mirror of
https://github.com/qpdf/qpdf.git
synced 2024-11-04 12:34:20 +00:00
d71f05ca07
This makes all integer type conversions that have potential data loss explicit with calls that do range checks and raise an exception. After this commit, qpdf builds with no warnings when -Wsign-conversion -Wconversion is used with gcc or clang or when -W3 -Wd4800 is used with MSVC. This significantly reduces the likelihood of potential crashes from bogus integer values. There are some parts of the code that take int when they should take size_t or an offset. Such places would make qpdf not support files with more than 2^31 of something that usually wouldn't be so large. In the event that such a file shows up and is valid, at least qpdf would raise an error in the right spot so the issue could be legitimately addressed rather than failing in some weird way because of a silent overflow condition.
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 <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<PointerHolder<Pipeline> > to_delete;
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Pipeline* p = pipeline;
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if (filter == "/DCTDecode")
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{
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p = new 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);
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}
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else if (filter == "/RunLengthDecode")
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{
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p = new Pl_RunLength(
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"image encoder", pipeline, Pl_RunLength::a_encode);
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to_delete.push_back(p);
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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(QPDFObjectHandle::parse(
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"<<"
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" /Type /XObject"
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" /Subtype /Image"
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" /BitsPerComponent 8"
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">>"));
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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 = QPDFObjectHandle::parse(
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"[/PDF /Text /ImageC]");
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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.getPageImages();
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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.isName() && (filter.getName() == 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.isName() &&
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(color_space.getName() == 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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QPDFObjectHandle::parse(
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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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">>"));
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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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