This article shows how to create a PDF file containing an image in iTextSharp. It covers the following features:
- Image is stored as an embedded resource in a .NET class library
- Content of the PDF is created from HTML
The iTextSharp library provides a way to create a PDF from HTML. But when the PDF should contain images that are not accessible via a public URL some adjustments are necessary. To demonstrate that I decided to embed the image to a .NET class library. This is just an example. The image could also be saved on a filesystem or even be stored as a base64 encoded string in a SQL database.
To be as close as possible to the HTML specification I use the img-tag to reference the image. The HTML markup is created via a XSL transformation.
Content of the xslt:
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
xmlns:msxsl="urn:schemas-microsoft-com:xslt"
exclude-result-prefixes="msxsl">
<xsl:output method="xml" indent="yes"/>
<xsl:template match="/">
<html>
<head>
<title></title>
</head>
<body>
<div style="min-width: 1237px;max-width: 1270px;position: relative;margin: 0 auto;">
<img src="data:imagestream/EmbeddedImage.Resources.image.jpg" />
</div>
<div>It´s working!!</div>
</body>
</html>
</xsl:template>
</xsl:stylesheet>
The src-attribute doesn´t contain a http-Url. Instead I use the prefix data:imagestream to identify the source type of the image. After the following slash the name of the resource in the manifest of the .NET library is listed. That´s the location where differenty source types could be defined.
Now I have to teach iTextSharp a different handling for the img-tag.
This method takes the HTML content and converts it to PDF.
public Stream CreateFromHtml(string html)
{
var stream = new MemoryStream();
using (var doc = new Document(PageSize.A4))
{
using (var ms = new MemoryStream())
{
using (var writer = PdfWriter.GetInstance(doc, ms))
{
writer.CloseStream = false;
doc.Open();
var tagProcessors = (DefaultTagProcessorFactory)Tags.GetHtmlTagProcessorFactory();
tagProcessors.RemoveProcessor(HTML.Tag.IMG);
tagProcessors.AddProcessor(HTML.Tag.IMG, new CustomImageTagProcessor());
var cssFiles = new CssFilesImpl();
cssFiles.Add(XMLWorkerHelper.GetInstance().GetDefaultCSS());
var cssResolver = new StyleAttrCSSResolver(cssFiles);
var charset = Encoding.UTF8;
var context = new HtmlPipelineContext(new CssAppliersImpl(new XMLWorkerFontProvider()));
context.SetAcceptUnknown(true).AutoBookmark(true).SetTagFactory(tagProcessors);
var htmlPipeline = new HtmlPipeline(context, new PdfWriterPipeline(doc, writer));
var cssPipeline = new CssResolverPipeline(cssResolver, htmlPipeline);
var worker = new XMLWorker(cssPipeline, true);
var xmlParser = new XMLParser(true, worker, charset);
using (var sr = new StringReader(html))
{
xmlParser.Parse(sr);
doc.Close();
ms.Position = 0;
ms.CopyTo(stream);
stream.Position = 0;
}
}
}
}
return stream;
}
Here is where the magic happens. The default handling for img-tags is replaced by a custom tag processor.
var tagProcessors = (DefaultTagProcessorFactory)Tags.GetHtmlTagProcessorFactory(); tagProcessors.RemoveProcessor(HTML.Tag.IMG); tagProcessors.AddProcessor(HTML.Tag.IMG, new CustomImageTagProcessor());
The custom tag processor only steps in with custom logic, when the src-tag starts with data:imagestream. That ensures that all other “legal” images are resolved by the logic of the default processor.
public class CustomImageTagProcessor : iTextSharp.tool.xml.html.Image
{
public override IList<IElement> End(IWorkerContext ctx, Tag tag, IList<IElement> currentContent)
{
var src = String.Empty;
if (!tag.Attributes.TryGetValue(HTML.Attribute.SRC, out src))
return new List<IElement>(1);
if (String.IsNullOrWhiteSpace(src))
return new List<IElement>(1);
if (src.StartsWith("data:imagestream/", StringComparison.InvariantCultureIgnoreCase))
{
var name = src.Substring(src.IndexOf("/", StringComparison.InvariantCultureIgnoreCase) + 1);
using (var stream = Assembly.GetExecutingAssembly().GetManifestResourceStream(name))
{
return CreateElementList(ctx, tag, Image.GetInstance(stream));
}
}
return base.End(ctx, tag, currentContent);
}
protected IList<IElement> CreateElementList(IWorkerContext ctx, Tag tag, Image image)
{
var htmlPipelineContext = GetHtmlPipelineContext(ctx);
var result = new List<IElement>();
var element = GetCssAppliers().Apply(new Chunk((Image) GetCssAppliers().Apply(image, tag, htmlPipelineContext), 0, 0, true), tag, htmlPipelineContext);
result.Add(element);
return result;
}
}
The following sample code creates the HTML, converts it to the PDF and saves the result to a file.
class Program
{
static void Main(string[] args)
{
string html;
using (var xsltStream = Assembly.GetExecutingAssembly().GetManifestResourceStream("EmbeddedImage.Resources.Pdf.xslt"))
{
var reader = XmlReader.Create(xsltStream);
var xslt = new XslCompiledTransform();
xslt.Load(reader);
using (var ms = new MemoryStream())
{
xslt.Transform(new XmlDocument(), new XsltArgumentList(), ms);
ms.Position = 0;
using (var r = new StreamReader(ms))
{
html = r.ReadToEnd();
}
}
}
var pdfService = new TextSharpPdfService();
using (var pdf = pdfService.CreateFromHtml(html))
{
using (var fs = new FileStream(@"c:\temp\embeddedimage.pdf", FileMode.Create))
{
pdf.CopyTo(fs);
}
}
}
}
And here´s the result:
In my next post I will show how to use the same embedded resource image as header for a HTML mail.
Yesterday it worked 