We had an inquiry today about converting PDF forms to HTML5 forms in some documents. When we investigated, this was not possible. This article explains what the issue was and why forms are not necessarily PDF forms.
The PDF file spec allows you to add Interactive Form elements to a PDF file as Annotations (on a page by page basis) or to the Document as FDF element or the new XFA style XML format. These are PDF forms (which have PDF form elements). Our software then converts the PDF forms to HTML5 form elements. You can double-check by seeing if the PDF contains any Annots of Forms elements.
It is also possible to create PDF versions of pages (for example Excel spreadsheets) which look like forms. They contain empty or filled boxes. But they are flat PDF files – they contain no interactive PDF form elements. So they are ‘forms’ but not PDF forms which you can interactive with or convert to HTML5.
The PDF file format is very powerful and does a brilliant job of showing content – sometimes too good as our brains imagine details are in the PDF (such as text structure or forms) which are not actually there.
This post is part of our “Understanding the PDF File Format” series. In each article, we discuss a PDF feature, bug, gotcha or tip. If you wish to learn more about PDF, we have 13 years worth of PDF knowledge and tips, so click here to visit our series index!
IDRsolutions develop a Java PDF library, a PDF forms to HTML5 converter, a PDF to HTML5 or SVG converter and a Java Image Library that doubles as an ImageIO replacement. On the blog our team post about anything interesting they learn about.