Xamarin PDF生成器：使用IronPDF構建移動PDF應用

using System.Net.Http;
using System.Text;
using System.Text.Json;

namespace XamarinPdfApp.Services
{
    public class PdfService
    {
        private readonly HttpClient _httpClient;
        private const string ApiUrl = "https://your-api.example.com/api/pdf/generate";

        public PdfService()
        {
            _httpClient = new HttpClient
            {
                Timeout = TimeSpan.FromSeconds(60)
            };
        }

        public async Task<byte[]> GeneratePdfAsync(string htmlContent)
        {
            var payload = new { HtmlContent = htmlContent };
            var json = JsonSerializer.Serialize(payload);
            var content = new StringContent(json, Encoding.UTF8, "application/json");

            var response = await _httpClient.PostAsync(ApiUrl, content);

            if (response.IsSuccessStatusCode)
                return await response.Content.ReadAsByteArrayAsync();

            var error = await response.Content.ReadAsStringAsync();
            throw new InvalidOperationException($"PDF generation failed ({(int)response.StatusCode}): {error}");
        }
    }
}

Imports System.Net.Http
Imports System.Text
Imports System.Text.Json

Namespace XamarinPdfApp.Services
    Public Class PdfService
        Private ReadOnly _httpClient As HttpClient
        Private Const ApiUrl As String = "https://your-api.example.com/api/pdf/generate"

        Public Sub New()
            _httpClient = New HttpClient With {
                .Timeout = TimeSpan.FromSeconds(60)
            }
        End Sub

        Public Async Function GeneratePdfAsync(htmlContent As String) As Task(Of Byte())
            Dim payload = New With {Key .HtmlContent = htmlContent}
            Dim json = JsonSerializer.Serialize(payload)
            Dim content = New StringContent(json, Encoding.UTF8, "application/json")

            Dim response = Await _httpClient.PostAsync(ApiUrl, content)

            If response.IsSuccessStatusCode Then
                Return Await response.Content.ReadAsByteArrayAsync()
            End If

            Dim error = Await response.Content.ReadAsStringAsync()
            Throw New InvalidOperationException($"PDF generation failed ({CInt(response.StatusCode)}): {error}")
        End Function
    End Class
End Namespace

using System.Threading.Tasks;

namespace XamarinPdfApp.Interfaces
{
    public interface ISaveFile
    {
        Task<string> SavePdfAsync(string filename, byte[] pdfData);
    }
}

Imports System.Threading.Tasks

Namespace XamarinPdfApp.Interfaces
    Public Interface ISaveFile
        Function SavePdfAsync(filename As String, pdfData As Byte()) As Task(Of String)
    End Interface
End Namespace

using Foundation;
using QuickLook;
using UIKit;
using XamarinPdfApp.Interfaces;
using Xamarin.Forms;

[assembly: Dependency(typeof(XamarinPdfApp.iOS.SaveFileIOS))]
namespace XamarinPdfApp.iOS
{
    public class SaveFileIOS : ISaveFile
    {
        public async Task<string> SavePdfAsync(string filename, byte[] pdfData)
        {
            var documents = Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments);
            var filePath = System.IO.Path.Combine(documents, filename);
            await System.IO.File.WriteAllBytesAsync(filePath, pdfData);
            return filePath;
        }
    }
}

Imports Foundation
Imports QuickLook
Imports UIKit
Imports XamarinPdfApp.Interfaces
Imports Xamarin.Forms

<Assembly: Dependency(GetType(XamarinPdfApp.iOS.SaveFileIOS))>
Namespace XamarinPdfApp.iOS
    Public Class SaveFileIOS
        Implements ISaveFile

        Public Async Function SavePdfAsync(filename As String, pdfData As Byte()) As Task(Of String) Implements ISaveFile.SavePdfAsync
            Dim documents = Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments)
            Dim filePath = System.IO.Path.Combine(documents, filename)
            Await System.IO.File.WriteAllBytesAsync(filePath, pdfData)
            Return filePath
        End Function
    End Class
End Namespace

public string BuildInvoiceHtml(Invoice invoice)
{
    var rows = string.Join(
        "\n",
        invoice.項目s.Select(i =>
            $"<tr><td>{i.Name}</td><td>{i.Quantity}</td><td>${i.UnitPrice:F2}</td><td>${i.Total:F2}</td></tr>"
        )
    );

    return $@"<!DOCTYPE html>
<html lang='en'>
<head>
<meta charset='UTF-8'>
<style>
  body {{ font-family: Arial, sans-serif; color: #333; margin: 0; padding: 30px; }}
  h1 {{ color: #1a73e8; }}
  table {{ width: 100%; border-collapse: collapse; margin-top: 20px; }}
  th {{ background: #1a73e8; color: #fff; padding: 10px; text-align: left; }}
  td {{ padding: 10px; border-bottom: 1px solid #e0e0e0; }}
  .total {{ font-weight: bold; font-size: 1.1em; text-align: right; margin-top: 15px; }}
</style>
</head>
<body>
  <h1>Invoice #{invoice.Number}</h1>
  <p>Date: {invoice.Date:yyyy-MM-dd} &nbsp;|&nbsp; Due: {invoice.DueDate:yyyy-MM-dd}</p>
  <p>Bill to: <strong>{invoice.ClientName}</strong></p>
  <table>
    <thead><tr><th>項目</th><th>Qty</th><th>Unit Price</th><th>Total</th></tr></thead>
    <tbody>{rows}</tbody>
  </table>
  <p class='total'>Grand Total: ${invoice.GrandTotal:F2}</p>
</body>
</html>";
}

Imports System
Imports System.Linq

Public Function BuildInvoiceHtml(invoice As Invoice) As String
    Dim rows = String.Join(
        vbLf,
        invoice.項目s.Select(Function(i) 
            $"<tr><td>{i.Name}</td><td>{i.Quantity}</td><td>${i.UnitPrice:F2}</td><td>${i.Total:F2}</td></tr>"
        )
    )

    Return $"<!DOCTYPE html>
<html lang='en'>
<head>
<meta charset='UTF-8'>
<style>
  body {{ font-family: Arial, sans-serif; color: #333; margin: 0; padding: 30px; }}
  h1 {{ color: #1a73e8; }}
  table {{ width: 100%; border-collapse: collapse; margin-top: 20px; }}
  th {{ background: #1a73e8; color: #fff; padding: 10px; text-align: left; }}
  td {{ padding: 10px; border-bottom: 1px solid #e0e0e0; }}
  .total {{ font-weight: bold; font-size: 1.1em; text-align: right; margin-top: 15px; }}
</style>
</head>
<body>
  <h1>Invoice #{invoice.Number}</h1>
  <p>Date: {invoice.Date:yyyy-MM-dd} &nbsp;|&nbsp; Due: {invoice.DueDate:yyyy-MM-dd}</p>
  <p>Bill to: <strong>{invoice.ClientName}</strong></p>
  <table>
    <thead><tr><th>項目</th><th>Qty</th><th>Unit Price</th><th>Total</th></tr></thead>
    <tbody>{rows}</tbody>
  </table>
  <p class='total'>Grand Total: ${invoice.GrandTotal:F2}</p>
</body>
</html>"
End Function

[HttpPost("form")]
public async Task<IActionResult> GenerateForm([FromBody] FormRequest request)
{
    var renderer = new ChromePdfRenderer();
    // Render an HTML form template to create an interactive PDF form
    var pdf = await renderer.RenderHtmlAsPdfAsync(request.HtmlTemplate);

    // Fill known values before returning
    var form = pdf.Form;
    foreach (var field in request.FieldValues)
    {
        var pdfField = form.Fields.FirstOrDefault(f => f.Name == field.Key);
        if (pdfField is IronPdf.Forms.PdfFormTextFieldField textField)
            textField.Value = field.Value;
    }

    return File(pdf.BinaryData, "application/pdf", "form.pdf");
}

Imports Microsoft.AspNetCore.Mvc
Imports IronPdf

<HttpPost("form")>
Public Async Function GenerateForm(<FromBody> request As FormRequest) As Task(Of IActionResult)
    Dim renderer As New ChromePdfRenderer()
    ' Render an HTML form template to create an interactive PDF form
    Dim pdf = Await renderer.RenderHtmlAsPdfAsync(request.HtmlTemplate)

    ' Fill known values before returning
    Dim form = pdf.Form
    For Each field In request.FieldValues
        Dim pdfField = form.Fields.FirstOrDefault(Function(f) f.Name = field.Key)
        If TypeOf pdfField Is IronPdf.Forms.PdfFormTextFieldField Then
            Dim textField = DirectCast(pdfField, IronPdf.Forms.PdfFormTextFieldField)
            textField.Value = field.Value
        End If
    Next

    Return File(pdf.BinaryData, "application/pdf", "form.pdf")
End Function

IronPdf.License.LicenseKey = Environment.GetEnvironmentVariable("IRONPDF_LICENSE_KEY")
    ?? throw new InvalidOperationException("IronPDF license key not set.");

Imports System
Imports IronPdf

IronPdf.License.LicenseKey = If(Environment.GetEnvironmentVariable("IRONPDF_LICENSE_KEY"), Throw New InvalidOperationException("IronPDF license key not set."))