From 41fa197db166d8c20f69ddac77d99c24971929c1 Mon Sep 17 00:00:00 2001
From: Alessandro Pasotti <elpaso@itopen.it>
Date: Tue, 6 May 2025 12:08:38 +0200
Subject: [PATCH 1/2] [bug] lazy vector extent not stored in the project

Fix #61181

When lazily set, if the project was stored without any
call to QgsVectorLayer::extent() the QgsMapLayer::mExtent2D
was null and not stored in the project.
---
 src/core/qgsmaplayer.cpp            | 11 +++++++--
 tests/src/python/test_qgsproject.py | 38 +++++++++++++++++++++++++++++
 2 files changed, 47 insertions(+), 2 deletions(-)

diff --git a/src/core/qgsmaplayer.cpp b/src/core/qgsmaplayer.cpp
index 93aa8bbe044..c763f2d4c9c 100644
--- a/src/core/qgsmaplayer.cpp
+++ b/src/core/qgsmaplayer.cpp
@@ -755,8 +755,15 @@ bool QgsMapLayer::writeLayerXml( QDomElement &layerElement, QDomDocument &docume
 
   if ( !mExtent3D.isNull() && dataProvider() && dataProvider()->elevationProperties() && dataProvider()->elevationProperties()->containsElevationData() )
     layerElement.appendChild( QgsXmlUtils::writeBox3D( mExtent3D, document ) );
-  else if ( !mExtent2D.isNull() )
-    layerElement.appendChild( QgsXmlUtils::writeRectangle( mExtent2D, document ) );
+  else
+  {
+    // Extent might be null because lazily set
+    const QgsRectangle extent2D { mExtent2D.isNull() ? extent() : mExtent2D };
+    if ( !extent2D.isNull() )
+    {
+      layerElement.appendChild( QgsXmlUtils::writeRectangle( mExtent2D, document ) );
+    }
+  }
 
   if ( const QgsRectangle lWgs84Extent = wgs84Extent( true ); !lWgs84Extent.isNull() )
   {
diff --git a/tests/src/python/test_qgsproject.py b/tests/src/python/test_qgsproject.py
index f2e4d725e4b..6473ea191f6 100644
--- a/tests/src/python/test_qgsproject.py
+++ b/tests/src/python/test_qgsproject.py
@@ -17,6 +17,7 @@ from io import BytesIO
 from shutil import copyfile
 from tempfile import TemporaryDirectory
 from zipfile import ZipFile
+from lxml import etree as et
 
 from osgeo import ogr
 from qgis.PyQt import sip
@@ -2119,6 +2120,43 @@ class TestQgsProject(QgisTestCase):
 
         del project
 
+    def testVectorExtentIsStored(self):
+        """
+        Test that vector layer extent is stored in the project
+        Test for GH #61181
+        """
+
+        tmpDir = QTemporaryDir()
+        tmpFile = f"{tmpDir.path()}/project.qgs"
+        for ext in ["shp", "shx", "dbf"]:
+            copyfile(
+                os.path.join(TEST_DATA_DIR, "points." + ext),
+                os.path.join(tmpDir.path(), "points." + ext),
+            )
+
+        project = QgsProject()
+
+        l0 = QgsVectorLayer(os.path.join(tmpDir.path(), "points.shp"), "points", "ogr")
+        #l0.extent()
+        self.assertTrue(l0.isValid())
+        self.assertTrue(project.addMapLayers([l0]))
+        self.assertTrue(project.write(tmpFile))
+
+        del project
+
+        # Read the project.qgs as XML using etree and check that the maplayer extent is in the XML file
+        with open(tmpFile, "r") as f:
+            xml = f.read()
+            root = et.XML(xml)
+            layerXML = root.findall('.//projectlayers/maplayer')[0]
+            extentXML = layerXML.findall('.//extent')[0]
+            self.assertNotEqual(len(extentXML.getchildren()), 0)
+
+
+
+
+
+
 
 if __name__ == "__main__":
     unittest.main()

From 6c0215fa1198814f6edb9eb34c608bd9a17310ed Mon Sep 17 00:00:00 2001
From: Alessandro Pasotti <elpaso@itopen.it>
Date: Wed, 7 May 2025 07:55:09 +0200
Subject: [PATCH 2/2] Update src/core/qgsmaplayer.cpp

Co-authored-by: Even Rouault <even.rouault@spatialys.com>
---
 src/core/qgsmaplayer.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/core/qgsmaplayer.cpp b/src/core/qgsmaplayer.cpp
index c763f2d4c9c..0f233ba63b6 100644
--- a/src/core/qgsmaplayer.cpp
+++ b/src/core/qgsmaplayer.cpp
@@ -761,7 +761,7 @@ bool QgsMapLayer::writeLayerXml( QDomElement &layerElement, QDomDocument &docume
     const QgsRectangle extent2D { mExtent2D.isNull() ? extent() : mExtent2D };
     if ( !extent2D.isNull() )
     {
-      layerElement.appendChild( QgsXmlUtils::writeRectangle( mExtent2D, document ) );
+      layerElement.appendChild( QgsXmlUtils::writeRectangle( extent2D, document ) );
     }
   }