When determining whether any symbol masking should be applied to a

layer, we need to skip any masks which refer to layers which aren't part of the current map render These layers can't be used as mask sources, since we aren't rendering them. This is a band-aid fix over a deeper problem -- symbol masking settings are not cleaned up when a layer is removed from a project. So it's possible to have layers with label settings which contain mask references to broken layers. These aren't ever shown in the UI, so it's impossible for a user to determine that the masking is even configured for the layer and fix it themselves. At least with the band-aid users won't have to fight with a random project force-rasterizing all labels (like I just did for the last 2 hours)
qgis · May 24, 2021 · ffc500d · ffc500d
1 parent f16c28b
commit ffc500d
Showing 1 changed file with 34 additions and 2 deletions.
diff --git a/src/core/maprenderer/qgsmaprendererjob.cpp b/src/core/maprenderer/qgsmaprendererjob.cpp
@@ -494,13 +494,24 @@ LayerRenderJobs QgsMapRendererJob::prepareSecondPassJobs( LayerRenderJobs &first
   // and the list of source layers that have a mask
   QHash<QString, QPair<QSet<QgsSymbolLayerId>, QList<MaskSource>>> maskedSymbolLayers;
 
+  // First up, create a mapping of layer id to jobs. We need this to filter out any masking
+  // which refers to layers which we aren't rendering as part of this map render
   for ( LayerRenderJob &job : firstPassJobs )
   {
     QgsVectorLayer *vl = qobject_cast<QgsVectorLayer *>( job.layer );
     if ( ! vl )
       continue;
 
     layerJobMapping[job.layer->id()] = &job;
+  }
+
+  // next, collate a master list of masked layers, skipping over any which refer to layers
+  // which don't have a corresponding render job
+  for ( LayerRenderJob &job : firstPassJobs )
+  {
+    QgsVectorLayer *vl = qobject_cast<QgsVectorLayer *>( job.layer );
+    if ( ! vl )
+      continue;
 
     // lambda function to factor code for both label masks and symbol layer masks
     auto collectMasks = [&]( QHash<QString, QSet<QgsSymbolLayerId>> *masks, QString sourceLayerId, QString ruleId = QString(), int labelMaskId = -1 )
@@ -531,12 +542,33 @@ LayerRenderJobs QgsMapRendererJob::prepareSecondPassJobs( LayerRenderJobs &first
     for ( auto it = labelMasks.begin(); it != labelMasks.end(); it++ )
     {
       QString labelRule = it.key();
+      // this is a hash of layer id to masks
       QHash<QString, QSet<QgsSymbolLayerId>> masks = it.value();
 
+      // filter out masks to those which we are actually rendering
+      QHash<QString, QSet<QgsSymbolLayerId>> usableMasks;
+      for ( auto mit = masks.begin(); mit != masks.end(); mit++ )
+      {
+        const QString sourceLayerId = mit.key();
+        // if we aren't rendering the source layer as part of this render, we can't process this mask
+        if ( !layerJobMapping.contains( sourceLayerId ) )
+          continue;
+        else
+          usableMasks.insert( sourceLayerId, mit.value() );
+      }
+
+      if ( usableMasks.empty() )
+        continue;
+
       // group layers by QSet<QgsSymbolLayerReference>
       QSet<QgsSymbolLayerReference> slRefs;
-      for ( auto mit = masks.begin(); mit != masks.end(); mit++ )
+      for ( auto mit = usableMasks.begin(); mit != usableMasks.end(); mit++ )
       {
+        const QString sourceLayerId = mit.key();
+        // if we aren't rendering the source layer as part of this render, we can't process this mask
+        if ( !layerJobMapping.contains( sourceLayerId ) )
+          continue;
+
         for ( auto slIt = mit.value().begin(); slIt != mit.value().end(); slIt++ )
         {
           slRefs.insert( QgsSymbolLayerReference( mit.key(), *slIt ) );
@@ -546,7 +578,7 @@ LayerRenderJobs QgsMapRendererJob::prepareSecondPassJobs( LayerRenderJobs &first
       int labelMaskId = labelJob.maskIdProvider.insertLabelLayer( vl->id(), it.key(), slRefs );
 
       // now collect masks
-      collectMasks( &masks, vl->id(), labelRule, labelMaskId );
+      collectMasks( &usableMasks, vl->id(), labelRule, labelMaskId );
     }
 
     // collect symbol layer masks