[core] Replace RenderSymbolLayer downcast with symbol interface

12 files changed, 109 insertions, 56 deletions

diff --git a/cmake/core-files.txt b/cmake/core-files.txt
index e7fd7d81c2..2d55807ee8 100644
--- a/cmake/core-files.txt
+++ b/cmake/core-files.txt
@@ -262,6 +262,7 @@ src/mbgl/renderer/layers/render_heatmap_layer.cpp
 src/mbgl/renderer/layers/render_heatmap_layer.hpp
 src/mbgl/renderer/layers/render_hillshade_layer.cpp
 src/mbgl/renderer/layers/render_hillshade_layer.hpp
+src/mbgl/renderer/layers/render_layer_symbol_interface.hpp
 src/mbgl/renderer/layers/render_line_layer.cpp
 src/mbgl/renderer/layers/render_line_layer.hpp
 src/mbgl/renderer/layers/render_raster_layer.cpp
diff --git a/src/mbgl/geometry/feature_index.cpp b/src/mbgl/geometry/feature_index.cpp
index 651e3b9c56..7dc46c4dfc 100644
--- a/src/mbgl/geometry/feature_index.cpp
+++ b/src/mbgl/geometry/feature_index.cpp
@@ -155,7 +155,7 @@ void FeatureIndex::addFeature(
             assert(geometryTileFeature);
         }
 
-        if (!renderLayer->is<RenderSymbolLayer>() &&
+        if (!renderLayer->getSymbolInterface() &&
              !renderLayer->queryIntersectsFeature(queryGeometry, *geometryTileFeature, tileID.z, transformState, pixelsToTileUnits, posMatrix)) {
             continue;
         }
diff --git a/src/mbgl/renderer/layers/render_layer_symbol_interface.hpp b/src/mbgl/renderer/layers/render_layer_symbol_interface.hpp
new file mode 100644
index 0000000000..e5c16c6e7c
--- /dev/null
+++ b/src/mbgl/renderer/layers/render_layer_symbol_interface.hpp
@@ -0,0 +1,22 @@
+#pragma once
+
+#include <memory>
+#include <vector>
+#include <string>
+
+namespace mbgl {
+
+class RenderTile;
+class SymbolBucket;
+
+class RenderLayerSymbolInterface {
+public:
+    virtual const std::string& layerID() const = 0;
+    virtual const std::vector<std::reference_wrapper<RenderTile>>& getRenderTiles() const = 0;
+    virtual SymbolBucket* getSymbolBucket(const RenderTile&) const = 0;
+
+protected:
+    virtual ~RenderLayerSymbolInterface() = default;
+};
+
+} // namespace mbgl
diff --git a/src/mbgl/renderer/layers/render_symbol_layer.cpp b/src/mbgl/renderer/layers/render_symbol_layer.cpp
index 6d2c090aef..2b3a7195c5 100644
--- a/src/mbgl/renderer/layers/render_symbol_layer.cpp
+++ b/src/mbgl/renderer/layers/render_symbol_layer.cpp
@@ -74,6 +74,22 @@ bool RenderSymbolLayer::hasCrossfade() const {
     return false;
 }
 
+const std::string& RenderSymbolLayer::layerID() const {
+    return RenderLayer::getID();
+}
+
+const RenderLayerSymbolInterface* RenderSymbolLayer::getSymbolInterface() const {
+    return this;
+}
+
+const std::vector<std::reference_wrapper<RenderTile>>& RenderSymbolLayer::getRenderTiles() const {
+    return renderTiles;
+}
+
+SymbolBucket* RenderSymbolLayer::getSymbolBucket(const RenderTile& renderTile) const {
+    return renderTile.tile.getBucket<SymbolBucket>(*baseImpl);
+}
+
 void RenderSymbolLayer::render(PaintParameters& parameters, RenderSource*) {
     if (parameters.pass == RenderPass::Opaque) {
         return;
diff --git a/src/mbgl/renderer/layers/render_symbol_layer.hpp b/src/mbgl/renderer/layers/render_symbol_layer.hpp
index 7c52467e56..105754befa 100644
--- a/src/mbgl/renderer/layers/render_symbol_layer.hpp
+++ b/src/mbgl/renderer/layers/render_symbol_layer.hpp
@@ -2,6 +2,7 @@
 
 #include <mbgl/text/glyph.hpp>
 #include <mbgl/renderer/render_layer.hpp>
+#include <mbgl/renderer/layers/render_layer_symbol_interface.hpp>
 #include <mbgl/style/image_impl.hpp>
 #include <mbgl/style/layers/symbol_layer_impl.hpp>
 #include <mbgl/style/layers/symbol_layer_properties.hpp>
@@ -56,7 +57,7 @@ class BucketParameters;
 class SymbolLayout;
 class GeometryTileLayer;
 
-class RenderSymbolLayer: public RenderLayer {
+class RenderSymbolLayer: public RenderLayer, public RenderLayerSymbolInterface {
 public:
     RenderSymbolLayer(Immutable<style::SymbolLayer::Impl>);
     ~RenderSymbolLayer() final = default;
@@ -80,6 +81,12 @@ public:
                                                GlyphDependencies&,
                                                ImageDependencies&) const override;
 
+    // RenderLayerSymbolInterface overrides
+    const RenderLayerSymbolInterface* getSymbolInterface() const final;
+    const std::string& layerID() const final;
+    const std::vector<std::reference_wrapper<RenderTile>>& getRenderTiles() const final;
+    SymbolBucket* getSymbolBucket(const RenderTile&) const final;
+
     // Paint properties
     style::SymbolPaintProperties::Unevaluated unevaluated;
     style::SymbolPaintProperties::PossiblyEvaluated evaluated;
diff --git a/src/mbgl/renderer/render_layer.cpp b/src/mbgl/renderer/render_layer.cpp
index efd890eda8..3e9a7caf24 100644
--- a/src/mbgl/renderer/render_layer.cpp
+++ b/src/mbgl/renderer/render_layer.cpp
@@ -86,6 +86,10 @@ void RenderLayer::sortRenderTiles(const TransformState&) {
     std::sort(renderTiles.begin(), renderTiles.end(), [](const auto& a, const auto& b) { return a.get().id < b.get().id; });
 }
 
+const RenderLayerSymbolInterface* RenderLayer::getSymbolInterface() const {
+    return nullptr;
+}
+
 void RenderLayer::update() {
     // no-op
 }
diff --git a/src/mbgl/renderer/render_layer.hpp b/src/mbgl/renderer/render_layer.hpp
index b335a468b0..349b5d412a 100644
--- a/src/mbgl/renderer/render_layer.hpp
+++ b/src/mbgl/renderer/render_layer.hpp
@@ -17,6 +17,7 @@ class TransitionParameters;
 class PropertyEvaluationParameters;
 class PaintParameters;
 class RenderSource;
+class RenderLayerSymbolInterface;
 class RenderTile;
 class TransformState;
 
@@ -43,6 +44,9 @@ public:
     // Returns true if the layer has a pattern property and is actively crossfading.
     virtual bool hasCrossfade() const = 0;
 
+    // Returns instance of RenderLayerSymbolInterface if RenderLayer supports it.
+    virtual const RenderLayerSymbolInterface* getSymbolInterface() const;
+
     // Check whether this layer is of the given subtype.
     template <class T>
     bool is() const;
@@ -118,10 +122,6 @@ protected:
     RenderTiles filterRenderTiles(RenderTiles, FilterFunctionPtr) const;
 
 protected:
-    // renderTiles are exposed directly to CrossTileSymbolIndex and Placement so they
-    // can update opacities in the symbol buckets immediately before rendering
-    friend class CrossTileSymbolIndex;
-    friend class Placement;
     // Stores current set of tiles to be rendered for this layer.
     std::vector<std::reference_wrapper<RenderTile>> renderTiles;
 
diff --git a/src/mbgl/renderer/renderer_impl.cpp b/src/mbgl/renderer/renderer_impl.cpp
index 124c16cb64..420d90b327 100644
--- a/src/mbgl/renderer/renderer_impl.cpp
+++ b/src/mbgl/renderer/renderer_impl.cpp
@@ -322,46 +322,48 @@ void Renderer::Impl::render(const UpdateParameters& updateParameters) {
         order.emplace_back(RenderItem { *layer, source });
     }
 
-    bool symbolBucketsChanged = false;
-    if (parameters.mapMode != MapMode::Continuous) {
-        // TODO: Think about right way for symbol index to handle still rendering
-        crossTileSymbolIndex.reset();
-    }
-    for (auto it = order.rbegin(); it != order.rend(); ++it) {
-        if (it->layer.is<RenderSymbolLayer>()) {
-            const float lng = parameters.state.getLatLng().longitude();
-            if (crossTileSymbolIndex.addLayer(*it->layer.as<RenderSymbolLayer>(), lng)) symbolBucketsChanged = true;
+    {
+        if (parameters.mapMode != MapMode::Continuous) {
+            // TODO: Think about right way for symbol index to handle still rendering
+            crossTileSymbolIndex.reset();
         }
-    }
 
-    bool placementChanged = false;
-    if (!placement->stillRecent(parameters.timePoint)) {
-        placementChanged = true;
+        std::vector<RenderItem> renderItemsWithSymbols;
+        std::copy_if(order.rbegin(), order.rend(), std::back_inserter(renderItemsWithSymbols),
+                [](const auto& item) { return item.layer.getSymbolInterface() != nullptr; });
 
-        auto newPlacement = std::make_unique<Placement>(parameters.state, parameters.mapMode, updateParameters.crossSourceCollisions);
+        bool symbolBucketsChanged = false;
+        const bool placementChanged = !placement->stillRecent(parameters.timePoint);
+        std::unique_ptr<Placement> newPlacement;
         std::set<std::string> usedSymbolLayers;
-        for (auto it = order.rbegin(); it != order.rend(); ++it) {
-            if (it->layer.is<RenderSymbolLayer>()) {
-                usedSymbolLayers.insert(it->layer.getID());
-                newPlacement->placeLayer(*it->layer.as<RenderSymbolLayer>(), parameters.projMatrix, parameters.debugOptions & MapDebugOptions::Collision);
+
+        if (placementChanged) {
+            newPlacement = std::make_unique<Placement>(parameters.state, parameters.mapMode, updateParameters.crossSourceCollisions);
+        }
+
+        for (const auto& item : renderItemsWithSymbols) {
+            if (crossTileSymbolIndex.addLayer(*item.layer.getSymbolInterface(), parameters.state.getLatLng().longitude())) symbolBucketsChanged = true;
+
+            if (newPlacement) {
+                usedSymbolLayers.insert(item.layer.getID());
+                newPlacement->placeLayer(*item.layer.getSymbolInterface(), parameters.projMatrix, parameters.debugOptions & MapDebugOptions::Collision);
             }
         }
 
-        newPlacement->commit(*placement, parameters.timePoint);
-        crossTileSymbolIndex.pruneUnusedLayers(usedSymbolLayers);
-        placement = std::move(newPlacement);
-        
-        updateFadingTiles();
-    } else {
-        placement->setStale();
-    }
+        if (newPlacement) {
+            newPlacement->commit(*placement, parameters.timePoint);
+            crossTileSymbolIndex.pruneUnusedLayers(usedSymbolLayers);
+            placement = std::move(newPlacement);
+            updateFadingTiles();
+        } else {
+            placement->setStale();
+        }
 
-    parameters.symbolFadeChange = placement->symbolFadeChange(parameters.timePoint);
+        parameters.symbolFadeChange = placement->symbolFadeChange(parameters.timePoint);
 
-    if (placementChanged || symbolBucketsChanged) {
-        for (auto it = order.rbegin(); it != order.rend(); ++it) {
-            if (it->layer.is<RenderSymbolLayer>()) {
-                placement->updateLayerOpacities(*it->layer.as<RenderSymbolLayer>());
+        if (placementChanged || symbolBucketsChanged) {
+            for (const auto& item : renderItemsWithSymbols) {
+                placement->updateLayerOpacities(*item.layer.getSymbolInterface());
             }
         }
     }
diff --git a/src/mbgl/text/cross_tile_symbol_index.cpp b/src/mbgl/text/cross_tile_symbol_index.cpp
index 98b9af1f94..0992433ccb 100644
--- a/src/mbgl/text/cross_tile_symbol_index.cpp
+++ b/src/mbgl/text/cross_tile_symbol_index.cpp
@@ -1,6 +1,7 @@
 #include <mbgl/text/cross_tile_symbol_index.hpp>
 #include <mbgl/layout/symbol_instance.hpp>
 #include <mbgl/renderer/buckets/symbol_bucket.hpp>
+#include <mbgl/renderer/layers/render_layer_symbol_interface.hpp>
 #include <mbgl/renderer/render_tile.hpp>
 #include <mbgl/tile/tile.hpp>
 
@@ -164,27 +165,27 @@ bool CrossTileSymbolLayerIndex::removeStaleBuckets(const std::unordered_set<uint
 
 CrossTileSymbolIndex::CrossTileSymbolIndex() {}
 
-bool CrossTileSymbolIndex::addLayer(RenderSymbolLayer& symbolLayer, float lng) {
+bool CrossTileSymbolIndex::addLayer(const RenderLayerSymbolInterface& symbolInterface, float lng) {
 
-    auto& layerIndex = layerIndexes[symbolLayer.getID()];
+    auto& layerIndex = layerIndexes[symbolInterface.layerID()];
 
     bool symbolBucketsChanged = false;
     std::unordered_set<uint32_t> currentBucketIDs;
 
     layerIndex.handleWrapJump(lng);
 
-    for (RenderTile& renderTile : symbolLayer.renderTiles) {
+    for (const RenderTile& renderTile : symbolInterface.getRenderTiles()) {
         if (!renderTile.tile.isRenderable()) {
             continue;
         }
 
-        auto bucket = renderTile.tile.getBucket<SymbolBucket>(*symbolLayer.baseImpl);
+        auto bucket = symbolInterface.getSymbolBucket(renderTile);
         if (!bucket) {
             continue;
         }
         SymbolBucket& symbolBucket = *bucket;
 
-        if (symbolBucket.bucketLeaderID != symbolLayer.getID()) {
+        if (symbolBucket.bucketLeaderID != symbolInterface.layerID()) {
             // Only add this layer if it's the "group leader" for the bucket
             continue;
         }
diff --git a/src/mbgl/text/cross_tile_symbol_index.hpp b/src/mbgl/text/cross_tile_symbol_index.hpp
index 051573e1d2..528147f146 100644
--- a/src/mbgl/text/cross_tile_symbol_index.hpp
+++ b/src/mbgl/text/cross_tile_symbol_index.hpp
@@ -15,7 +15,7 @@
 namespace mbgl {
 
 class SymbolInstance;
-class RenderSymbolLayer;
+class RenderLayerSymbolInterface;
 class SymbolBucket;
 
 class IndexedSymbolInstance {
@@ -58,7 +58,7 @@ class CrossTileSymbolIndex {
 public:
     CrossTileSymbolIndex();
 
-    bool addLayer(RenderSymbolLayer&, float lng);
+    bool addLayer(const RenderLayerSymbolInterface&, float lng);
     void pruneUnusedLayers(const std::set<std::string>&);
 
     void reset();
diff --git a/src/mbgl/text/placement.cpp b/src/mbgl/text/placement.cpp
index 5c6cdcde6c..367e421412 100644
--- a/src/mbgl/text/placement.cpp
+++ b/src/mbgl/text/placement.cpp
@@ -1,6 +1,6 @@
 #include <mbgl/text/placement.hpp>
 #include <mbgl/renderer/render_layer.hpp>
-#include <mbgl/renderer/layers/render_symbol_layer.hpp>
+#include <mbgl/renderer/layers/render_layer_symbol_interface.hpp>
 #include <mbgl/renderer/render_tile.hpp>
 #include <mbgl/tile/geometry_tile.hpp>
 #include <mbgl/renderer/buckets/symbol_bucket.hpp>
@@ -62,24 +62,24 @@ Placement::Placement(const TransformState& state_, MapMode mapMode_, const bool
     , collisionGroups(crossSourceCollisions)
 {}
 
-void Placement::placeLayer(RenderSymbolLayer& symbolLayer, const mat4& projMatrix, bool showCollisionBoxes) {
+void Placement::placeLayer(const RenderLayerSymbolInterface& symbolInterface, const mat4& projMatrix, bool showCollisionBoxes) {
 
     std::unordered_set<uint32_t> seenCrossTileIDs;
 
-    for (RenderTile& renderTile : symbolLayer.renderTiles) {
+    for (const RenderTile& renderTile : symbolInterface.getRenderTiles()) {
         if (!renderTile.tile.isRenderable()) {
             continue;
         }
         assert(renderTile.tile.kind == Tile::Kind::Geometry);
         GeometryTile& geometryTile = static_cast<GeometryTile&>(renderTile.tile);
 
-        auto bucket = renderTile.tile.getBucket<SymbolBucket>(*symbolLayer.baseImpl);
+        auto bucket = symbolInterface.getSymbolBucket(renderTile);
         if (!bucket) {
             continue;
         }
         SymbolBucket& symbolBucket = *bucket;
 
-        if (symbolBucket.bucketLeaderID != symbolLayer.getID()) {
+        if (symbolBucket.bucketLeaderID != symbolInterface.layerID()) {
             // Only place this layer if it's the "group leader" for the bucket
             continue;
         }
@@ -276,20 +276,20 @@ void Placement::commit(const Placement& prevPlacement, TimePoint now) {
     fadeStartTime = placementChanged ? commitTime : prevPlacement.fadeStartTime;
 }
 
-void Placement::updateLayerOpacities(RenderSymbolLayer& symbolLayer) {
+void Placement::updateLayerOpacities(const RenderLayerSymbolInterface& symbolInterface) {
     std::set<uint32_t> seenCrossTileIDs;
-    for (RenderTile& renderTile : symbolLayer.renderTiles) {
+    for (const RenderTile& renderTile : symbolInterface.getRenderTiles()) {
         if (!renderTile.tile.isRenderable()) {
             continue;
         }
 
-        auto bucket = renderTile.tile.getBucket<SymbolBucket>(*symbolLayer.baseImpl);
+        auto bucket = symbolInterface.getSymbolBucket(renderTile);
         if (!bucket) {
             continue;
         }
         SymbolBucket& symbolBucket = *bucket;
 
-        if (symbolBucket.bucketLeaderID != symbolLayer.getID()) {
+        if (symbolBucket.bucketLeaderID != symbolInterface.layerID()) {
             // Only update opacities this layer if it's the "group leader" for the bucket
             continue;
         }
diff --git a/src/mbgl/text/placement.hpp b/src/mbgl/text/placement.hpp
index 8527d6df57..f34a8a25c2 100644
--- a/src/mbgl/text/placement.hpp
+++ b/src/mbgl/text/placement.hpp
@@ -9,7 +9,7 @@
 
 namespace mbgl {
 
-class RenderSymbolLayer;
+class RenderLayerSymbolInterface;
 class SymbolBucket;
 
 class OpacityState {
@@ -80,9 +80,9 @@ private:
 class Placement {
 public:
     Placement(const TransformState&, MapMode mapMode, const bool crossSourceCollisions);
-    void placeLayer(RenderSymbolLayer&, const mat4&, bool showCollisionBoxes);
+    void placeLayer(const RenderLayerSymbolInterface&, const mat4&, bool showCollisionBoxes);
     void commit(const Placement& prevPlacement, TimePoint);
-    void updateLayerOpacities(RenderSymbolLayer&);
+    void updateLayerOpacities(const RenderLayerSymbolInterface&);
     float symbolFadeChange(TimePoint now) const;
     bool hasTransitions(TimePoint now) const;