Lychee

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A tiny always-on-top floating ball for Windows that shows CPU, memory, network speed, public IP, and latency at a glance. Hover to expand the info panel; move away to collapse. Built with .NET 8 WPF + WinForms. No installer, no background services.

Good for anyone who wants system stats visible without alt-tabbing to Task Manager — remote workers keeping an eye on VPN status, developers running long builds, or anyone who finds full system monitors too heavy.

🚀 Quick start

Download Lychee.exe from Releases, double-click to run. That's it — no installer, no admin rights needed. If the browser warns about the EXE, try the Lychee-v*.zip instead — it usually works.

To close, click ✕ on the panel or right-click the tray icon → Quit.

✨ Features

• 📅 Date & time — refreshes every second
• 🌐 Network speed — auto-selects active adapter, samples up/down rate every second
• 📍 Public IP / location — queries ip-api.com every 20s, shows a toast + tray balloon when the IP changes (optional)
• 💻 CPU usage — per-core utilization via GetSystemTimes, refreshes every second
• 🧠 Memory — RAM and page file stats via GlobalMemoryStatusEx
• ⏱️ Network latency — pings 223.5.5.5 / 1.1.1.1 / 8.8.8.8 every 5s, reports the best RTT
• 🖼️ Frame Performance (v1.2.0) — two modes:
  • Desktop output — samples DWM composition cadence via DwmGetCompositionTimingInfo, shows FPS + display refresh rate
  • Foreground app — launches PresentMon 2.5.1 to capture per-process frame presents, reports current FPS, 60s average, 1% low, and frame range. Requires administrator privileges or membership in Performance Log Users group

Each module can be toggled on/off individually in Settings.

Frame Performance modes

Frame Performance has two modes:

• Desktop output — samples the Windows DWM composition cadence. It does not require PresentMon.
• Foreground app — uses the bundled PresentMon_x64.exe to capture frame presents from the selected application. Keep Lychee.exe and PresentMon_x64.exe in the same directory when using a release build.

Foreground app mode requires administrator privileges or membership in the Windows Performance Log Users group. If the bundled executable is not found, Lychee can only use a compatible PresentMon installation found in the NVIDIA FrameView or Intel PresentMon directories; otherwise the mode reports that PresentMon was not found. The bundled executable is excluded from single-file embedding and must remain a separate file.

What's new

Version	Change	Detail
v1.4.0	???	Nothing happened (?)
v1.3.0	🧲 Snap to edge	Floating ball snaps to the nearest screen edge after dragging (toggle in Settings)
v1.2.0	🖼️ Frame Performance	No longer experimental

Full history: CHANGELOG

🖱️ Usage

• 👆 Hover the ball to expand the panel; move away to collapse
• ✋ Drag the ball anywhere across monitors — the panel flips direction based on screen position
• 👆👆 Double-click the ball to pin/unpin the panel
• 📌 Pin — keep the panel open even when the mouse leaves
• ⚙️ Settings — open the settings window
• ◀️ Collapse — force-close the panel
• ❌ Quit — exit Lychee
• 📋 Tray icon — right-click for Show/Hide, Settings, Quit; double-click to toggle visibility

When the public IP changes (possible VPN drop or network switch), a red toast pops up in the bottom-right corner with a tray balloon showing old and new IPs.

🔧 Build

Requires .NET SDK 8.0+ with WPF and WinForms workloads.

dotnet build -c Release
dotnet publish -c Release -r win-x64

Output: bin\Release\net8.0-windows\win-x64\publish\Lychee.exe (self-contained, double-click to run).

🏗️ Architecture

Lychee/
├── Core/                       # Core abstractions
│   ├── IInfoModule.cs          # Module interface + InfoModuleBase
│   ├── ModuleManager.cs        # Module registration / lifecycle
│   ├── SettingsService.cs      # JSON settings persistence
│   ├── TrayIconService.cs      # System tray icon
│   └── IpChangedEventArgs.cs   # IP change event
├── Modules/                    # Built-in modules
│   ├── DateTimeModule.cs
│   ├── NetworkSpeedModule.cs
│   ├── PublicIpModule.cs
│   ├── CpuModule.cs
│   ├── MemoryModule.cs
│   ├── LatencyModule.cs
│   └── FpsModule.cs            # v1.2.0 · Frame Performance
├── Core/
│   ├── FrameMetrics.cs         # Frame monitoring types & interfaces
│   ├── DwmFrameMetricsSource.cs
│   ├── PresentMonFrameMetricsSource.cs
│   ├── ForegroundProcessProvider.cs
│   └── ...

🔌 Module interface

public interface IInfoModule : IDisposable
{
    string Id { get; }              // unique id
    string DisplayName { get; }     // list label
    string Icon { get; }            // Segoe MDL2 Assets glyph
    bool IsEnabled { get; set; }    // user toggle
    string CurrentValue { get; }    // current value (data-bound)
    string? Detail { get; }         // optional secondary line
    event EventHandler? ValueChanged;
    void Start();
    void Stop();
}

📦 Adding a module

1. Inherit InfoModuleBase, implement Start() / Stop(), and set CurrentValue when data updates:

using Lychee.Core;

public sealed class WeatherModule : InfoModuleBase
{
    public override string Id => "weather";
    public override string DisplayName => "Weather";
    public override string Icon => "";

    private PeriodicTimer? _timer;
    private CancellationTokenSource? _cts;

    public override void Start()
    {
        _cts = new CancellationTokenSource();
        _timer = new PeriodicTimer(TimeSpan.FromMinutes(10));
        _ = Task.Run(async () =>
        {
            await QueryAsync(_cts.Token);
            while (await _timer.WaitForNextTickAsync(_cts.Token))
                await QueryAsync(_cts.Token);
        });
    }

    private async Task QueryAsync(CancellationToken ct)
    {
        // ... fetch data ...
        CurrentValue = "Shanghai 26°C Sunny";
    }

    public override void Stop()
    {
        _cts?.Cancel();
        _timer?.Dispose();
    }
}

2. Register in MainWindow.xaml.cs:

_moduleManager.RegisterModule(new WeatherModule());

3. Rebuild. The module appears in the info panel and settings toggle list automatically — no UI changes needed.

⚙️ Settings

%AppData%\Lychee\settings.json

{
  "AlwaysShowPanel": false,
  "AlertOnIpChange": true,
  "AlertOnQueryFailure": true,
  "ShowTrayIcon": true,
  "SnapToEdge": false,
  "FloatingBallSize": 56,
  "ModuleEnabled": {
    "datetime": true,
    "network-speed": true,
    "public-ip": true,
    "cpu": true,
    "memory": true,
    "latency": true,
    "fps": true
  }
}

⚠️ Known limitations

• Some exclusive fullscreen games may still cover the ball despite topmost
• Public IP may show as IP-only (no city/country) when the geo lookup returns empty
• Some antivirus software may flag Lychee.exe as a false positive due to P/Invoke, COM interop, and the bundled PresentMon tool. The source code is fully open — you can inspect and build it yourself, or add an exclusion for Lychee if needed

🤝 Community

• Contributing guide
• Code of Conduct
• Security policy

📄 License

Lychee is licensed under the MIT License.

The bundled PresentMon component is distributed under its own license. See PresentMon-LICENSE.txt.