.NET MAUI Application - Appsiel Print Manager (APM)

Overview

The UI application is a .NET MAUI (Multi-platform App UI) application that provides a graphical interface for managing APM. It runs on both Windows and Android, with platform-specific features and services. Location: source/UI/ Platforms: Windows, Android Framework: .NET MAUI with .NET 10.0 Entry Point: source/UI/MauiProgram.cs

Purpose

The MAUI application provides:

Printer Management - Configure thermal and dot matrix printers
Scale Management - Configure and monitor serial scales
Template Editor - Create and edit print templates visually
System Logs - View application logs and debugging information
Settings - Configure application behavior
Service Control (Windows) - Start/stop WorkerService
Print Testing - Test print jobs and preview output

Architecture Pattern

The UI follows the MVVM (Model-View-ViewModel) pattern:

MVVM Benefits

Separation of Concerns - UI logic separate from business logic
Testability - ViewModels can be unit tested
Data Binding - Automatic UI updates when data changes
Platform Abstraction - Platform-specific code isolated

MauiProgram.cs - Application Bootstrap

Location: source/UI/MauiProgram.cs

Builder Configuration

public static class MauiProgram
{
    public static MauiApp CreateMauiApp()
    {
        var builder = MauiApp.CreateBuilder();
        builder
            .UseMauiApp<App>()
            .UseMauiCommunityToolkit()
            .ConfigureFonts(fonts =>
            {
                fonts.AddFont("OpenSans-Regular.ttf", "OpenSansRegular");
                fonts.AddFont("OpenSans-Semibold.ttf", "OpenSansSemibold");
            });

#if DEBUG
        builder.Logging.AddDebug();
#endif

        // Service registration...
    }
}

Configuration:

.UseMauiApp<App>() - Sets the main application class
.UseMauiCommunityToolkit() - Adds community toolkit components
.ConfigureFonts() - Registers custom fonts
Debug logging enabled in development

Core Service Registration

Location: source/UI/MauiProgram.cs:32

// Core services (shared with WorkerService)
builder.Services.AddSingleton<ILoggingService, Logger>();
builder.Services.AddSingleton<ISettingsRepository, SettingsRepository>();
builder.Services.AddSingleton<ITemplateRepository, TemplateRepository>();
builder.Services.AddSingleton<ITicketRenderer, TicketRendererService>();
builder.Services.AddSingleton<IEscPosGenerator, EscPosGeneratorService>();
builder.Services.AddSingleton<TcpIpPrinterClient>();

// Dot matrix printer support
builder.Services.AddSingleton<DotMatrixRendererService>();
builder.Services.AddSingleton<EscPGeneratorService>();
builder.Services.AddSingleton<LocalRawPrinterClient>();
builder.Services.AddSingleton<IppPrinterClient>();

builder.Services.AddSingleton<IPrintService, PrintService>();

// Scale services
builder.Services.AddSingleton<IScaleRepository, JsonScaleRepository>();

Platform-Specific Services

Location: source/UI/MauiProgram.cs:50

Windows Platform

#if WINDOWS
builder.Services.AddSingleton<IWorkerServiceManager, WindowsWorkerServiceManager>();
builder.Services.AddSingleton<ITrayAppService, WindowsTrayAppService>();
builder.Services.AddSingleton<IPlatformService, WindowsPlatformService>();

// Scale service for dependency resolution
builder.Services.AddSingleton<IScaleService, SerialScaleService>();

// WebSocket server (for controller mode)
builder.Services.AddSingleton<IWebSocketService, WebSocketServerService>();
#endif

Windows-Specific Features:

IWorkerServiceManager - Control Windows Service (start/stop/status)
ITrayAppService - System tray interaction
WindowsPlatformService - Windows-specific file operations
WebSocketServerService - Can act as server if needed
SerialScaleService - Direct serial port access

Android Platform

#if ANDROID
builder.Services.AddSingleton<IPlatformService, AndroidPlatformService>();
builder.Services.AddSingleton<IWebSocketService, AndroidWebSocketService>();
#endif

Android-Specific Features:

AndroidPlatformService - Android file system operations
AndroidWebSocketService - Runs WebSocket server in-app (no separate service)

ViewModel Registration

Location: source/UI/MauiProgram.cs:68

builder.Services.AddTransient<HomeViewModel>();
builder.Services.AddTransient<PrintersViewModel>();
builder.Services.AddTransient<PrinterDetailViewModel>();
builder.Services.AddTransient<ScalesViewModel>();
builder.Services.AddTransient<ScaleDetailViewModel>();
builder.Services.AddTransient<LogsViewModel>();
builder.Services.AddTransient<SettingsViewModel>();
builder.Services.AddTransient<TemplateEditorViewModel>();

Lifetime: Transient - New instance created each time the page is navigated to

View Registration

Location: source/UI/MauiProgram.cs:77

builder.Services.AddTransient<LoginView>();
builder.Services.AddSingleton<AppShell>();
builder.Services.AddTransient<HomePage>();
builder.Services.AddTransient<PrintersPage>();
builder.Services.AddTransient<ScalesPage>();
builder.Services.AddTransient<ScaleDetailPage>();
builder.Services.AddTransient<SettingsPage>();
builder.Services.AddTransient<TemplateEditorPage>();

Lifetimes:

Pages: Transient - New instance per navigation
AppShell: Singleton - Single shell for app lifetime

Value Converters

Location: source/UI/MauiProgram.cs:86

builder.Services.AddSingleton<InverseBoolConverter>();
builder.Services.AddSingleton<NumericToStringConverter>();
builder.Services.AddSingleton<LogLevelToColorConverter>();

Purpose: Convert data types for XAML data binding

Service Provider Exposure

Location: source/UI/MauiProgram.cs:90

var app = builder.Build();
Services = app.Services;
return app;

public static IServiceProvider Services { get; private set; }

Purpose: Allows static access to services for non-injected scenarios

Application Structure

Folder Organization

UI/
├── Converters/          # Value converters for data binding
├── Models/              # UI-specific models
├── Platforms/           # Platform-specific implementations
│   ├── Android/
│   │   └── Services/
│   └── Windows/
│       └── Services/
├── Resources/           # Images, fonts, styles
├── Services/            # UI-specific services
├── ViewModels/          # MVVM view models
├── Views/               # XAML pages
├── App.xaml             # Application resources
├── AppShell.xaml        # Navigation shell
└── MauiProgram.cs       # Application bootstrap

Key ViewModels

HomeViewModel

Purpose: Dashboard with system status overview Features:

Service status (Windows only)
Quick stats (printer count, scale count)
Recent logs
Quick actions

PrintersViewModel

Purpose: Manage printer configurations Features:

List all configured printers
Add new printer
Edit existing printer
Delete printer
Test print

Dependencies:

IPrintService - Printer operations
ISettingsRepository - Load/save settings
ILoggingService - Logging

PrinterDetailViewModel

Purpose: Configure individual printer settings Properties:

Printer ID, Name
Connection Type (TCP, USB, IPP)
IP Address, Port (for TCP)
Local Printer Name (for USB)
URI (for IPP)
Paper Width
Character Set
Copy-to Printers

Actions:

Save configuration
Test print
Delete printer

ScalesViewModel

Purpose: Manage scale configurations Features:

List all configured scales
Add new scale
Edit existing scale
Delete scale
Start/stop monitoring

Dependencies:

IScaleRepository - Scale configuration
IScaleService - Scale communication

ScaleDetailViewModel

Purpose: Configure individual scale settings Properties:

Scale ID, Name
COM Port
Baud Rate
Data Bits, Parity, Stop Bits
Protocol settings

Real-time Data:

Current weight
Stability indicator
Connection status

Actions:

Save configuration
Start/stop listening
Tare scale

TemplateEditorViewModel

Purpose: Edit print templates Features:

Load template by document type
Visual template editor
Section management (header, items, footer)
Element properties (text, alignment, font)
Save template
Preview rendering

Dependencies:

ITemplateRepository - Template storage
ITicketRenderer - Preview rendering

LogsViewModel

Purpose: View system logs Features:

Live log streaming
Filter by level (Info, Warning, Error)
Search logs
Clear logs
Export logs

Dependencies:

ILoggingService - Log access

SettingsViewModel

Purpose: Application settings Features:

Default paper width
Default encoding
Log level
Auto-start settings (Windows)
Data directory

Platform-Specific Services

Windows Platform Services

WindowsWorkerServiceManager

Purpose: Control the WorkerService Windows Service Interface:

public interface IWorkerServiceManager
{
    Task<ServiceStatus> GetStatusAsync();
    Task StartServiceAsync();
    Task StopServiceAsync();
    Task RestartServiceAsync();
}

Implementation:

Uses System.ServiceProcess.ServiceController
Queries service status
Sends start/stop commands
Requires appropriate permissions

WindowsTrayAppService

Purpose: Interact with TrayApp Features:

Launch TrayApp
Check if TrayApp is running
Send messages to TrayApp

WindowsPlatformService

Purpose: Windows-specific operations Features:

File system access with Windows paths
Registry access
Process management

Android Platform Services

AndroidPlatformService

Purpose: Android-specific operations Features:

Android file system access
Storage permissions
Intent handling

AndroidWebSocketService

Purpose: Run WebSocket server within the Android app Differences from Windows:

No separate service process
Runs in app’s background
Lifecycle tied to app (can be killed by OS)
Requires background service permissions

APM uses Shell Navigation for routing:

AppShell.xaml

<Shell>
    <FlyoutItem Title="Home" Icon="home.png">
        <ShellContent ContentTemplate="{DataTemplate local:HomePage}" />
    </FlyoutItem>
    
    <FlyoutItem Title="Printers" Icon="printer.png">
        <ShellContent ContentTemplate="{DataTemplate local:PrintersPage}" />
    </FlyoutItem>
    
    <FlyoutItem Title="Scales" Icon="scale.png">
        <ShellContent ContentTemplate="{DataTemplate local:ScalesPage}" />
    </FlyoutItem>
    
    <FlyoutItem Title="Templates" Icon="template.png">
        <ShellContent ContentTemplate="{DataTemplate local:TemplateEditorPage}" />
    </FlyoutItem>
    
    <FlyoutItem Title="Logs" Icon="logs.png">
        <ShellContent ContentTemplate="{DataTemplate local:LogsPage}" />
    </FlyoutItem>
    
    <FlyoutItem Title="Settings" Icon="settings.png">
        <ShellContent ContentTemplate="{DataTemplate local:SettingsPage}" />
    </FlyoutItem>
</Shell>

Navigation Methods:

// Navigate to route
await Shell.Current.GoToAsync("//printers");

// Navigate with parameters
await Shell.Current.GoToAsync($"printerdetail?printerId={id}");

// Go back
await Shell.Current.GoToAsync("..");

Data Binding

Example: Printer List Binding

ViewModel:

public class PrintersViewModel : INotifyPropertyChanged
{
    private ObservableCollection<PrinterSettings> _printers;
    
    public ObservableCollection<PrinterSettings> Printers
    {
        get => _printers;
        set
        {
            _printers = value;
            OnPropertyChanged();
        }
    }
    
    public async Task LoadPrintersAsync()
    {
        var printers = await _printService.GetAllPrinterSettingsAsync();
        Printers = new ObservableCollection<PrinterSettings>(printers);
    }
}

View (XAML):

<CollectionView ItemsSource="{Binding Printers}">
    <CollectionView.ItemTemplate>
        <DataTemplate>
            <Frame>
                <StackLayout>
                    <Label Text="{Binding Name}" FontSize="18" FontAttributes="Bold" />
                    <Label Text="{Binding ConnectionType}" />
                    <Label Text="{Binding IpAddress}" />
                </StackLayout>
            </Frame>
        </DataTemplate>
    </CollectionView.ItemTemplate>
</CollectionView>

Dependency Injection in Views

Constructor Injection

public partial class PrintersPage : ContentPage
{
    private readonly PrintersViewModel _viewModel;
    
    public PrintersPage(PrintersViewModel viewModel)
    {
        InitializeComponent();
        _viewModel = viewModel;
        BindingContext = _viewModel;
    }
    
    protected override async void OnAppearing()
    {
        base.OnAppearing();
        await _viewModel.LoadPrintersAsync();
    }
}

Registered in MauiProgram.cs:

builder.Services.AddTransient<PrintersPage>();
builder.Services.AddTransient<PrintersViewModel>();

Community Toolkit Components

APM uses MAUI Community Toolkit for enhanced functionality:

Converters

InverseBoolConverter - Invert boolean values
IsNotNullOrEmptyConverter - Check for null/empty strings

Behaviors

EventToCommandBehavior - Convert events to commands
ValidationBehavior - Input validation

Markup Extensions

TranslateExtension - Localization support

Platform Differences

Windows

Features:

Full access to WorkerService control
System tray integration
All printer connection types (TCP, USB, IPP)
Direct serial port access
Full file system access

Limitations:

Desktop only (no mobile)

Android

Features:

Mobile-friendly UI
TCP printer support
Built-in WebSocket server
Background service

Limitations:

No USB printer support (without OTG adapter)
Limited serial port access
No Windows Service control
File system restrictions
Background service limitations (can be killed by OS)

Deployment

Windows Deployment

Output: UI.exe (self-contained or framework-dependent) Distribution:

MSIX installer (Microsoft Store)
Traditional installer (Inno Setup, WiX)
Portable executable

Requirements:

.NET 10.0 Runtime (if framework-dependent)
Windows 10/11

Android Deployment

Output: com.appsiel.printmanager.apk (or AAB for Play Store) Distribution:

Google Play Store
Direct APK installation (sideloading)

Requirements:

Android 7.0+ (API 24+)
Storage permissions
Network permissions
Background service permissions

Testing

Unit Testing ViewModels

public class PrintersViewModelTests
{
    [Fact]
    public async Task LoadPrinters_PopulatesList()
    {
        // Arrange
        var mockPrintService = new Mock<IPrintService>();
        mockPrintService.Setup(s => s.GetAllPrinterSettingsAsync())
            .ReturnsAsync(new List<PrinterSettings> { /* test data */ });
        
        var viewModel = new PrintersViewModel(mockPrintService.Object);
        
        // Act
        await viewModel.LoadPrintersAsync();
        
        // Assert
        Assert.NotEmpty(viewModel.Printers);
    }
}

UI Testing

MAUI supports UI testing with:

Appium - Cross-platform UI automation
Platform-specific: UITest (iOS), Espresso (Android), WinAppDriver (Windows)

Performance Optimization

Lazy Loading - ViewModels created on-demand
CollectionView - Virtualized list rendering
Async Operations - Non-blocking UI
Image Caching - Reuse loaded images
Compiled Bindings - Faster data binding (when possible)

Next Steps

Worker Service - Background service integration
Core Components - Services and interfaces
System Overview - Complete system architecture

Getting Started

Core Features

Architecture

User Guides

​Overview

​Purpose

​Architecture Pattern

​MVVM Benefits

​MauiProgram.cs - Application Bootstrap

​Builder Configuration

​Core Service Registration

​Platform-Specific Services

​Windows Platform

​Android Platform

​ViewModel Registration

​View Registration

​Value Converters

​Service Provider Exposure

​Application Structure

​Folder Organization

​Key ViewModels

​HomeViewModel

​PrintersViewModel

​PrinterDetailViewModel

​ScalesViewModel

​ScaleDetailViewModel

​TemplateEditorViewModel

​LogsViewModel

​SettingsViewModel

​Platform-Specific Services

​Windows Platform Services

​WindowsWorkerServiceManager

​WindowsTrayAppService

​WindowsPlatformService

​Android Platform Services

​AndroidPlatformService

​AndroidWebSocketService

​Navigation

​AppShell.xaml

​Data Binding

​Example: Printer List Binding

​Dependency Injection in Views

​Constructor Injection

​Community Toolkit Components

​Converters

​Behaviors

​Markup Extensions

​Platform Differences

​Windows

​Android

​Deployment

​Windows Deployment

​Android Deployment

​Testing

​Unit Testing ViewModels

​UI Testing

​Performance Optimization

​Next Steps

Build docs developers (and LLMs) love

Overview

Purpose

Architecture Pattern

MVVM Benefits

MauiProgram.cs - Application Bootstrap

Builder Configuration

Core Service Registration

Platform-Specific Services

Windows Platform

Android Platform

ViewModel Registration

View Registration

Value Converters

Service Provider Exposure

Application Structure

Folder Organization

Key ViewModels

HomeViewModel

PrintersViewModel

PrinterDetailViewModel

ScalesViewModel

ScaleDetailViewModel

TemplateEditorViewModel

LogsViewModel

SettingsViewModel

Platform-Specific Services

Windows Platform Services

WindowsWorkerServiceManager

WindowsTrayAppService

WindowsPlatformService

Android Platform Services

AndroidPlatformService

AndroidWebSocketService

Navigation

AppShell.xaml

Data Binding

Example: Printer List Binding

Dependency Injection in Views

Constructor Injection

Community Toolkit Components

Converters

Behaviors

Markup Extensions

Platform Differences

Windows

Android

Deployment

Windows Deployment

Android Deployment

Testing

Unit Testing ViewModels

UI Testing

Performance Optimization

Next Steps