Field Class

Flatten/Merge existing form field appearances with the page content and remove widget annotation. Form 'flattening' refers to the operation that changes active form fields into a static area that is part of the PDF document, just like the other text and images in the document. A completely flattened PDF form does not have any widget annotations or interactive fields.

An interactive form (sometimes referred to as an AcroForm) is a collection of fields for gathering information interactively from the user. A PDF document may contain any number of Fields appearing on any combination of pages, all of which make up a single, global interactive form spanning the entire document.

PDFNet fully supports reading, writing, and editing PDF forms and provides many utility methods so that work with forms is simple and efficient. Using PDFNet forms API arbitrary subsets of form fields can be imported or exported from the document, new forms can be created from scratch, and the appearance of existing forms can be modified.

Examples

In PDFNet Fields are accessed through FieldIterator-s. For a full sample, please refer to 'InteractiveForms' sample project. The list of all Fields present in the document can be traversed as follows:

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for(FieldIterator itr = doc.getFieldIterator(); itr.hasNext();) {
Field current=(Field)(itr.next());
System.out.println("Field name: " + current.getName());
System.out.println("Field partial name: " + current.getPartialName());
}

To search field by name use FieldFind method. For example:

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// Search for a specific field
FieldIterator itr = doc.fieldFind("employee.name.first");
if (itr.hasNext()) System.out.println("Field search for " + ((Field)(itr.next())).getName() + " was successful");
else System.out.println("Field search failed");

If a given field name was not found or if the end of the field list was reached the iterator HasNext() will return false. If you have a valid iterator you can access the Field using Current() method. For example:

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Field field = itr.Current();

Using Flatten(...) method it is possible to merge field appearances with the page content. Form 'flattening' refers to the operation that changes active form fields into a static area that is part of the PDF document, just like the other text and images in the document. A completely flattened PDF form does not have any widget annotations or interactive fields.

Inheritance Hierarchy

SystemObject
pdftron.PDFField

Namespace: pdftron.PDF
Assembly: pdftron (in pdftron.dll) Version: 255.255.255.255

Syntax

C++

JavaScript

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public sealed class Field : IClosable

Public NotInheritable Class Field
	Implements IClosable

public ref class Field sealed : IClosable

pdftron.PDF.Field = function();

Type.createClass(
	'pdftron.PDF.Field',
	null,
	Windows.Foundation.IClosable);

The Field type exposes the following members.

Constructors

	Name	Description
	Field	Construct a Field from a SDF dictionary representing a terminal field node.

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Methods

	Name	Description
	Close
	Equals	Determines whether the specified Object is equal to the current Object. (Inherited from Object.)
	EraseAppearance	Removes any appearances associated with the field.
	FindInheritedAttribute	Some of the Field attributes are designated as inheritable. If such an attribute is omitted from a Field object, its value is inherited from an ancestor node in the Field tree. If the attribute is a required one, a value must be supplied in an ancestor node; if it is optional and no inherited value is specified, the default value should be used. The function walks up the Field inhritance tree in search for specified attribute.
	Flatten	Flatten/Merge existing form field appearances with the page content and remove widget annotation. Form 'flattening' refers to the operation that changes active form fields into a static area that is part of the PDF document, just like the other text and images in the document. A completely flattened PDF form does not have any widget annotations or interactive fields.
	GetDefaultAppearance	Gets the default graphics state.
	GetDefaultValue	Gets the default value.
	GetDefaultValueAsString	Gets the default value as string.
	GetFlag	Gets the flag.
	GetHashCode	Serves as a hash function for a particular type. (Inherited from Object.)
	GetJustification	Gets the justification.
	GetMaxLen	Gets the maximum length.
	GetName	Gets the name.
	GetOpt	Gets the name of the option in a list or combo box for a given index.
	GetOptCount	Gets the number of options for a list box or combo box.
	GetPartialName	Gets the partial name.
	GetSDFObj	Gets the SDFObj.
	GetTriggerAction	Get the Action associated with the selected Field Trigger event
	GetType	Gets the type.
	GetUpdateRect	Return the rectangle that should be refreshed after changing a field.
	GetValue	Gets the value.
	GetValueAsBool	Gets the value as bool.
	GetValueAsString	Gets the value as string.
	IsAnnot	Checks if is annot.
	IsLockedByDigitalSignature	Returns whether modifying this field would invalidate a digital signature in the document.
	IsValid	Checks if current field is valid.
	RefreshAppearance	Regenerates the appearance stream for the Widget Annotation containing variable text. Call this method if you modified field's value and would like to update field's appearance.
	Rename	Modifies the field name.
	Set	Sets to given Field object
	SetFlag	Set the value of given FieldFlag.
	SetJustification	Sets the justification to be used in displaying the text field.
	SetMaxLen	Sets the maximum length of the field's text, in Characters.
	SetValue(Boolean)	Sets the value.
	SetValue(String)	Sets the value.
	SetValue(Obj)	Sets the value of the Field (i.e. the value of the field's /V key). The format of field's value varies depending on the field type.
	ToString	Returns a string that represents the current object. (Inherited from Object.)
	UseSignatureHandler	Sets the signature handler to use for adding a signature to this field. If the signature handler is not found in PDFDoc's signature handlers list, this field will not be signed. To add signature handlers, use PDFDoc.AddSignatureHandler method. If a signature handler is already assigned to this field and this method is called once again, the associated signature handler for this field will be updated with the new handler.

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Remarks

An alternative approach to set the field as read only is using Field.SetFlag(Field::e_read_only, true) method. Unlike Field.SetFlag(...), the result of FlattenField() operation can not be programatically reversed.

Reference

pdftron.PDF Namespace