.Net Maui Ui Virtualization And Performance Tuning Complete Guide

Table of Contents

1. Introduction to .NET MAUI
2. Understanding UI Virtualization
3. Performance Tuning in .NET MAUI
4. Example: Implementing UI Virtualization for a ListView
5. Advanced Example: Improving Scrolling Performance with Data Binding
6. Additional Tips for Performance Tuning

1. Introduction to .NET MAUI

.NET Multi-platform App UI (MAUI) is a framework for building native mobile and desktop applications from a single codebase using C# and .NET. It allows you to target iOS, Android, macOS, and Windows with one project setup, reducing development time and maintaining consistency across platforms.

2. Understanding UI Virtualization

UI Virtualization is a technique used to optimize performance when displaying large sets of data. Instead of rendering all items at once, UI virtualization only renders the items that are currently visible to the user. This significantly improves the responsiveness of your application, especially during scrolling through lists.

3. Performance Tuning in .NET MAUI

Performance tuning involves several strategies, including but not limited to:

• UI Virtualization: Efficiently rendering visible items only.
• Data Binding Optimization: Minimizing data binding overhead.
• Image Loading and Caching: Ensuring images are loaded quickly and efficiently.
• Avoiding Layout Inflation: Structuring your UI to minimize unnecessary layout calculations.
• Thread Management: Offloading heavy operations to background threads while keeping the UI responsive.

4. Example: Implementing UI Virtualization for a ListView

In .NET MAUI, UI virtualization is generally handled for you automatically when using controls like ListView or CollectionView. However, you can still optimize the way items are rendered and managed within these controls. Below is a step-by-step guide to implementing a ListView with UI virtualization and optimizing performance.

Step 1: Create a New .NET MAUI Project

1. Open Visual Studio.
2. Go to Create a new project.
3. Select .NET MAUI App and click Next.
4. Enter your project name and location and click Next.
5. Configure the project settings (target frameworks, etc.) and click Create.

Step 2: Define Your Data Model

First, we'll create a simple data model class that represents the items we want to display.

public class Person
{
    public string Name { get; set; }
    public int Age { get; set; }
}

Step 3: Create a ViewModel

Next, we'll create a ViewModel that will hold the data collection and any other logic required for our UI.

using System.Collections.ObjectModel;

public class PeopleViewModel
{
    public ObservableCollection<Person> People { get; set; }

    public PeopleViewModel()
    {
        People = new ObservableCollection<Person>();

        // Adding a lot of items to simulate a large dataset
        for (int i = 0; i < 1000; i++)
        {
            People.Add(new Person { Name = $"Person {i + 1}", Age = 20 + i % 10 });
        }
    }
}

Step 4: Create a User Interface (XAML)

Now, we'll create a XAML page for our ListView and bind it to the ViewModel.

<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             x:Class="MauiApp.MainPage"
             xmlns:local="clr-namespace:MauiApp"
             BackgroundColor="{DynamicResource PageBackgroundColor}">

    <ContentPage.BindingContext>
        <local:PeopleViewModel />
    </ContentPage.BindingContext>

    <ListView ItemsSource="{Binding People}"
              HasUnevenRows="True">
        <ListView.ItemTemplate>
            <DataTemplate>
                <ViewCell>
                    <StackLayout Padding="10">
                        <Label Text="{Binding Name}"
                               FontSize="20"
                               FontAttributes="Bold" />
                        <Label Text="{Binding Age}"
                               FontSize="16" />
                    </StackLayout>
                </ViewCell>
            </DataTemplate>
        </ListView.ItemTemplate>
    </ListView>
</ContentPage>

Step 5: Code-Behind (CS) File

In the code-behind file, ensure you have the necessary namespace references.

using Microsoft.Maui.Controls;
using Microsoft.Maui.LifecycleEvents;

namespace MauiApp
{
    public partial class MainPage : ContentPage
    {
        public MainPage()
        {
            InitializeComponent();
        }
    }
}

Step 6: Run Your Application

1. Set your desired target platform (iOS, Android, etc.).
2. Start the debugging session by pressing F5 or clicking the run button in Visual Studio.

You should now see a list with 1000 items, and the ListView efficiently handles UI virtualization for you.

5. Advanced Example: Improving Scrolling Performance with Data Binding

In addition to UI virtualization, there are several practices to enhance the performance of large lists.

Step 1: Create a Custom Cell Template

To help reduce layout inflation, use a grid instead of a stack layout with hardcoded padding for each cell.

<ListView ItemsSource="{Binding People}"
          HasUnevenRows="True">
    <ListView.ItemTemplate>
        <DataTemplate>
            <ViewCell>
                <Grid ColumnSpacing="10" RowSpacing="5">
                    <Grid.ColumnDefinitions>
                        <ColumnDefinition Width="*"/>
                        <ColumnDefinition Width="Auto"/>
                    </Grid.ColumnDefinitions>

                    <Label Grid.Row="0" Grid.Column="0"
                           LineBreakMode="TailTruncation"
                           FontSize="20"
                           FontAttributes="Bold"
                           Text="{Binding Name}" />

                    <Label Grid.Row="0" Grid.Column="1"
                           Text="{Binding Age}"
                           FontSize="16" />

                    <BoxView Grid.RowSpan="2" Grid.Row="0" Grid.Column="0"
                             Color="#eee"
                             HeightRequest="1"/>

                    <BoxView Grid.Row="1" Grid.Column="0" Grid.ColumnSpan="2"
                             Color="#eee"
                             HeightRequest="1"/>
                </Grid>
            </ViewCell>
        </DataTemplate>
    </ListView.ItemTemplate>
</ListView>

Step 2: Enable Recycling for GridViewCell

Ensure recycling of cells is enabled. This is usually handled automatically but good to confirm.

<ListView ItemsSource="{Binding People}"
          HasUnevenRows="True"
          CachingStrategy="RecycleElementAndDataTemplate">
    <ListView.ItemTemplate>
        <DataTemplate>
            <ViewCell>
                <Grid>...</Grid>
            </ViewCell>
        </DataTemplate>
    </ListView.ItemTemplate>
</ListView>

Step 3: Use Asynchronous Data Loading

If your data is loaded asynchronously (e.g., from a web service or database), offload this operation to a background thread and update the UI only once the data is ready.

Modify the ViewModel:

using System.Collections.ObjectModel;
using System.Threading.Tasks;

public class PeopleViewModel
{
    public ObservableCollection<Person> People { get; set; }

    public PeopleViewModel()
    {
        People = new ObservableCollection<Person>();
        LoadDataAsync();
    }

    private async Task LoadDataAsync()
    {
        var peopleList = await GetDataFromApiAsync();

        foreach (var person in peopleList)
        {
            People.Add(person);
        }
    }

    private async Task<List<Person>> GetDataFromApiAsync()
    {
        // Simulate fetching data from an API
        await Task.Delay(1000); // Delay to mimic network latency

        List<Person> result = new List<Person>();

        for (int i = 0; i < 1000; i++)
        {
            result.Add(new Person { Name = $"Person {i + 1}", Age = 20 + i % 10 });
        }

        return result;
    }
}

Step 4: Use Efficient Property Notifications

Implement INotifyPropertyChanged if you need to update individual properties of your data model dynamically.

using System.ComponentModel;

public class Person : INotifyPropertyChanged
{
    private string _name;
    public string Name
    {
        get => _name;
        set
        {
            if (_name != value)
            {
                _name = value;
                OnPropertyChanged(nameof(Name));
            }
        }
    }

    private int _age;
    public int Age
    {
        get => _age;
        set
        {
            if (_age != value)
            {
                _age = value;
                OnPropertyChanged(nameof(Age));
            }
        }
    }

    public event PropertyChangedEventHandler PropertyChanged;

    protected void OnPropertyChanged(string propertyName)
    {
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
    }
}

Step 5: Optimize Image Loading (if applicable)

When dealing with images, use efficient loading and caching mechanisms to prevent memory issues.

Install the FFImageLoading.Forms package via NuGet. Update XAML:

<ListView ItemsSource="{Binding People}"
          HasUnevenRows="True">
    <ListView.ItemTemplate>
        <DataTemplate>
            <ViewCell>
                <Grid ColumnSpacing="10" RowSpacing="5">
                    <Grid.ColumnDefinitions>
                        <ColumnDefinition Width="*"/>
                        <ColumnDefinition Width="Auto"/>
                    </Grid.ColumnDefinitions>
                    
                    <ffimageloading:CachedImage Grid.Row="0" Grid.Column="0"
                                                VerticalOptions="Center"
                                                Source="profile.png"
                                                DownsampleWidth="40"
                                                DownsampleHeight="40"
                                                CachingEnabled="True"
                                                CacheDuration="30d" />
                    
                    <StackLayout Grid.Row="0" Grid.Column="1">
                        <Label Text="{Binding Name}"
                               FontSize="20"
                               FontAttributes="Bold" />
                        <Label Text="{Binding Age}"
                               FontSize="16" />
                    </StackLayout>
                    
                    <!-- Separators -->
                    <BoxView Grid.RowSpan="2" Grid.Row="0" Grid.Column="0"
                             Color="#eee"
                             HeightRequest="1"/>
                    <BoxView Grid.Row="1" Grid.Column="0" Grid.ColumnSpan="2"
                             Color="#eee"
                             HeightRequest="1"/>
                </Grid>
            </ViewCell>
        </DataTemplate>
    </ListView.ItemTemplate>
</ListView>

Adjust namespaces in your XAML:

xmlns:ffimageloading="http://ffimage.loading.com"

Install FFImageLoading:

dotnet add package FFImageLoading.Forms

Step 6: Run Your Application Again

Re-run the application to observe the performance improvements.

6. Additional Tips for Performance Tuning

• Pre-fetching Data: Load data in advance before the user scrolls or interacts with your control.
• Using CollectionView Instead of ListView: CollectionView is the newer, more efficient replacement for ListView. It supports better layout options and automatic virtualization.
• Minimizing Nested Views: Avoid nesting too many views within each cell. Use simpler layouts where possible.
• Offloading Workloads: Move computation-intensive tasks to background threads.
• Profiling Tools: Use profiling tools built into Visual Studio to identify bottlenecks in your application.

Summary

By following the above steps, you can effectively implement UI virtualization in your .NET MAUI application and apply various performance tuning techniques to ensure smooth scrolling and faster response times, especially when dealing with large datasets.

Feel free to experiment and fine-tune these examples based on your specific requirements and application scenarios. Happy coding! 🚀

Further Resources

• .NET MAUI Documentation
• FFImageLoading
• Profiling Applications