[core] Keep symbol and non-symbol buckets segregated

Discard prior symbol buckets only when new symbol buckets became available, in order to eliminate flickering when tiles are refreshed.

2 files changed, 8 insertions, 7 deletions

diff --git a/src/mbgl/tile/geometry_tile.cpp b/src/mbgl/tile/geometry_tile.cpp
index 2a0047fecf..4c5a61672d 100644
--- a/src/mbgl/tile/geometry_tile.cpp
+++ b/src/mbgl/tile/geometry_tile.cpp
@@ -6,6 +6,7 @@
 #include <mbgl/style/layer_impl.hpp>
 #include <mbgl/style/layers/background_layer.hpp>
 #include <mbgl/style/layers/custom_layer.hpp>
+#include <mbgl/style/layers/symbol_layer.hpp>
 #include <mbgl/style/style.hpp>
 #include <mbgl/storage/file_source.hpp>
 #include <mbgl/geometry/feature_index.hpp>
@@ -105,7 +106,7 @@ void GeometryTile::redoLayout() {
 
 void GeometryTile::onLayout(LayoutResult result) {
     availableData = DataAvailability::Some;
-    buckets = std::move(result.buckets);
+    nonSymbolBuckets = std::move(result.nonSymbolBuckets);
     featureIndex = std::move(result.featureIndex);
     data = std::move(result.tileData);
     observer->onTileChanged(*this);
@@ -115,9 +116,7 @@ void GeometryTile::onPlacement(PlacementResult result) {
     if (result.correlationID == correlationID) {
         availableData = DataAvailability::All;
     }
-    for (auto& bucket : result.buckets) {
-        buckets[bucket.first] = std::move(bucket.second);
-    }
+    symbolBuckets = std::move(result.symbolBuckets);
     featureIndex->setCollisionTile(std::move(result.collisionTile));
     observer->onTileChanged(*this);
 }
@@ -128,6 +127,7 @@ void GeometryTile::onError(std::exception_ptr err) {
 }
 
 Bucket* GeometryTile::getBucket(const Layer& layer) {
+    const auto& buckets = layer.is<SymbolLayer>() ? symbolBuckets : nonSymbolBuckets;
     const auto it = buckets.find(layer.baseImpl->id);
     if (it == buckets.end()) {
         return nullptr;
diff --git a/src/mbgl/tile/geometry_tile.hpp b/src/mbgl/tile/geometry_tile.hpp
index 993f7b018e..5e7e501e89 100644
--- a/src/mbgl/tile/geometry_tile.hpp
+++ b/src/mbgl/tile/geometry_tile.hpp
@@ -50,7 +50,7 @@ public:
 
     class LayoutResult {
     public:
-        std::unordered_map<std::string, std::shared_ptr<Bucket>> buckets;
+        std::unordered_map<std::string, std::shared_ptr<Bucket>> nonSymbolBuckets;
         std::unique_ptr<FeatureIndex> featureIndex;
         std::unique_ptr<GeometryTileData> tileData;
         uint64_t correlationID;
@@ -59,7 +59,7 @@ public:
 
     class PlacementResult {
     public:
-        std::unordered_map<std::string, std::shared_ptr<Bucket>> buckets;
+        std::unordered_map<std::string, std::shared_ptr<Bucket>> symbolBuckets;
         std::unique_ptr<CollisionTile> collisionTile;
         uint64_t correlationID;
     };
@@ -80,7 +80,8 @@ private:
     uint64_t correlationID = 0;
     optional<PlacementConfig> requestedConfig;
 
-    std::unordered_map<std::string, std::shared_ptr<Bucket>> buckets;
+    std::unordered_map<std::string, std::shared_ptr<Bucket>> nonSymbolBuckets;
+    std::unordered_map<std::string, std::shared_ptr<Bucket>> symbolBuckets;
     std::unique_ptr<FeatureIndex> featureIndex;
     std::unique_ptr<const GeometryTileData> data;
 };