From 08b6b6065a6c0aea8302b68739a5e8d902feba11 Mon Sep 17 00:00:00 2001
From: Alessandro Pasotti <elpaso@itopen.it>
Date: Sat, 6 Oct 2018 10:53:12 +0200
Subject: [PATCH] Show a warning when pasted feature geometry collapsed

... due to due to intersection avoidance

Features are still pasted but the user is warned.

Fixes #20020
---
 src/app/qgisapp.cpp | 30 ++++++++++++++++++------------
 1 file changed, 18 insertions(+), 12 deletions(-)

diff --git a/src/app/qgisapp.cpp b/src/app/qgisapp.cpp
index bc66e7d79cf..0bc072e6509 100644
--- a/src/app/qgisapp.cpp
+++ b/src/app/qgisapp.cpp
@@ -8611,7 +8611,7 @@ void QgisApp::pasteFromClipboard( QgsMapLayer *destinationLayer )
 
   QgsExpressionContext context = pasteVectorLayer->createExpressionContext();
 
-
+  int invalidGeometriesCount = 0;
   QgsFeatureList newFeatures;
   QgsFeatureList::const_iterator featureIt = features.constBegin();
   while ( featureIt != features.constEnd() )
@@ -8653,13 +8653,14 @@ void QgisApp::pasteFromClipboard( QgsMapLayer *destinationLayer )
       // avoid intersection if enabled in digitize settings
       geom.avoidIntersections( QgsProject::instance()->avoidIntersectionsLayers() );
     }
+    if ( geom.isEmpty() || geom.isNull( ) )
+      invalidGeometriesCount++;
 
     // now create new feature using pasted feature as a template. This automatically handles default
     // values and field constraints
     newFeatures << QgsVectorLayerUtils::createFeature( pasteVectorLayer, geom, dstAttr, &context );
     ++featureIt;
   }
-
   pasteVectorLayer->addFeatures( newFeatures );
   QgsFeatureIds newIds;
   for ( const QgsFeature &f : qgis::as_const( newFeatures ) )
@@ -8673,26 +8674,31 @@ void QgisApp::pasteFromClipboard( QgsMapLayer *destinationLayer )
   pasteVectorLayer->updateExtents();
 
   int nCopiedFeatures = features.count();
+  Qgis::MessageLevel level = ( nCopiedFeatures == 0 || nCopiedFeatures < nTotalFeatures || invalidGeometriesCount > 0 ) ? Qgis::Warning : Qgis::Info;
+  QString message;
   if ( nCopiedFeatures == 0 )
   {
-    messageBar()->pushMessage( tr( "Paste features" ),
-                               tr( "no features could be successfully pasted." ),
-                               Qgis::Warning, messageTimeout() );
-
+    message = tr( "No features could be successfully pasted." );
   }
   else if ( nCopiedFeatures == nTotalFeatures )
   {
-    messageBar()->pushMessage( tr( "Paste features" ),
-                               tr( "%1 features were successfully pasted." ).arg( nCopiedFeatures ),
-                               Qgis::Info, messageTimeout() );
+    message = tr( "%1 features were successfully pasted." ).arg( nCopiedFeatures );
   }
   else
   {
-    messageBar()->pushMessage( tr( "Paste features" ),
-                               tr( "%1 of %2 features could be successfully pasted." ).arg( nCopiedFeatures ).arg( nTotalFeatures ),
-                               Qgis::Warning, messageTimeout() );
+    message = tr( "%1 of %2 features could be successfully pasted." ).arg( nCopiedFeatures ).arg( nTotalFeatures );
   }
 
+  // warn the user if the pasted features have invalid geometries
+  if ( invalidGeometriesCount > 0 )
+    message +=  invalidGeometriesCount == 1 ? tr( " Geometry collapsed due to intersection avoidance." ) :
+                tr( "%1 geometries collapsed due to intersection avoidance." )
+                .arg( invalidGeometriesCount );
+
+  messageBar()->pushMessage( tr( "Paste features" ),
+                             message,
+                             level, messageTimeout() );
+
   pasteVectorLayer->triggerRepaint();
 }