mirror of https://github.com/qpdf/qpdf.git
Add example of name/number trees and dictionary/array iteration
This commit is contained in:
Jay Berkenbilt
parent
ce19ec5c4b
commit
1fec40454e
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@ -1,3 +1,8 @@
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2021-01-30 Jay Berkenbilt <ejb@ql.org>
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* Add examples/pdf-name-number-tree.cc to illustrate new
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name/number tree API and new array/dictionary iterator API.
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2021-01-29 Jay Berkenbilt <ejb@ql.org>
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* Add wrappers QPDFDictItems and QPDFArrayItems around
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@ -7,6 +7,7 @@ BINS_examples = \
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pdf-filter-tokens \
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pdf-invert-images \
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pdf-mod-info \
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pdf-name-number-tree \
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pdf-npages \
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pdf-overlay-page \
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pdf-parse-content \
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@ -0,0 +1,214 @@
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#include <qpdf/QPDF.hh>
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#include <qpdf/QPDFNameTreeObjectHelper.hh>
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#include <qpdf/QPDFNumberTreeObjectHelper.hh>
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#include <qpdf/QPDFWriter.hh>
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#include <qpdf/QUtil.hh>
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#include <iostream>
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#include <cstring>
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static char const* whoami = 0;
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void usage()
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{
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std::cerr << "Usage: " << whoami << " outfile.pdf"
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<< std::endl
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<< "Create some name/number trees and write to a file"
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<< std::endl;
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exit(2);
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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* outfilename = argv[1];
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QPDF qpdf;
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qpdf.emptyPDF();
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// This example doesn't do anything particularly useful other than
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// just illustrate how to use the APIs for name and number trees.
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// It also demonstrates use of the iterators for dictionaries and
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// arrays introduced at the same time with qpdf 10.2.
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// To use this example, compile it and run it. Study the output
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// and compare it to what you expect. When done, look at the
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// generated output file in a text editor to inspect the structure
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// of the trees as left in the file.
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// We're just going to create some name and number trees, hang
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// them off the document catalog (root), and write an empty PDF to
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// a file. The PDF will have no pages and won't be viewable, but
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// you can look at it in a text editor to see the resulting
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// structure of the PDF.
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// Create a dictionary off the root where we will hang our name
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// and number tree.
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auto root = qpdf.getRoot();
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auto example = QPDFObjectHandle::newDictionary();
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root.replaceKey("/Example", example);
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// Create a name tree, attach it to the file, and add some items.
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auto name_tree = QPDFNameTreeObjectHelper::newEmpty(qpdf);
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auto name_tree_oh = name_tree.getObjectHandle();
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example.replaceKey("/NameTree", name_tree_oh);
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name_tree.insert("K", QPDFObjectHandle::newUnicodeString("king"));
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name_tree.insert("Q", QPDFObjectHandle::newUnicodeString("queen"));
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name_tree.insert("R", QPDFObjectHandle::newUnicodeString("rook"));
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name_tree.insert("B", QPDFObjectHandle::newUnicodeString("bishop"));
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name_tree.insert("N", QPDFObjectHandle::newUnicodeString("knight"));
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auto iter = name_tree.insert(
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"P", QPDFObjectHandle::newUnicodeString("pawn"));
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// Look at the iterator
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std::cout << "just inserted " << iter->first << " -> "
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<< iter->second.unparse() << std::endl;
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--iter;
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std::cout << "predecessor: " << iter->first << " -> "
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<< iter->second.unparse() << std::endl;
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++iter;
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++iter;
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std::cout << "successor: " << iter->first << " -> "
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<< iter->second.unparse() << std::endl;
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// Use range-for iteration
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std::cout << "Name tree items:" << std::endl;
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for (auto i: name_tree)
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{
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std::cout << " " << i.first << " -> "
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<< i.second.unparse() << std::endl;
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}
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// This is a small tree, so everything will be at the root. We can
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// look at it using dictionary and array iterators.
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std::cout << "Keys in name tree object:" << std::endl;
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QPDFObjectHandle names;
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for (auto const& i: QPDFDictItems(name_tree_oh))
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{
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std::cout << i.first << std::endl;
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if (i.first == "/Names")
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{
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names = i.second;
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}
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}
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// Values in names array:
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std::cout << "Values in names:" << std::endl;
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for (auto& i: QPDFArrayItems(names))
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{
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std::cout << " " << i.unparse() << std::endl;
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}
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// pre 10.2 API
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std::cout << "Has Q?: " << name_tree.hasName("Q") << std::endl;
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std::cout << "Has W?: " << name_tree.hasName("W") << std::endl;
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QPDFObjectHandle obj;
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std::cout << "Found W?: " << name_tree.findObject("W", obj) << std::endl;
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std::cout << "Found Q?: " << name_tree.findObject("Q", obj) << std::endl;
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std::cout << "Q: " << obj.unparse() << std::endl;
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// 10.2 API
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iter = name_tree.find("Q");
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std::cout << "Q: " << iter->first << " -> "
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<< iter->second.unparse() << std::endl;
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iter = name_tree.find("W");
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std::cout << "W found: " << (iter != name_tree.end()) << std::endl;
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// Allow find to return predecessor
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iter = name_tree.find("W", true);
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std::cout << "W's predecessor: " << iter->first << " -> "
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<< iter->second.unparse() << std::endl;
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// We can also remove items
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std::cout << "Remove P: " << name_tree.remove("P", &obj) << std::endl;
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std::cout << "Value removed: " << obj.unparse() << std::endl;
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std::cout << "Has P?: " << name_tree.hasName("P") << std::endl;
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// Or we can remove using an iterator
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iter = name_tree.find("K");
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std::cout << "Find K: " << iter->second.unparse() << std::endl;
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iter.remove();
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std::cout << "Iter after removing K: " << iter->first << " -> "
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<< iter->second.unparse() << std::endl;
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std::cout << "Has K?: " << name_tree.hasName("K") << std::endl;
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// Illustrate some more advanced usage using number trees. These
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// calls work for name trees too.
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// The safe way to populate a tree is to call insert repeatedly as
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// above, but if you know you are definitely inserting items in
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// order, it is more efficient to insert them using insertAfter,
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// which avoids doing a binary search through the tree for each
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// insertion. Note that if you don't insert items in order using
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// this method, you will create an invalid tree.
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auto number_tree = QPDFNumberTreeObjectHelper::newEmpty(qpdf);
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auto number_tree_oh = number_tree.getObjectHandle();
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example.replaceKey("/NumberTree", number_tree_oh);
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auto iter2 = number_tree.begin();
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for (int i = 7; i <= 350; i += 7)
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{
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iter2.insertAfter(i, QPDFObjectHandle::newString(
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"-" + QUtil::int_to_string(i) + "-"));
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}
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std::cout << "Numbers:" << std::endl;
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int n = 1;
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for (auto& i: number_tree)
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{
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std::cout << i.first << " -> " << i.second.getUTF8Value();
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if (n % 5)
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{
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std::cout << ", ";
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}
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else
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{
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std::cout << std::endl;
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}
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++n;
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}
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// When you remove an item with an iterator, the iterator
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// advances. This makes it possible to filter while iterating.
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// Remove all items that are multiples of 5.
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iter2 = number_tree.begin();
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while (iter2 != number_tree.end())
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{
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if (iter2->first % 5 == 0)
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{
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iter2.remove(); // also advances
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}
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else
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{
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++iter2;
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}
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}
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std::cout << "Numbers after filtering:" << std::endl;
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n = 1;
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for (auto& i: number_tree)
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{
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std::cout << i.first << " -> " << i.second.getUTF8Value();
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if (n % 5)
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{
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std::cout << ", ";
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}
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else
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{
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std::cout << std::endl;
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}
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++n;
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}
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// Write to an output file
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QPDFWriter w(qpdf, outfilename);
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w.setQDFMode(true);
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w.setStaticID(true); // for testing only
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w.write();
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return 0;
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}
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@ -0,0 +1,30 @@
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#!/usr/bin/env perl
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require 5.008;
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BEGIN { $^W = 1; }
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use strict;
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chdir("name-number-tree") or die "chdir testdir failed: $!\n";
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require TestDriver;
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my $td = new TestDriver('name-number-tree');
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cleanup();
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$td->runtest("name/number tree",
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{$td->COMMAND => 'pdf-name-number-tree a.pdf'},
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{$td->FILE => 'nn.out', $td->EXIT_STATUS => 0},
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$td->NORMALIZE_NEWLINES);
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$td->runtest("check output",
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{$td->FILE => "a.pdf"},
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{$td->FILE => "out.pdf"});
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cleanup();
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$td->report(2);
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sub cleanup
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{
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unlink 'a.pdf';
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}
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@ -0,0 +1,59 @@
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just inserted P -> (pawn)
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predecessor: N -> (knight)
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successor: Q -> (queen)
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Name tree items:
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B -> (bishop)
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K -> (king)
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N -> (knight)
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P -> (pawn)
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Q -> (queen)
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R -> (rook)
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Keys in name tree object:
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/Names
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Values in names:
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(B)
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(bishop)
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(K)
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(king)
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(N)
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(knight)
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(P)
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(pawn)
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(Q)
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(queen)
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(R)
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(rook)
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Has Q?: 1
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Has W?: 0
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Found W?: 0
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Found Q?: 1
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Q: (queen)
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Q: Q -> (queen)
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W found: 0
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W's predecessor: R -> (rook)
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Remove P: 1
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Value removed: (pawn)
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Has P?: 0
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Find K: (king)
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Iter after removing K: N -> (knight)
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Has K?: 0
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Numbers:
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7 -> -7-, 14 -> -14-, 21 -> -21-, 28 -> -28-, 35 -> -35-
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42 -> -42-, 49 -> -49-, 56 -> -56-, 63 -> -63-, 70 -> -70-
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77 -> -77-, 84 -> -84-, 91 -> -91-, 98 -> -98-, 105 -> -105-
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112 -> -112-, 119 -> -119-, 126 -> -126-, 133 -> -133-, 140 -> -140-
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147 -> -147-, 154 -> -154-, 161 -> -161-, 168 -> -168-, 175 -> -175-
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182 -> -182-, 189 -> -189-, 196 -> -196-, 203 -> -203-, 210 -> -210-
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217 -> -217-, 224 -> -224-, 231 -> -231-, 238 -> -238-, 245 -> -245-
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252 -> -252-, 259 -> -259-, 266 -> -266-, 273 -> -273-, 280 -> -280-
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287 -> -287-, 294 -> -294-, 301 -> -301-, 308 -> -308-, 315 -> -315-
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322 -> -322-, 329 -> -329-, 336 -> -336-, 343 -> -343-, 350 -> -350-
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Numbers after filtering:
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7 -> -7-, 14 -> -14-, 21 -> -21-, 28 -> -28-, 42 -> -42-
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49 -> -49-, 56 -> -56-, 63 -> -63-, 77 -> -77-, 84 -> -84-
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91 -> -91-, 98 -> -98-, 112 -> -112-, 119 -> -119-, 126 -> -126-
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133 -> -133-, 147 -> -147-, 154 -> -154-, 161 -> -161-, 168 -> -168-
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182 -> -182-, 189 -> -189-, 196 -> -196-, 203 -> -203-, 217 -> -217-
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224 -> -224-, 231 -> -231-, 238 -> -238-, 252 -> -252-, 259 -> -259-
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266 -> -266-, 273 -> -273-, 287 -> -287-, 294 -> -294-, 301 -> -301-
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308 -> -308-, 322 -> -322-, 329 -> -329-, 336 -> -336-, 343 -> -343-
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@ -0,0 +1,179 @@
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%PDF-1.3
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%¿÷¢þ
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%QDF-1.0
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%% Original object ID: 1 0
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1 0 obj
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<<
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/Example <<
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/NameTree <<
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/Names [
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(B)
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(bishop)
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(N)
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(knight)
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(Q)
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(queen)
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(R)
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(rook)
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]
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>>
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/NumberTree <<
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/Kids [
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2 0 R
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3 0 R
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4 0 R
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]
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/Limits [
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7
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343
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]
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>>
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>>
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/Pages 5 0 R
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/Type /Catalog
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>>
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endobj
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%% Original object ID: 3 0
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2 0 obj
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<<
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/Limits [
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7
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112
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]
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/Nums [
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7
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(-7-)
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14
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(-14-)
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21
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(-21-)
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28
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(-28-)
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42
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(-42-)
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49
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(-49-)
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56
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(-56-)
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63
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(-63-)
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77
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(-77-)
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84
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(-84-)
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91
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(-91-)
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98
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(-98-)
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112
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(-112-)
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]
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>>
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endobj
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%% Original object ID: 4 0
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3 0 obj
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<<
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/Limits [
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119
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224
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]
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/Nums [
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119
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(-119-)
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126
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(-126-)
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133
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(-133-)
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147
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(-147-)
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154
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(-154-)
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161
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(-161-)
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168
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(-168-)
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182
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(-182-)
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189
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(-189-)
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196
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(-196-)
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203
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(-203-)
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217
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(-217-)
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224
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(-224-)
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]
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>>
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endobj
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%% Original object ID: 5 0
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4 0 obj
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<<
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/Limits [
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231
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343
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]
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/Nums [
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231
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(-231-)
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238
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(-238-)
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252
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(-252-)
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259
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(-259-)
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266
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(-266-)
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273
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(-273-)
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287
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(-287-)
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294
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(-294-)
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301
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(-301-)
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308
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(-308-)
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322
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(-322-)
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329
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(-329-)
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336
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(-336-)
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343
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(-343-)
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]
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>>
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endobj
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%% Original object ID: 2 0
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5 0 obj
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<<
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/Count 0
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/Kids [
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]
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/Type /Pages
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>>
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endobj
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xref
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0 6
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0000000000 65535 f
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0000000052 00000 n
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0000000448 00000 n
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0000000775 00000 n
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0000001130 00000 n
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0000001505 00000 n
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trailer <<
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/Root 1 0 R
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/Size 6
|
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/ID [<31415926535897932384626433832795><31415926535897932384626433832795>]
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>>
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startxref
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1567
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%%EOF
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@ -35,6 +35,9 @@
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// up items in the name tree, use UTF-8 strings. All names are
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// normalized for lookup purposes.
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// See examples/pdf-name-number-tree.cc for a demonstration of using
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// QPDFNameTreeObjectHelper.
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|
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class NNTreeImpl;
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class NNTreeIterator;
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class NNTreeDetails;
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|
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@ -32,6 +32,9 @@
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// This is an object helper for number trees. See section 7.9.7 in the
|
||||
// PDF spec (ISO 32000) for a description of number trees.
|
||||
|
||||
// See examples/pdf-name-number-tree.cc for a demonstration of using
|
||||
// QPDFNumberTreeObjectHelper.
|
||||
|
||||
class NNTreeImpl;
|
||||
class NNTreeIterator;
|
||||
class NNTreeDetails;
|
||||
|
|
|
|||
|
|
@ -1237,6 +1237,9 @@ class QPDFDictItems
|
|||
// // iter.second is a QPDFObjectHandle
|
||||
// }
|
||||
|
||||
// See examples/pdf-name-number-tree.cc for a demonstration of
|
||||
// using this API.
|
||||
|
||||
public:
|
||||
QPDF_DLL
|
||||
QPDFDictItems(QPDFObjectHandle& oh);
|
||||
|
|
@ -1324,6 +1327,9 @@ class QPDFArrayItems
|
|||
// // iter is a QPDFObjectHandle
|
||||
// }
|
||||
|
||||
// See examples/pdf-name-number-tree.cc for a demonstration of
|
||||
// using this API.
|
||||
|
||||
public:
|
||||
QPDF_DLL
|
||||
QPDFArrayItems(QPDFObjectHandle& oh);
|
||||
|
|
|
|||
|
|
@ -4854,7 +4854,8 @@ print "\n";
|
|||
<classname>QPDFObjectHandle</classname>, allowing C++-style
|
||||
iteration, including range-for iteration, over dictionary
|
||||
and array QPDFObjectHandles. See comments in
|
||||
<filename>include/qpdf/QPDFObjectHandle.hh</filename> for
|
||||
<filename>include/qpdf/QPDFObjectHandle.hh</filename> and
|
||||
<filename>examples/pdf-name-number-tree.cc</filename> for
|
||||
details.
|
||||
</para>
|
||||
</listitem>
|
||||
|
|
|
|||
Loading…
Reference in New Issue