如何在 Itextsharp c# 中使用 Base64 图像

Question

在此代码片段中，我用它来将 HTML 转换为 PDF，然后再转换回

MemoryStream

。

private MemoryStream createPDF(string html)
{
    try
    {
        MemoryStream msOutput = new MemoryStream();
        TextReader reader = new StringReader(html);

        Document document = new Document(PageSize.A4, 30, 30, 30, 30);

        PdfWriter writer = PdfWriter.GetInstance(document, msOutput);

        HTMLWorker worker = new HTMLWorker(document);

        document.Open();
        worker.StartDocument();

        worker.Parse(reader); //error occurs in here
        
        worker.EndDocument();
        worker.Close();
        document.Close();
        var bytedata = msOutput.ToArray();
        var pdfContent = new MemoryStream(bytedata);
        return pdfContent;
    }
    catch (Exception ex)
    {

        throw;
    }
}

但是当 HTML 内容包含 Base64 图像时。我在这一行中收到此错误 (

worker.Parse(reader);

)。

The URI prefix is not recognized.

我做了几个解决方法，并且知道发生这种情况是因为可以解释

itextsharp

的 URI 必须没有数据前缀。我该如何解决这个问题？

Answer 1

您好，我已经在 base64 中实现了图像的小型管理（对我来说来自 html 上传，所以我也删除了标签）。我报告解决方案，同时知道您将会解决（考虑到过去的时间），但至少如果其他人有相同的问题，他们将有一个起始输入

VB代码

    Dim myText As String = dictionary.Item("@template.testo").ToString()
    Dim phrase As String = "<img src=""data:image/png;base64,"
    Dim phrase2 As String = """ alt="""">"
    Dim Occurrences As Integer = (myText.Length - myText.Replace(phrase, String.Empty).Length) / phrase.Length

    For value As Integer = 0 To Occurrences
        Dim immagineBase64 As String = myText.Substring(myText.IndexOf(phrase), myText.IndexOf(phrase2) - (phrase2.Length + 2)).Replace(phrase, "").Replace(phrase2, "")
        Dim imageBytes As Byte() = Convert.FromBase64String(immagineBase64)
        Dim image As iTextSharp.text.Image = iTextSharp.text.Image.GetInstance(imageBytes)

        documento.Add(image)

        myText = myText.Replace(myText.Substring(myText.IndexOf(phrase), myText.IndexOf(phrase2) - (phrase2.Length + 2)), "")
    Next

C# 代码

        string myText = dictionary.Item("@template.testo").ToString()   // my base64 image with html tag
        string phrase = "<img src=\"data:image/png;base64,"
        string phrase2 = "\" alt=\"\">"
        int Occurrences = (myText.Length - myText.Replace(phrase, String.Empty).Length) / phrase.Length

        for(int value = 0; value < Occurrences; value++){
            string immagineBase64 = myText.Substring(myText.IndexOf(phrase), myText.IndexOf(phrase2) - (phrase2.Length + 2)).Replace(phrase, "").Replace(phrase2, "")
            Byte[] imageBytes = Convert.FromBase64String(immagineBase64)
            iTextSharp.text.Image image = iTextSharp.text.Image.GetInstance(imageBytes)

            documento.Add(image)
        }

希望有帮助

Answer 2

您只需以 64 为基数创建字节数组和图像。

Document doc = new Document(PageSize.LETTER, 25, 25, 110, 25);

string imgBase64 = "iVBORw0KGgoAAAANSUhEUgAAClgAAAE0CAYAAABKe6wlA...";
Byte[] bytes = Convert.FromBase64String(imgBase64 );
Image image = Image.GetInstance(bytes);

doc.Add(image);