Greenshot for Ubuntu/Linux

A port of Greenshot screenshot tool from Windows/.NET 4.8/WinForms to Ubuntu/.NET 8/Avalonia.

Architecture

Original (Windows)

• .NET Framework 4.8
• WinForms (System.Windows.Forms)
• Win32 P/Invoke via Dapplo.Windows.* libraries
• GDI+ screen capture (BitBlt)
• DWM/Aero window capture
• Dapplo.Ini config system (INI files)
• Windows Registry access
• UWP Toast notifications
• COM/OLE clipboard
• log4net logging

Ported (Ubuntu/Linux)

• .NET 8
• Avalonia 11 (XAML-based, GTK backend)
• X11 P/Invoke (libX11.so.6) for screen capture and hotkeys
• SixLabors.ImageSharp for image processing
• SkiaSharp (via Avalonia.Skia) for editor rendering
• JSON config stored in ~/.config/greenshot/
• D-Bus notifications via notify-send
• X11 clipboard via xclip/xsel/wl-clipboard
• Microsoft.Extensions.Logging

Project Structure

src/
├── Greenshot.sln                 # Solution file
├── Directory.Build.props         # Global build settings (targets net8.0)
├── Greenshot.Base/               # Platform-agnostic core
│   ├── Core/                     # ICapture, ICoreConfiguration, enums
│   ├── Interfaces/               # IDestination, IGreenshotPlugin
│   └── Platform/                 # IScreenCaptureProvider, IHotkeyProvider
├── Greenshot.Linux/              # Linux platform implementations
│   ├── X11/X11Api.cs             # X11 P/Invoke declarations (libX11.so.6)
│   ├── X11/X11ScreenCapture.cs  # Screen capture via XGetImage
│   ├── X11/X11HotkeyProvider.cs # Global hotkeys via XGrabKey
│   └── DBus/DbusNotificationService.cs  # notify-send wrapper
├── Greenshot.Editor/             # Avalonia image editor
│   ├── Drawing/Surface.cs        # Avalonia Canvas + SkiaSharp drawing
│   ├── Drawing/*.cs              # Drawing containers (Rect, Ellipse, Arrow, etc.)
│   └── Views/EditorWindow.axaml  # Editor UI
├── Greenshot/                    # Main application
│   ├── App.axaml                 # Avalonia application root
│   ├── Views/CaptureOverlayWindow.axaml  # Fullscreen capture overlay
│   ├── Views/SettingsWindow.axaml
│   ├── Helpers/CaptureHelper.cs  # Capture orchestration
│   ├── Destinations/             # File, Clipboard, Editor destinations
│   └── ViewModels/MainViewModel.cs # Tray icon, hotkey coordination
├── Greenshot.Plugin.Imgur/       # Imgur upload plugin
└── Greenshot.Plugin.Dropbox/     # Dropbox upload plugin

Features Ported

Screen Capture

• Full screen capture (all monitors via X11 XGetImage)
• Region capture (interactive overlay with magnifier)
• Last region repeat
• Window capture (interactive selection)
• Active window capture (X11 _NET_ACTIVE_WINDOW to come)
• Wayland capture (portal API — XWayland fallback works)

Image Editor

• Rectangle annotation
• Ellipse annotation
• Arrow annotation
• Text annotation
• Freehand drawing
• Highlight overlay
• Obfuscate/blur region
• Undo/Redo
• Save (PNG, JPEG, BMP, TIFF)
• Copy to clipboard
• Step labels
• Image effects (blur, brightness, contrast)

System Integration

• System tray (Avalonia TrayIcon → GTK StatusIcon)
• Global hotkeys (X11 XGrabKey; doesn't work on pure Wayland without XWayland)
• Desktop notifications (notify-send)
• Clipboard copy (xclip/xsel/wl-clipboard)
• Wayland global hotkeys (portal API TBD)

Configuration

• JSON config in ~/.config/greenshot/greenshot.json
• Settings UI

Requirements

Runtime

• Ubuntu 22.04+ (or other modern Linux)
• libX11.so.6 (X11 display server or XWayland)
• notify-send (from libnotify-bin) for notifications
• xclip or xsel for clipboard, or wl-clipboard for Wayland

Build

• .NET 8 SDK

# Install dependencies
sudo apt install libnotify-bin xclip

# Build
./build.sh

# Run
./publish/Greenshot

Key Porting Decisions

Aspect	Windows Original	Linux Port
UI Framework	WinForms	Avalonia 11
Screen Capture	GDI BitBlt / DWM	X11 XGetImage
Global Hotkeys	SetWindowsHookEx	X11 XGrabKey
Clipboard	Win32 OLE Clipboard	xclip/wl-clipboard
System Tray	NotifyIcon	Avalonia TrayIcon
Notifications	UWP Toast	notify-send
Config	Dapplo.Ini + %APPDATA%	JSON + ~/.config
Image Processing	System.Drawing (GDI+)	SixLabors.ImageSharp
Editor Rendering	WinForms Control + GDI+	Avalonia + SkiaSharp

Excluded (Windows-only features)

• Microsoft Office integration (Word, Excel, PowerPoint, Outlook, OneNote)
• Confluence plugin (depends on WPF XAML forms)
• OCR features

Upload Plugins

• [] Imgur (anonymous upload)
• [] Dropbox (requires access token)

License

MIT