qpdf/examples/pdf-attach-file.cc

#include <qpdf/QPDF.hh>
#include <qpdf/QPDFEmbeddedFileDocumentHelper.hh>
#include <qpdf/QPDFFileSpecObjectHelper.hh>
#include <qpdf/QPDFWriter.hh>
#include <qpdf/QUtil.hh>

#include <cstring>
#include <iostream>

//
// This example attaches a file to an input file, adds a page to the beginning of the file that
// includes a file attachment annotation, and writes the result to an output file. It also
// illustrates a number of new API calls that were added in qpdf 10.2 as well as the use of the qpdf
// literal syntax introduced in qpdf 10.6.
//

static char const* whoami = nullptr;

static void
usage(std::string const& msg)
{
    std::cerr << msg << std::endl
              << std::endl
              << "Usage: " << whoami << " options" << std::endl
              << "Options:" << std::endl
              << " --infile infile.pdf" << std::endl
              << " --outfile outfile.pdf" << std::endl
              << " --attachment attachment" << std::endl
              << " [--password infile-password]" << std::endl
              << " [--mimetype attachment mime type]" << std::endl;
    exit(2);
}

static void
process(
    char const* infilename,
    char const* password,
    char const* attachment,
    char const* mimetype,
    char const* outfilename)
{
    QPDF q;
    q.processFile(infilename, password);

    // Create an indirect object for the built-in Helvetica font. This uses the qpdf literal syntax
    // introduced in qpdf 10.6.
    auto f1 = q.makeIndirectObject(
        // force line-break
        "<<"
        "  /Type /Font"
        "  /Subtype /Type1"
        "  /Name /F1"
        "  /BaseFont /Helvetica"
        "  /Encoding /WinAnsiEncoding"
        ">>"_qpdf);

    // Create a resources dictionary with fonts. This uses the new parse introduced in qpdf 10.2
    // that takes a QPDF* and allows indirect object references.
    auto resources = q.makeIndirectObject(
        // line-break
        QPDFObjectHandle::parse(
            &q,
            ("<<"
             "  /Font <<"
             "    /F1 " +
             f1.unparse() +
             "  >>"
             ">>")));

    // Create a file spec.
    std::string key = QUtil::path_basename(attachment);
    std::cout << whoami << ": attaching " << attachment << " as " << key << std::endl;
    auto fs = QPDFFileSpecObjectHelper::createFileSpec(q, key, attachment);

    if (mimetype) {
        // Get an embedded file stream and set mimetype
        auto ef = QPDFEFStreamObjectHelper(fs.getEmbeddedFileStream());
        ef.setSubtype(mimetype);
    }

    // Add the embedded file at the document level as an attachment.
    auto efdh = QPDFEmbeddedFileDocumentHelper(q);
    efdh.replaceEmbeddedFile(key, fs);

    // Create a file attachment annotation.

    // Create appearance stream for the attachment.

    auto ap = q.newStream("0 10 m\n"
                          "10 0 l\n"
                          "20 10 l\n"
                          "10 0 m\n"
                          "10 20 l\n"
                          "0 0 20 20 re\n"
                          "S\n");
    auto apdict = ap.getDict();

    // The following four lines demonstrate the use of the qpdf literal syntax introduced in
    // qpdf 10.6. They could have been written as:
    // apdict.replaceKey("/Resources", QPDFObjectHandle::newDictionary());
    // apdict.replaceKey("/Type", QPDFObjectHandle::newName("/XObject"));
    // apdict.replaceKey("/Subtype", QPDFObjectHandle::newName("/Form"));
    // apdict.replaceKey("/BBox", QPDFObjectHandle::parse("[ 0 0 20 20 ]"));
    apdict.replaceKey("/Resources", "<< >>"_qpdf);
    apdict.replaceKey("/Type", "/XObject"_qpdf);
    apdict.replaceKey("/Subtype", "/Form"_qpdf);
    apdict.replaceKey("/BBox", "[ 0 0 20 20 ]"_qpdf);
    auto annot = q.makeIndirectObject(QPDFObjectHandle::parse(
        &q,
        ("<<"
         "  /AP <<"
         "    /N " +
         ap.unparse() +
         "  >>"
         "  /Contents " +
         QPDFObjectHandle::newUnicodeString(attachment).unparse() + "  /FS " +
         fs.getObjectHandle().unparse() + "  /NM " +
         QPDFObjectHandle::newUnicodeString(attachment).unparse() +
         "  /Rect [ 72 700 92 720 ]"
         "  /Subtype /FileAttachment"
         "  /Type /Annot"
         ">>")));

    // Generate contents for the page.
    auto contents = q.newStream(("q\n"
                                 "BT\n"
                                 "  102 700 Td\n"
                                 "  /F1 16 Tf\n"
                                 "  (Here is an attachment.) Tj\n"
                                 "ET\n"
                                 "Q\n"));

    // Create the page object.
    auto page = QPDFObjectHandle::parse(
        &q,
        ("<<"
         "  /Annots [ " +
         annot.unparse() +
         " ]"
         "  /Contents " +
         contents.unparse() +
         "  /MediaBox [0 0 612 792]"
         "  /Resources " +
         resources.unparse() +
         "  /Type /Page"
         ">>"));

    // Add the page.
    q.addPage(page, true);

    QPDFWriter w(q, outfilename);
    w.setQDFMode(true);
    w.setSuppressOriginalObjectIDs(true);
    w.setDeterministicID(true);
    w.write();
}

int
main(int argc, char* argv[])
{
    whoami = QUtil::getWhoami(argv[0]);

    char const* infilename = nullptr;
    char const* password = nullptr;
    char const* attachment = nullptr;
    char const* outfilename = nullptr;
    char const* mimetype = nullptr;

    auto check_arg = [](char const* arg, std::string const& msg) {
        if (arg == nullptr) {
            usage(msg);
        }
    };

    for (int i = 1; i < argc; ++i) {
        char* arg = argv[i];
        char* next = argv[i + 1];
        if (strcmp(arg, "--infile") == 0) {
            check_arg(next, "--infile takes an argument");
            infilename = next;
            ++i;
        } else if (strcmp(arg, "--password") == 0) {
            check_arg(next, "--password takes an argument");
            password = next;
            ++i;
        } else if (strcmp(arg, "--attachment") == 0) {
            check_arg(next, "--attachment takes an argument");
            attachment = next;
            ++i;
        } else if (strcmp(arg, "--outfile") == 0) {
            check_arg(next, "--outfile takes an argument");
            outfilename = next;
            ++i;
        } else if (strcmp(arg, "--mimetype") == 0) {
            check_arg(next, "--mimetype takes an argument");
            mimetype = next;
            ++i;
        } else {
            usage("unknown argument " + std::string(arg));
        }
    }
    if (!(infilename && attachment && outfilename)) {
        usage("required arguments were not provided");
    }

    try {
        process(infilename, password, attachment, mimetype, outfilename);
    } catch (std::exception& e) {
        std::cerr << whoami << " exception: " << e.what() << std::endl;
        exit(2);
    }

    return 0;
}