How do you use IFormFieldAnnotation in C# code?

Accept IFormFieldAnnotation as a parameter or return type in C# code that needs to work uniformly across IronPDF implementors. The interface defines the contract; concrete behavior is provided by the implementor returned at runtime.

What is the difference between IFormFieldAnnotation and a concrete implementor?

IFormFieldAnnotation is the interface contract; its concrete implementors carry the actual behavior. Reference IFormFieldAnnotation when writing code that should work across multiple implementors; use a concrete type when a single implementor's behavior is required.

What namespace is IFormFieldAnnotation defined in?

IFormFieldAnnotation is in the IronSoftware.Forms namespace, shipped in IronPdf.dll. It extends IFormFieldAnnotationObject. Concrete classes such as FormFieldAnnotation implement it.

Interface IFormFieldAnnotation

Q: What implements IFormFieldAnnotation in IronPDF?

Concrete implementors of IFormFieldAnnotation in IronPDF include FormFieldAnnotation. Code that accepts IFormFieldAnnotation works uniformly across all implementors, with a cast to the concrete type only required when type-specific behavior is needed.

Document form field annotation

Inherited Members

IFormFieldAnnotationObject.X

IFormFieldAnnotationObject.Y

IFormFieldAnnotationObject.Width

IFormFieldAnnotationObject.Height

IPdfDocumentObject.Client

Namespace: IronSoftware.Forms

Assembly: IronPdf.dll

Syntax

public interface IFormFieldAnnotation : IFormFieldAnnotationObject, IPdfDocumentObject

IFormFieldAnnotation is what IronPDF hands back when C# code reads PDF forms. It represents document form field annotation, so code can work with PDF forms uniformly across implementors rather than binding to a concrete type.

Concrete implementors include FormFieldAnnotation, IronPDF concrete implementor. Code that accepts IFormFieldAnnotation works uniformly across these implementors, so applications can read or configure C# PDF features without binding to a specific concrete type.

Most of the usable surface is inherited. The members that carry everyday use of this contract are X, Y, Width, Height; consult these first when implementing or consuming IFormFieldAnnotation.

using IronPdf;

// IFormFieldAnnotation is consumed as the API surface for the family of implementors
void Consume(IFormFieldAnnotation target)
{
    // Use members defined on the interface; concrete behavior follows the implementor
}

For collection-wide operations and end-to-end examples, see the IronPDF C# documentation for related guides. For collection-wide operations on IFormFieldAnnotation instances, the IronPDF C# documentation lists the relevant container types and their methods. Concrete behavior depends on which implementor of IFormFieldAnnotation is returned at runtime; consult the specific class reference for type-specific members. Polymorphic access through IFormFieldAnnotation lets code work uniformly across the family of implementors, with a cast required only when type-specific behavior is needed. The reference tables below list the full set of members defined on IFormFieldAnnotation along with any inherited members exposed through the contract. In a typical IronPDF C# workflow, IFormFieldAnnotation appears as a parameter or return type at the boundary between the application and the IronPDF API. See the methods table below for the complete set of members defined directly on IFormFieldAnnotation. Implementing IFormFieldAnnotation directly in application code is uncommon; the typical pattern is to consume instances returned from the IronPDF API. When iterating over a collection of IFormFieldAnnotation instances, prefer the inherited members for portable code; downcast only when type-specific behavior is required.

Properties

AnnotationFlags

Annotation flags

Declaration

PdfAnnotationFlags AnnotationFlags { get; set; }

Property Value

Type	Description
PdfAnnotationFlags

Appearances

Annotation appearance names

Declaration

List<string> Appearances { get; }

Property Value

Type	Description
System.Collections.Generic.List<System.String>

AppearanceState

Current active appearance

Declaration

string AppearanceState { get; set; }

Property Value

Type	Description
System.String

FormField

Parent form

Declaration

IFormFieldObject FormField { get; set; }

Property Value

Type	Description
IFormFieldObject

Javascript

Javascript to execute when the annotation is interacted with

Declaration

string Javascript { get; set; }

Property Value

Type	Description
System.String

Remarks

See ISO 21757-1:2020 for an ECMAScript reference

OnAppearance

Name of the appearance which is active when this annotation is selected

Declaration

string OnAppearance { get; set; }

Property Value

Type	Description
System.String

Inherited members

Width

Height

Client