[core] Port global symbol query from GL JS:

 - Symbol querying is now global instead of per-tile
 - Symbols that bleed over tile boundaries no longer missed in queries
 - Symbol results now sorted based on rendering order (ie overlapping symbols change their sort order when a bearing change causes their render order to change)
 - Placement::retainedQueryData now responsible for maintaining symbol querying data for buckets that may no longer be in the TilePyramid.

1 files changed, 19 insertions, 1 deletions

diff --git a/src/mbgl/text/placement.hpp b/src/mbgl/text/placement.hpp
index 653ae352ed..0e1751b127 100644
--- a/src/mbgl/text/placement.hpp
+++ b/src/mbgl/text/placement.hpp
@@ -44,7 +44,21 @@ public:
     // visible right away.
     const bool skipFade;
 };
-
+    
+struct RetainedQueryData {
+    uint32_t bucketInstanceId;
+    std::shared_ptr<FeatureIndex> featureIndex;
+    OverscaledTileID tileID;
+    std::shared_ptr<std::vector<size_t>> featureSortOrder;
+    
+    RetainedQueryData(uint32_t bucketInstanceId_,
+                      std::shared_ptr<FeatureIndex> featureIndex_,
+                      OverscaledTileID tileID_)
+        : bucketInstanceId(bucketInstanceId_)
+        , featureIndex(std::move(featureIndex_))
+        , tileID(std::move(tileID_)) {}
+};
+    
 class Placement {
 public:
     Placement(const TransformState&, MapMode mapMode);
@@ -59,6 +73,8 @@ public:
     bool stillRecent(TimePoint now) const;
     void setRecent(TimePoint now);
     void setStale();
+    
+    const RetainedQueryData& getQueryData(uint32_t bucketInstanceId) const;
 private:
 
     void placeLayerBucket(
@@ -85,6 +101,8 @@ private:
 
     TimePoint recentUntil;
     bool stale = false;
+    
+    std::unordered_map<uint32_t, RetainedQueryData> retainedQueryData;
 };
 
 } // namespace mbgl