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