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qpdf/examples/pdf-overlay-page.cc
2023-12-22 21:45:10 -05:00

89 lines
3.1 KiB
C++

#include <qpdf/QPDF.hh>
#include <qpdf/QPDFPageDocumentHelper.hh>
#include <qpdf/QPDFPageObjectHelper.hh>
#include <qpdf/QPDFWriter.hh>
#include <qpdf/QUtil.hh>
#include <cstdlib>
#include <iostream>
// This program demonstrates use of form XObjects to overlay a page from one file onto all pages of
// another file. The qpdf program's --overlay and --underlay options provide a more general version
// of this capability.
static char const* whoami = nullptr;
void
usage()
{
std::cerr << "Usage: " << whoami << " infile pagefile outfile" << std::endl
<< "Stamp page 1 of pagefile on every page of infile, writing to outfile"
<< std::endl;
exit(2);
}
static void
stamp_page(char const* infile, char const* stampfile, char const* outfile)
{
QPDF inpdf;
inpdf.processFile(infile);
QPDF stamppdf;
stamppdf.processFile(stampfile);
// Get first page from other file
QPDFPageObjectHelper stamp_page_1 = QPDFPageDocumentHelper(stamppdf).getAllPages().at(0);
// Convert page to a form XObject
QPDFObjectHandle foreign_fo = stamp_page_1.getFormXObjectForPage();
// Copy form XObject to the input file
QPDFObjectHandle stamp_fo = inpdf.copyForeignObject(foreign_fo);
// For each page...
for (auto& ph: QPDFPageDocumentHelper(inpdf).getAllPages()) {
// Find a unique resource name for the new form XObject
QPDFObjectHandle resources = ph.getAttribute("/Resources", true);
int min_suffix = 1;
std::string name = resources.getUniqueResourceName("/Fx", min_suffix);
// Generate content to place the form XObject centered within destination page's trim box.
QPDFMatrix m;
std::string content =
ph.placeFormXObject(stamp_fo, name, ph.getTrimBox().getArrayAsRectangle(), m);
if (!content.empty()) {
// Append the content to the page's content. Surround the original content with q...Q to
// the new content from the page's original content.
resources.mergeResources("<< /XObject << >> >>"_qpdf);
resources.getKey("/XObject").replaceKey(name, stamp_fo);
ph.addPageContents(inpdf.newStream("q\n"), true);
ph.addPageContents(inpdf.newStream("\nQ\n" + content), false);
}
// Copy the annotations and form fields from the original page to the new page. For more
// efficiency when copying multiple pages, we can create a QPDFAcroFormDocumentHelper and
// pass it in. See comments in QPDFPageObjectHelper.hh for details.
ph.copyAnnotations(stamp_page_1, m);
}
QPDFWriter w(inpdf, outfile);
w.setStaticID(true); // for testing only
w.write();
}
int
main(int argc, char* argv[])
{
whoami = QUtil::getWhoami(argv[0]);
if (argc != 4) {
usage();
}
char const* infile = argv[1];
char const* stampfile = argv[2];
char const* outfile = argv[3];
try {
stamp_page(infile, stampfile, outfile);
} catch (std::exception& e) {
std::cerr << whoami << ": " << e.what() << std::endl;
exit(2);
}
return 0;
}