JetsonPDF.Forms 1.0.0

JetsonPDF.Forms

Open an existing PDF, discover its AcroForm fields, modify them, and save back via a single-layer incremental update. Built on top of JetsonPDF.Reader and JetsonPDF.Writer.

using JetsonPDF;
using JetsonPDF.Forms;

using var form = Form.Open("input.pdf");

foreach (var field in form.Fields)
    Console.WriteLine($"{field.Name}: {field.Type} = {field.Value}");

form.Fields["Name"].SetText("Jordan");
form.Fields["IsActive"].SetChecked(true);
form.Fields["State"].SetChoice("CA");
var states = form.Fields["State"].Options;     // (Export, Display) pairs

// Stamp an image into a text widget. ReadOnly is set by default so Adobe
// Acrobat renders the appearance immediately (it otherwise treats an
// empty-/V text widget's /AP /N as a stale cache).
form.Fields["Photo"].SetImage(Image.FromFile("signature.jpg"));

// Stamp into an unsigned /FT /Sig widget. ReadOnly is never applied to
// signature fields — the user must remain able to click Sign.
if (!form.Fields["SignHere"].IsSigned)
    form.Fields["SignHere"].SetImage(Image.FromFile("signature.png"));

// Keep a stamped text field editable (image only visible after focus
// in Acrobat; other viewers render it immediately).
form.Fields["EditablePhoto"].SetImage(img, markReadOnly: false);

form.Fields["OldValue"].Clear();   // per-field reset
// form.Clear();                   // reset everything

form.Save("output.pdf");

Features

• Discovers every /Tx, /Btn, /Ch, /Sig widget across all pages and groups multi-widget fields (radio groups) under one entry.
• Type-safe mutations: SetText, SetImage, SetChecked, Toggle, SelectRadio, SetChoice, SetChoices, Clear.
• SetImage bakes a PDF Form XObject /AP /N. Aspect-preserved and centered by default (six alignments + Stretch available). Valid on text fields, push buttons, and unsigned signature widgets.
• markReadOnly opt-out on SetImage for the rare case where a text field should stay editable after stamping.
• FormField.IsSigned flag for inspecting signature widgets without poking at internals.
• Combo / list-box Options exposed as (Export, Display) pairs.
• Encrypted PDFs supported: incremental update encrypts new objects under the source file's existing key, no re-keying required.
• Single-layer save: repeated Save() calls within one Form instance produce byte-identical output — mutations are re-applied against the original source bytes, never stacked on a previous save's output.

SetImage matrix

Limitations

• Read-only on signed signature fields (mutation throws).
• Field creation / deletion is out of scope; only existing fields can be edited.
• Rich-text (/RV) entries are not produced — SetText writes plain /V.