Qt: Fix FPS counter on Windows

CHANGES

@@ -113,6 +113,7 @@ Bugfixes:
  - Switch: Fix incorrect mapping for fast forward cap
  - GB, GBA: Fix broken opposing button filter (fixes mgba.io/i/1191)
  - Qt: Fix jumbled background when paused
+ - Qt: Fix FPS counter on Windows
 Misc:
  - mGUI: Add SGB border configuration option
  - mGUI: Add support for different settings types

src/platform/qt/Window.cpp

@@ -138,13 +138,11 @@ Window::Window(CoreManager* manager, ConfigController* config, int playerId, QWi
 
 	connect(this, &Window::shutdown, m_logView, &QWidget::hide);
 	connect(&m_fpsTimer, &QTimer::timeout, this, &Window::showFPS);
-	connect(&m_frameTimer, &QTimer::timeout, this, &Window::delimitFrames);
 	connect(&m_focusCheck, &QTimer::timeout, this, &Window::focusCheck);
 	connect(&m_inputController, &InputController::profileLoaded, m_shortcutController, &ShortcutController::loadProfile);
 
 	m_log.setLevels(mLOG_WARN | mLOG_ERROR | mLOG_FATAL);
 	m_fpsTimer.setInterval(FPS_TIMER_INTERVAL);
-	m_frameTimer.setInterval(FRAME_LIST_INTERVAL);
 	m_focusCheck.setInterval(200);
 
 	m_shortcutController->setConfigController(m_config);
@@ -773,7 +771,6 @@ void Window::gameStopped() {
 	m_audioChannels->clear();
 
 	m_fpsTimer.stop();
-	m_frameTimer.stop();
 	m_focusCheck.stop();
 
 	emit paused(false);
@@ -903,19 +900,8 @@ void Window::mustRestart() {
 }
 
 void Window::recordFrame() {
-	if (m_frameList.isEmpty()) {
-		m_frameList.append(1);
-	} else {
-		++m_frameList.back();
-	}
-}
-
-void Window::delimitFrames() {
-	if (m_frameList.size() >= FRAME_LIST_SIZE) {
-		m_frameCounter -= m_frameList.takeAt(0);
-	}
-	m_frameCounter += m_frameList.back();
-	m_frameList.append(0);
+	m_frameList.append(m_frameTimer.nsecsElapsed());
+	m_frameTimer.restart();
 }
 
 void Window::showFPS() {
@@ -923,7 +909,12 @@ void Window::showFPS() {
 		updateTitle();
 		return;
 	}
-	float fps = m_frameCounter * 10000.f / (FRAME_LIST_INTERVAL * (m_frameList.size() - 1));
+	qint64 total = 0;
+	for (qint64 t : m_frameList) {
+		total += t;
+	}
+	double fps = (m_frameList.size() * 1e10) / total;
+	m_frameList.clear();
 	fps = round(fps) / 10.f;
 	updateTitle(fps);
 }
@@ -1655,7 +1646,6 @@ void Window::setupMenu(QMenuBar* menubar) {
 	showFps->connect([this](const QVariant& value) {
 		if (!value.toInt()) {
 			m_fpsTimer.stop();
-			m_frameTimer.stop();
 			updateTitle();
 		} else if (m_controller) {
 			m_fpsTimer.start();

src/platform/qt/Window.h

@@ -7,6 +7,7 @@
 
 #include <QAction>
 #include <QDateTime>
+#include <QElapsedTimer>
 #include <QList>
 #include <QMainWindow>
 #include <QTimer>
@@ -132,7 +133,6 @@ private slots:
 	void mustRestart();
 
 	void recordFrame();
-	void delimitFrames();
 	void showFPS();
 	void focusCheck();
 
@@ -140,8 +140,6 @@ private slots:
 
 private:
 	static const int FPS_TIMER_INTERVAL = 2000;
-	static const int FRAME_LIST_INTERVAL = 100;
-	static const int FRAME_LIST_SIZE = 40;
 
 	void setupMenu(QMenuBar*);
 	void openStateWindow(LoadSave);
@@ -189,10 +187,9 @@ private:
 	QPixmap m_logo{":/res/mgba-1024.png"};
 	ConfigController* m_config;
 	InputController m_inputController;
-	QList<int> m_frameList;
-	int m_frameCounter = 0;
+	QList<qint64> m_frameList;
+	QElapsedTimer m_frameTimer;
 	QTimer m_fpsTimer;
-	QTimer m_frameTimer;
 	QList<QString> m_mruFiles;
 	QMenu* m_mruMenu = nullptr;
 	QMenu* m_videoLayers;