IronPDFを使用してBlazorでPDFを表示する方法

Install-Package IronPdf

dotnet add package IronPdf

@page "/pdfviewer"
@rendermode 相互の作用Server
@using IronPdf
@inject IJSRuntime JSRuntime
@inject Microsoft.AspNetCore.Hosting.IWebHostEnvironment WebHostEnvironment

<h3>PDF Viewer Component</h3>
<div>
    <button @onclick="LoadPdfDocument">Open File</button>
    <div id="pdfContainer">
        @if (!string.IsNullOrEmpty(pdfUrl))
        {
            <iframe src="@pdfUrl" style="width:100%; height:600px;"></iframe>
        }
    </div>
</div>

@code {
    private string pdfUrl = "";
    private byte[] pdfData = Array.Empty<byte>();

    private async Task LoadPdfDocument()
    {
        var pdfDocument = PdfDocument.FromFile("wwwroot/sample.pdf");
        pdfData = pdfDocument.BinaryData;
        var base64 = Convert.ToBase64String(pdfData);
        pdfUrl = $"data:application/pdf;base64,{base64}";
    }
}

Imports IronPdf
Imports Microsoft.AspNetCore.Hosting
Imports Microsoft.AspNetCore.Components
Imports Microsoft.JSInterop

@page "/pdfviewer"
@rendermode Server

<h3>PDF Viewer Component</h3>
<div>
    <button @onclick="LoadPdfDocument">Open File</button>
    <div id="pdfContainer">
        @If Not String.IsNullOrEmpty(pdfUrl) Then
            <iframe src="@pdfUrl" style="width:100%; height:600px;"></iframe>
        End If
    </div>
</div>

@code {
    Private pdfUrl As String = ""
    Private pdfData As Byte() = Array.Empty(Of Byte)()

    Private Async Function LoadPdfDocument() As Task
        Dim pdfDocument = PdfDocument.FromFile("wwwroot/sample.pdf")
        pdfData = pdfDocument.BinaryData
        Dim base64 = Convert.ToBase64String(pdfData)
        pdfUrl = $"data:application/pdf;base64,{base64}"
    End Function
}

@page "/pdf-jsinterop"
@rendermode 相互の作用Server
@using IronPdf
@inject IJSRuntime JSRuntime
@inject Microsoft.AspNetCore.Hosting.IWebHostEnvironment WebHostEnvironment
@implements IAsyncDisposable

<h3>IronPDF JavaScript Interop Viewer</h3>
<p>Displays PDF using JavaScript Blob/ObjectURL capabilities.</p>

@if (!string.IsNullOrEmpty(ErrorMessage))
{
    <div class="alert alert-danger">Error: @ErrorMessage</div>
}

<div id="@documentId" style="border: 1px solid #ccc; width: 100%; min-height: 600px;">
    Loading PDF...
</div>

@code {
    private string documentId = Guid.NewGuid().ToString();
    private string ErrorMessage = string.Empty;
    private bool pdfLoaded = false;
    private IJSObjectReference? jsModule;

    protected override async Task OnAfterRenderAsync(bool firstRender)
    {
        if (firstRender && !pdfLoaded)
        {
            try
            {
                jsModule = await JSRuntime.InvokeAsync<IJSObjectReference>(
                    "import", "./pdfViewerInterop.js");
                await LoadPdfWithJavaScript();
                pdfLoaded = true;
            }
            catch (Exception ex)
            {
                ErrorMessage = $"Failed to load JS module: {ex.Message}";
            }
            finally
            {
                StateHasChanged();
            }
        }
    }

    private async Task LoadPdfWithJavaScript()
    {
        if (jsModule is null) return;
        var pdfPath = Path.Combine(WebHostEnvironment.WebRootPath, "sample.pdf");
        if (!File.Exists(pdfPath))
        {
            ErrorMessage = $"File not found: {pdfPath}";
            return;
        }
        var pdf = PdfDocument.FromFile(pdfPath);
        await jsModule.InvokeVoidAsync("displayPdf", documentId, pdf.BinaryData);
    }

    public async ValueTask DisposeAsync()
    {
        if (jsModule is not null)
            await jsModule.DisposeAsync();
    }
}

Imports System
Imports System.IO
Imports System.Threading.Tasks
Imports Microsoft.AspNetCore.Components
Imports Microsoft.JSInterop
Imports IronPdf
Imports Microsoft.AspNetCore.Hosting

@page "/pdf-jsinterop"
@rendermode Server
@inject IJSRuntime JSRuntime
@inject IWebHostEnvironment WebHostEnvironment
@implements IAsyncDisposable

<h3>IronPDF JavaScript Interop Viewer</h3>
<p>Displays PDF using JavaScript Blob/ObjectURL capabilities.</p>

@if Not String.IsNullOrEmpty(ErrorMessage) Then
    <div class="alert alert-danger">Error: @ErrorMessage</div>
End If

<div id="@documentId" style="border: 1px solid #ccc; width: 100%; min-height: 600px;">
    Loading PDF...
</div>

@code {
    Private documentId As String = Guid.NewGuid().ToString()
    Private ErrorMessage As String = String.Empty
    Private pdfLoaded As Boolean = False
    Private jsModule As IJSObjectReference

    Protected Overrides Async Function OnAfterRenderAsync(firstRender As Boolean) As Task
        If firstRender AndAlso Not pdfLoaded Then
            Try
                jsModule = Await JSRuntime.InvokeAsync(Of IJSObjectReference)(
                    "import", "./pdfViewerInterop.js")
                Await LoadPdfWithJavaScript()
                pdfLoaded = True
            Catch ex As Exception
                ErrorMessage = $"Failed to load JS module: {ex.Message}"
            Finally
                StateHasChanged()
            End Try
        End If
    End Function

    Private Async Function LoadPdfWithJavaScript() As Task
        If jsModule Is Nothing Then Return
        Dim pdfPath = Path.Combine(WebHostEnvironment.WebRootPath, "sample.pdf")
        If Not File.Exists(pdfPath) Then
            ErrorMessage = $"File not found: {pdfPath}"
            Return
        End If
        Dim pdf = PdfDocument.FromFile(pdfPath)
        Await jsModule.InvokeVoidAsync("displayPdf", documentId, pdf.BinaryData)
    End Function

    Public Async Function DisposeAsync() As ValueTask Implements IAsyncDisposable.DisposeAsync
        If jsModule IsNot Nothing Then
            Await jsModule.DisposeAsync()
        End If
    End Function
}

export function displayPdf(elementId, data) {
    const blob = new Blob([new Uint8Array(data)], { type: 'application/pdf' });
    const url = URL.createObjectURL(blob);
    const container = document.getElementById(elementId);
    if (!container) return;
    container.innerHTML = '';
    const iframe = document.createElement('iframe');
    iframe.src = url;
    iframe.style.width = '100%';
    iframe.style.height = '600px';
    iframe.style.border = 'none';
    container.appendChild(iframe);
}

The provided code is JavaScript, not C#. Therefore, it cannot be directly converted to VB.NET, as VB.NET is a server-side language and JavaScript is a client-side language. If you have C# code that you need converted to VB.NET, please provide that code for conversion.

private async Task LoadFromUrl(string url)
{
    using var client = new HttpClient();
    client.Timeout = TimeSpan.FromSeconds(30);
    var response = await client.GetAsync(url);
    response.EnsureSuccessStatusCode();
    var stream = await response.Content.ReadAsStreamAsync();
    var pdfDocument = new PdfDocument(stream);
    await DisplayPdfContent(pdfDocument);
}

private async Task LoadFromHtmlContent()
{
    var renderer = new ChromePdfRenderer();
    var htmlContent = "<h1>Generated PDF</h1><p>Dynamic content from Blazor.</p>";
    var pdfDocument = renderer.RenderHtmlAsPdf(htmlContent);
    await DisplayPdfContent(pdfDocument);
}

private Task DisplayPdfContent(PdfDocument document)
{
    var data = document.BinaryData;
    pdfUrl = $"data:application/pdf;base64,{Convert.ToBase64String(data)}";
    return Task.CompletedTask;
}

Imports System
Imports System.Net.Http
Imports System.Threading.Tasks

Private Async Function LoadFromUrl(url As String) As Task
    Using client As New HttpClient()
        client.Timeout = TimeSpan.FromSeconds(30)
        Dim response = Await client.GetAsync(url)
        response.EnsureSuccessStatusCode()
        Dim stream = Await response.Content.ReadAsStreamAsync()
        Dim pdfDocument As New PdfDocument(stream)
        Await DisplayPdfContent(pdfDocument)
    End Using
End Function

Private Async Function LoadFromHtmlContent() As Task
    Dim renderer As New ChromePdfRenderer()
    Dim htmlContent As String = "<h1>Generated PDF</h1><p>Dynamic content from Blazor.</p>"
    Dim pdfDocument = renderer.RenderHtmlAsPdf(htmlContent)
    Await DisplayPdfContent(pdfDocument)
End Function

Private Function DisplayPdfContent(document As PdfDocument) As Task
    Dim data = document.BinaryData
    pdfUrl = $"data:application/pdf;base64,{Convert.ToBase64String(data)}"
    Return Task.CompletedTask
End Function

@code {
    private int currentPage = 1;
    private int totalPages;
    private byte[] pdfData = Array.Empty<byte>();
    private string pdfUrl = "";
    private string rotationClass = "";
    private string documentId = Guid.NewGuid().ToString();

    private async Task NavigateToPage(int page)
    {
        currentPage = page;
        await JSRuntime.InvokeVoidAsync("navigateTo", page);
    }

    private void RotateCounterclockwise()
    {
        rotationClass = "rotate-270";
    }

    private async Task PrintPdf()
    {
        await JSRuntime.InvokeVoidAsync("printDocument", documentId);
    }

    private async Task DownloadPdf()
    {
        await JSRuntime.InvokeVoidAsync("downloadFile", pdfData, "document.pdf");
    }
}

Imports System

Public Class CodeBehind
    Private currentPage As Integer = 1
    Private totalPages As Integer
    Private pdfData As Byte() = Array.Empty(Of Byte)()
    Private pdfUrl As String = ""
    Private rotationClass As String = ""
    Private documentId As String = Guid.NewGuid().ToString()

    Private Async Function NavigateToPage(page As Integer) As Task
        currentPage = page
        Await JSRuntime.InvokeVoidAsync("navigateTo", page)
    End Function

    Private Sub RotateCounterclockwise()
        rotationClass = "rotate-270"
    End Sub

    Private Async Function PrintPdf() As Task
        Await JSRuntime.InvokeVoidAsync("printDocument", documentId)
    End Function

    Private Async Function DownloadPdf() As Task
        Await JSRuntime.InvokeVoidAsync("downloadFile", pdfData, "document.pdf")
    End Function
End Class

private async Task ProcessFormFields()
{
    var pdfDocument = PdfDocument.FromFile("form.pdf");

    foreach (var field in pdfDocument.Form.Fields)
    {
        if (field.Type == PdfFormFieldType.Text)
        {
            field.Value = "User Input";
        }
    }

    await DisplayPdfContent(pdfDocument);
}

private async Task SaveFormData()
{
    var pdfWithFormData = PdfDocument.FromFile("filled-form.pdf");
    var formData = pdfWithFormData.Form.Fields
        .ToDictionary(f => f.Name, f => f.Value);

    var json = System.Text.Json.JsonSerializer.Serialize(formData);
    await File.WriteAllTextAsync("form-data.json", json);

    pdfWithFormData.Form.Flatten();
    pdfWithFormData.SaveAs("form-submission.pdf");
}

Imports System.IO
Imports System.Threading.Tasks
Imports System.Text.Json

Private Async Function ProcessFormFields() As Task
    Dim pdfDocument = PdfDocument.FromFile("form.pdf")

    For Each field In pdfDocument.Form.Fields
        If field.Type = PdfFormFieldType.Text Then
            field.Value = "User Input"
        End If
    Next

    Await DisplayPdfContent(pdfDocument)
End Function

Private Async Function SaveFormData() As Task
    Dim pdfWithFormData = PdfDocument.FromFile("filled-form.pdf")
    Dim formData = pdfWithFormData.Form.Fields.ToDictionary(Function(f) f.Name, Function(f) f.Value)

    Dim json = JsonSerializer.Serialize(formData)
    Await File.WriteAllTextAsync("form-data.json", json)

    pdfWithFormData.Form.Flatten()
    pdfWithFormData.SaveAs("form-submission.pdf")
End Function

private async Task LoadLargePdf()
{
    const int chunkSize = 1024 * 1024; // 1MB chunks
    var pdfPath = "largefile.pdf";

    using var fileStream = File.OpenRead(pdfPath);
    var buffer = new byte[chunkSize];
    var chunks = new List<byte[]>();
    int bytesRead;

    while ((bytesRead = await fileStream.ReadAsync(buffer)) > 0)
    {
        var chunk = new byte[bytesRead];
        Array.Copy(buffer, chunk, bytesRead);
        chunks.Add(chunk);
    }

    await ProcessPdfChunks(chunks);
}

Imports System.IO
Imports System.Threading.Tasks

Private Async Function LoadLargePdf() As Task
    Const chunkSize As Integer = 1024 * 1024 ' 1MB chunks
    Dim pdfPath As String = "largefile.pdf"

    Using fileStream As FileStream = File.OpenRead(pdfPath)
        Dim buffer(chunkSize - 1) As Byte
        Dim chunks As New List(Of Byte())()
        Dim bytesRead As Integer

        Do
            bytesRead = Await fileStream.ReadAsync(buffer, 0, buffer.Length)
            If bytesRead > 0 Then
                Dim chunk(bytesRead - 1) As Byte
                Array.Copy(buffer, chunk, bytesRead)
                chunks.Add(chunk)
            End If
        Loop While bytesRead > 0
    End Using

    Await ProcessPdfChunks(chunks)
End Function

private async Task LoadSecurePdf(string password)
{
    var pdfDocument = PdfDocument.FromFile("secure.pdf", password);

    var headers = new Dictionary<string, string>
    {
        { "X-Frame-Options", "SAMEORIGIN" },
        { "Content-セキュリティ-Policy", "default-src 'self'" },
        { "X-Content-Type-Options", "nosniff" },
        { "Referrer-Policy", "no-referrer" }
    };

    await DisplayPdfContent(pdfDocument);
}

Imports System.Collections.Generic
Imports System.Threading.Tasks

Private Async Function LoadSecurePdf(password As String) As Task
    Dim pdfDocument = PdfDocument.FromFile("secure.pdf", password)

    Dim headers As New Dictionary(Of String, String) From {
        {"X-Frame-Options", "SAMEORIGIN"},
        {"Content-セキュリティ-Policy", "default-src 'self'"},
        {"X-Content-Type-Options", "nosniff"},
        {"Referrer-Policy", "no-referrer"}
    }

    Await DisplayPdfContent(pdfDocument)
End Function