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pdftron::PDF::Field Class Reference

#include <Field.h>

Public Types

enum  Type {
  e_button, e_check, e_radio, e_text,
  e_choice, e_signature, e_null
enum  ActionTriggerEvent { e_action_trigger_keystroke = 13, e_action_trigger_format = 14, e_action_trigger_validate = 15, e_action_trigger_calculate = 16 }
enum  Flag {
  e_read_only, e_required, e_no_export, e_pushbutton_flag,
  e_radio_flag, e_toggle_to_off, e_radios_in_unison, e_multiline,
  e_password, e_file_select, e_no_spellcheck, e_no_scroll,
  e_comb, e_rich_text, e_combo, e_edit,
  e_sort, e_multiselect, e_commit_on_sel_change
enum  TextJustification { e_left_justified, e_centered, e_right_justified }

Public Member Functions

 Field (SDF::Obj field_dict)
 Field (const Field &p)
Fieldoperator= (const Field &p)
 ~Field ()
bool IsValid () const
Type GetType () const
SDF::Obj GetValue ()
UString GetValueAsString ()
bool GetValueAsBool ()
ViewChangeCollection SetValue (const UString &value)
ViewChangeCollection SetValue (SDF::Obj value)
ViewChangeCollection SetValue (const char *value)
ViewChangeCollection SetValue (bool value)
SDF::Obj GetTriggerAction (Field::ActionTriggerEvent trigger)
void RefreshAppearance ()
void EraseAppearance ()
SDF::Obj GetDefaultValue ()
UString GetDefaultValueAsString ()
UString GetName ()
UString GetPartialName ()
void Rename (const UString &field_name)
bool IsAnnot () const
bool GetFlag (Flag flag) const
void SetFlag (Flag flag, bool value)
TextJustification GetJustification ()
void SetJustification (TextJustification j)
void SetMaxLen (int max_len)
int GetOptCount () const
UString GetOpt (int index)
int GetMaxLen () const
GState GetDefaultAppearance ()
void Flatten (class Page page)
Rect GetUpdateRect () const
SDF::Obj FindInheritedAttribute (const char *attrib) const
SDF::Obj GetSDFObj () const
 operator bool ()
void Destroy ()
SDF::Obj UseSignatureHandler (const SDF::SignatureHandlerId signature_handler_id)
bool IsLockedByDigitalSignature () const

Detailed Description

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.

In PDFNet Fields are accessed through FieldIterator-s. The list of all Fields present in the document can be traversed as follows:

* FieldIterator itr = pdfdoc.GetFieldIterator();
* for(; itr.HasNext(); itr.Next()) {
* Field field = itr.Current();
* Console.WriteLine("Field name: {0}", field.GetName());
* }

For a full sample, please refer to 'InteractiveForms' sample project.

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

* FieldIterator itr = pdfdoc.FieldFind("name");
* if (itr.HasNext()) {
* Console.WriteLine("Field name: {0}", itr.Current().GetName());
* }
* else { ...field was not found... }

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: 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.

Definition at line 67 of file Field.h.

Member Enumeration Documentation


Definition at line 159 of file Field.h.

Flags specifying various characteristics of the fields.

Field flags common to all field types:

  • If e_read_only flag is set the user may not change the value of the field. Any associated widget annotations will not interact with the user; that is, they will not respond to mouse clicks or change their appearance in response to mouse motions. This flag is useful for fields whose values are computed or imported from a database.
  • If e_required flag is set, the field must have a value at the time it is exported by a submit-form action.
  • If e_no_export flag is set, the field must not be exported by a submit-form action.

Field flags specific to radio buttons:

  • If e_toggle_to_off is clear, exactly one radio button must be selected at all times; clicking the currently selected button has no effect. If set, clicking the selected button deselects it, leaving no button selected.
  • If e_radios_in_unison is set, a group of radio buttons within a radio button field that use the same value for the on state will turn on and off in unison; that is if one is checked, they are all checked. If clear, the buttons are mutually exclusive (the same behavior as HTML radio buttons).

Field flags specific to text fields:

  • If e_multiline is set, the field can contain multiple lines of text; if clear, the field's text is restricted to a single line.
  • If e_password If set, the field is intended for entering a secure password that should not be echoed visibly to the screen. Characters typed from the keyboard should instead be echoed in some unreadable form, such as asterisks or bullet characters. The value is not stored if this flag is set.
  • If e_file_select is set, the text entered in the field represents the pathname of a file whose contents are to be submitted as the value of the field.
  • If e_no_spellcheck is set, text entered in the field is not spell-checked.
  • If e_no_scroll is set, the field does not scroll (horizontally for single-line fields, vertically for multiple-line fields) to accommodate more text than fits within its annotation rectangle. Once the field is full, no further text is accepted.
  • If e_comb is set, the field is automatically divided into as many equally spaced positions, or combs, as the value of MaxLen, and the text is laid out into those combs. Meaningful only if the MaxLen entry is present in the text field and if the Multiline, Password, and FileSelect flags are clear.
  • If e_rich_text is set, the value of this field should be represented as a rich text string. If the field has a value, the RV entry of the field dictionary specifies the rich text string.

Field flags specific to choice fields:

  • If e_combo is set, the field is a combo box; if clear, the field is a list box.
  • If e_edit is set, the combo box includes an editable text box as well as a dropdown list; if clear, it includes only a drop-down list. This flag is meaningful only if the e_combo flag is set.
  • If e_sort is set, the field's option items should be sorted alphabetically. This flag is intended for use by form authoring tools, not by PDF viewer applications. Viewers should simply display the options in the order in which they occur in the Opt array.
  • If e_multiselect is set, more than one of the field's option items may be selected simultaneously; if clear, no more than one item at a time may be selected.
  • If e_commit_on_sel_change is set, the new value is committed as soon as a selection is made with the pointing device. This option enables applications to perform an action once a selection is made, without requiring the user to exit the field. If clear, the new value is not committed until the user exits the field.

Definition at line 323 of file Field.h.

Enumeration specifying the form of quadding (justification) to be used in displaying the text fields.


Definition at line 369 of file Field.h.

Interactive forms support the following field types:

  • Button fields represent interactive controls on the screen that the user can manipulate with the mouse. They include pushbuttons, check-boxes, and radio buttons.
  • Text fields are boxes or spaces in which the user can enter text from the keyboard.
  • Choice fields contain several text items, at most one of which may be selected as the field value. They include scrollable list boxes and combo boxes.
  • Signature fields represent electronic 'signatures' for authenticating the identity of a user and the validity of the document's contents.

Definition at line 98 of file Field.h.

Constructor & Destructor Documentation

pdftron::PDF::Field::Field ( SDF::Obj  field_dict)

Construct a PDF::Field from a SDF dictionary representing a terminal field node.

field_dictthe SDF dictionary to construct the field from.
pdftron::PDF::Field::Field ( const Field p)
pdftron::PDF::Field::~Field ( )

Member Function Documentation

void pdftron::PDF::Field::Destroy ( )

Frees the native memory of the object.

void pdftron::PDF::Field::EraseAppearance ( )

Removes any appearances associated with the field.

SDF::Obj pdftron::PDF::Field::FindInheritedAttribute ( const char *  attrib) const

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 inheritance tree in search for specified attribute.

The attribute value if the given attribute name was found or a NULL object if the given attribute name was not found.

Resources dictionary (Required; inheritable) MediaBox rectangle (Required; inheritable) CropBox rectangle (Optional; inheritable) Rotate integer (Optional; inheritable)

void pdftron::PDF::Field::Flatten ( class Page  page)

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.

pagepage object to flatten
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 Flatten() operation can not be programatically reversed.
GState pdftron::PDF::Field::GetDefaultAppearance ( )
The default graphics state that should be used in formatting the text. The state corresponds to /DA entry in the field dictionary.
SDF::Obj pdftron::PDF::Field::GetDefaultValue ( )
The default value to which the field reverts when a reset-form action is executed or NULL if the default value is not specified.

The format of field's value varies depending on the field type.

UString pdftron::PDF::Field::GetDefaultValueAsString ( )
bool pdftron::PDF::Field::GetFlag ( Flag  flag) const
the value of given field flag
TextJustification pdftron::PDF::Field::GetJustification ( )
the form of quadding (justification) to be used in displaying the text fields.
int pdftron::PDF::Field::GetMaxLen ( ) const
The maximum length of the field's text, in characters, or a negative number if the length is not limited.
This method is specific to a text field.
UString pdftron::PDF::Field::GetName ( )
a string representing the fully qualified name of the field (e.g. "").
UString pdftron::PDF::Field::GetOpt ( int  index)
indexindex position of the option to retrieve.
The string of the option at the givent index.
The index must be less than the value returned by GetOptCount().
int pdftron::PDF::Field::GetOptCount ( ) const

Returns the total number of options in a list or combo box.

UString pdftron::PDF::Field::GetPartialName ( )
a string representing the partial name of the field (e.g. "first" when "" is fully qualified name).
SDF::Obj pdftron::PDF::Field::GetSDFObj ( ) const
the underlying SDF/Cos object.
SDF::Obj pdftron::PDF::Field::GetTriggerAction ( Field::ActionTriggerEvent  trigger)

Get the Action associated with the selected Field Trigger event.

triggerthe type of trigger event to get
the Action Obj if present, otherwise NULL
Type pdftron::PDF::Field::GetType ( ) const
The field's value, whose type/format varies depending on the field type. See the descriptions of individual field types for further information.
Rect pdftron::PDF::Field::GetUpdateRect ( ) const
The rectangle that should be refreshed after changing a field.
SDF::Obj pdftron::PDF::Field::GetValue ( )
the value of the Field (the value of its /V key) or NULL if the value is not specified.

The format of field's value varies depending on the field type.

bool pdftron::PDF::Field::GetValueAsBool ( )
Field value as a boolean.
This method is usually for check-box and radio button fields.
UString pdftron::PDF::Field::GetValueAsString ( )
bool pdftron::PDF::Field::IsAnnot ( ) const
true if this Field is a Widget Annotation

Determines whether or not this Field is an Annotation.

bool pdftron::PDF::Field::IsLockedByDigitalSignature ( ) const

Returns whether modifying this field would invalidate a digital signature in the document.

whether modifying this field would invalidate a digital signature in the document
bool pdftron::PDF::Field::IsValid ( ) const
whether this is a valid (non-null) Field. If the function returns false the underlying SDF/Cos object is null and the Field object should be treated as null as well.
pdftron::PDF::Field::operator bool ( )
true if the object is not null, false otherwise.

Definition at line 470 of file Field.h.

Field& pdftron::PDF::Field::operator= ( const Field p)
void pdftron::PDF::Field::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.

If this field contains text, and has been added to a rotated page, the text in the field may be rotated. If RefreshAppearance is called after the field is added to a rotated page, then any text will be rotated in the opposite direction of the page rotation. If this method is called before the field is added to any rotated page, then no counter rotation will be applied. If you wish to call RefreshAppearance on a field already added to a rotated page, but you don't want the text to be rotated, you can do one of the following; temporarily un-rotate the page, or, temporarily remove the "P" object from the field.
void pdftron::PDF::Field::Rename ( const UString field_name)

Modifies the field name.

field_namea string representing the fully qualified name of the field (e.g. "").
void pdftron::PDF::Field::SetFlag ( Flag  flag,
bool  value 

Set the value of given FieldFlag.

You can use this method to set the field as read-only. An alternative approach to set the field as read only is using Page.Flatten(...) method. Unlike Flatten(...), the result of SetFlag(...) can be programatically reversed.
void pdftron::PDF::Field::SetJustification ( TextJustification  j)

Sets the justification to be used in displaying the text field.

jenum representing justification to set the text field to, options are e_left_justified, e_centered and e_right_justified
This method is specific to a text field.
void pdftron::PDF::Field::SetMaxLen ( int  max_len)

Sets the maximum length of the field's text, in characters.

max_lenmaximum length of a field's text.
This method is specific to a text field.
ViewChangeCollection pdftron::PDF::Field::SetValue ( const UString value)

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.

valuethe new field value.
in order to remove/erase the existing value use pass a SDF::Null object to SetValue().

In PDF, Field's value is separate from its annotation (i.e. how the field appears on the page). After you modify Field's value you need to refresh Field's appearance using RefreshAppearance() method.

Alternatively, you can delete "AP" entry from the Widget annotation and set "NeedAppearances" flag in AcroForm dictionary (i.e. doc.GetAcroForm().Put("NeedAppearances", Obj.CreateBool(true)); ) This will force viewer application to auto-generate new field appearances every time the document is opened.

Yet another option is to generate a custom annotation appearance using ElementBuilder and ElementWriter and then set the "AP" entry in the widget dictionary to the new appearance stream. This functionality is useful in applications that need advanced control over how the form fields are rendered.

ViewChangeCollection pdftron::PDF::Field::SetValue ( SDF::Obj  value)
ViewChangeCollection pdftron::PDF::Field::SetValue ( const char *  value)
ViewChangeCollection pdftron::PDF::Field::SetValue ( bool  value)

Sets the value of a check-box or radio-button field.

valueIf true, the filed will be set to 'True', if false the field will be set to 'False'.
This method is usually for check-box and radio button fields.
SDF::Obj pdftron::PDF::Field::UseSignatureHandler ( const SDF::SignatureHandlerId  signature_handler_id)

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 associate signature handler for this field will be updated with the new handler.

signature_handler_idThe unique id of the SignatureHandler to use for adding signature in this field.
The signature dictionary created using the SignatureHandler, or NULL pointer if the signature handler is not found.

The documentation for this class was generated from the following file: