% Simple pdfmark form example
% by Jim DeLaHunt, jdlh.com, 3. March 2012
%
% This PostScript language code, when converted to PDF by
% Adobe Acrobat Distiller or the like, creates a PDF file with form
% fields, and a Submit button which sends the values of the fields
% via an HTTP POST request.
%
% In reply to Stack Overflow question, "How can I create a PDF form
% using PDFMARK and/or PERL cpan module PDF::API2?",
% http://stackoverflow.com/questions/9440930/
%

% AcroForm dictionary setup. From pdfmark Reference, Example 5.11, p.70
%
% Read also PDF specification PDF32000:2008
% "Document management — Portable document format — Part 1: PDF 1.7",
% Section 12.7 "Interactive Forms", p.430
% To understand the syntax: [/_objdef {foo} /type /dict /OBJ pdfmark
% read carefully pdfMark reference, "User-defined named objects", p.13.

% Define font objects for the widgets to use
[ /_objdef {ZaDb} /type /dict /OBJ pdfmark
[ {ZaDb} <<
    /Type /Font
    /Subtype /Type1
    /Name /ZaDb
    /BaseFont /ZapfDingbats
>> /PUT pdfmark
[ /_objdef {Helv} /type /dict /OBJ pdfmark
[ {Helv} <<
    /Type /Font
    /Subtype /Type1
    /Name /Helv
    /BaseFont /Helvetica
    % /Encoding {pdfDocEncoding} % for simplicity, use font's own encoding
    % pdfmark Reference, Example 5.11, p.70, provides an Encoding
    % array defining PDFDocEncoding
>> /PUT pdfmark

[ /_objdef {aform} /type /dict /OBJ pdfmark

% Define Fields array of Acroform dictionary. It will contain entries for
% each of the widgets defined below.
% NOTE: It is not necessary to explicitly assign the widget annotations
% to the Fields array; Acrobat does it automatically when the file is
% opened.

[ /_objdef {afields} /type /array /OBJ pdfmark
[ {aform} <<
    /Fields {afields}
    /DR << /Font << /ZaDb {ZaDb} /Helv {Helv} >> >>
    /DA (/Helv 0 Tf 0 g)
    /NeedAppearances true
    % "/NeedAppearances true" tells reader 'to construct appearance
    % streams and appearance dictionaries for all widget annotations
    % in the document...' --PDF32000:2008 Table 218 p.431
>> /PUT pdfmark

% Put Acroform entry in catalog dictionary
[ {Catalog} << /AcroForm {aform} >> /PUT pdfmark


% Example 5.12 Define the Widget annotations
% pdfmark Reference pp. 72-75, with clarifications by Jim DeLaHunt
%
% These Widget annotations are also field dictionaries for this form.
% This is the collection of all individual widget annotations.
% It is possible to have multiple instances of these sections, such as
% for defining a single widget on each instance.
%
% See PDF32000:2008 Section 12.5.6.19 "Widget Annotations", p.408
% especially tables 188 and 189.

[ /Subtype /Widget
    /Rect [100 223 245 260]
    /F 4
    /T (SL Text)
    /FT /Tx
    /DA (/Helv 14 Tf 0 0 1 rg)
    /V (5)
    /AA <<
        /K <<
            /S /JavaScript
            /JS (AFNumber_Keystroke\(2, 0, 0, 0, "$", true\);)
        >>
        /V <<
            /S /JavaScript
            /JS (2;)
        >>
        /F <<
            /S /JavaScript
            /JS (AFNumber_Format\(2, 0, 0, 0, "$", true\);)
            % pdfmark Reference p.72 seems to omit closing ")" above. Oops.
        >>
    >>
/ANN pdfmark

showpage  % make sure a page gets produced