octoleo
/
qpdf
mirror of https://github.com/qpdf/qpdf.git
2
1
Fork 0
Code Issues Releases Wiki Activity
qpdf/examples/pdf-create.cc

404 lines
14 KiB
C++
Raw Blame History

//
// This is an example of creating a PDF file from scratch. It
// illustrates use of several QPDF operations for creating objects and
// streams. It also serves as an illustration of how to use
// StreamDataProvider with different types of filters.
//
#include <qpdf/Pl_Buffer.hh>
#include <qpdf/Pl_DCT.hh>
#include <qpdf/Pl_RunLength.hh>
#include <qpdf/QIntC.hh>
#include <qpdf/QPDF.hh>
#include <qpdf/QPDFObjectHandle.hh>
#include <qpdf/QPDFPageDocumentHelper.hh>
#include <qpdf/QPDFPageObjectHelper.hh>
#include <qpdf/QPDFWriter.hh>
#include <qpdf/QUtil.hh>
#include <iostream>
#include <memory>
#include <stdlib.h>
#include <string.h>
static char const* whoami = 0;
// This is a simple StreamDataProvider that writes image data for an
// orange square of the given width and height.
class ImageProvider: public QPDFObjectHandle::StreamDataProvider
{
public:
ImageProvider(std::string const& color_space, std::string const& filter);
virtual ~ImageProvider() = default;
virtual void
provideStreamData(int objid, int generation, Pipeline* pipeline);
size_t getWidth() const;
size_t getHeight() const;
private:
size_t width;
size_t stripe_height;
std::string color_space;
std::string filter;
size_t n_stripes;
std::vector<std::string> stripes;
J_COLOR_SPACE j_color_space;
};
ImageProvider::ImageProvider(
std::string const& color_space, std::string const& filter) :
width(400),
stripe_height(80),
color_space(color_space),
filter(filter),
n_stripes(6),
j_color_space(JCS_UNKNOWN)
{
if (color_space == "/DeviceCMYK") {
j_color_space = JCS_CMYK;
stripes.push_back(std::string("\xff\x00\x00\x00", 4));
stripes.push_back(std::string("\x00\xff\x00\x00", 4));
stripes.push_back(std::string("\x00\x00\xff\x00", 4));
stripes.push_back(std::string("\xff\x00\xff\x00", 4));
stripes.push_back(std::string("\xff\xff\x00\x00", 4));
stripes.push_back(std::string("\x00\x00\x00\xff", 4));
} else if (color_space == "/DeviceRGB") {
j_color_space = JCS_RGB;
stripes.push_back(std::string("\xff\x00\x00", 3));
stripes.push_back(std::string("\x00\xff\x00", 3));
stripes.push_back(std::string("\x00\x00\xff", 3));
stripes.push_back(std::string("\xff\x00\xff", 3));
stripes.push_back(std::string("\xff\xff\x00", 3));
stripes.push_back(std::string("\x00\x00\x00", 3));
} else if (color_space == "/DeviceGray") {
j_color_space = JCS_GRAYSCALE;
stripes.push_back(std::string("\xee", 1));
stripes.push_back(std::string("\xcc", 1));
stripes.push_back(std::string("\x99", 1));
stripes.push_back(std::string("\x66", 1));
stripes.push_back(std::string("\x33", 1));
stripes.push_back(std::string("\x00", 1));
}
}
size_t
ImageProvider::getWidth() const
{
return width;
}
size_t
ImageProvider::getHeight() const
{
return stripe_height * n_stripes;
}
void
ImageProvider::provideStreamData(int objid, int generation, Pipeline* pipeline)
{
std::vector<std::shared_ptr<Pipeline>> to_delete;
Pipeline* p = pipeline;
std::shared_ptr<Pipeline> p_new;
if (filter == "/DCTDecode") {
p_new = std::make_shared<Pl_DCT>(
"image encoder",
pipeline,
QIntC::to_uint(width),
QIntC::to_uint(getHeight()),
QIntC::to_int(stripes[0].length()),
j_color_space);
to_delete.push_back(p_new);
p = p_new.get();
} else if (filter == "/RunLengthDecode") {
p_new = std::make_shared<Pl_RunLength>(
"image encoder", pipeline, Pl_RunLength::a_encode);
to_delete.push_back(p_new);
p = p_new.get();
}
for (size_t i = 0; i < n_stripes; ++i) {
for (size_t j = 0; j < width * stripe_height; ++j) {
p->write(
QUtil::unsigned_char_pointer(stripes[i].c_str()),
stripes[i].length());
}
}
p->finish();
}
void
usage()
{
std::cerr << "Usage: " << whoami << " filename" << std::endl
<< "Creates a simple PDF and writes it to filename" << std::endl;
exit(2);
}
static QPDFObjectHandle
createPageContents(QPDF& pdf, std::string const& text)
{
// Create a stream that displays our image and the given text in
// our font.
std::string contents = "BT /F1 24 Tf 72 320 Td (" + text +
") Tj ET\n"
"q 244 0 0 144 184 100 cm /Im1 Do Q\n";
return QPDFObjectHandle::newStream(&pdf, contents);
}
QPDFObjectHandle
newName(std::string const& name)
{
return QPDFObjectHandle::newName(name);
}
QPDFObjectHandle
newInteger(size_t val)
{
return QPDFObjectHandle::newInteger(QIntC::to_int(val));
}
void
add_page(
QPDFPageDocumentHelper& dh,
QPDFObjectHandle font,
std::string const& color_space,
std::string const& filter)
{
QPDF& pdf(dh.getQPDF());
// Create a stream to encode our image. QPDFWriter will fill in
// the length and will respect our filters based on stream data
// mode. Since we are not specifying, QPDFWriter will compress
// with /FlateDecode if we don't provide any other form of
// compression.
ImageProvider* p = new ImageProvider(color_space, filter);
std::shared_ptr<QPDFObjectHandle::StreamDataProvider> provider(p);
size_t width = p->getWidth();
size_t height = p->getHeight();
QPDFObjectHandle image = QPDFObjectHandle::newStream(&pdf);
auto image_dict =
// line-break
"<<"
" /Type /XObject"
" /Subtype /Image"
" /BitsPerComponent 8"
">>"_qpdf;
image_dict.replaceKey("/ColorSpace", newName(color_space))
.replaceKey("/Width", newInteger(width))
.replaceKey("/Height", newInteger(height));
image.replaceDict(image_dict);
// Provide the stream data.
image.replaceStreamData(
provider, QPDFObjectHandle::parse(filter), QPDFObjectHandle::newNull());
// Create direct objects as needed by the page dictionary.
QPDFObjectHandle procset = "[/PDF /Text /ImageC]"_qpdf;
QPDFObjectHandle rfont = QPDFObjectHandle::newDictionary();
rfont.replaceKey("/F1", font);
QPDFObjectHandle xobject = QPDFObjectHandle::newDictionary();
xobject.replaceKey("/Im1", image);
QPDFObjectHandle resources = QPDFObjectHandle::newDictionary();
resources.replaceKey("/ProcSet", procset)
.replaceKey("/Font", rfont)
.replaceKey("/XObject", xobject);
// Create the page content stream
QPDFObjectHandle contents =
createPageContents(pdf, color_space + " with filter " + filter);
// Create the page dictionary
QPDFObjectHandle page = pdf.makeIndirectObject("<<"
" /Type /Page"
" /MediaBox [0 0 612 392]"
">>"_qpdf);
page.replaceKey("/Contents", contents).replaceKey("/Resources", resources);
// Add the page to the PDF file
dh.addPage(page, false);
}
static void
check(
char const* filename,
std::vector<std::string> const& color_spaces,
std::vector<std::string> const& filters)
{
// Each stream is compressed the way it is supposed to be. We will
// add additional tests in qpdf.test to exercise QPDFWriter more
// fully. In this case, we want to make sure that we actually have
// RunLengthDecode and DCTDecode where we are supposed to and
// FlateDecode where we provided no filters.
// Each image is correct. For non-lossy image compression, the
// uncompressed image data should exactly match what ImageProvider
// provided. For the DCTDecode data, allow for some fuzz to handle
// jpeg compression as well as its variance on different systems.
// These tests should use QPDFObjectHandle's stream data retrieval
// methods, but don't try to fully exercise them here. That is
// done elsewhere.
size_t n_color_spaces = color_spaces.size();
size_t n_filters = filters.size();
QPDF pdf;
pdf.processFile(filename);
auto pages = QPDFPageDocumentHelper(pdf).getAllPages();
if (n_color_spaces * n_filters != pages.size()) {
throw std::logic_error("incorrect number of pages");
}
size_t pageno = 1;
bool errors = false;
for (auto& page: pages) {
auto images = page.getImages();
if (images.size() != 1) {
throw std::logic_error("incorrect number of images on page");
}
// Check filter and color space.
std::string desired_color_space =
color_spaces[(pageno - 1) / n_color_spaces];
std::string desired_filter = filters[(pageno - 1) % n_filters];
// In the default mode, QPDFWriter will compress with
// /FlateDecode if no filters are provided.
if (desired_filter == "null") {
desired_filter = "/FlateDecode";
}
QPDFObjectHandle image = images.begin()->second;
QPDFObjectHandle image_dict = image.getDict();
QPDFObjectHandle color_space = image_dict.getKey("/ColorSpace");
QPDFObjectHandle filter = image_dict.getKey("/Filter");
bool this_errors = false;
if (!filter.isNameAndEquals(desired_filter)) {
this_errors = errors = true;
std::cout << "page " << pageno << ": expected filter "
<< desired_filter
<< "; actual filter = " << filter.unparse() << std::endl;
}
if (!color_space.isNameAndEquals(desired_color_space)) {
this_errors = errors = true;
std::cout << "page " << pageno << ": expected color space "
<< desired_color_space
<< "; actual color space = " << color_space.unparse()
<< std::endl;
}
if (!this_errors) {
// Check image data
auto actual_data = image.getStreamData(qpdf_dl_all);
ImageProvider* p = new ImageProvider(desired_color_space, "null");
std::shared_ptr<QPDFObjectHandle::StreamDataProvider> provider(p);
Pl_Buffer b_p("get image data");
provider->provideStreamData(0, 0, &b_p);
std::shared_ptr<Buffer> desired_data(b_p.getBuffer());
if (desired_data->getSize() != actual_data->getSize()) {
std::cout << "page " << pageno << ": image data length mismatch"
<< std::endl;
this_errors = errors = true;
} else {
// Compare bytes. For JPEG, allow a certain number of
// the bytes to be off desired by more than a given
// tolerance. Any of the samples may be a little off
// because of lossy compression, and around sharp
// edges, things can be quite off. For non-lossy
// compression, do not allow any tolerance.
unsigned char const* actual_bytes = actual_data->getBuffer();
unsigned char const* desired_bytes = desired_data->getBuffer();
size_t len = actual_data->getSize();
unsigned int mismatches = 0;
int tolerance = (desired_filter == "/DCTDecode" ? 10 : 0);
size_t threshold =
(desired_filter == "/DCTDecode" ? len / 40U : 0);
for (size_t i = 0; i < len; ++i) {
int delta = actual_bytes[i] - desired_bytes[i];
if ((delta > tolerance) || (delta < -tolerance)) {
++mismatches;
}
}
if (mismatches > threshold) {
std::cout << "page " << pageno << ": "
<< desired_color_space << ", " << desired_filter
<< ": mismatches: " << mismatches << " of " << len
<< std::endl;
this_errors = errors = true;
}
}
}
++pageno;
}
if (errors) {
throw std::logic_error("errors found");
} else {
std::cout << "all checks passed" << std::endl;
}
}
static void
create_pdf(char const* filename)
{
QPDF pdf;
// Start with an empty PDF that has no pages or non-required objects.
pdf.emptyPDF();
// Add an indirect object to contain a font descriptor for the
// built-in Helvetica font.
QPDFObjectHandle font = pdf.makeIndirectObject(
// line-break
"<<"
" /Type /Font"
" /Subtype /Type1"
" /Name /F1"
" /BaseFont /Helvetica"
" /Encoding /WinAnsiEncoding"
">>"_qpdf);
std::vector<std::string> color_spaces;
color_spaces.push_back("/DeviceCMYK");
color_spaces.push_back("/DeviceRGB");
color_spaces.push_back("/DeviceGray");
std::vector<std::string> filters;
filters.push_back("null");
filters.push_back("/DCTDecode");
filters.push_back("/RunLengthDecode");
QPDFPageDocumentHelper dh(pdf);
for (auto const& color_space: color_spaces) {
for (auto const& filter: filters) {
add_page(dh, font, color_space, filter);
}
}
QPDFWriter w(pdf, filename);
w.write();
// For test suite, verify that everything is the way it is
// supposed to be.
check(filename, color_spaces, filters);
}
int
main(int argc, char* argv[])
{
whoami = QUtil::getWhoami(argv[0]);
if (argc != 2) {
usage();
}
char const* filename = argv[1];
try {
create_pdf(filename);
} catch (std::exception& e) {
std::cerr << e.what() << std::endl;
exit(2);
}
return 0;
}
View Git Blame Copy Permalink