ask for datum transform update on layer or project crs change

in the case of project crs change, if several transforms are available, pop up a message rather than showing multiple dialogs

Author: 3nids

doc/api_break.dox

@@ -1647,6 +1647,7 @@ QgsMapCanvas        {#qgis_api_break_3_0_QgsMapCanvas}
 - setCrsTransformEnabled(), hasCrsTransformEnabled(), hasCrsTransformEnabledChanged() were removed. CRS transformation is now always enabled.
 - setMapUnits() was removed. The map units are dictated by the units for the destination CRS.
 - The mapUnitsChanged() signal was removed. Listen for the destinationCrsChanged() signal instead, as the destination CRS dictates the map units.
+- layerCrsChange() slot was removed. Datum transforms are now handled in QgisApp.
 
 QgsMapCanvasItem        {#qgis_api_break_3_0_QgsMapCanvasItem}
 ----------------

python/gui/qgsmapcanvas.sip

@@ -695,11 +695,6 @@ Save the convtents of the map canvas to disk as an image
     void layerStateChange();
 %Docstring
 This slot is connected to the visibility change of one or more layers
-%End
-
-    void layerCrsChange();
-%Docstring
-This slot is connected to the layer's CRS change
 %End
 
     void setRenderFlag( bool flag );
@@ -952,11 +947,6 @@ called when panning is in action, reset indicates end of panning
 
 
 
-    void updateDatumTransformEntries();
-%Docstring
-Make sure the datum transform store is properly populated
-%End
-
   protected slots:
     void updateCanvasItemPositions();
 %Docstring

src/app/qgisapp.cpp

@@ -3184,14 +3184,7 @@ void QgisApp::setupConnections()
            this, &QgisApp::mapCanvas_keyPressed );
 
   // project crs connections
-  connect( QgsProject::instance(), &QgsProject::crsChanged,
-           this, &QgisApp::updateCrsStatusBar );
-  connect( QgsProject::instance(), &QgsProject::crsChanged,
-           this, [ = ]
-  {
-    QgsDebugMsgLevel( QString( "QgisApp::setupConnections -1- : QgsProject::instance()->crs().description[%1]ellipsoid[%2]" ).arg( QgsProject::instance()->crs().description() ).arg( QgsProject::instance()->crs().ellipsoidAcronym() ), 3 );
-    mMapCanvas->setDestinationCrs( QgsProject::instance()->crs() );
-  } );
+  connect( QgsProject::instance(), &QgsProject::crsChanged, this, &QgisApp::onProjectCrsChanged );
 
   connect( QgsProject::instance(), &QgsProject::labelingEngineSettingsChanged,
            this, [ = ]
@@ -9126,6 +9119,45 @@ void QgisApp::onFocusChanged( QWidget *oldWidget, QWidget *newWidget )
   }
 }
 
+void QgisApp::onProjectCrsChanged()
+{
+  updateCrsStatusBar();
+  QgsDebugMsgLevel( QString( "QgisApp::setupConnections -1- : QgsProject::instance()->crs().description[%1]ellipsoid[%2]" ).arg( QgsProject::instance()->crs().description() ).arg( QgsProject::instance()->crs().ellipsoidAcronym() ), 3 );
+  mMapCanvas->setDestinationCrs( QgsProject::instance()->crs() );
+
+  // handle datum transforms
+  QList<QgsCoordinateReferenceSystem> transformsToAskFor = QList<QgsCoordinateReferenceSystem>();
+  QMap<QString, QgsMapLayer *> layers = QgsProject::instance()->mapLayers();
+  for ( QMap<QString, QgsMapLayer *>::iterator it = layers.begin(); it != layers.end(); ++it )
+  {
+    if ( !transformsToAskFor.contains( it.value()->crs() ) &&
+         it.value()->crs() != QgsProject::instance()->crs() &&
+         !QgsProject::instance()->transformContext().hasTransform( it.value()->crs(), QgsProject::instance()->crs() ) &&
+         QgsCoordinateTransform::datumTransformations( it.value()->crs(), QgsProject::instance()->crs() ).count() > 1 )
+    {
+      transformsToAskFor.append( it.value()->crs() );
+    }
+  }
+  if ( transformsToAskFor.count() == 1 )
+  {
+    askForDatumTransform( transformsToAskFor.at( 0 ),
+                          QgsProject::instance()->crs() );
+  }
+  else if ( transformsToAskFor.count() > 1 )
+  {
+    bool ask = QgsSettings().value( QStringLiteral( "/Projections/showDatumTransformDialog" ), false ).toBool();
+    if ( ask )
+    {
+      messageBar()->pushMessage( tr( "Datum transforms" ),
+                                 tr( "Project CRS changed and datum transforms might need to be adapted." ),
+                                 QgsMessageBar::WARNING,
+                                 5 );
+    }
+  }
+
+
+}
+
 // toggle overview status
 void QgisApp::isInOverview()
 {
@@ -9425,6 +9457,7 @@ void QgisApp::setLayerCrs()
       {
         if ( child->layer() )
         {
+          askForDatumTransform( crs, QgsProject::instance()->crs() );
           child->layer()->setCrs( crs );
           child->layer()->triggerRepaint();
         }
@@ -9435,6 +9468,7 @@ void QgisApp::setLayerCrs()
       QgsLayerTreeLayer *nodeLayer = QgsLayerTree::toLayer( node );
       if ( nodeLayer->layer() )
       {
+        askForDatumTransform( crs, QgsProject::instance()->crs() );
         nodeLayer->layer()->setCrs( crs );
         nodeLayer->layer()->triggerRepaint();
       }

src/app/qgisapp.h

@@ -1615,6 +1615,9 @@ class APP_EXPORT QgisApp : public QMainWindow, private Ui::MainWindow
 
     void onFocusChanged( QWidget *oldWidget, QWidget *newWidget );
 
+    //! handles project crs changes
+    void onProjectCrsChanged();
+
   signals:
 
     /**

src/app/qgsrasterlayerproperties.cpp

@@ -1221,6 +1221,7 @@ void QgsRasterLayerProperties::pbnAddValuesManually_clicked()
 
 void QgsRasterLayerProperties::mCrsSelector_crsChanged( const QgsCoordinateReferenceSystem &crs )
 {
+  QgisApp::instance()->askForDatumTransform( crs, QgsProject::instance()->crs() );
   mRasterLayer->setCrs( crs );
 }
 

src/app/qgsvectorlayerproperties.cpp

@@ -831,6 +831,7 @@ void QgsVectorLayerProperties::mLayerOrigNameLineEdit_textEdited( const QString
 
 void QgsVectorLayerProperties::mCrsSelector_crsChanged( const QgsCoordinateReferenceSystem &crs )
 {
+  QgisApp::instance()->askForDatumTransform( crs, QgsProject::instance()->crs() );
   mLayer->setCrs( crs );
   mMetadataFilled = false;
 }

src/gui/qgsmapcanvas.cpp

@@ -317,7 +317,6 @@ void QgsMapCanvas::setLayersPrivate( const QList<QgsMapLayer *> &layers )
   Q_FOREACH ( QgsMapLayer *layer, oldLayers )
   {
     disconnect( layer, &QgsMapLayer::repaintRequested, this, &QgsMapCanvas::layerRepaintRequested );
-    disconnect( layer, &QgsMapLayer::crsChanged, this, &QgsMapCanvas::layerCrsChange );
     disconnect( layer, &QgsMapLayer::autoRefreshIntervalChanged, this, &QgsMapCanvas::updateAutoRefreshTimer );
     if ( QgsVectorLayer *vlayer = qobject_cast<QgsVectorLayer *>( layer ) )
     {
@@ -332,14 +331,12 @@ void QgsMapCanvas::setLayersPrivate( const QList<QgsMapLayer *> &layers )
     if ( !layer )
       continue;
     connect( layer, &QgsMapLayer::repaintRequested, this, &QgsMapCanvas::layerRepaintRequested );
-    connect( layer, &QgsMapLayer::crsChanged, this, &QgsMapCanvas::layerCrsChange );
     connect( layer, &QgsMapLayer::autoRefreshIntervalChanged, this, &QgsMapCanvas::updateAutoRefreshTimer );
     if ( QgsVectorLayer *vlayer = qobject_cast<QgsVectorLayer *>( layer ) )
     {
       connect( vlayer, &QgsVectorLayer::selectionChanged, this, &QgsMapCanvas::selectionChangedSlot );
     }
   }
-  updateDatumTransformEntries();
 
   QgsDebugMsg( "Layers have changed, refreshing" );
   emit layersChanged();
@@ -386,8 +383,6 @@ void QgsMapCanvas::setDestinationCrs( const QgsCoordinateReferenceSystem &crs )
   QgsDebugMsg( "refreshing after destination CRS changed" );
   refresh();
 
-  updateDatumTransformEntries();
-
   emit destinationCrsChanged();
 }
 
@@ -1732,14 +1727,6 @@ void QgsMapCanvas::layerStateChange()
   refresh();
 }
 
-void QgsMapCanvas::layerCrsChange()
-{
-  // called when a layer's CRS has been changed
-  QgsMapLayer *layer = qobject_cast<QgsMapLayer *>( sender() );
-  // TODO datum we should trigger a message to say one could choose datum transform
-  //getDatumTransformInfo( layer->crs(), mSettings.destinationCrs() );
-}
-
 void QgsMapCanvas::freeze( bool frozen )
 {
   mFrozen = frozen;
@@ -1816,24 +1803,6 @@ void QgsMapCanvas::connectNotify( const char *signal )
 } //connectNotify
 #endif
 
-void QgsMapCanvas::updateDatumTransformEntries()
-{
-  const QList< QgsMapLayer * > layers = mSettings.layers();
-  for ( QgsMapLayer *layer : layers )
-  {
-    if ( !layer->isSpatial() )
-      continue;
-
-    // if there are more options, ask the user which datum transform to use
-
-#if 0 //old logic - TODO - what is the new logic for when we show this dialog?
-    if ( !mSettings.datumTransformStore().hasEntryForLayer( layer ) )
-#endif
-      // TODO datum we should trigger a message to say one could choose datum transform
-      // getDatumTransformInfo( layer->crs(), mSettings.destinationCrs() );
-    }
-}
-
 void QgsMapCanvas::layerRepaintRequested( bool deferred )
 {
   if ( !deferred )

src/gui/qgsmapcanvas.h

@@ -652,9 +652,6 @@ class GUI_EXPORT QgsMapCanvas : public QGraphicsView
     //! This slot is connected to the visibility change of one or more layers
     void layerStateChange();
 
-    //! This slot is connected to the layer's CRS change
-    void layerCrsChange();
-
     /**
      * Sets whether a user has disabled canvas renders via the GUI.
      * \param flag set to false to indicate that user has disabled renders
@@ -879,9 +876,6 @@ class GUI_EXPORT QgsMapCanvas : public QGraphicsView
     void connectNotify( const char *signal ) override;
 #endif
 
-    //! Make sure the datum transform store is properly populated
-    void updateDatumTransformEntries();
-
   protected slots:
     //! called on resize or changed extent to notify canvas items to change their rectangle
     void updateCanvasItemPositions();