From b3a88a247a1c6e8fea34cdc3d15c8f94834f5017 Mon Sep 17 00:00:00 2001
From: Patrik Sylve <patrik.sylve@t-kartor.com>
Date: Thu, 30 Jan 2025 16:45:05 +0100
Subject: [PATCH] Register vector tile label features first when all tiles are
 fetched

---
 src/core/vectortile/qgsvectortilelayerrenderer.cpp | 12 +++++++++++-
 src/core/vectortile/qgsvectortilelayerrenderer.h   |  3 +++
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/src/core/vectortile/qgsvectortilelayerrenderer.cpp b/src/core/vectortile/qgsvectortilelayerrenderer.cpp
index 3e854dd931e5..797e960615b4 100644
--- a/src/core/vectortile/qgsvectortilelayerrenderer.cpp
+++ b/src/core/vectortile/qgsvectortilelayerrenderer.cpp
@@ -224,6 +224,15 @@ bool QgsVectorTileLayerRenderer::render()
       mErrors.append( asyncLoader->error() );
   }
 
+  // Register labels features when all tiles are fetched to ensure consistent labeling
+  if ( mLabelProvider )
+  {
+    for ( const auto &tile : mTileDataMap )
+    {
+      mLabelProvider->registerTileFeatures( tile, ctx );
+    }
+  }
+
   if ( ctx.flags() & Qgis::RenderContextFlag::DrawSelection )
     mRenderer->renderSelectedFeatures( mSelectedFeatures, ctx );
 
@@ -309,8 +318,9 @@ void QgsVectorTileLayerRenderer::decodeAndDrawTile( const QgsVectorTileRawData &
     mTotalDrawTime += tDraw.elapsed();
   }
 
+  // Store tile for later use
   if ( mLabelProvider )
-    mLabelProvider->registerTileFeatures( tile, ctx );
+    mTileDataMap.insert( tile.id().toString(), tile );
 
   if ( mDrawTileBoundaries )
   {
diff --git a/src/core/vectortile/qgsvectortilelayerrenderer.h b/src/core/vectortile/qgsvectortilelayerrenderer.h
index 127f55d860a7..e024d636b418 100644
--- a/src/core/vectortile/qgsvectortilelayerrenderer.h
+++ b/src/core/vectortile/qgsvectortilelayerrenderer.h
@@ -71,6 +71,9 @@ class QgsVectorTileLayerRenderer : public QgsMapLayerRenderer
      */
     QgsVectorTileLabelProvider *mLabelProvider = nullptr;
 
+    // Decoded tile data
+    QMap<QString, QgsVectorTileRendererData> mTileDataMap;
+
     //! Whether to draw boundaries of tiles (useful for debugging)
     bool mDrawTileBoundaries = false;