From a30d031a9c7c6f52c52c90512d5a03e9d533395d Mon Sep 17 00:00:00 2001
From: itsmattkc <itsmattkc@gmail.com>
Date: Mon, 15 Mar 2021 11:34:09 +1100
Subject: [PATCH] improved FPS counter

Shows real frame update time rather than refresh time
---
 app/widget/viewer/viewer.cpp        |  8 +++--
 app/widget/viewer/viewerdisplay.cpp | 47 ++++++++++++++++++++---------
 app/widget/viewer/viewerdisplay.h   | 13 +++++---
 3 files changed, 46 insertions(+), 22 deletions(-)

diff --git a/app/widget/viewer/viewer.cpp b/app/widget/viewer/viewer.cpp
index 3dbd0e83e..f16f9793f 100644
--- a/app/widget/viewer/viewer.cpp
+++ b/app/widget/viewer/viewer.cpp
@@ -428,9 +428,12 @@ void ViewerWidget::UpdateTextureFromNode(const rational& time)
         PopOldestFrameFromPlaybackQueue();
         if (popped) {
           // We've already popped a frame in this loop, meaning a frame has been skipped
-          display_widget_->SetSkippedFrames(display_widget_->GetSkippedFrames()+1);
+          display_widget_->IncrementSkippedFrames();
+        } else {
+          // Shown a frame and progressed to the next one
+          display_widget_->IncrementFrameCount();
+          popped = true;
         }
-        popped = true;
 
       }
     }
@@ -492,7 +495,6 @@ void ViewerWidget::PlayInternal(int speed, bool in_to_out_only)
 
   playback_speed_ = speed;
   play_in_to_out_only_ = in_to_out_only;
-  display_widget_->SetSkippedFrames(0);
 
   playback_queue_next_frame_ = ruler()->GetTime();
 
diff --git a/app/widget/viewer/viewerdisplay.cpp b/app/widget/viewer/viewerdisplay.cpp
index 7af1a1f64..192059b5a 100644
--- a/app/widget/viewer/viewerdisplay.cpp
+++ b/app/widget/viewer/viewerdisplay.cpp
@@ -55,6 +55,9 @@ ViewerDisplayWidget::ViewerDisplayWidget(QWidget *parent) :
 
   // Initializes cursor based on tool
   UpdateCursor();
+
+  const int kFrameRateAverageCount = 8;
+  frame_rate_averages_.resize(kFrameRateAverageCount);
 }
 
 ViewerDisplayWidget::~ViewerDisplayWidget()
@@ -187,6 +190,8 @@ void ViewerDisplayWidget::ResetFPSTimer()
 {
   fps_timer_start_ = QDateTime::currentMSecsSinceEpoch();
   fps_timer_update_count_ = 0;
+  frames_skipped_ = 0;
+  frame_rate_average_count_ = 0;
 }
 
 void ViewerDisplayWidget::mousePressEvent(QMouseEvent *event)
@@ -357,22 +362,36 @@ void ViewerDisplayWidget::OnPaint()
     p.drawLines(lines, 2);
   }
 
-  fps_timer_update_count_++;
   if (show_fps_) {
-    QPainter p(inner_widget());
-    qint64 now = QDateTime::currentMSecsSinceEpoch();
-    double frame_rate;
-    if (now == fps_timer_start_) {
-      // This will cause a divide by zero, so we do nothing here
-      frame_rate = 0;
-    } else {
-      frame_rate = double(fps_timer_update_count_) / double((now - fps_timer_start_)/1000.0);
-    }
-    DrawTextWithCrudeShadow(&p, inner_widget()->rect(), tr("%1 FPS").arg(QString::number(frame_rate, 'f', 2)));
+    {
+      qint64 now = QDateTime::currentMSecsSinceEpoch();
+      double frame_rate;
+      if (now == fps_timer_start_) {
+        // This will cause a divide by zero, so we do nothing here
+        frame_rate = 0;
+      } else {
+        frame_rate = double(fps_timer_update_count_) / double((now - fps_timer_start_)/1000.0);
+      }
 
-    if (frames_skipped_ > 0) {
-      DrawTextWithCrudeShadow(&p, inner_widget()->rect().adjusted(0, p.fontMetrics().height(), 0, 0),
-                              tr("%1 frames skipped").arg(frames_skipped_));
+      frame_rate_averages_[frame_rate_average_count_%frame_rate_averages_.size()] = frame_rate;
+      frame_rate_average_count_++;
+    }
+
+    if (frame_rate_average_count_ >= frame_rate_averages_.size()) {
+      QPainter p(inner_widget());
+
+      double average = 0.0;
+      for (int i=0; i<frame_rate_averages_.size(); i++) {
+        average += frame_rate_averages_[i];
+      }
+      average /= double(frame_rate_averages_.size());
+
+      DrawTextWithCrudeShadow(&p, inner_widget()->rect(), tr("%1 FPS").arg(QString::number(average, 'f', 1)));
+
+      if (frames_skipped_ > 0) {
+        DrawTextWithCrudeShadow(&p, inner_widget()->rect().adjusted(0, p.fontMetrics().height(), 0, 0),
+                                tr("%1 frames skipped").arg(frames_skipped_));
+      }
     }
   }
 }
diff --git a/app/widget/viewer/viewerdisplay.h b/app/widget/viewer/viewerdisplay.h
index 20b75a06f..e00af4af9 100644
--- a/app/widget/viewer/viewerdisplay.h
+++ b/app/widget/viewer/viewerdisplay.h
@@ -91,14 +91,14 @@ public:
     return show_fps_;
   }
 
-  int GetSkippedFrames() const
+  void IncrementSkippedFrames()
   {
-    return frames_skipped_;
+    frames_skipped_++;
   }
 
-  void SetSkippedFrames(int i)
+  void IncrementFrameCount()
   {
-    frames_skipped_ = i;
+    fps_timer_update_count_++;
   }
 
 public slots:
@@ -268,11 +268,14 @@ private:
   bool deinterlace_;
 
   qint64 fps_timer_start_;
-  qint64 fps_timer_update_count_;
+  int fps_timer_update_count_;
 
   bool show_fps_;
   int frames_skipped_;
 
+  QVector<double> frame_rate_averages_;
+  int frame_rate_average_count_;
+
 private slots:
   void EmitColorAtCursor(QMouseEvent* e);