Class ComboboxFormField

List of items selectable by the user

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

ComboboxFormField is what you receive when you read a dropdown or list-box field from a PDF form in IronPDF, the surface you enumerate options or set a selection through. A configured instance carries both the choice surface (Choices, Value, AllowMultipleSelections, AllowCustomOption) and the visual surface (IsDropDown, DefaultAppearance, RichText) that distinguish a combo from the other concrete form field types.

The class is the natural read or write surface when filling a PDF form whose template includes a priority selector, a country picker, a department list, or any other constrained-vocabulary field. It is also the type to reach for when the form was authored in Acrobat as a list box rather than a dropdown, because IronPDF models both shapes as one class differentiated by the IsDropDown flag. Enumerating choices and writing a selection is demonstrated in the fill and edit PDF forms how-to, while authoring a new combo box from scratch belongs to the create PDF forms how-to.

FindFormField returns the field as IFormField, which carries Name, FullName, Value, ReadOnly, and the placement properties through its three extended interfaces. To reach the combo-specific surface, cast to ComboboxFormField. The salient members fall into four groups. Selection: Choices (the List<string> of available options, get and set) and Value (the currently selected option as a string). Behavior toggles: IsDropDown selects the dropdown versus list-box visual, AllowMultipleSelections permits more than one option, and AllowCustomOption lets the user type a value outside Choices. Identity and gating: inherited Name, FullName, ReadOnly, plus the read-only FormType and Type (PdfFormFieldType) and the writable FormFlags (PdfFormFieldFlags). Appearance: MaxLength, DefaultAppearance, RichText, and the SetDefaultFont(string FontName, int FontSize, Color FontColor) method that sets the per-field font.

using IronPdf;
using IronSoftware.Forms;

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

// FindFormField returns IFormField. Cast to ComboboxFormField to read
// the combo-specific surface (Choices, IsDropDown, AllowMultipleSelections).
var priority = pdf.Form.FindFormField("priority") as ComboboxFormField;
if (priority != null && !priority.ReadOnly)
{
    // Enumerate the available options the PDF author defined.
    foreach (string option in priority.Choices)
    {
        Console.WriteLine(option);
    }

    // Assign the selected option. With AllowCustomOption = true, Value
    // may be any string; otherwise it must match an entry in Choices.
    priority.Value = "Low";

    // For multi-selection lists, Value is still a single string; the
    // selected entries are delimited per the PDF's AcroForm convention:
    //   priority.AllowMultipleSelections = true;
    //   priority.Value = "Low";
}

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

For a broader pass through every concrete form field type, see the fill and edit PDF forms how-to. For working examples of reading form data programmatically, see the PDF form data example.

Constructors

ComboboxFormField(String, String, UInt32, Double, Double, Double, Double, IEnumerable<String>)

Create a new combobox field with the specified parameters

Declaration
public ComboboxFormField(string name, string value, uint page_index, double x, double y, double width, double height, IEnumerable<string> choices)
Parameters
Type Name Description
System.String name

Form name
System.String value

Form 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
System.Collections.Generic.IEnumerable<System.String> choices

List of selectable choices

Properties

AllowCustomOption

Allows users to enter a custom option

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

AllowMultipleSelections

Allows users to select multiple options

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

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; set; }
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

IsDropDown

Displays options within a scrollable drop-down list

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

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

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

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