A form XObject: a self-contained content stream with its own bounding box, matrix and resources. A live view over the stream.
public sealed class PdfFormXObject
ISO 32000-2 §8.10.1, Table 93. Annotation appearances (§12.5.5) are form XObjects. Every property reads the stream dictionary on
every call and returns the default the table gives when an entry is absent or malformed (the identity matrix, no bounding box),
without a diagnostic: the object that uses the form (an annotation's appearance, the content interpreter's Do) reports
what it cannot use.
Decode() returns the content's bytes through the document's filters; RewriteContent(ContentEditor) runs it through an editor and stores the edited content.
kind:method, kind:property, kind:ctor. Press Esc to clear.BoundingBoxGets the form's bounding box in form space, its clip; null when BBox is absent or not four numbers.DictionaryGets the stream's dictionary.GroupGets the group attributes dictionary that makes the form a transparency group, or null.IsFormGets a value indicating whether the stream's Subtype is Form, as Table 93 requires.MatrixGets or sets the form matrix, which maps form space to the user space of the content that paints it; the identity when absent or not six numbers.OptionalContentGets the optional content group or membership dictionary of the form, or null.ReferenceGets the indirect reference to the stream, or null when it was reached directly.ResourcesGets the resources the form's content uses, or null when the form has none of its own.StreamGets the form's stream.StructParentGets the form's key in the structural parent tree when it is one content item, or null.StructParentsGets the form's key in the structural parent tree for the marked content in it, or null.TransparencyGroupGets the transparency group attributes of the form when it is a transparency group XObject (Group with S /Transparency), else null.CreateCanvas()Returns a canvas that draws in the form, after its existing content; dispose it to store what was drawn.CreateTransparencyGroup()Makes the form a transparency group XObject, writing << /Type /Group /S /Transparency >> as its Group, and returns the group's attributes to set; returns the existing attributes when the form already is one.Decode()Returns the form's content decoded through the filters its Filter entry names.RemoveOptionalContent()Removes the form's OC entry: it is no longer optional content.RewriteContent(ContentEditor, ContentOptions)Runs the form's content through editor with limits and cancellation, and stores the edited content.RewriteContent(ContentEditor)Runs the form's content through editor and, when it made edits, replaces the form's data with the result, in which every byte the edits did not touch is as it was. Every use of the form shows the change.SetOptionalContent(PdfOptionalContentGroup)Makes the form optional content of group (OC): shown only while the group is ON.SetOptionalContent(PdfOptionalContentMembership)Makes the form optional content whose visibility membership decides (OC).