refresh frame rate reporting

Author: Chris Yang

shell/common/animator.cc

@@ -133,9 +133,10 @@ void Animator::BeginFrame(
   // We have acquired a valid continuation from the pipeline and are ready
   // to service potential frame.
   FML_DCHECK(producer_continuation_);
+  const fml::TimePoint vsync_start_time =
+      frame_timings_recorder_->GetVsyncStartTime();
   fml::tracing::TraceEventAsyncComplete(
-      "flutter", "VsyncSchedulingOverhead",
-      frame_timings_recorder_->GetVsyncStartTime(),
+      "flutter", "VsyncSchedulingOverhead", vsync_start_time,
       frame_timings_recorder_->GetBuildStartTime());
   const fml::TimePoint frame_target_time =
       frame_timings_recorder_->GetVsyncTargetTime();
@@ -144,7 +145,8 @@ void Animator::BeginFrame(
     TRACE_EVENT2("flutter", "Framework Workload", "mode", "basic", "frame",
                  FrameParity());
     uint64_t frame_number = frame_timings_recorder_->GetFrameNumber();
-    delegate_.OnAnimatorBeginFrame(frame_target_time, frame_number);
+    delegate_.OnAnimatorBeginFrame(vsync_start_time, frame_target_time,
+                                   frame_number);
   }
 
   if (!frame_scheduled_ && has_rendered_) {

shell/common/animator.h

@@ -31,7 +31,8 @@ class Animator final {
  public:
   class Delegate {
    public:
-    virtual void OnAnimatorBeginFrame(fml::TimePoint frame_target_time,
+    virtual void OnAnimatorBeginFrame(fml::TimePoint vsync_start_time,
+                                      fml::TimePoint frame_target_time,
                                       uint64_t frame_number) = 0;
 
     virtual void OnAnimatorNotifyIdle(int64_t deadline) = 0;

shell/common/animator_unittests.cc

@@ -20,7 +20,8 @@ namespace testing {
 
 class FakeAnimatorDelegate : public Animator::Delegate {
  public:
-  void OnAnimatorBeginFrame(fml::TimePoint frame_target_time,
+  void OnAnimatorBeginFrame(fml::TimePoint vsync_start_time,
+                            fml::TimePoint frame_target_time,
                             uint64_t frame_number) override {}
 
   void OnAnimatorNotifyIdle(int64_t deadline) override {

shell/common/display_manager.cc

@@ -32,6 +32,13 @@ void DisplayManager::HandleDisplayUpdates(
       FML_CHECK(displays_.empty());
       displays_ = std::move(displays);
       return;
+    case DisplayUpdateType::kNewFrame:
+      displays_.insert(displays_.end(),
+                       std::make_move_iterator(displays.begin()),
+                       std::make_move_iterator(displays.end()));
+      FML_DLOG(ERROR) << "display updated "
+                      << displays_.back()->GetRefreshRate();
+      break;
     default:
       FML_CHECK(false) << "Unknown DisplayUpdateType.";
   }

shell/common/display_manager.h

@@ -20,7 +20,11 @@ enum class DisplayUpdateType {
   ///    1. The frame buffer hardware is connected.
   ///    2. The display is drawable, e.g. it isn't being mirrored from another
   ///       connected display or sleeping.
-  kStartup
+  kStartup,
+
+  /// The `flutter::Display` that were active and a new frame requests an
+  /// update.
+  kNewFrame,
 };
 
 /// Manages lifecycle of the connected displays. This class is thread-safe.

shell/common/shell.cc

@@ -1059,11 +1059,27 @@ void Shell::OnPlatformViewSetNextFrameCallback(const fml::closure& closure) {
 }
 
 // |Animator::Delegate|
-void Shell::OnAnimatorBeginFrame(fml::TimePoint frame_target_time,
+void Shell::OnAnimatorBeginFrame(fml::TimePoint vsync_start_time,
+                                 fml::TimePoint frame_target_time,
                                  uint64_t frame_number) {
   FML_DCHECK(is_setup_);
   FML_DCHECK(task_runners_.GetUITaskRunner()->RunsTasksOnCurrentThread());
 
+  auto is_frame_rate_same = [](double fr1, double fr2) {
+    const double kRefreshRateCompareEpsilon = 1;
+    return fabs(fr1 - fr2) < kRefreshRateCompareEpsilon;
+  };
+
+  double new_frame_rate =
+      round((1 / (frame_target_time - vsync_start_time).ToSecondsF()));
+  if (!is_frame_rate_same(frame_rate_, new_frame_rate)) {
+    frame_rate_ = new_frame_rate;
+    std::vector<std::unique_ptr<flutter::Display>> displays;
+    displays.push_back(std::make_unique<flutter::Display>(frame_rate_));
+    OnDisplayUpdates(flutter::DisplayUpdateType::kNewFrame,
+                     std::move(displays));
+  }
+
   // record the target time for use by rasterizer.
   {
     std::scoped_lock time_recorder_lock(time_recorder_mutex_);

shell/common/shell.h

@@ -565,7 +565,8 @@ class Shell final : public PlatformView::Delegate,
       AssetResolver::AssetResolverType type) override;
 
   // |Animator::Delegate|
-  void OnAnimatorBeginFrame(fml::TimePoint frame_target_time,
+  void OnAnimatorBeginFrame(fml::TimePoint vsync_start_time,
+                            fml::TimePoint frame_target_time,
                             uint64_t frame_number) override;
 
   // |Animator::Delegate|
@@ -690,6 +691,11 @@ class Shell final : public PlatformView::Delegate,
   fml::WeakPtrFactory<Shell> weak_factory_;
   friend class testing::ShellTest;
 
+  // Indicates the current frame_rate_.
+  //
+  // Every new frame may update this value if necessary.
+  double frame_rate_ = -1;
+
   FML_DISALLOW_COPY_AND_ASSIGN(Shell);
 };
 

shell/common/vsync_waiter.h

@@ -75,6 +75,7 @@ class VsyncWaiter : public std::enable_shared_from_this<VsyncWaiter> {
   std::mutex callback_mutex_;
   Callback callback_;
   std::unordered_map<uintptr_t, fml::closure> secondary_callbacks_;
+  double frame_rate_ = -1;
 
   void PauseDartMicroTasks();
   static void ResumeDartMicroTasks(fml::TaskQueueId ui_task_queue_id);