Fix loading of XYZ tile layer data item provider

src/core/qgsdataitemproviderregistry.cpp

@@ -21,6 +21,8 @@
 #include "qgslogger.h"
 #include "qgsproviderregistry.h"
 
+typedef QList<QgsDataItemProvider*> dataItemProviders_t();
+
 
 /**
  * \ingroup core
@@ -64,6 +66,17 @@ QgsDataItemProviderRegistry::QgsDataItemProviderRegistry()
     if ( !library )
       continue;
 
+    // new / better way of returning data items from providers
+
+    dataItemProviders_t* dataItemProvidersFn = reinterpret_cast< dataItemProviders_t * >( cast_to_fptr( library->resolve( "dataItemProviders" ) ) );
+    if ( dataItemProvidersFn )
+    {
+      // the function is a factory - we keep ownership of the returned providers
+      mProviders << dataItemProvidersFn();
+    }
+
+    // legacy support - using dataItem() and dataCapabilities() methods
+
     dataCapabilities_t * dataCapabilities = reinterpret_cast< dataCapabilities_t * >( cast_to_fptr( library->resolve( "dataCapabilities" ) ) );
     if ( !dataCapabilities )
     {

src/providers/wms/qgswmsdataitems.cpp

@@ -420,23 +420,15 @@ void QgsWMSRootItem::newConnection()
 QGISEXTERN void registerGui( QMainWindow *mainWindow )
 {
   QgsTileScaleWidget::showTileScale( mainWindow );
-
-  // with dataItem(...) at provider level we can only have one root item,
-  // so we have a data item provider for XYZ tile layers
-  QgsDataItemProviderRegistry::instance()->addProvider( new QgsXyzTileDataItemProvider );
 }
 
 QGISEXTERN QgsWMSSourceSelect * selectWidget( QWidget * parent, Qt::WindowFlags fl )
 {
   return new QgsWMSSourceSelect( parent, fl );
 }
 
-QGISEXTERN int dataCapabilities()
-{
-  return  QgsDataProvider::Net;
-}
 
-QGISEXTERN QgsDataItem * dataItem( QString thePath, QgsDataItem* parentItem )
+QgsDataItem* QgsWmsDataItemProvider::createDataItem( const QString& thePath, QgsDataItem *parentItem )
 {
   QgsDebugMsg( "thePath = " + thePath );
   if ( thePath.isEmpty() )
@@ -458,6 +450,12 @@ QGISEXTERN QgsDataItem * dataItem( QString thePath, QgsDataItem* parentItem )
   return nullptr;
 }
 
+QGISEXTERN QList<QgsDataItemProvider*> dataItemProviders()
+{
+  return QList<QgsDataItemProvider*>()
+         << new QgsWmsDataItemProvider
+         << new QgsXyzTileDataItemProvider;
+}
 
 // ---------------------------------------------------------------------------
 

src/providers/wms/qgswmsdataitems.h

@@ -106,6 +106,19 @@ class QgsWMSRootItem : public QgsDataCollectionItem
     void newConnection();
 };
 
+
+//! Provider for WMS root data item
+class QgsWmsDataItemProvider : public QgsDataItemProvider
+{
+  public:
+    virtual QString name() override { return "WMS"; }
+
+    virtual int capabilities() override { return QgsDataProvider::Net; }
+
+    virtual QgsDataItem* createDataItem( const QString& path, QgsDataItem* parentItem ) override;
+};
+
+
 //! Root item for XYZ tile layers
 class QgsXyzTileRootItem : public QgsDataCollectionItem
 {