringLiteral( "ogr" ) );
+  QVERIFY( layer->isValid() );
+  QCOMPARE( QgsLayerItem::typeFromMapLayer( layer.get() ), QgsLayerItem::Line );
+
+  layer = qgis::make_unique< QgsVectorLayer >( mTestDataDir + "nonspatial.dbf",
+          QString(), QStringLiteral( "ogr" ) );
+  QVERIFY( layer->isValid() );
+  QCOMPARE( QgsLayerItem::typeFromMapLayer( layer.get() ), QgsLayerItem::TableLayer );
+
+  layer = qgis::make_unique< QgsVectorLayer >( mTestDataDir + "invalid.dbf",
+          QString(), QStringLiteral( "ogr" ) );
+  QCOMPARE( QgsLayerItem::typeFromMapLayer( layer.get() ), QgsLayerItem::Vector );
+
+  layer = qgis::make_unique< QgsRasterLayer >( mTestDataDir + "rgb256x256.png",
+          QString(), QStringLiteral( "gdal" ) );
+  QVERIFY( layer->isValid() );
+  QCOMPARE( QgsLayerItem::typeFromMapLayer( layer.get() ), QgsLayerItem::Raster );
+
+  layer = qgis::make_unique< QgsMeshLayer >( mTestDataDir + "mesh/quad_and_triangle.2dm",
+          QString(), QStringLiteral( "mdal" ) );
+  QVERIFY( layer->isValid() );
+  QCOMPARE( QgsLayerItem::typeFromMapLayer( layer.get() ), QgsLayerItem::Mesh );
+
+
+}
+
 QGSTEST_MAIN( TestQgsDataItem )
 #include "testqgsdataitem.moc"