[desktop] Add basic Frametime/FPS overlay (#3537)

Just displays min, max, avg frametime/fps, alongside a chart of FPS in
the last 30 seconds.

Notes:
- Qt Charts is now required
- FPS/frametime collector now runs 2x as often. TODO: keep status bar at
  500ms, but put perf overlay at 250ms

Signed-off-by: crueter <crueter@eden-emu.dev>

Reviewed-on: https://git.eden-emu.dev/eden-emu/eden/pulls/3537
Reviewed-by: Lizzie <lizzie@eden-emu.dev>
Reviewed-by: MaranBr <maranbr@eden-emu.dev>

1 files changed, 207 insertions, 0 deletions

diff --git a/src/yuzu/render/performance_overlay.cpp b/src/yuzu/render/performance_overlay.cpp
new file mode 100644
index 0000000000..13003dce7b
--- /dev/null
+++ b/src/yuzu/render/performance_overlay.cpp
@@ -0,0 +1,207 @@
+// SPDX-FileCopyrightText: Copyright 2026 Eden Emulator Project
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include "core/perf_stats.h"
+#include "performance_overlay.h"
+#include "ui_performance_overlay.h"
+
+#include "main_window.h"
+
+#include <QChart>
+#include <QChartView>
+#include <QGraphicsLayout>
+#include <QLineSeries>
+#include <QMouseEvent>
+#include <QPainter>
+#include <QValueAxis>
+
+// TODO(crueter): Reset samples when user changes turbo, slow, etc.
+PerformanceOverlay::PerformanceOverlay(MainWindow* parent)
+    : QWidget(parent), m_mainWindow{parent}, ui(new Ui::PerformanceOverlay) {
+    ui->setupUi(this);
+
+    setAttribute(Qt::WA_TranslucentBackground);
+    setWindowFlags(Qt::FramelessWindowHint | Qt::Tool);
+    raise();
+
+    // chart setup
+    m_fpsSeries = new QLineSeries(this);
+
+    QPen pen(Qt::red);
+    pen.setWidth(2);
+    m_fpsSeries->setPen(pen);
+
+    m_fpsChart = new QChart;
+    m_fpsChart->addSeries(m_fpsSeries);
+    m_fpsChart->legend()->hide();
+    m_fpsChart->setBackgroundBrush(Qt::black);
+    m_fpsChart->setBackgroundVisible(true);
+    m_fpsChart->layout()->setContentsMargins(2, 2, 2, 2);
+    m_fpsChart->setMargins(QMargins{4, 4, 4, 4});
+
+    // axes
+    m_fpsX = new QValueAxis(this);
+    m_fpsX->setRange(0, NUM_FPS_SAMPLES);
+    m_fpsX->setVisible(false);
+
+    m_fpsY = new QValueAxis(this);
+    m_fpsY->setRange(0, 60);
+    m_fpsY->setLabelFormat(QStringLiteral("%d"));
+    m_fpsY->setLabelsColor(Qt::white);
+
+    QFont axisFont = m_fpsY->labelsFont();
+    axisFont.setPixelSize(10);
+    m_fpsY->setLabelsFont(axisFont);
+    m_fpsY->setTickCount(3);
+
+    // gray-ish label w/ white lines
+    m_fpsY->setLabelsVisible(true);
+    m_fpsY->setGridLineColor(QColor(50, 50, 50));
+    m_fpsY->setLinePenColor(Qt::white);
+
+    m_fpsChart->addAxis(m_fpsX, Qt::AlignBottom);
+    m_fpsChart->addAxis(m_fpsY, Qt::AlignLeft);
+    m_fpsSeries->attachAxis(m_fpsX);
+    m_fpsSeries->attachAxis(m_fpsY);
+
+    // chart view
+    m_fpsChartView = new QChartView(m_fpsChart, this);
+    m_fpsChartView->setRenderHint(QPainter::Antialiasing);
+    m_fpsChartView->setMinimumHeight(100);
+
+    ui->verticalLayout->addWidget(m_fpsChartView, 1);
+
+    // thanks Debian.
+    QFont font = ui->fps->font();
+    font.setWeight(QFont::DemiBold);
+
+    ui->fps->setFont(font);
+    ui->frametime->setFont(font);
+
+    // pos/stats
+    resetPosition(m_mainWindow->pos());
+    connect(parent, &MainWindow::positionChanged, this, &PerformanceOverlay::resetPosition);
+    connect(m_mainWindow, &MainWindow::statsUpdated, this, &PerformanceOverlay::updateStats);
+}
+
+PerformanceOverlay::~PerformanceOverlay() {
+    delete ui;
+}
+
+void PerformanceOverlay::resetPosition(const QPoint& _) {
+    auto pos = m_mainWindow->pos();
+    move(pos.x() + m_offset.x(), pos.y() + m_offset.y());
+}
+
+void PerformanceOverlay::updateStats(const Core::PerfStatsResults& results,
+                                     const VideoCore::ShaderNotify& shaders) {
+    auto fps = results.average_game_fps;
+    if (!std::isnan(fps)) {
+        // don't sample measurements < 3 fps because they are probably outliers or freezes
+        static constexpr double FPS_SAMPLE_THRESHOLD = 3.0;
+
+        QString fpsText = tr("%1 fps").arg(std::round(fps), 0, 'f', 0);
+        // if (!m_fpsSuffix.isEmpty()) fpsText = fpsText % QStringLiteral(" (%1)").arg(m_fpsSuffix);
+        ui->fps->setText(fpsText);
+
+        // sampling
+        if (fps > FPS_SAMPLE_THRESHOLD) {
+            m_fpsSamples.push_back(fps);
+            m_fpsPoints.push_back(QPointF{m_xPos++, fps});
+        }
+
+        if (m_fpsSamples.size() > NUM_FPS_SAMPLES) {
+            m_fpsSamples.pop_front();
+            m_fpsPoints.pop_front();
+        }
+
+        // For the average only go back 10 samples max
+        if (m_fpsSamples.size() >= 2) {
+            const int back_search = std::min(size_t(10), m_fpsSamples.size() - 1);
+            double sum = std::accumulate(m_fpsSamples.end() - back_search, m_fpsSamples.end(), 0.0);
+            double avg = sum / back_search;
+
+            ui->fps_avg->setText(tr("Avg: %1").arg(avg, 0, 'f', 0));
+        }
+
+        // chart it :)
+        if (!m_fpsPoints.empty()) {
+            auto [min_it, max_it] = std::minmax_element(m_fpsSamples.begin(), m_fpsSamples.end());
+            double min_fps = *min_it;
+            double max_fps = *max_it;
+
+            ui->fps_min->setText(tr("Min: %1").arg(min_fps, 0, 'f', 0));
+            ui->fps_max->setText(tr("Max: %1").arg(max_fps, 0, 'f', 0));
+
+            m_fpsSeries->replace(QList<QPointF>(m_fpsPoints.begin(), m_fpsPoints.end()));
+
+            qreal x_min = std::max(0.0, m_xPos - NUM_FPS_SAMPLES);
+            qreal x_max = std::max(qreal(10), m_xPos);
+            m_fpsX->setRange(x_min, x_max);
+            m_fpsY->setRange(0.0, max_fps);
+        }
+    }
+
+    auto ft = results.frametime;
+    if (!std::isnan(ft)) {
+        // don't sample measurements > 500 ms because they are probably outliers
+        static constexpr double FT_SAMPLE_THRESHOLD = 500.0;
+
+        double ft_ms = results.frametime * 1000.0;
+        ui->frametime->setText(tr("%1 ms").arg(ft_ms, 0, 'f', 2));
+
+        // sampling
+        if (ft_ms <= FT_SAMPLE_THRESHOLD)
+            m_frametimeSamples.push_back(ft_ms);
+
+        if (m_frametimeSamples.size() > NUM_FRAMETIME_SAMPLES)
+            m_frametimeSamples.pop_front();
+
+        if (!m_frametimeSamples.empty()) {
+            auto [min_it, max_it] =
+                std::minmax_element(m_frametimeSamples.begin(), m_frametimeSamples.end());
+            ui->ft_min->setText(tr("Min: %1").arg(*min_it, 0, 'f', 1));
+            ui->ft_max->setText(tr("Max: %1").arg(*max_it, 0, 'f', 1));
+        }
+
+        // For the average only go back 10 samples max
+        if (m_frametimeSamples.size() >= 2) {
+            const int back_search = std::min(size_t(10), m_frametimeSamples.size() - 1);
+            double sum = std::accumulate(m_frametimeSamples.end() - back_search,
+                                         m_frametimeSamples.end(), 0.0);
+            double avg = sum / back_search;
+
+            ui->ft_avg->setText(tr("Avg: %1").arg(avg, 0, 'f', 1));
+        }
+    }
+}
+
+void PerformanceOverlay::paintEvent(QPaintEvent* event) {
+    QPainter painter(this);
+
+    painter.setRenderHint(QPainter::Antialiasing);
+
+    painter.setBrush(m_background);
+    painter.setPen(Qt::NoPen);
+
+    painter.drawRoundedRect(rect(), 10.0, 10.0);
+}
+
+void PerformanceOverlay::mousePressEvent(QMouseEvent* event) {
+    if (event->button() == Qt::LeftButton) {
+        m_drag_start_pos = event->pos();
+    }
+}
+
+void PerformanceOverlay::mouseMoveEvent(QMouseEvent* event) {
+    // drag
+    if (event->buttons() & Qt::LeftButton) {
+        QPoint new_global_pos = event->globalPosition().toPoint() - m_drag_start_pos;
+        m_offset = new_global_pos - m_mainWindow->pos();
+        move(new_global_pos);
+    }
+}
+
+void PerformanceOverlay::closeEvent(QCloseEvent* event) {
+    emit closed();
+}