Fillable forms

Form controls become fillable PDF form fields (AcroForm), drawn as Chrome prints them and filled with their current values. Adobe Reader, Preview, Chrome, Firefox and other viewers let the reader fill them in and save the result.

var html = """
    <p>Name <input name="name" value="Jane Doe" required></p>
    <p><label><input type="checkbox" name="newsletter" checked> Send me the newsletter</label></p>
    <p><input type="radio" name="size" value="S"> S <input type="radio" name="size" value="M" checked> M</p>
    <p><select name="country"><option value="dk">Denmark</option><option value="se">Sweden</option></select></p>
    <p><textarea name="comments" rows="4" cols="40"></textarea></p>
    """;
byte[] pdf = HtmlToPdf.Convert(html);

// Or print the controls as they are, without form fields:
byte[] flat = HtmlToPdf.Convert(html, new PdfOptions { FormFields = false });

HTML	PDF field
`<input>` of type `text`, `email`, `tel`, `url`, `search`, `number`, `date` and the like	Text field (`maxlength` sets the maximum length)
`<input type="password">`	Password text field; the value is drawn as dots and not stored
`<textarea>`	Multi-line text field
`<input type="checkbox">`	Check box; its `value` is the export value (default `Yes`)
`<input type="radio">`	Radio buttons: those with the same `name` are one field, and each `value` is a choice
`<select>`	Drop-down list (combo box); with `multiple` or `size` > 1 a list box, multi-select with `multiple`
`<button>`, `<input type="submit">`, `reset`, `button`	Drawn only: a PDF has nothing to submit

Field names and behaviour

Fields are named after the name attribute (a period becomes _, since PDF uses it to nest fields; a repeated name gets _2, _3, ...; a control without a name gets text1, checkbox1, ...). readonly and required set the field's flags, title, aria-label or its <label> becomes its tooltip, and a placeholder is drawn in grey while the field is empty. Disabled controls (or controls in a disabled <fieldset>) are drawn but not fillable, and hidden inputs are left out. Each field has its own appearance, so the PDF looks right before anyone touches it and in viewers that never redraw fields; while a field is edited, the viewer draws its text in Helvetica, Courier or Times at the control's size and colour. Forms work with Security (the values are encrypted with the rest), Conformance (veraPDF passes the fields as PDF/A-2b and 3b), Accessibility (each widget sits in a Form element described by its label, title or name, and veraPDF passes PDF/UA-1), Signature (the signature field joins the form) and PdfMerger (repeated names are renamed).