[android] renderer frontend - add mutex to guard update parameters

- solves a bunch of crashes
- solves the flikkering issue when zooming with pinch gestures

2 files changed, 20 insertions, 3 deletions

diff --git a/platform/android/src/android_renderer_frontend.cpp b/platform/android/src/android_renderer_frontend.cpp
index 73cb0a817e..6ad7872f89 100644
--- a/platform/android/src/android_renderer_frontend.cpp
+++ b/platform/android/src/android_renderer_frontend.cpp
@@ -98,14 +98,27 @@ void AndroidRendererFrontend::setObserver(RendererObserver& observer) {
 }
 
 void AndroidRendererFrontend::update(std::shared_ptr<UpdateParameters> params) {
-    updateParameters = std::move(params);
+    {
+        // Lock on the parameters
+        std::lock_guard<std::mutex> lock(updateMutex);
+        updateParameters = std::move(params);
+    }
     asyncInvalidate.send();
 }
 
 // Called on OpenGL thread
 void AndroidRendererFrontend::render() {
     assert (renderer);
-    if (!updateParameters) return;
+
+    std::shared_ptr<UpdateParameters> params;
+    {
+        // Lock on the parameters
+        std::unique_lock<std::mutex> lock(updateMutex);
+        if (!updateParameters) return;
+
+        // Hold on to the update parameters during render
+        params = updateParameters;
+    }
 
     // Activate the backend
     BackendScope backendGuard { *backend };
@@ -122,7 +135,7 @@ void AndroidRendererFrontend::render() {
         framebufferSizeChanged = false;
     }
 
-    rendererGuard.object().render(*updateParameters);
+    rendererGuard.object().render(*params);
 }
 
 void AndroidRendererFrontend::onLowMemory() {
diff --git a/platform/android/src/android_renderer_frontend.hpp b/platform/android/src/android_renderer_frontend.hpp
index ca7c27b196..36db705f2e 100644
--- a/platform/android/src/android_renderer_frontend.hpp
+++ b/platform/android/src/android_renderer_frontend.hpp
@@ -70,7 +70,11 @@ private:
     std::unique_ptr<AndroidRendererBackend> backend;
     std::unique_ptr<util::Thread<Renderer>> renderer;
     std::unique_ptr<RendererObserver> rendererObserver;
+
+    std::mutex updateMutex;
     std::shared_ptr<UpdateParameters> updateParameters;
+
+
     util::AsyncTask asyncInvalidate;
 
     util::RunLoop* mapRunLoop;