Substitute nudgeTransitions with async view invalidation

android/cpp/native_map_view.cpp

@@ -712,7 +712,6 @@ void NativeMapView::onInvalidate() {
         map.setSourceTileCacheSize(cacheSize);
 
         map.renderSync();
-        map.nudgeTransitions();
     }
 }
 

include/mbgl/map/map.hpp

@@ -69,9 +69,6 @@ public:
     // Triggers a synchronous render.
     void renderSync();
 
-    // Nudges transitions one step, possibly notifying of the need for a rerender, if any.
-    void nudgeTransitions();
-
     // Notifies the Map thread that the state has changed and an update might be necessary.
     void update(Update update);
 

platform/default/glfw_view.cpp

@@ -352,7 +352,6 @@ void GLFWView::run() {
             if (benchmark) {
                 map->setNeedsRepaint();
             }
-            map->nudgeTransitions();
         }
     }
 }

platform/ios/MGLMapView.mm

@@ -724,8 +724,6 @@ std::chrono::steady_clock::duration secondsAsDuration(float duration)
         _mbglMap->renderSync();
 
         [self updateUserLocationAnnotationView];
-
-        _mbglMap->nudgeTransitions();
     }
 }
 

src/mbgl/map/map.cpp

@@ -55,6 +55,7 @@ void Map::renderSync() {
 
     view.notifyMapChange(MapChangeWillStartRenderingFrame);
 
+    const Update flags = transform->updateTransitions(Clock::now());
     const bool fullyLoaded = context->invokeSync<bool>(
             &MapContext::renderSync, transform->getState(), FrameData { view.getFramebufferSize() });
 
@@ -68,14 +69,12 @@ void Map::renderSync() {
         renderState = RenderState::fully;
         view.notifyMapChange(MapChangeDidFinishRenderingMapFullyRendered);
     }
-}
 
-void Map::nudgeTransitions() {
-    Update flags = transform->updateTransitions(Clock::now());
-    if (data->getNeedsRepaint()) {
-        flags |= Update::Repaint;
+    // Triggers an asynchronous update, that eventually triggers a view
+    // invalidation, causing renderSync to be called again if in transition.
+    if (transform->inTransition()) {
+        update(flags);
     }
-    update(flags);
 }
 
 void Map::update(Update flags) {

src/mbgl/map/map_context.cpp

@@ -256,6 +256,8 @@ void MapContext::update() {
 
     if (!style) {
         updateFlags = Update::Nothing;
+    } else if (data.getNeedsRepaint()) {
+        updateFlags |= Update::Repaint;
     }
 
     if (updateFlags == Update::Nothing || (data.mode == MapMode::Still && !callback)) {
@@ -347,7 +349,12 @@ bool MapContext::renderSync(const TransformState& state, const FrameData& frame)
 
     view.afterRender();
 
-    data.setNeedsRepaint(style->hasTransitions() || painter->needsAnimation());
+    if (style->hasTransitions() || painter->needsAnimation()) {
+        data.setNeedsRepaint(true);
+        asyncUpdate->send();
+    } else {
+        data.setNeedsRepaint(false);
+    }
 
     return isLoaded();
 }

src/mbgl/map/transform.cpp

@@ -386,6 +386,10 @@ void Transform::startTransition(std::function<Update(double)> frame,
     transitionFinishFn = finish;
 }
 
+bool Transform::inTransition() const {
+    return transitionFrameFn != nullptr;
+}
+
 Update Transform::updateTransitions(const TimePoint& now) {
     return transitionFrameFn ? transitionFrameFn(now) : Update::Nothing;
 }

src/mbgl/map/transform.hpp

@@ -46,6 +46,7 @@ public:
     double getPitch() const;
 
     // Transitions
+    bool inTransition() const;
     Update updateTransitions(const TimePoint& now);
     void cancelTransitions();