3 files changed, 25 insertions, 11 deletions

diff --git a/include/mbgl/map/map.hpp b/include/mbgl/map/map.hpp
index 7473a0694a..e77149a4d7 100644
--- a/include/mbgl/map/map.hpp
+++ b/include/mbgl/map/map.hpp
@@ -78,9 +78,10 @@ public:
     // Notifies the Map thread that the state has changed and an update might be necessary.
     using UpdateType = uint32_t;
     enum class Update : UpdateType {
-        Nothing   = 0,
-        StyleInfo = 1 << 0,
-        Debug     = 1 << 1,
+        Nothing                   = 0,
+        StyleInfo                 = 1 << 0,
+        Debug                     = 1 << 1,
+        DefaultTransitionDuration = 1 << 2,
     };
     void triggerUpdate(Update = Update::Nothing);
 
@@ -253,8 +254,6 @@ private:
     std::vector<std::string> classes;
     std::string accessToken;
 
-    std::chrono::steady_clock::duration defaultTransitionDuration;
-
     std::set<util::ptr<StyleSource>> activeSources;
 
     std::atomic<UpdateType> updated;
diff --git a/src/mbgl/map/map.cpp b/src/mbgl/map/map.cpp
index 8d4dd1461d..4ebd4100b9 100644
--- a/src/mbgl/map/map.cpp
+++ b/src/mbgl/map/map.cpp
@@ -649,14 +649,15 @@ std::vector<std::string> Map::getClasses() const {
 }
 
 void Map::setDefaultTransitionDuration(std::chrono::steady_clock::duration duration) {
-    defaultTransitionDuration = duration;
-    if (style) {
-        style->setDefaultTransitionDuration(duration);
-    }
+    assert(Environment::currentlyOn(ThreadType::Main));
+
+    data->setDefaultTransitionDuration(duration);
+    triggerUpdate(Update::DefaultTransitionDuration);
 }
 
 std::chrono::steady_clock::duration Map::getDefaultTransitionDuration() {
-    return defaultTransitionDuration;
+    assert(Environment::currentlyOn(ThreadType::Main));
+    return data->getDefaultTransitionDuration();
 }
 
 void Map::updateSources() {
@@ -753,7 +754,7 @@ void Map::loadStyleJSON(const std::string& json, const std::string& base) {
     style->base = base;
     style->loadJSON((const uint8_t *)json.c_str());
     style->cascadeClasses(classes);
-    style->setDefaultTransitionDuration(defaultTransitionDuration);
+    style->setDefaultTransitionDuration(data->getDefaultTransitionDuration());
 
     const std::string glyphURL = util::mapbox::normalizeGlyphsURL(style->glyph_url, getAccessToken());
     glyphStore->setURL(glyphURL);
@@ -772,6 +773,11 @@ void Map::prepare() {
         assert(painter);
         painter->setDebug(data->getDebug());
     }
+    if (u & static_cast<UpdateType>(Update::DefaultTransitionDuration)) {
+        if (style) {
+            style->setDefaultTransitionDuration(data->getDefaultTransitionDuration());
+        }
+    }
 
     // Update transform transitions.
 
diff --git a/src/mbgl/map/map_data.hpp b/src/mbgl/map/map_data.hpp
index 8efa43911b..972ad34064 100644
--- a/src/mbgl/map/map_data.hpp
+++ b/src/mbgl/map/map_data.hpp
@@ -20,6 +20,7 @@ class MapData {
 public:
     inline MapData() {
         setAnimationTime(std::chrono::steady_clock::time_point::min());
+        setDefaultTransitionDuration(std::chrono::steady_clock::duration::zero());
     }
 
     inline StyleInfo getStyleInfo() const {
@@ -50,12 +51,20 @@ public:
         animationTime = timePoint.time_since_epoch();
     };
 
+    inline std::chrono::steady_clock::duration getDefaultTransitionDuration() const {
+        return defaultTransitionDuration;
+    }
+    inline void setDefaultTransitionDuration(std::chrono::steady_clock::duration duration) {
+        defaultTransitionDuration = duration;
+    };
+
 private:
     mutable std::mutex mtx;
 
     StyleInfo styleInfo;
     std::atomic<uint8_t> debug { false };
     std::atomic<std::chrono::steady_clock::time_point::duration> animationTime;
+    std::atomic<std::chrono::steady_clock::duration> defaultTransitionDuration;
 };
 
 }