[needs-docs] Don't restrict project ellipsoid choice when

canvas OTF reprojection is disabled

These two settings aren't necessarily related - you may want
to disable OTF canvas reprojection while still wanting accurate
distance/area measurements using an ellipsoid.

This change should make distance/area calculation in QGIS more
reliable and predictable for users. Calculations are now
based entirely on the ellipsoid choice in project properties, so
it only takes checking a single setting to verify how
measurements are calculated.

Author: nyalldawson

src/app/qgisapp.cpp

@@ -7513,7 +7513,7 @@ void QgisApp::selectByForm()
   QgsDistanceArea myDa;
 
   myDa.setSourceCrs( vlayer->crs().srsid() );
-  myDa.setEllipsoidalMode( mMapCanvas->mapSettings().hasCrsTransformEnabled() );
+  myDa.setEllipsoidalMode( true );
   myDa.setEllipsoid( QgsProject::instance()->ellipsoid() );
 
   QgsAttributeEditorContext context;

src/app/qgisappinterface.cpp

@@ -699,7 +699,7 @@ QgsAttributeDialog* QgisAppInterface::getFeatureForm( QgsVectorLayer *l, QgsFeat
   QgsDistanceArea myDa;
 
   myDa.setSourceCrs( l->crs().srsid() );
-  myDa.setEllipsoidalMode( QgisApp::instance()->mapCanvas()->mapSettings().hasCrsTransformEnabled() );
+  myDa.setEllipsoidalMode( true );
   myDa.setEllipsoid( QgsProject::instance()->ellipsoid() );
 
   QgsAttributeEditorContext context;

src/app/qgsattributeactionpropertiesdialog.cpp

@@ -200,7 +200,7 @@ void QgsAttributeActionPropertiesDialog::init( const QSet<QString>& actionScopes
 
   QgsDistanceArea myDa;
   myDa.setSourceCrs( mLayer->crs().srsid() );
-  myDa.setEllipsoidalMode( QgisApp::instance()->mapCanvas()->mapSettings().hasCrsTransformEnabled() );
+  myDa.setEllipsoidalMode( true );
   myDa.setEllipsoid( QgsProject::instance()->ellipsoid() );
 
   mFieldExpression->setLayer( mLayer );

src/app/qgsattributetabledialog.cpp

@@ -126,7 +126,7 @@ QgsAttributeTableDialog::QgsAttributeTableDialog( QgsVectorLayer *theLayer, QWid
   myDa = new QgsDistanceArea();
 
   myDa->setSourceCrs( mLayer->crs() );
-  myDa->setEllipsoidalMode( QgisApp::instance()->mapCanvas()->mapSettings().hasCrsTransformEnabled() );
+  myDa->setEllipsoidalMode( true );
   myDa->setEllipsoid( QgsProject::instance()->ellipsoid() );
 
   mEditorContext.setDistanceArea( *myDa );
@@ -587,7 +587,7 @@ void QgsAttributeTableDialog::filterExpressionBuilder()
 
   QgsDistanceArea myDa;
   myDa.setSourceCrs( mLayer->crs().srsid() );
-  myDa.setEllipsoidalMode( QgisApp::instance()->mapCanvas()->mapSettings().hasCrsTransformEnabled() );
+  myDa.setEllipsoidalMode( true );
   myDa.setEllipsoid( QgsProject::instance()->ellipsoid() );
   dlg.setGeomCalculator( myDa );
 
@@ -948,7 +948,7 @@ void QgsAttributeTableDialog::setFilterExpression( const QString& filterString,
   QgsDistanceArea myDa;
 
   myDa.setSourceCrs( mLayer->crs().srsid() );
-  myDa.setEllipsoidalMode( QgisApp::instance()->mapCanvas()->mapSettings().hasCrsTransformEnabled() );
+  myDa.setEllipsoidalMode( true );
   myDa.setEllipsoid( QgsProject::instance()->ellipsoid() );
 
   // parse search string and build parsed tree

src/app/qgsdiagramproperties.cpp

@@ -177,7 +177,7 @@ QgsDiagramProperties::QgsDiagramProperties( QgsVectorLayer* layer, QWidget* pare
   mSizeFieldExpressionWidget->setLayer( mLayer );
   QgsDistanceArea myDa;
   myDa.setSourceCrs( mLayer->crs().srsid() );
-  myDa.setEllipsoidalMode( mMapCanvas->mapSettings().hasCrsTransformEnabled() );
+  myDa.setEllipsoidalMode( true );
   myDa.setEllipsoid( QgsProject::instance()->ellipsoid() );
   mSizeFieldExpressionWidget->setGeomCalculator( myDa );
 
@@ -869,7 +869,7 @@ QString QgsDiagramProperties::showExpressionBuilder( const QString& initialExpre
 
   QgsDistanceArea myDa;
   myDa.setSourceCrs( mLayer->crs().srsid() );
-  myDa.setEllipsoidalMode( mMapCanvas->mapSettings().hasCrsTransformEnabled() );
+  myDa.setEllipsoidalMode( true );
   myDa.setEllipsoid( QgsProject::instance()->ellipsoid() );
   dlg.setGeomCalculator( myDa );
 

src/app/qgsfeatureaction.cpp

@@ -57,7 +57,7 @@ QgsAttributeDialog *QgsFeatureAction::newDialog( bool cloneFeature )
   QgsDistanceArea myDa;
 
   myDa.setSourceCrs( mLayer->crs() );
-  myDa.setEllipsoidalMode( QgisApp::instance()->mapCanvas()->mapSettings().hasCrsTransformEnabled() );
+  myDa.setEllipsoidalMode( true );
   myDa.setEllipsoid( QgsProject::instance()->ellipsoid() );
 
   context.setDistanceArea( myDa );

src/app/qgsfieldcalculator.cpp

@@ -56,7 +56,7 @@ QgsFieldCalculator::QgsFieldCalculator( QgsVectorLayer* vl, QWidget* parent )
 
   QgsDistanceArea myDa;
   myDa.setSourceCrs( vl->crs().srsid() );
-  myDa.setEllipsoidalMode( QgisApp::instance()->mapCanvas()->mapSettings().hasCrsTransformEnabled() );
+  myDa.setEllipsoidalMode( true );
   myDa.setEllipsoid( QgsProject::instance()->ellipsoid() );
   builder->setGeomCalculator( myDa );
 
@@ -156,7 +156,7 @@ void QgsFieldCalculator::accept()
   QgsDistanceArea myDa;
 
   myDa.setSourceCrs( mVectorLayer->crs().srsid() );
-  myDa.setEllipsoidalMode( QgisApp::instance()->mapCanvas()->mapSettings().hasCrsTransformEnabled() );
+  myDa.setEllipsoidalMode( true );
   myDa.setEllipsoid( QgsProject::instance()->ellipsoid() );
 
   QString calcString = builder->expressionText();

src/app/qgslabelinggui.cpp

@@ -94,7 +94,7 @@ void QgsLabelingGui::setLayer( QgsMapLayer* mapLayer )
   mFieldExpressionWidget->setLayer( mLayer );
   QgsDistanceArea da;
   da.setSourceCrs( mLayer->crs().srsid() );
-  da.setEllipsoidalMode( QgisApp::instance()->mapCanvas()->mapSettings().hasCrsTransformEnabled() );
+  da.setEllipsoidalMode( true );
   da.setEllipsoid( QgsProject::instance()->ellipsoid() );
   mFieldExpressionWidget->setGeomCalculator( da );
 

src/app/qgsmaptoolmeasureangle.cpp

@@ -184,6 +184,5 @@ void QgsMapToolMeasureAngle::configureDistanceArea()
   QString ellipsoidId = QgsProject::instance()->ellipsoid();
   mDa.setSourceCrs( mCanvas->mapSettings().destinationCrs().srsid() );
   mDa.setEllipsoid( ellipsoidId );
-  // Only use ellipsoidal calculation when project wide transformation is enabled.
-  mDa.setEllipsoidalMode( mCanvas->mapSettings().hasCrsTransformEnabled() );
+  mDa.setEllipsoidalMode( true );
 }

src/app/qgsmeasuredialog.cpp

@@ -80,15 +80,7 @@ void QgsMeasureDialog::updateSettings()
   mAreaUnits = QgsProject::instance()->areaUnits();
   mDa.setSourceCrs( mTool->canvas()->mapSettings().destinationCrs().srsid() );
   mDa.setEllipsoid( QgsProject::instance()->ellipsoid() );
-  // Only use ellipsoidal calculation when project wide transformation is enabled.
-  if ( mTool->canvas()->mapSettings().hasCrsTransformEnabled() )
-  {
-    mDa.setEllipsoidalMode( true );
-  }
-  else
-  {
-    mDa.setEllipsoidalMode( false );
-  }
+  mDa.setEllipsoidalMode( true );
 
   QgsDebugMsg( "****************" );
   QgsDebugMsg( QString( "Ellipsoid ID : %1" ).arg( mDa.ellipsoid() ) );
@@ -301,33 +293,21 @@ void QgsMeasureDialog::updateUi()
     else
     {
       QgsUnitTypes::AreaUnit resultUnit = QgsUnitTypes::AreaUnknownUnit;
-      if ( ! mTool->canvas()->hasCrsTransformEnabled() )
+      if ( mDa.willUseEllipsoid() )
       {
-        resultUnit = QgsUnitTypes::distanceToAreaUnit( mTool->canvas()->mapSettings().destinationCrs().mapUnits() );
-        toolTip += "<br> * " + tr( "Project CRS transformation is turned off." ) + ' ';
-        toolTip += tr( "Area is calculated in %1, based on project CRS (%2)." ).arg( QgsUnitTypes::toString( resultUnit ),
-                   mTool->canvas()->mapSettings().destinationCrs().description() );
-        toolTip += "<br> * " + tr( "Ellipsoidal calculation is not possible with CRS transformation disabled." );
-        setWindowTitle( tr( "Measure (OTF off)" ) );
+        resultUnit = QgsUnitTypes::AreaSquareMeters;
+        toolTip += "<br> * " + tr( "Project ellipsoidal calculation is selected." ) + ' ';
+        toolTip += "<br> * " + tr( "The coordinates are transformed to the chosen ellipsoid (%1), and the area is calculated in %2." ).arg( mDa.ellipsoid(),
+                   QgsUnitTypes::toString( resultUnit ) );
       }
       else
       {
-        if ( mDa.willUseEllipsoid() )
-        {
-          resultUnit = QgsUnitTypes::AreaSquareMeters;
-          toolTip += "<br> * " + tr( "Project CRS transformation is turned on and ellipsoidal calculation is selected." ) + ' ';
-          toolTip += "<br> * " + tr( "The coordinates are transformed to the chosen ellipsoid (%1), and the area is calculated in %2." ).arg( mDa.ellipsoid(),
-                     QgsUnitTypes::toString( resultUnit ) );
-        }
-        else
-        {
-          resultUnit = QgsUnitTypes::distanceToAreaUnit( mTool->canvas()->mapSettings().destinationCrs().mapUnits() );
-          toolTip += "<br> * " + tr( "Project CRS transformation is turned on but ellipsoidal calculation is not selected." ) + ' ';
-          toolTip += tr( "Area is calculated in %1, based on project CRS (%2)." ).arg( QgsUnitTypes::toString( resultUnit ),
-                     mTool->canvas()->mapSettings().destinationCrs().description() );
-        }
-        setWindowTitle( tr( "Measure (OTF on)" ) );
+        resultUnit = QgsUnitTypes::distanceToAreaUnit( mTool->canvas()->mapSettings().destinationCrs().mapUnits() );
+        toolTip += "<br> * " + tr( "Project ellipsoidal calculation is not selected." ) + ' ';
+        toolTip += tr( "Area is calculated in %1, based on project CRS (%2)." ).arg( QgsUnitTypes::toString( resultUnit ),
+                   mTool->canvas()->mapSettings().destinationCrs().description() );
       }
+      setWindowTitle( tr( "Measure (OTF on)" ) );
 
       if ( QgsUnitTypes::unitType( resultUnit ) == QgsUnitTypes::Geographic &&
            QgsUnitTypes::unitType( mAreaUnits ) == QgsUnitTypes::Standard )
@@ -375,33 +355,21 @@ void QgsMeasureDialog::updateUi()
     else
     {
       QgsUnitTypes::DistanceUnit resultUnit = QgsUnitTypes::DistanceUnknownUnit;
-      if ( ! mTool->canvas()->hasCrsTransformEnabled() )
+      if ( mDa.willUseEllipsoid() )
       {
-        resultUnit =  mTool->canvas()->mapSettings().destinationCrs().mapUnits();
-        toolTip += "<br> * " + tr( "Project CRS transformation is turned off." ) + ' ';
-        toolTip += tr( "Distance is calculated in %1, based on project CRS (%2)." ).arg( QgsUnitTypes::toString( resultUnit ),
-                   mTool->canvas()->mapSettings().destinationCrs().description() );
-        toolTip += "<br> * " + tr( "Ellipsoidal calculation is not possible with CRS transformation disabled." );
-        setWindowTitle( tr( "Measure (OTF off)" ) );
+        resultUnit = QgsUnitTypes::DistanceMeters;
+        toolTip += "<br> * " + tr( "Project ellipsoidal calculation is selected." ) + ' ';
+        toolTip += "<br> * " + tr( "The coordinates are transformed to the chosen ellipsoid (%1), and the distance is calculated in %2." ).arg( mDa.ellipsoid(),
+                   QgsUnitTypes::toString( resultUnit ) );
       }
       else
       {
-        if ( mDa.willUseEllipsoid() )
-        {
-          resultUnit = QgsUnitTypes::DistanceMeters;
-          toolTip += "<br> * " + tr( "Project CRS transformation is turned on and ellipsoidal calculation is selected." ) + ' ';
-          toolTip += "<br> * " + tr( "The coordinates are transformed to the chosen ellipsoid (%1), and the distance is calculated in %2." ).arg( mDa.ellipsoid(),
-                     QgsUnitTypes::toString( resultUnit ) );
-        }
-        else
-        {
-          resultUnit = mTool->canvas()->mapSettings().destinationCrs().mapUnits();
-          toolTip += "<br> * " + tr( "Project CRS transformation is turned on but ellipsoidal calculation is not selected." ) + ' ';
-          toolTip += tr( "Distance is calculated in %1, based on project CRS (%2)." ).arg( QgsUnitTypes::toString( resultUnit ),
-                     mTool->canvas()->mapSettings().destinationCrs().description() );
-        }
-        setWindowTitle( tr( "Measure (OTF on)" ) );
+        resultUnit = mTool->canvas()->mapSettings().destinationCrs().mapUnits();
+        toolTip += "<br> * " + tr( "Project ellipsoidal calculation is not selected." ) + ' ';
+        toolTip += tr( "Distance is calculated in %1, based on project CRS (%2)." ).arg( QgsUnitTypes::toString( resultUnit ),
+                   mTool->canvas()->mapSettings().destinationCrs().description() );
       }
+      setWindowTitle( tr( "Measure (OTF on)" ) );
 
       if ( QgsUnitTypes::unitType( resultUnit ) == QgsUnitTypes::Geographic &&
            QgsUnitTypes::unitType( mDistanceUnits ) == QgsUnitTypes::Standard )