Add "mainAnnotationLayer" to QgsProject

This returns a reference to a main/default annotation layer for use by the project. It forms the default location to place new annotation items which should appear above all map layers.
qgis · Sep 1, 2020 · 39fbc2a · 39fbc2a
1 parent aefd777
commit 39fbc2a
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diff --git a/python/core/auto_generated/qgsproject.sip.in b/python/core/auto_generated/qgsproject.sip.in
@@ -13,6 +13,7 @@
 
 
 
+
 class QgsProject : QObject, QgsExpressionContextGenerator, QgsExpressionContextScopeGenerator, QgsProjectTranslator
 {
 %Docstring
@@ -1077,6 +1078,19 @@ the layer and is responsible for deleting it.
 .. seealso:: :py:func:`removeMapLayer`
 
 .. versionadded:: 3.0
+%End
+
+    QgsAnnotationLayer *mainAnnotationLayer();
+%Docstring
+Returns the main annotation layer associated with the project.
+
+This layer is always present in projects, and will always be rendered
+above any other map layers during map render jobs.
+
+It forms the default location to place new annotation items which
+should appear above all map layers.
+
+.. versionadded:: 3.16
 %End
 
     void removeAllMapLayers();

diff --git a/src/core/qgsproject.cpp b/src/core/qgsproject.cpp
@@ -433,6 +433,8 @@ QgsProject::QgsProject( QObject *parent )
   Q_NOWARN_DEPRECATED_PUSH
   connect( mViewSettings, &QgsProjectViewSettings::mapScalesChanged, this, &QgsProject::mapScalesChanged );
   Q_NOWARN_DEPRECATED_POP
+
+  mMainAnnotationLayer = new QgsAnnotationLayer( QObject::tr( "Annotations" ), QgsAnnotationLayer::LayerOptions( mTransformContext ) );
 }
 
 
@@ -761,6 +763,7 @@ void QgsProject::setTransformContext( const QgsCoordinateTransformContext &conte
   mTransformContext = context;
   mProjectScope.reset();
 
+  mMainAnnotationLayer->setTransformContext( context );
   for ( auto &layer : mLayerStore.get()->mapLayers() )
   {
     layer->setTransformContext( context );
@@ -850,6 +853,8 @@ void QgsProject::clear()
 
   removeAllMapLayers();
   mRootGroup->clear();
+  if ( mMainAnnotationLayer )
+    mMainAnnotationLayer->reset();
 
   setDirty( false );
   emit homePathChanged();
@@ -1543,6 +1548,9 @@ bool QgsProject::readProjectFile( const QString &filename, QgsProject::ReadFlags
     mBadLayerHandler->handleBadLayers( brokenNodes );
   }
 
+  mMainAnnotationLayer->readLayerXml( doc->documentElement().firstChildElement( QStringLiteral( "main-annotation-layer" ) ), context );
+  mMainAnnotationLayer->setTransformContext( mTransformContext );
+
   // Resolve references to other layers
   // Needs to be done here once all dependent layers are loaded
   profile.switchTask( tr( "Resolving layer references" ) );
@@ -2210,6 +2218,10 @@ bool QgsProject::writeProjectFile( const QString &filename )
   // within top level node save list of layers
   const QMap<QString, QgsMapLayer *> &layers = mapLayers();
 
+  QDomElement annotationLayerNode = doc->createElement( QStringLiteral( "main-annotation-layer" ) );
+  mMainAnnotationLayer->writeLayerXml( annotationLayerNode, *doc, context );
+  qgisNode.appendChild( annotationLayerNode );
+
   // Iterate over layers in zOrder
   // Call writeXml() on each
   QDomElement projectLayersNode = doc->createElement( QStringLiteral( "projectlayers" ) );
@@ -3378,6 +3390,11 @@ QgsMapLayer *QgsProject::takeMapLayer( QgsMapLayer *layer )
   return mLayerStore->takeMapLayer( layer );
 }
 
+QgsAnnotationLayer *QgsProject::mainAnnotationLayer()
+{
+  return mMainAnnotationLayer;
+}
+
 void QgsProject::removeAllMapLayers()
 {
   mProjectScope.reset();

diff --git a/src/core/qgsproject.h b/src/core/qgsproject.h
@@ -75,6 +75,8 @@ class QgsBookmarkManager;
 class QgsProjectViewSettings;
 class QgsProjectDisplaySettings;
 class QgsProjectTimeSettings;
+class QgsAnnotationLayer;
+
 
 /**
  * \ingroup core
@@ -1154,6 +1156,19 @@ class CORE_EXPORT QgsProject : public QObject, public QgsExpressionContextGenera
      */
     QgsMapLayer *takeMapLayer( QgsMapLayer *layer ) SIP_TRANSFERBACK;
 
+    /**
+     * Returns the main annotation layer associated with the project.
+     *
+     * This layer is always present in projects, and will always be rendered
+     * above any other map layers during map render jobs.
+     *
+     * It forms the default location to place new annotation items which
+     * should appear above all map layers.
+     *
+     * \since QGIS 3.16
+     */
+    QgsAnnotationLayer *mainAnnotationLayer();
+
     /**
      * Removes all registered layers. If the registry has ownership
      * of any layers these layers will also be deleted.
@@ -1927,6 +1942,8 @@ class CORE_EXPORT QgsProject : public QObject, public QgsExpressionContextGenera
 
     QgsLayerTreeRegistryBridge *mLayerTreeRegistryBridge = nullptr;
 
+    QgsAnnotationLayer *mMainAnnotationLayer = nullptr;
+
     //! map of transaction group: QPair( providerKey, connString ) -> transactionGroup
     QMap< QPair< QString, QString>, QgsTransactionGroup *> mTransactionGroups;
 

diff --git a/tests/src/python/test_qgsannotationlayer.py b/tests/src/python/test_qgsannotationlayer.py
@@ -13,7 +13,8 @@
 import qgis  # NOQA
 
 from qgis.PyQt.QtCore import (QSize,
-                              QDir)
+                              QDir,
+                              QTemporaryDir)
 from qgis.PyQt.QtGui import (QImage,
                              QPainter,
                              QColor)
@@ -33,9 +34,8 @@
                        QgsAnnotationLayer,
                        QgsAnnotationLineItem,
                        QgsAnnotationMarkerItem,
-                       QgsPointXY,
                        QgsLineSymbol,
-                       QgsMarkerSymbol
+                       QgsMarkerSymbol,
                        )
 from qgis.PyQt.QtXml import QDomDocument
 
@@ -171,6 +171,32 @@ def testClone(self):
         self.assertIsInstance(layer2.items()[linestring_item_id], QgsAnnotationLineItem)
         self.assertIsInstance(layer2.items()[marker_item_id], QgsAnnotationMarkerItem)
 
+    def testProjectMainAnnotationLayer(self):
+        p = QgsProject()
+        self.assertIsNotNone(p.mainAnnotationLayer())
+
+        # add some items to project annotation layer
+        polygon_item_id = p.mainAnnotationLayer().addItem(QgsAnnotationPolygonItem(QgsPolygon(QgsLineString([QgsPoint(12, 13), QgsPoint(14, 13), QgsPoint(14, 15), QgsPoint(12, 13)]))))
+        linestring_item_id = p.mainAnnotationLayer().addItem(QgsAnnotationLineItem(QgsLineString([QgsPoint(11, 13), QgsPoint(12, 13), QgsPoint(12, 15)])))
+        marker_item_id = p.mainAnnotationLayer().addItem(QgsAnnotationMarkerItem(QgsPoint(12, 13)))
+
+        # save project to xml
+        tmpDir = QTemporaryDir()
+        tmpFile = "{}/project.qgs".format(tmpDir.path())
+        self.assertTrue(p.write(tmpFile))
+
+        # test that annotation layer is cleared with project
+        p.clear()
+        self.assertEqual(len(p.mainAnnotationLayer().items()), 0)
+
+        # check that main annotation layer is restored on project read
+        p2 = QgsProject()
+        self.assertTrue(p2.read(tmpFile))
+        self.assertEqual(len(p2.mainAnnotationLayer().items()), 3)
+        self.assertIsInstance(p2.mainAnnotationLayer().items()[polygon_item_id], QgsAnnotationPolygonItem)
+        self.assertIsInstance(p2.mainAnnotationLayer().items()[linestring_item_id], QgsAnnotationLineItem)
+        self.assertIsInstance(p2.mainAnnotationLayer().items()[marker_item_id], QgsAnnotationMarkerItem)
+
     def testRenderLayer(self):
         layer = QgsAnnotationLayer('test', QgsAnnotationLayer.LayerOptions(QgsProject.instance().transformContext()))
         layer.setCrs(QgsCoordinateReferenceSystem('EPSG:4326'))