[core] LayerManager can disable annotations

At the moment, the annotations implementation in the `mapbox-gl-native`
core is creating concrete layer instances apart from `LayerManager/LayerFactory`
code path.

So, annotations must be disabled if the `LayerManager` implementation does
not provide line, fill or symbol layers (those, used by the annotations).

Note: in future, annotations implementation will be moved from the core to the
platform SDK level(see https://github.com/mapbox/mapbox-plugins-android/tree/master/plugin-annotation)
and `LayerManager` won't need to disable it.

3 files changed, 6 insertions, 0 deletions

diff --git a/platform/android/src/style/layers/layer_manager.cpp b/platform/android/src/style/layers/layer_manager.cpp
index 9f13fa0640..706c5a76a1 100644
--- a/platform/android/src/style/layers/layer_manager.cpp
+++ b/platform/android/src/style/layers/layer_manager.cpp
@@ -100,4 +100,6 @@ LayerManager* LayerManager::get() noexcept {
     return android::LayerManagerAndroid::get();
 }
 
+const bool LayerManager::annotationsEnabled = true;
+
 } // namespace mbgl
diff --git a/platform/darwin/src/MGLStyleLayerManager.mm b/platform/darwin/src/MGLStyleLayerManager.mm
index 90272851c3..bdcc303de5 100644
--- a/platform/darwin/src/MGLStyleLayerManager.mm
+++ b/platform/darwin/src/MGLStyleLayerManager.mm
@@ -78,4 +78,6 @@ LayerManager* LayerManager::get() noexcept {
     return LayerManagerDarwin::get();
 }
 
+const bool LayerManager::annotationsEnabled = true;
+
 } // namespace mbgl
diff --git a/platform/default/layer_manager.cpp b/platform/default/layer_manager.cpp
index 60cd0855b8..32d5cbc0fc 100644
--- a/platform/default/layer_manager.cpp
+++ b/platform/default/layer_manager.cpp
@@ -73,4 +73,6 @@ LayerManager* LayerManager::get() noexcept {
     return &instance;
 }
 
+const bool LayerManager::annotationsEnabled = true;
+
 } // namespace mbgl