Fix loading 2.x projects with custom CRS

Fixes #17257

src/core/qgsproject.cpp

@@ -451,9 +451,6 @@ QgsCoordinateReferenceSystem QgsProject::crs() const
 void QgsProject::setCrs( const QgsCoordinateReferenceSystem &crs )
 {
   mCrs = crs;
-  writeEntry( QStringLiteral( "SpatialRefSys" ), QStringLiteral( "/ProjectCRSProj4String" ), crs.toProj4() );
-  writeEntry( QStringLiteral( "SpatialRefSys" ), QStringLiteral( "/ProjectCRSID" ), static_cast< int >( crs.srsid() ) );
-  writeEntry( QStringLiteral( "SpatialRefSys" ), QStringLiteral( "/ProjectCrs" ), crs.authid() );
   writeEntry( QStringLiteral( "SpatialRefSys" ), QStringLiteral( "/ProjectionsEnabled" ), crs.isValid() ? 1 : 0 );
   setDirty( true );
   emit crsChanged();
@@ -884,10 +881,31 @@ bool QgsProject::readProjectFile( const QString &filename )
   QgsCoordinateReferenceSystem projectCrs;
   if ( readNumEntry( QStringLiteral( "SpatialRefSys" ), QStringLiteral( "/ProjectionsEnabled" ), 0 ) )
   {
-    long currentCRS = readNumEntry( QStringLiteral( "SpatialRefSys" ), QStringLiteral( "/ProjectCRSID" ), -1 );
+    // first preference - dedicated projectCrs node
-    if ( currentCRS != -1 )
+    QDomNode srsNode = doc->documentElement().namedItem( QStringLiteral( "projectCrs" ) );
+    if ( !srsNode.isNull() )
     {
-      projectCrs = QgsCoordinateReferenceSystem::fromSrsId( currentCRS );
+      projectCrs.readXml( srsNode );
+    }
+
+    if ( !projectCrs.isValid() )
+    {
+      // else we try using the stored proj4 string - it's consistent across different QGIS installs,
+      // whereas the srsid can vary (e.g. for custom projections)
+      QString projCrsString = readEntry( QStringLiteral( "SpatialRefSys" ), QStringLiteral( "/ProjectCRSProj4String" ) );
+      if ( !projCrsString.isEmpty() )
+      {
+        projectCrs = QgsCoordinateReferenceSystem::fromProj4( projCrsString );
+      }
+      // last try using crs id - most fragile
+      if ( !projectCrs.isValid() )
+      {
+        long currentCRS = readNumEntry( QStringLiteral( "SpatialRefSys" ), QStringLiteral( "/ProjectCRSID" ), -1 );
+        if ( currentCRS != -1 && currentCRS < USER_CRS_START_ID )
+        {
+          projectCrs = QgsCoordinateReferenceSystem::fromSrsId( currentCRS );
+        }
+      }
     }
   }
   mCrs = projectCrs;
@@ -1340,6 +1358,11 @@ bool QgsProject::writeProjectFile( const QString &filename )
   QDomText titleText = doc->createTextNode( title() );  // XXX why have title TWICE?
   titleNode.appendChild( titleText );
 
+  // write project CRS
+  QDomElement srsNode = doc->createElement( QStringLiteral( "projectCrs" ) );
+  mCrs.writeXml( srsNode, *doc );
+  qgisNode.appendChild( srsNode );
+
   // write layer tree - make sure it is without embedded subgroups
   QgsLayerTreeNode *clonedRoot = mRootGroup->clone();
   QgsLayerTreeUtils::replaceChildrenOfEmbeddedGroups( QgsLayerTree::toGroup( clonedRoot ) );

tests/src/core/testqgscoordinatereferencesystem.cpp

@@ -15,13 +15,14 @@ Email                : sherman at mrcc dot com
 #include "qgstest.h"
 #include <QPixmap>
 
-#include <qgsapplication.h>
+#include "qgsapplication.h"
 #include "qgslogger.h"
 
 //header for class being tested
-#include <qgscoordinatereferencesystem.h>
+#include "qgscoordinatereferencesystem.h"
-#include <qgis.h>
+#include "qgis.h"
-#include <qgsvectorlayer.h>
+#include "qgsvectorlayer.h"
+#include "qgsproject.h"
 
 #include <proj_api.h>
 #include <gdal.h>
@@ -77,6 +78,7 @@ class TestQgsCoordinateReferenceSystem: public QObject
     void asVariant();
     void bounds();
     void saveAsUserCrs();
+    void projectWithCustomCrs();
 
   private:
     void debugPrint( QgsCoordinateReferenceSystem &crs );
@@ -834,5 +836,14 @@ void TestQgsCoordinateReferenceSystem::saveAsUserCrs()
   QCOMPARE( userCrs2.description(), QStringLiteral( "babies first projection" ) );
 }
 
+void TestQgsCoordinateReferenceSystem::projectWithCustomCrs()
+{
+  // tests loading a 2.x project with a custom CRS defined
+  QgsProject p;
+  QVERIFY( p.read( TEST_DATA_DIR + QStringLiteral( "/projects/custom_crs.qgs" ) ) );
+  QVERIFY( p.crs().isValid() );
+  QCOMPARE( p.crs().toProj4(), QStringLiteral( "+proj=ortho +lat_0=42.1 +lon_0=12.8 +x_0=0 +y_0=0 +a=6371000 +b=6371000 +units=m +no_defs" ) );
+}
+
 QGSTEST_MAIN( TestQgsCoordinateReferenceSystem )
 #include "testqgscoordinatereferencesystem.moc"

tests/testdata/projects/custom_crs.qgs

@@ -0,0 +1,129 @@
+<!DOCTYPE qgis PUBLIC 'http://mrcc.com/qgis.dtd' 'SYSTEM'>
+<qgis projectname="" version="2.18.9">
+  <title></title>
+  <autotransaction active="0"/>
+  <evaluateDefaultValues active="0"/>
+  <layer-tree-group expanded="1" checked="Qt::Checked" name="">
+    <customproperties/>
+  </layer-tree-group>
+  <relations/>
+  <mapcanvas>
+    <units>meters</units>
+    <extent>
+      <xmin>-1579730.21282207453623414</xmin>
+      <ymin>-4271174.32985332515090704</ymin>
+      <xmax>-1242009.40286419028416276</xmax>
+      <ymax>-4054770.71263487357646227</ymax>
+    </extent>
+    <rotation>0</rotation>
+    <projections>1</projections>
+    <destinationsrs>
+      <spatialrefsys>
+        <proj4>+proj=ortho +lat_0=42.1 +lon_0=12.8 +x_0=0 +y_0=0 +a=6371000 +b=6371000 +units=m +no_defs</proj4>
+        <srsid>100001</srsid>
+        <srid>0</srid>
+        <authid>USER:100001</authid>
+        <description>new CRS</description>
+        <projectionacronym>ortho</projectionacronym>
+        <ellipsoidacronym></ellipsoidacronym>
+        <geographicflag>false</geographicflag>
+      </spatialrefsys>
+    </destinationsrs>
+    <rendermaptile>0</rendermaptile>
+    <layer_coordinate_transform_info/>
+  </mapcanvas>
+  <layer-tree-canvas>
+    <custom-order enabled="0"/>
+  </layer-tree-canvas>
+  <legend updateDrawingOrder="true"/>
+  <projectlayers/>
+  <properties>
+    <WMSContactPerson type="QString"></WMSContactPerson>
+    <Variables>
+      <variableNames type="QStringList"/>
+      <variableValues type="QStringList"/>
+    </Variables>
+    <WMSOnlineResource type="QString"></WMSOnlineResource>
+    <WMSUseLayerIDs type="bool">false</WMSUseLayerIDs>
+    <WMSContactOrganization type="QString"></WMSContactOrganization>
+    <WMSKeywordList type="QStringList">
+      <value></value>
+    </WMSKeywordList>
+    <WFSUrl type="QString"></WFSUrl>
+    <Paths>
+      <Absolute type="bool">false</Absolute>
+    </Paths>
+    <WMSServiceTitle type="QString"></WMSServiceTitle>
+    <WFSLayers type="QStringList"/>
+    <WMSContactMail type="QString"></WMSContactMail>
+    <PositionPrecision>
+      <DecimalPlaces type="int">2</DecimalPlaces>
+      <Automatic type="bool">true</Automatic>
+      <DegreeFormat type="QString">MU</DegreeFormat>
+    </PositionPrecision>
+    <WCSUrl type="QString"></WCSUrl>
+    <WMSContactPhone type="QString"></WMSContactPhone>
+    <WMSServiceCapabilities type="bool">false</WMSServiceCapabilities>
+    <WMSServiceAbstract type="QString"></WMSServiceAbstract>
+    <WMSContactPosition type="QString"></WMSContactPosition>
+    <WMSAddWktGeometry type="bool">false</WMSAddWktGeometry>
+    <Measure>
+      <Ellipsoid type="QString">NONE</Ellipsoid>
+    </Measure>
+    <WMSPrecision type="QString">8</WMSPrecision>
+    <WMSSegmentizeFeatureInfoGeometry type="bool">false</WMSSegmentizeFeatureInfoGeometry>
+    <WFSTLayers>
+      <Insert type="QStringList"/>
+      <Update type="QStringList"/>
+      <Delete type="QStringList"/>
+    </WFSTLayers>
+    <Gui>
+      <SelectionColorBluePart type="int">0</SelectionColorBluePart>
+      <CanvasColorGreenPart type="int">255</CanvasColorGreenPart>
+      <CanvasColorRedPart type="int">255</CanvasColorRedPart>
+      <SelectionColorRedPart type="int">255</SelectionColorRedPart>
+      <SelectionColorAlphaPart type="int">255</SelectionColorAlphaPart>
+      <SelectionColorGreenPart type="int">255</SelectionColorGreenPart>
+      <CanvasColorBluePart type="int">255</CanvasColorBluePart>
+    </Gui>
+    <Digitizing>
+      <DefaultSnapToleranceUnit type="int">2</DefaultSnapToleranceUnit>
+      <SnappingMode type="QString">current_layer</SnappingMode>
+      <DefaultSnapType type="QString">off</DefaultSnapType>
+      <DefaultSnapTolerance type="double">0</DefaultSnapTolerance>
+    </Digitizing>
+    <Identify>
+      <disabledLayers type="QStringList"/>
+    </Identify>
+    <Macros>
+      <pythonCode type="QString"></pythonCode>
+    </Macros>
+    <WMSAccessConstraints type="QString">None</WMSAccessConstraints>
+    <WCSLayers type="QStringList"/>
+    <Legend>
+      <filterByMap type="bool">false</filterByMap>
+    </Legend>
+    <SpatialRefSys>
+      <ProjectCRSProj4String type="QString">+proj=ortho +lat_0=42.1 +lon_0=12.8 +x_0=0 +y_0=0 +a=6371000 +b=6371000 +units=m +no_defs</ProjectCRSProj4String>
+      <ProjectCrs type="QString">USER:100001</ProjectCrs>
+      <ProjectCRSID type="int">100001</ProjectCRSID>
+      <ProjectionsEnabled type="int">1</ProjectionsEnabled>
+    </SpatialRefSys>
+    <DefaultStyles>
+      <Fill type="QString"></Fill>
+      <Line type="QString"></Line>
+      <Marker type="QString"></Marker>
+      <RandomColors type="bool">true</RandomColors>
+      <AlphaInt type="int">255</AlphaInt>
+      <ColorRamp type="QString"></ColorRamp>
+    </DefaultStyles>
+    <WMSFees type="QString">conditions unknown</WMSFees>
+    <WMSImageQuality type="int">90</WMSImageQuality>
+    <Measurement>
+      <DistanceUnits type="QString">meters</DistanceUnits>
+      <AreaUnits type="QString">m2</AreaUnits>
+    </Measurement>
+    <WMSUrl type="QString"></WMSUrl>
+  </properties>
+  <visibility-presets/>
+</qgis>