How to Generate a PDF from HTML in C#

Generating a PDF from an HTML source is rarely an easy task. PDFs were designed with print needs in mind, which doesn’t always mesh well with the different forms and functions of web programs and applications. It can be a challenge for even the most seasoned developer to learn how to convert HTML to PDF in C#, without spending a lot of extra time fixing the post-conversion layout.

Luckily, you can harness the power of C# to make the process a little easier, and quickly produce great-looking PDFs from your web pages and applications.

 Use the right tools

As a developer, you don’t need to spend a lot of time playing around with new APIs or learning different file formats to generate dynamic PDF files. There are several tool options to make the HTML-to-PDF conversion process easier by passing HTML to a function and generating the PDF file with formatting features intact. The quality of PDF generator tools can vary, particularly if your code involves tables or complex functions.

Design Elements to Consider

When you’re creating a PDF from HTML using C#, there are several design factors to keep in mind:

• Internal browser width and height
• CSS styles
• JavaScript files
• URLs of embedded images
• Headers and footers
• Dynamic data
• Page breaks
• Watermarks
• Page size of the generated PDF
• Orientation and margins of the generated PDF

 These elements can all influence the final output of your PDF, so be sure to check their settings before beginning your HTML conversion project.

 Creating a PDF from HTML

Most C# PDF generator tools can easily handle common coding elements, such as:

• HTML Strings and Files – Any HTML (HTML5) string or existing URL can be rendered into a PDF in a very efficient way. This includes referencing images, stylesheets, web fonts or even jQuery.
• CSS – Print and Screen CSS can both be rendered to PDF. Responsive CSS elements may be rendered at their smallest size, so Print CSS media types are strongly recommended.
• Javascript – Most C# PDF generator tools support Javascript, jQuery and AJAX, and is fully compliant with the Javascript standard.

This detailed tutorial includes several code examples for using C code to generate PDFs.

 C# HTML to PDF PrintOptions Settings

The HtmlToPdf class contains a PrintOptions object that can help ensure the highest quality design rendering. For examples:

• DPI – sets the output DPI of the generated PDF
• FitToPaperWidth – sets the PDF content to fit the page width
• GrayScale – generates a black-and-white PDF
• PrintHtmlBackgrounds – includes background colors and images in the generated PDF
• CustomCssUrl – allows you to use a local file path or remote URL to apply a custom CSS style-sheet to the HTML before rendering it as a PDF.
• RenderDelay – ensures JavaScript, AJAX and other animations are fully rendered before generating the PDF
• Header and Footer – sets the header and footer content, respectively, for every PDF page
• Zoom – sets the zoom level to a specified percentage, allowing you to enlarge the rendering size of the HTML document.

You may learn more about this comprehensive tutorial for a C# HTML to PDF settings.

 Batch PDF Creation

Most developers have a need for creating multiple PDFs from HTML. You can set up batch PDF generation by creating an HTML template. This is an effective way to use C# String.Format to dynamically create PDF documents using a simple “mail-merge” methodology.

 For more complex applications, such as those where a database query may be involved, a more sophisticated method is recommended. The Handlebars Templating Standard can be used to render a well-designed PDF layout when an unknown number of rows may be returned, such as an invoice or product inventory application.

 Need more help learning how to convert HTML to PDF in C? This tutorial also includes an easy downloadable C# PDF QuickStart Guide to help kickstart you first project using C code to generate PDF.