How display PDF file in WinUI 3 Desktop App

I have Desktop aplication in C# Net Core WinUI 3 that encrypt files. I success to decrypt PDF file and now I want to Display the file in my application. I have decrypt PDF file in stream and from this stream I want to display the file in my application without use with another program and without install external program. I need only Display read-only PDF file without edit option. In Addition my App need run in offline mode.

I tried WebView2 but need install WebView2 in computer. I also try convert PDF to Image but i need exteral program. What can I do?

You can use the PdfDocument class to load a PDF file.

Let me show you an example with Drag and Drop feature.

Shell.xaml

<Page
    x:Class="PdfDemo.Shell"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:local="using:PdfDemo"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    Background="{ThemeResource ApplicationPageBackgroundThemeBrush}"
    mc:Ignorable="d">

    <Grid RowDefinitions="Auto,*">
        <Grid
            x:Name="DroppingSpaceGrid"
            Grid.Row="0"
            AllowDrop="True"
            Background="Transparent"
            DragOver="DroppingSpaceGrid_DragOver"
            Drop="DroppingSpaceGrid_Drop">
            <TextBlock
                HorizontalAlignment="Center"
                VerticalAlignment="Center"
                Text="Drop your PDF here." />
        </Grid>
        <GridView
            Grid.Row="1"
            ItemsSource="{x:Bind Pages, Mode=OneWay}">
            <GridView.ItemTemplate>
                <DataTemplate x:DataType="BitmapImage">
                    <Image Source="{x:Bind}" />
                </DataTemplate>
            </GridView.ItemTemplate>
        </GridView>
    </Grid>

</Page>

Shell.xaml.cs

using Microsoft.UI.Xaml;
using Microsoft.UI.Xaml.Controls;
using Microsoft.UI.Xaml.Media.Imaging;
using System;
using System.Collections.ObjectModel;
using System.Linq;
using Windows.ApplicationModel.DataTransfer;
using Windows.Data.Pdf;
using Windows.Storage;
using Windows.Storage.Streams;

namespace PdfDemo;

public sealed partial class Shell : Page
{
    public Shell()
    {
        InitializeComponent();
    }

    private void DroppingSpaceGrid_DragOver(object sender, DragEventArgs e)
    {
        e.AcceptedOperation = DataPackageOperation.Copy;
        e.DragUIOverride.IsCaptionVisible = false;
        e.DragUIOverride.IsGlyphVisible = false;
    }

    private async void DroppingSpaceGrid_Drop(object sender, DragEventArgs e)
    {
        if ((await e.DataView.GetStorageItemsAsync()).FirstOrDefault() is not StorageFile file ||
            file.FileType is not ".pdf")
        {
            return;
        }

        PdfDocument pdfDocument = await PdfDocument.LoadFromFileAsync(file);

        Pages.Clear();

        for (int i = 0; i < pdfDocument.PageCount; i++)
        {
            PdfPage pdfPage = pdfDocument.GetPage((uint)i);
            using var stream = new InMemoryRandomAccessStream();
            await pdfPage.RenderToStreamAsync(stream);
            var bitmapImage = new BitmapImage();
            await bitmapImage.SetSourceAsync(stream);
            Pages.Add(bitmapImage);
        }
    }

    public ObservableCollection<BitmapImage> Pages { get; } = [];
}