Class RadioFormField

Inheritance
System.Object
RadioFormField
Implements
IronSoftware.Abstractions.Pdf.IPdfDocumentObject
IronSoftware.Abstractions.IDocumentObject
Namespace: IronSoftware.Forms
Assembly: IronPdf.dll
Syntax
public class RadioFormField : Object, ICheckableFormField, IFormField, IFormFieldObject, IFormFieldAnnotationObject, IPdfDocumentObject, IPdfDocumentObject, IDocumentObject

Filling, reading, or clearing a single radio-button group in a fillable PDF form runs through RadioFormField, where the group itself is the form field and each visible button is an option inside it. The constructor takes a name, an initial value, a zero-based page index, and the four coordinate doubles needed to place the group on the page.

Working with radio groups in PDF forms is unusual because a group of three radio buttons is one field with three annotations, not three separate fields. RadioFormField reflects that structure: Choices lists the available option strings, Annotations exposes the per-button geometry, Value reads or writes the currently selected option by its string value, and SelectedIndex reads or writes by zero-based index. Set Value to RadioFormField.OffValue to clear the group, or call Clear() for the same effect through the ICheckableFormField contract.

Most instances are obtained from a loaded PdfDocument rather than constructed. Call FindFormField on the form collection with the group's field name and cast the returned IFormField to RadioFormField to reach the radio-specific surface. Value assignment is the canonical fill idiom and matches how the edit-forms how-to demonstrates radio handling. The geometry and identity properties (X, Y, Width, Height, PageIndex, Name, FullName, MaxLength, ReadOnly, FormFlags, RichText) come from the inherited interfaces and behave the same as every other concrete form field type. Select(int) returns the value at the selected index and throws when called with no argument on a group that has more than one option.

using IronPdf;
using IronSoftware.Forms;

PdfDocument pdf = PdfDocument.FromFile("application.pdf");

// FindFormField returns IFormField; cast to RadioFormField to reach Choices,
// Select, Clear, and the radio-specific Value semantics.
if (pdf.Form.FindFormField("traveltype") is RadioFormField travel)
{
    // Inspect the available option labels for this group
    foreach (string choice in travel.Choices)
    {
        Console.WriteLine(choice);
    }

    // Select by label, the canonical idiom
    travel.Value = "Airplane";

    // Or select by zero-based index instead of by label
    // travel.Select(1);

    // Clear the group (no button selected)
    // travel.Clear();
}

pdf.SaveAs("application-filled.pdf");

Selecting and clearing options across the surrounding text, checkbox, and combo fields is demonstrated in the fill and edit PDF forms how-to. Building a PDF with radio groups from scratch in C# or from HTML belongs to the create PDF forms guide. The IFormField interface page documents the unified contract that lets the same code path read or fill every concrete field type a PDF can contain.

Constructors

RadioFormField(String, String, UInt32, Double, Double, Double, Double)

Create a new radio form field using the specified parameters

Declaration
public RadioFormField(string name, string value, uint page_index, double x, double y, double width, double height)
Parameters
Type Name Description
System.String name

Form field name
System.String value

Form field value
System.UInt32 page_index

Form page index
System.Double x

Form x-coordinate
System.Double y

Form y-coordinate
System.Double width

Form width
System.Double height

Form height

Fields

OffValue

Value which can be assigned to a radio button to disable it

Declaration
public static string OffValue
Field Value
Type Description
System.String

Properties

Annotations

Form field annotations

Declaration
public List<IFormFieldAnnotation> Annotations { get; protected set; }
Property Value
Type Description
System.Collections.Generic.List<IFormFieldAnnotation>

Choices

Selection choices

Declaration
public List<string> Choices { get; }
Property Value
Type Description
System.Collections.Generic.List<System.String>

Client

Pdf client

Declaration
public IPdfClient Client { get; set; }
Property Value
Type Description
IronSoftware.Pdfium.IPdfClient

DefaultAppearance

Default appearance string

Declaration
public string DefaultAppearance { get; set; }
Property Value
Type Description
System.String

DocumentId

Declaration
public IDocumentId DocumentId { get; set; }
Property Value
Type Description
IronSoftware.Abstractions.Pdf.IDocumentId

FormFlags

Form field flags

Declaration
public PdfFormFieldFlags FormFlags { get; set; }
Property Value
Type Description
PdfFormFieldFlags

FormType

Form type

Declaration
public string FormType { get; }
Property Value
Type Description
System.String

FullName

Fully qualified name

Declaration
public string FullName { get; protected set; }
Property Value
Type Description
System.String

Height

Annotation height

Declaration
public double Height { get; set; }
Property Value
Type Description
System.Double

MaxLength

Maximum number of characters which can be specified in the value

Declaration
public int MaxLength { get; set; }
Property Value
Type Description
System.Int32

Name

Partial name

Declaration
public string Name { get; set; }
Property Value
Type Description
System.String

ObjNum

Declaration
public uint ObjNum { get; set; }
Property Value
Type Description
System.UInt32

ObjType

Object type

Declaration
public string ObjType { get; }
Property Value
Type Description
System.String

PageIndex

Declaration
public uint PageIndex { get; set; }
Property Value
Type Description
System.UInt32

ReadOnly

True if read-only

Declaration
public bool ReadOnly { get; set; }
Property Value
Type Description
System.Boolean

RichText

Form value using rich text

Declaration
public string RichText { get; set; }
Property Value
Type Description
System.String

SelectedIndex

Currently selected index

Declaration
public int SelectedIndex { get; set; }
Property Value
Type Description
System.Int32

Type

Pdf form field type

Declaration
public PdfFormFieldType Type { get; }
Property Value
Type Description
PdfFormFieldType

Value

Form value

Declaration
public string Value { get; set; }
Property Value
Type Description
System.String

Width

Annotation width

Declaration
public double Width { get; set; }
Property Value
Type Description
System.Double

X

Annotation X position

Declaration
public double X { get; set; }
Property Value
Type Description
System.Double

Y

Annotation y position

Declaration
public double Y { get; set; }
Property Value
Type Description
System.Double

Methods

Clear()

Clear any and all selected values

Declaration
public void Clear()

Select(Int32)

Select the value at the specified index

If no index is provided, selects the first value. If there are more than one options, throws an exception

Declaration
public string Select(int Index = -1)
Parameters
Type Name Description
System.Int32 Index
Returns
Type Description
System.String

Value at the selected index
Exceptions
Type Condition
System.Exception

No index was provided and there is more than one selectable option

SetDefaultFont(String, Int32, Color)

Set the default font to be used by this form field and any associated annotations

Declaration
public void SetDefaultFont(string FontName, int FontSize, Color FontColor)
Parameters
Type Name Description
System.String FontName

Font name with weight. Example "AdobeThai-Bold"
System.Int32 FontSize

Font size (whole integer such as 12 or 24)
System.Drawing.Color FontColor

Font color (only R, G, and B are used)
Remarks

This option may be overwritten by fonts applied to specific form field annotations

Implements

IronSoftware.Abstractions.Pdf.IPdfDocumentObject
IronSoftware.Abstractions.IDocumentObject