Where is IFormFieldAnnotationObject located in the IronPDF object model?

IFormFieldAnnotationObject is in the IronSoftware.Forms namespace, shipped in IronPdf.dll. It extends IPdfDocumentObject and declares the X, Y, Width, and Height geometry properties. It composes into IFormField alongside IFormFieldObject, so concrete form-field classes such as TextFormField and SignatureFormField expose this geometry surface, which is what a developer adjusts when repositioning a field.

What is the difference between IFormFieldAnnotationObject, IFormFieldObject, and IFormFieldAnnotation?

IFormField is the master contract that composes the other three. IFormFieldAnnotationObject covers on-page geometry: X, Y, Width, and Height. IFormFieldObject covers field data: Name, FullName, Value, FormType, MaxLength, ReadOnly, and related members. IFormFieldAnnotation combines geometry with annotation metadata such as AnnotationFlags, Appearances, AppearanceState, and the back-reference FormField.

What units do X, Y, Width, and Height use?

All four geometry properties are doubles in PDF user-space units, which default to points at 72 per inch. The coordinate origin is the bottom-left corner of the page, so larger Y values move upward. Width and Height describe the field's footprint extending from the X, Y anchor.

Interface IFormFieldAnnotationObject

Q: What implements IFormFieldAnnotationObject?

The concrete form-field classes implement IFormFieldAnnotationObject through their implementation of IFormField. These include TextFormField, CheckboxFormField, ComboboxFormField, RadioFormField, SignatureFormField, and ImageFormField. The standalone FormFieldAnnotation type also exposes the same geometry properties.

Refers to an annotation or is an annotation

Inherited Members

IPdfDocumentObject.Client

Namespace: IronSoftware.Forms

Assembly: IronPdf.dll

Syntax

public interface IFormFieldAnnotationObject : IPdfDocumentObject, IPdfDocumentObject, IDocumentObject

IFormFieldAnnotationObject describes where a fillable PDF form field sits on a page in IronPDF, so code can read or adjust its placement through one narrow surface. It declares the four positional properties that describe a field's placement: X, Y, Width, and Height. Concrete implementors include TextFormField, CheckboxFormField, ComboboxFormField, RadioFormField, SignatureFormField, and ImageFormField, alongside the standalone FormFieldAnnotation type.

The contract matters because form-field layout and form-field data are intentionally split across separate interfaces. IFormField is the master contract that composes IFormFieldAnnotationObject (this geometry contract) with IFormFieldObject (field data such as Name, Value, and ReadOnly). A method that accepts IFormFieldAnnotationObject works purely in layout terms and stays decoupled from value-handling logic, which is useful when auditing form layouts, repositioning fields, or rendering visual overlays.

All four declared properties are double get/set in PDF user-space units, with the origin at the page's bottom-left. X and Y give the anchor position; Width and Height give the field's footprint. The interface also inherits Client from IPdfDocumentObject. Reach for the edit PDF forms how-to when you need to see how these annotations surface on a loaded document.

using IronPdf;
using IronSoftware.Forms;

PdfDocument pdf = PdfDocument.FromFile("application.pdf");
IFormField field = pdf.Form.FindFormField("FullName");

// IFormField composes IFormFieldAnnotationObject, so the geometry
// properties are accessible directly on any concrete form field.
LogBounds(field);

void LogBounds(IFormFieldAnnotationObject box)
{
    System.Console.WriteLine($"x={box.X}, y={box.Y}, w={box.Width}, h={box.Height}");
}

PDF user-space units are device-independent, so a Width of 144 represents two inches at any zoom level or print resolution. Code that repositions or resizes fields should treat the four properties as a single coordinate frame and update them together to avoid mismatched anchor and footprint values. For programmatic field placement on new documents, see the create PDF forms how-to, which covers HTML-driven and code-driven field generation in C#.

Properties

Height

Annotation height

Declaration

double Height { get; set; }

Property Value

Type	Description
System.Double

Width

Annotation width

Declaration

double Width { get; set; }

Property Value

Type	Description
System.Double

X

Annotation X position

Declaration

double X { get; set; }

Property Value

Type	Description
System.Double

Y

Annotation y position

Declaration

double Y { get; set; }

Property Value

Type	Description
System.Double

Inherited members

Client