GlobalKeyboardCapture.Maui 1.0.2

GlobalKeyboardCapture.Maui

A powerful .NET MAUI library for global keyboard capture with strong support for barcode scanners. Provides system-wide key interception, hotkeys management.

Demo application showing key capture, barcode scanning, and hotkeys functionality

Features

• 🔑 Global keyboard capture
• 📊 Advanced keyboard input processing
• 🏷️ Built-in barcode scanner support
• ⌨️ Customizable hotkeys system
• 📱 Cross-platform (Windows & Android)
• 🎛️ Highly configurable
• 🧩 Easy to integrate
• 🔧 Built for .NET MAUI

Common Use Cases

• Barcode scanner integration
• Global hotkeys and shortcuts
• System-wide keyboard monitoring
• Custom keyboard input handling
• Input automation
• Multi-mode keyboard capture

Full key support:

• Standard keys (A-Z, 0-9)
• Function keys (F1-F24)
• Modifier keys (Ctrl, Alt, Shift)
• Windows OEM keys (;, /, [, ], etc)
• Android special keys (Volume, Back, Menu)
• Navigation keys
• Special characters

Installation

dotnet add package GlobalKeyboardCapture.Maui

Or via the NuGet Package Manager:

Install-Package GlobalKeyboardCapture.Maui

Quick Start

1. Register the service in your MauiProgram.cs:

public static MauiApp CreateMauiApp()
{
    var builder = MauiApp.CreateBuilder();
    builder
        .UseMauiApp<App>()
        .UseKeyboardHandling();

    builder.Services.AddKeyboardHandling(options =>
    {
        // Barcode specific settings
        options.BarcodeTimeout = 150;
        options.MinBarcodeLength = 8;
    });

    return builder.Build();
}

2. Basic usage example:

public partial class MainPage : ContentPage
{
    private readonly IKeyHandlerService _keyHandlerService;
    private readonly BarcodeHandler _barcodeHandler;
    private readonly HotkeyHandler _hotkeyHandler;

    public MainPage(
        IKeyHandlerService keyHandlerService, 
        BarcodeHandler barcodeHandler,
        HotkeyHandler hotkeyHandler)
    {
        InitializeComponent();
        
        _keyHandlerService = keyHandlerService;
        _barcodeHandler = barcodeHandler;
        _hotkeyHandler = hotkeyHandler;
        
        SetupHandlers();
    }

    private void SetupHandlers()
    {
        // Setup barcode handling
        _barcodeHandler.BarcodeScanned += (sender, input) =>
        {
            MainThread.BeginInvokeOnMainThread(() =>
            {
                ProcessInput(input);
            });
        };

        // Setup global hotkeys
        _hotkeyHandler.RegisterHotkey("F2", () =>
        {
            EnableEditMode();
        });

        // Register handlers
        _keyHandlerService.RegisterHandler(_barcodeHandler);           
        _keyHandlerService.RegisterHandler(_hotkeyHandler);
    }
}

Advanced Usage

Custom Key Handler

Create your own key handler for specific needs:

public class CustomKeyHandler : IKeyHandler
{
    public bool ShouldHandle(string key) => true;

    public void HandleKey(string key)
    {
        // Your custom key handling logic
    }
}

Global Hotkeys

The library features a smart hotkey normalization system that allows flexible registration of keyboard shortcuts:

// Single key hotkeys
_hotkeyHandler.RegisterHotkey("F2", EnableEditMode);
_hotkeyHandler.RegisterHotkey("ESC", CancelOperation);

// All these registrations trigger the same hotkey (Ctrl+Alt+Shift+P)
_hotkeyHandler.RegisterHotkey("Ctrl+Alt+Shift+P", PrintAction);
_hotkeyHandler.RegisterHotkey("Shift+Ctrl+Alt+P", PrintAction);
_hotkeyHandler.RegisterHotkey("Alt+Shift+Control+P", PrintAction);

// Supports common aliases
_hotkeyHandler.RegisterHotkey("Control+Alt+P", PrintAction);  // "Control" is normalized to "Ctrl"
_hotkeyHandler.RegisterHotkey("Windows+Shift+X", ActionX);    // "Windows" is normalized to "Win"

// Case-insensitive handling
_hotkeyHandler.RegisterHotkey("CTRL+ALT+P", PrintAction);
_hotkeyHandler.RegisterHotkey("ctrl+alt+p", PrintAction);

//Special keys
_hotkeyHandler.RegisterHotkey("VolumeUp", VolumeControlAction); //Android Volume Up
_hotkeyHandler.RegisterHotkey("OEM173", VolumeControlAction); //OEM 173

The hotkey system provides:

• Automatic normalization of modifier order (Ctrl → Alt → Shift → Win)
• Case-insensitive handling
• Common alias support (e.g., "Control" → "Ctrl")
• Consistent behavior regardless of registration order
• High-performance implementation with minimal allocations

Barcode Scanner Mode

_barcodeHandler.BarcodeScanned += (sender, input) =>
{    
    ProcessProduct(input); 
};

Performance Optimizations

The library is optimized for performance and efficiency:

• Minimal Allocations: Uses modern .NET features to minimize garbage collection pressure
• Fast Lookups: Optimized dictionary implementations for hotkey matching
• Efficient String Handling: Smart string comparison and normalization
• Aggressive Inlining: Critical paths are optimized for speed
• Memory Efficiency: Careful management of memory allocations in hot paths

Key Features

Global Key Capture

• Capture keyboard input regardless of focus
• Works with all UI controls
• System-wide key interception

Input Processing

• Configurable input timeout
• Input validation and filtering
• Custom processing rules

Platform Support

• Windows desktop applications
• Android mobile applications
• Consistent API across platforms

API Reference

Core Services

• IKeyHandlerService: Main service for global keyboard handling
• BarcodeHandler: Specialized handler for barcode input scenarios
• HotkeyHandler: Global hotkeys management

Interfaces

• IKeyHandler: Base interface for custom handlers
• ILifecycleHandler: Application lifecycle management

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

License

This project is licensed under the MIT License - see the LICENSE file for details.

Author

Anderson Fernandes do Nascimento

Support

If you encounter any issues or need help, please open an issue.