[core] Add runtime API for setting tile prefetch delta for Source

New setPrefetchZoomDelta(optional<uint8_t> delta) method allow overriding
default tile prefetch setting that is defined by the Map instance. The
method can be moved to generic style specification if found to be useful
for gl-js engine.

6 files changed, 22 insertions, 0 deletions

diff --git a/include/mbgl/style/source.hpp b/include/mbgl/style/source.hpp
index c3c0609a9f..59afd6916e 100644
--- a/include/mbgl/style/source.hpp
+++ b/include/mbgl/style/source.hpp
@@ -73,6 +73,8 @@ public:
     SourceObserver* observer = nullptr;
 
     virtual void loadDescription(FileSource&) = 0;
+    void setPrefetchZoomDelta(optional<uint8_t> delta) noexcept;
+    optional<uint8_t> getPrefetchZoomDelta() const noexcept;
     void dumpDebugLogs() const;
 
     virtual bool supportsLayerType(const mbgl::style::LayerTypeInfo*) const = 0;
@@ -85,6 +87,9 @@ public:
     mapbox::base::TypeWrapper peer;
 
     virtual mapbox::base::WeakPtr<Source> makeWeakPtr() = 0;
+
+protected:
+    virtual Mutable<Impl> createMutable() const noexcept = 0;
 };
 
 } // namespace style
diff --git a/include/mbgl/style/sources/custom_geometry_source.hpp b/include/mbgl/style/sources/custom_geometry_source.hpp
index ff04505699..504ec42ea8 100644
--- a/include/mbgl/style/sources/custom_geometry_source.hpp
+++ b/include/mbgl/style/sources/custom_geometry_source.hpp
@@ -50,6 +50,10 @@ public:
     mapbox::base::WeakPtr<Source> makeWeakPtr() override {
         return weakFactory.makeWeakPtr();
     }
+
+protected:
+    Mutable<Source::Impl> createMutable() const noexcept final;
+
 private:
     std::shared_ptr<ThreadPool> threadPool;
     std::unique_ptr<Actor<CustomTileLoader>> loader;
diff --git a/include/mbgl/style/sources/geojson_source.hpp b/include/mbgl/style/sources/geojson_source.hpp
index 750d29627d..4bd250b895 100644
--- a/include/mbgl/style/sources/geojson_source.hpp
+++ b/include/mbgl/style/sources/geojson_source.hpp
@@ -81,6 +81,9 @@ public:
         return weakFactory.makeWeakPtr();
     }
 
+protected:
+    Mutable<Source::Impl> createMutable() const noexcept final;
+
 private:
     optional<std::string> url;
     std::unique_ptr<AsyncRequest> req;
diff --git a/include/mbgl/style/sources/image_source.hpp b/include/mbgl/style/sources/image_source.hpp
index 699a3c6494..d2b7c37bdf 100644
--- a/include/mbgl/style/sources/image_source.hpp
+++ b/include/mbgl/style/sources/image_source.hpp
@@ -33,6 +33,10 @@ public:
     mapbox::base::WeakPtr<Source> makeWeakPtr() override {
         return weakFactory.makeWeakPtr();
     }
+
+protected:
+    Mutable<Source::Impl> createMutable() const noexcept final;
+
 private:
     optional<std::string> url;
     std::unique_ptr<AsyncRequest> req;
diff --git a/include/mbgl/style/sources/raster_source.hpp b/include/mbgl/style/sources/raster_source.hpp
index 00a3b788c2..e06c3404e9 100644
--- a/include/mbgl/style/sources/raster_source.hpp
+++ b/include/mbgl/style/sources/raster_source.hpp
@@ -31,6 +31,9 @@ public:
         return weakFactory.makeWeakPtr();
     }
 
+protected:
+    Mutable<Source::Impl> createMutable() const noexcept final;
+
 private:
     const variant<std::string, Tileset> urlOrTileset;
     std::unique_ptr<AsyncRequest> req;
diff --git a/include/mbgl/style/sources/vector_source.hpp b/include/mbgl/style/sources/vector_source.hpp
index 4165af0a61..83fcae95d6 100644
--- a/include/mbgl/style/sources/vector_source.hpp
+++ b/include/mbgl/style/sources/vector_source.hpp
@@ -30,6 +30,9 @@ public:
         return weakFactory.makeWeakPtr();
     }
 
+protected:
+    Mutable<Source::Impl> createMutable() const noexcept final;
+
 private:
     const variant<std::string, Tileset> urlOrTileset;
     std::unique_ptr<AsyncRequest> req;