Introduce FPS counter on the bottom right

src/frontend/EmuThread.cpp

@@ -1,14 +1,22 @@
 #include <Core.hpp>
 #include <EmuThread.hpp>
 
-EmuThread::EmuThread(const std::shared_ptr<n64::Core> &core, RenderWidget &renderWidget,
-                     SettingsWindow &settings) noexcept : renderWidget(renderWidget), core(core), settings(settings) {}
+EmuThread::EmuThread(const std::shared_ptr<n64::Core> &core, QLabel &fps, RenderWidget &renderWidget,
+                     SettingsWindow &settings) noexcept :
+    renderWidget(renderWidget), core(core), settings(settings), fps(fps) {}
 
 void EmuThread::run() noexcept {
   core->parallel.Init(renderWidget.qtVkInstanceFactory, renderWidget.wsiPlatform, renderWidget.windowInfo,
                       core->cpu->GetMem().GetRDRAMPtr());
 
+  auto lastSample = std::chrono::high_resolution_clock::now();
+  auto avgFps = 16.667;
+  auto sampledFps = 0;
+
+  fps.setText(fmt::format("{:.2f} FPS", 1000.0 / avgFps).c_str());
+
   while (!isInterruptionRequested()) {
+    const auto startFrameTime = std::chrono::high_resolution_clock::now();
     if (!core->pause) {
       core->Run(settings.getVolumeL(), settings.getVolumeR());
     }
@@ -16,6 +24,21 @@ void EmuThread::run() noexcept {
     if (core->render) {
       core->parallel.UpdateScreen(core->cpu->GetMem().mmio.vi);
     }
+
+    const auto endFrameTime = std::chrono::high_resolution_clock::now();
+    using namespace std::chrono_literals;
+    const auto frameTimeMs = std::chrono::duration<double>(endFrameTime - startFrameTime) / 1ms;
+    avgFps += frameTimeMs;
+
+    sampledFps++;
+
+    if (const auto elapsedSinceLastSample = std::chrono::duration<double>(endFrameTime - lastSample) / 1s;
+        elapsedSinceLastSample >= 1.0) {
+      lastSample = endFrameTime;
+      avgFps /= sampledFps;
+      sampledFps = 0;
+      fps.setText(fmt::format("{:.2f} FPS", 1000.0 / avgFps).c_str());
+    }
   }
 
   SetRender(false);

src/frontend/EmuThread.hpp

@@ -14,7 +14,7 @@ class EmuThread final : public QThread {
   RenderWidget &renderWidget;
 
 public:
-  explicit EmuThread(const std::shared_ptr<n64::Core> &, RenderWidget &, SettingsWindow &) noexcept;
+  explicit EmuThread(const std::shared_ptr<n64::Core> &, QLabel &, RenderWidget &, SettingsWindow &) noexcept;
 
   void run() noexcept override;
   void TogglePause() const noexcept;
@@ -24,4 +24,5 @@ public:
 
   std::shared_ptr<n64::Core> core;
   SettingsWindow &settings;
+  QLabel &fps;
 };

src/frontend/KaizenQt.cpp

@@ -11,7 +11,7 @@ KaizenQt::KaizenQt() noexcept : QWidget(nullptr) {
   core = std::make_shared<n64::Core>();
   mainWindow = std::make_unique<MainWindow>(core);
   settingsWindow = std::make_unique<SettingsWindow>();
-  emuThread = std::make_unique<EmuThread>(core, *mainWindow->vulkanWidget, *settingsWindow);
+  emuThread = std::make_unique<EmuThread>(core, *mainWindow->fpsCounter, *mainWindow->vulkanWidget, *settingsWindow);
   debugger = std::make_unique<Debugger>();
 
   ConnectMainWindowSignalsToSlots();
@@ -40,7 +40,7 @@ void KaizenQt::ConnectMainWindowSignalsToSlots() noexcept {
   connect(mainWindow.get(), &MainWindow::OpenROM, this, &KaizenQt::LoadROM);
   connect(mainWindow.get(), &MainWindow::Exit, this, &KaizenQt::Quit);
   connect(mainWindow.get(), &MainWindow::Reset, emuThread.get(), &EmuThread::Reset);
-  connect(mainWindow.get(), &MainWindow::Stop, emuThread.get(), &EmuThread::Stop);
+  connect(mainWindow.get(), &MainWindow::Stop, this, [this] { emuThread->requestInterruption(); });
   connect(mainWindow.get(), &MainWindow::Pause, emuThread.get(), &EmuThread::TogglePause);
 }
 

src/frontend/MainWindow.cpp

@@ -1,4 +1,5 @@
 #include <MainWindow.hpp>
+#include <QLabel>
 
 MainWindow::MainWindow(const std::shared_ptr<n64::Core> &core) noexcept {
   if (objectName().isEmpty())
@@ -48,6 +49,8 @@ MainWindow::MainWindow(const std::shared_ptr<n64::Core> &core) noexcept {
   setMenuBar(menubar.get());
   statusbar = std::make_unique<QStatusBar>(this);
   statusbar->setObjectName("statusbar");
+  fpsCounter = std::make_unique<QLabel>("Not playing");
+  statusbar->addPermanentWidget(fpsCounter.get());
   setStatusBar(statusbar.get());
 
   menubar->addAction(menuFile->menuAction());

src/frontend/MainWindow.hpp

@@ -35,6 +35,7 @@ public:
   std::unique_ptr<QMenu> menuTools{};
   std::unique_ptr<QMenu> menuAbout{};
   std::unique_ptr<QStatusBar> statusbar{};
+  std::unique_ptr<QLabel> fpsCounter{};
 
 private:
   void Retranslate();