[android] Make AndroidRendererFrontend to request render once per event loop (#12586)

When AndroidRendererFrontend::update() called multiple times in a single loop, updateAsyncTask->send() will perform nothing, thus MapRenderer::update()/requestRender() will be coalesced.

5 files changed, 34 insertions, 3 deletions

diff --git a/platform/android/MapboxGLAndroidSDKTestApp/src/main/java/com/mapbox/mapboxsdk/testapp/activity/style/RuntimeStyleActivity.java b/platform/android/MapboxGLAndroidSDKTestApp/src/main/java/com/mapbox/mapboxsdk/testapp/activity/style/RuntimeStyleActivity.java
index f49d80d704..20fa2e7d52 100644
--- a/platform/android/MapboxGLAndroidSDKTestApp/src/main/java/com/mapbox/mapboxsdk/testapp/activity/style/RuntimeStyleActivity.java
+++ b/platform/android/MapboxGLAndroidSDKTestApp/src/main/java/com/mapbox/mapboxsdk/testapp/activity/style/RuntimeStyleActivity.java
@@ -197,6 +197,9 @@ public class RuntimeStyleActivity extends AppCompatActivity {
       case R.id.action_numeric_filter:
         styleNumericFillLayer();
         return true;
+      case R.id.action_bring_water_to_front:
+        bringWaterToFront();
+        return true;
       default:
         return super.onOptionsItemSelected(item);
     }
@@ -572,6 +575,16 @@ public class RuntimeStyleActivity extends AppCompatActivity {
     }, 2000);
   }
 
+  private void bringWaterToFront() {
+    Layer water = mapboxMap.getLayer("water");
+    if (water != null) {
+      mapboxMap.removeLayer(water);
+      mapboxMap.addLayerAt(water, mapboxMap.getLayers().size() - 1);
+    } else {
+      Toast.makeText(this, "No water layer in this style", Toast.LENGTH_SHORT).show();
+    }
+  }
+
   private static class DefaultCallback implements MapboxMap.CancelableCallback {
 
     @Override
diff --git a/platform/android/MapboxGLAndroidSDKTestApp/src/main/res/menu/menu_runtime_style.xml b/platform/android/MapboxGLAndroidSDKTestApp/src/main/res/menu/menu_runtime_style.xml
index 5c77179272..e3d7c8cfa0 100644
--- a/platform/android/MapboxGLAndroidSDKTestApp/src/main/res/menu/menu_runtime_style.xml
+++ b/platform/android/MapboxGLAndroidSDKTestApp/src/main/res/menu/menu_runtime_style.xml
@@ -66,4 +66,8 @@
         android:id="@+id/action_numeric_filter"
         android:title="@string/apply_numeric_fill_filter"
         mapbox:showAsAction="never" />
+    <item
+        android:id="@+id/action_bring_water_to_front"
+        android:title="@string/bring_water_to_front"
+        mapbox:showAsAction="never" />
 </menu>
diff --git a/platform/android/MapboxGLAndroidSDKTestApp/src/main/res/values/actions.xml b/platform/android/MapboxGLAndroidSDKTestApp/src/main/res/values/actions.xml
index 6d94c03529..e3cdc06dc1 100644
--- a/platform/android/MapboxGLAndroidSDKTestApp/src/main/res/values/actions.xml
+++ b/platform/android/MapboxGLAndroidSDKTestApp/src/main/res/values/actions.xml
@@ -79,6 +79,7 @@
     <string name="apply_filtered_fill">Apply filtered fill</string>
     <string name="apply_filtered_line">Apply filtered line</string>
     <string name="apply_numeric_fill_filter">Apply numeric fill filter</string>
+    <string name="bring_water_to_front">Bring water to front</string>
     <string name="toggle_text_size">Toggle text size</string>
     <string name="toggle_text_field_contents">Toggle text field contents</string>
     <string name="toggle_text_font">Toggle text font</string>
diff --git a/platform/android/src/android_renderer_frontend.cpp b/platform/android/src/android_renderer_frontend.cpp
index 2a03d9de9e..8b4a25a4d9 100644
--- a/platform/android/src/android_renderer_frontend.cpp
+++ b/platform/android/src/android_renderer_frontend.cpp
@@ -4,6 +4,7 @@
 #include <mbgl/renderer/renderer.hpp>
 #include <mbgl/renderer/renderer_observer.hpp>
 #include <mbgl/storage/file_source.hpp>
+#include <mbgl/util/async_task.hpp>
 #include <mbgl/util/thread.hpp>
 #include <mbgl/util/run_loop.hpp>
 
@@ -56,7 +57,11 @@ private:
 
 AndroidRendererFrontend::AndroidRendererFrontend(MapRenderer& mapRenderer_)
         : mapRenderer(mapRenderer_)
-        , mapRunLoop(util::RunLoop::Get()) {
+        , mapRunLoop(util::RunLoop::Get())
+        , updateAsyncTask(std::make_unique<util::AsyncTask>([this]() {
+              mapRenderer.update(std::move(updateParams));
+              mapRenderer.requestRender();
+          })) {
 }
 
 AndroidRendererFrontend::~AndroidRendererFrontend() = default;
@@ -73,8 +78,8 @@ void AndroidRendererFrontend::setObserver(RendererObserver& observer) {
 }
 
 void AndroidRendererFrontend::update(std::shared_ptr<UpdateParameters> params) {
-    mapRenderer.update(std::move(params));
-    mapRenderer.requestRender();
+    updateParams = std::move(params);
+    updateAsyncTask->send();
 }
 
 void AndroidRendererFrontend::reduceMemoryUse() {
diff --git a/platform/android/src/android_renderer_frontend.hpp b/platform/android/src/android_renderer_frontend.hpp
index b61904e388..9bd64e4819 100644
--- a/platform/android/src/android_renderer_frontend.hpp
+++ b/platform/android/src/android_renderer_frontend.hpp
@@ -18,6 +18,12 @@ namespace mbgl {
 class RenderedQueryOptions;
 class SourceQueryOptions;
 
+namespace util {
+
+class AsyncTask;
+
+} // namespace util
+
 namespace android {
 
 class AndroidRendererFrontend : public RendererFrontend {
@@ -44,6 +50,8 @@ public:
 private:
     MapRenderer& mapRenderer;
     util::RunLoop* mapRunLoop;
+    std::unique_ptr<util::AsyncTask> updateAsyncTask;
+    std::shared_ptr<UpdateParameters> updateParams;
 };
 
 } // namespace android