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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.
531 lines
17 KiB
C++
531 lines
17 KiB
C++
// See the "Optimization" section of the manual.
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#include <qpdf/QPDF.hh>
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#include <qpdf/QTC.hh>
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#include <qpdf/QPDFExc.hh>
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#include <qpdf/QPDF_Dictionary.hh>
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#include <qpdf/QPDF_Array.hh>
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#include <assert.h>
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QPDF::ObjUser::ObjUser() :
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ou_type(ou_bad),
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pageno(0)
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{
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}
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QPDF::ObjUser::ObjUser(user_e type) :
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ou_type(type),
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pageno(0)
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{
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assert(type == ou_root);
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}
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QPDF::ObjUser::ObjUser(user_e type, int pageno) :
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ou_type(type),
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pageno(pageno)
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{
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assert((type == ou_page) || (type == ou_thumb));
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}
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QPDF::ObjUser::ObjUser(user_e type, std::string const& key) :
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ou_type(type),
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pageno(0),
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key(key)
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{
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assert((type == ou_trailer_key) || (type == ou_root_key));
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}
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bool
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QPDF::ObjUser::operator<(ObjUser const& rhs) const
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{
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if (this->ou_type < rhs.ou_type)
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{
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return true;
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}
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else if (this->ou_type == rhs.ou_type)
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{
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if (this->pageno < rhs.pageno)
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{
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return true;
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}
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else if (this->pageno == rhs.pageno)
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{
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return (this->key < rhs.key);
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}
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}
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return false;
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}
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void
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QPDF::optimize(std::map<int, int> const& object_stream_data,
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bool allow_changes)
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{
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optimize(object_stream_data, allow_changes, nullptr);
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}
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void
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QPDF::optimize(std::map<int, int> const& object_stream_data,
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bool allow_changes,
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std::function<int(QPDFObjectHandle&)> skip_stream_parameters)
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{
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if (! this->m->obj_user_to_objects.empty())
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{
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// already optimized
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return;
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}
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// The PDF specification indicates that /Outlines is supposed to
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// be an indirect reference. Force it to be so if it exists and
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// is direct. (This has been seen in the wild.)
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QPDFObjectHandle root = getRoot();
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if (root.getKey("/Outlines").isDictionary())
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{
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QPDFObjectHandle outlines = root.getKey("/Outlines");
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if (! outlines.isIndirect())
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{
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QTC::TC("qpdf", "QPDF_optimization indirect outlines");
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root.replaceKey("/Outlines", makeIndirectObject(outlines));
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}
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}
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// Traverse pages tree pushing all inherited resources down to the
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// page level. This also initializes this->m->all_pages.
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pushInheritedAttributesToPage(allow_changes, false);
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// Traverse pages
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int n = toI(this->m->all_pages.size());
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for (int pageno = 0; pageno < n; ++pageno)
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{
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updateObjectMaps(ObjUser(ObjUser::ou_page, pageno),
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this->m->all_pages.at(toS(pageno)),
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skip_stream_parameters);
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}
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// Traverse document-level items
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std::set<std::string> keys = this->m->trailer.getKeys();
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for (std::set<std::string>::iterator iter = keys.begin();
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iter != keys.end(); ++iter)
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{
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std::string const& key = *iter;
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if (key == "/Root")
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{
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// handled separately
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}
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else
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{
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updateObjectMaps(ObjUser(ObjUser::ou_trailer_key, key),
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this->m->trailer.getKey(key),
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skip_stream_parameters);
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}
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}
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keys = root.getKeys();
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for (std::set<std::string>::iterator iter = keys.begin();
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iter != keys.end(); ++iter)
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{
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// Technically, /I keys from /Thread dictionaries are supposed
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// to be handled separately, but we are going to disregard
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// that specification for now. There is loads of evidence
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// that pdlin and Acrobat both disregard things like this from
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// time to time, so this is almost certain not to cause any
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// problems.
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std::string const& key = *iter;
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updateObjectMaps(ObjUser(ObjUser::ou_root_key, key),
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root.getKey(key),
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skip_stream_parameters);
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}
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ObjUser root_ou = ObjUser(ObjUser::ou_root);
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QPDFObjGen root_og = QPDFObjGen(root.getObjGen());
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this->m->obj_user_to_objects[root_ou].insert(root_og);
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this->m->object_to_obj_users[root_og].insert(root_ou);
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filterCompressedObjects(object_stream_data);
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}
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void
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QPDF::pushInheritedAttributesToPage()
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{
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// Public API should not have access to allow_changes.
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pushInheritedAttributesToPage(true, false);
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}
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void
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QPDF::pushInheritedAttributesToPage(bool allow_changes, bool warn_skipped_keys)
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{
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// Traverse pages tree pushing all inherited resources down to the
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// page level.
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// The record of whether we've done this is cleared by
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// updateAllPagesCache(). If we're warning for skipped keys,
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// re-traverse unconditionally.
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if (this->m->pushed_inherited_attributes_to_pages && (! warn_skipped_keys))
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{
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return;
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}
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// Calling getAllPages() resolves any duplicated page objects.
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getAllPages();
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// key_ancestors is a mapping of page attribute keys to a stack of
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// Pages nodes that contain values for them.
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std::map<std::string, std::vector<QPDFObjectHandle> > key_ancestors;
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this->m->all_pages.clear();
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std::set<QPDFObjGen> visited;
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pushInheritedAttributesToPageInternal(
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this->m->trailer.getKey("/Root").getKey("/Pages"),
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key_ancestors, this->m->all_pages, allow_changes, warn_skipped_keys,
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visited);
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if (! key_ancestors.empty())
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{
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throw std::logic_error(
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"key_ancestors not empty after"
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" pushing inherited attributes to pages");
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}
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this->m->pushed_inherited_attributes_to_pages = true;
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}
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void
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QPDF::pushInheritedAttributesToPageInternal(
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QPDFObjectHandle cur_pages,
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std::map<std::string, std::vector<QPDFObjectHandle> >& key_ancestors,
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std::vector<QPDFObjectHandle>& pages,
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bool allow_changes, bool warn_skipped_keys,
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std::set<QPDFObjGen>& visited)
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{
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QPDFObjGen this_og = cur_pages.getObjGen();
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if (visited.count(this_og) > 0)
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{
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throw QPDFExc(
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qpdf_e_pages, this->m->file->getName(),
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this->m->last_object_description, 0,
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"Loop detected in /Pages structure (inherited attributes)");
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}
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visited.insert(this_og);
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if (! cur_pages.isDictionary())
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{
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throw QPDFExc(qpdf_e_damaged_pdf, this->m->file->getName(),
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this->m->last_object_description,
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this->m->file->getLastOffset(),
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"invalid object in page tree");
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}
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// Extract the underlying dictionary object
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std::string type = cur_pages.getKey("/Type").getName();
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if (type == "/Pages")
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{
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// Make a list of inheritable keys. Only the keys /MediaBox,
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// /CropBox, /Resources, and /Rotate are inheritable
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// attributes. Push this object onto the stack of pages nodes
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// that have values for this attribute.
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std::set<std::string> inheritable_keys;
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std::set<std::string> keys = cur_pages.getKeys();
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for (std::set<std::string>::iterator iter = keys.begin();
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iter != keys.end(); ++iter)
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{
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std::string const& key = *iter;
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if ( (key == "/MediaBox") || (key == "/CropBox") ||
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(key == "/Resources") || (key == "/Rotate") )
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{
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if (! allow_changes)
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{
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throw QPDFExc(qpdf_e_internal, this->m->file->getName(),
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this->m->last_object_description,
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this->m->file->getLastOffset(),
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"optimize detected an "
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"inheritable attribute when called "
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"in no-change mode");
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}
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// This is an inheritable resource
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inheritable_keys.insert(key);
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QPDFObjectHandle oh = cur_pages.getKey(key);
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QTC::TC("qpdf", "QPDF opt direct pages resource",
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oh.isIndirect() ? 0 : 1);
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if (! oh.isIndirect())
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{
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if (! oh.isScalar())
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{
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// Replace shared direct object non-scalar
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// resources with indirect objects to avoid
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// copying large structures around.
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cur_pages.replaceKey(key, makeIndirectObject(oh));
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oh = cur_pages.getKey(key);
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}
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else
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{
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// It's okay to copy scalars.
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QTC::TC("qpdf", "QPDF opt inherited scalar");
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}
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}
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key_ancestors[key].push_back(oh);
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if (key_ancestors[key].size() > 1)
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{
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QTC::TC("qpdf", "QPDF opt key ancestors depth > 1");
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}
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// Remove this resource from this node. It will be
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// reattached at the page level.
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cur_pages.removeKey(key);
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}
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else if (! ((key == "/Type") || (key == "/Parent") ||
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(key == "/Kids") || (key == "/Count")))
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{
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// Warn when flattening, but not if the key is at the top
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// level (i.e. "/Parent" not set), as we don't change these;
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// but flattening removes intermediate /Pages nodes.
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if ( (warn_skipped_keys) && (cur_pages.hasKey("/Parent")) )
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{
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QTC::TC("qpdf", "QPDF unknown key not inherited");
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setLastObjectDescription("Pages object",
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cur_pages.getObjectID(),
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cur_pages.getGeneration());
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warn(QPDFExc(qpdf_e_pages, this->m->file->getName(),
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this->m->last_object_description, 0,
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"Unknown key " + key + " in /Pages object"
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" is being discarded as a result of"
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" flattening the /Pages tree"));
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}
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}
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}
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// Visit descendant nodes.
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QPDFObjectHandle kids = cur_pages.getKey("/Kids");
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int n = kids.getArrayNItems();
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for (int i = 0; i < n; ++i)
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{
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pushInheritedAttributesToPageInternal(
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kids.getArrayItem(i), key_ancestors, pages,
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allow_changes, warn_skipped_keys, visited);
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}
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// For each inheritable key, pop the stack. If the stack
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// becomes empty, remove it from the map. That way, the
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// invariant that the list of keys in key_ancestors is exactly
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// those keys for which inheritable attributes are available.
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if (! inheritable_keys.empty())
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{
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QTC::TC("qpdf", "QPDF opt inheritable keys");
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for (std::set<std::string>::iterator iter =
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inheritable_keys.begin();
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iter != inheritable_keys.end(); ++iter)
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{
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std::string const& key = (*iter);
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key_ancestors[key].pop_back();
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if (key_ancestors[key].empty())
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{
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QTC::TC("qpdf", "QPDF opt erase empty key ancestor");
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key_ancestors.erase(key);
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}
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}
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}
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else
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{
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QTC::TC("qpdf", "QPDF opt no inheritable keys");
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}
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}
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else if (type == "/Page")
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{
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// Add all available inheritable attributes not present in
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// this object to this object.
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for (std::map<std::string, std::vector<QPDFObjectHandle> >::iterator
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iter = key_ancestors.begin();
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iter != key_ancestors.end(); ++iter)
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{
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std::string const& key = (*iter).first;
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if (! cur_pages.hasKey(key))
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{
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QTC::TC("qpdf", "QPDF opt resource inherited");
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cur_pages.replaceKey(key, (*iter).second.back());
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}
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else
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{
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QTC::TC("qpdf", "QPDF opt page resource hides ancestor");
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}
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}
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pages.push_back(cur_pages);
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}
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else
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{
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throw QPDFExc(qpdf_e_damaged_pdf, this->m->file->getName(),
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this->m->last_object_description,
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this->m->file->getLastOffset(),
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"invalid Type " + type + " in page tree");
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}
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visited.erase(this_og);
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}
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void
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QPDF::updateObjectMaps(
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ObjUser const& ou, QPDFObjectHandle oh,
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std::function<int(QPDFObjectHandle&)> skip_stream_parameters)
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{
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std::set<QPDFObjGen> visited;
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updateObjectMapsInternal(ou, oh, skip_stream_parameters, visited, true, 0);
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}
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void
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QPDF::updateObjectMapsInternal(
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ObjUser const& ou, QPDFObjectHandle oh,
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std::function<int(QPDFObjectHandle&)> skip_stream_parameters,
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std::set<QPDFObjGen>& visited, bool top,
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int depth)
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{
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// Traverse the object tree from this point taking care to avoid
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// crossing page boundaries.
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bool is_page_node = false;
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if (oh.isDictionaryOfType("/Page"))
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{
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is_page_node = true;
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if (! top)
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{
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return;
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}
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}
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if (oh.isIndirect())
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{
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QPDFObjGen og(oh.getObjGen());
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if (visited.count(og))
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{
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QTC::TC("qpdf", "QPDF opt loop detected");
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return;
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}
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this->m->obj_user_to_objects[ou].insert(og);
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this->m->object_to_obj_users[og].insert(ou);
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visited.insert(og);
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}
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if (oh.isArray())
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{
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int n = oh.getArrayNItems();
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for (int i = 0; i < n; ++i)
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{
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updateObjectMapsInternal(
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ou, oh.getArrayItem(i), skip_stream_parameters,
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visited, false, 1 + depth);
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}
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}
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else if (oh.isDictionary() || oh.isStream())
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{
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QPDFObjectHandle dict = oh;
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bool is_stream = oh.isStream();
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int ssp = 0;
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if (is_stream)
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{
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dict = oh.getDict();
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if (skip_stream_parameters)
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{
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ssp = skip_stream_parameters(oh);
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}
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}
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std::set<std::string> keys = dict.getKeys();
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for (std::set<std::string>::iterator iter = keys.begin();
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iter != keys.end(); ++iter)
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{
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std::string const& key = *iter;
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if (is_page_node && (key == "/Thumb"))
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{
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// Traverse page thumbnail dictionaries as a special
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// case.
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updateObjectMapsInternal(
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ObjUser(ObjUser::ou_thumb, ou.pageno),
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dict.getKey(key), skip_stream_parameters,
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visited, false, 1 + depth);
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}
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else if (is_page_node && (key == "/Parent"))
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{
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// Don't traverse back up the page tree
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}
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else if (((ssp >= 1) && (key == "/Length")) ||
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((ssp >= 2) && ((key == "/Filter") ||
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(key == "/DecodeParms"))))
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{
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// Don't traverse into stream parameters that we are
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// not going to write.
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}
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else
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{
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updateObjectMapsInternal(
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ou, dict.getKey(key), skip_stream_parameters,
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visited, false, 1 + depth);
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}
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}
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}
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}
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void
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QPDF::filterCompressedObjects(std::map<int, int> const& object_stream_data)
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{
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if (object_stream_data.empty())
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{
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return;
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}
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// Transform object_to_obj_users and obj_user_to_objects so that
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// they refer only to uncompressed objects. If something is a
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// user of a compressed object, then it is really a user of the
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// object stream that contains it.
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std::map<ObjUser, std::set<QPDFObjGen> > t_obj_user_to_objects;
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std::map<QPDFObjGen, std::set<ObjUser> > t_object_to_obj_users;
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for (std::map<ObjUser, std::set<QPDFObjGen> >::iterator i1 =
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this->m->obj_user_to_objects.begin();
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i1 != this->m->obj_user_to_objects.end(); ++i1)
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{
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ObjUser const& ou = (*i1).first;
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std::set<QPDFObjGen> const& objects = (*i1).second;
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for (std::set<QPDFObjGen>::const_iterator i2 = objects.begin();
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i2 != objects.end(); ++i2)
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{
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QPDFObjGen const& og = (*i2);
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std::map<int, int>::const_iterator i3 =
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object_stream_data.find(og.getObj());
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if (i3 == object_stream_data.end())
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{
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t_obj_user_to_objects[ou].insert(og);
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}
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else
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{
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t_obj_user_to_objects[ou].insert(QPDFObjGen((*i3).second, 0));
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}
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}
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}
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for (std::map<QPDFObjGen, std::set<ObjUser> >::iterator i1 =
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this->m->object_to_obj_users.begin();
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i1 != this->m->object_to_obj_users.end(); ++i1)
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{
|
|
QPDFObjGen const& og = (*i1).first;
|
|
std::set<ObjUser> const& objusers = (*i1).second;
|
|
for (std::set<ObjUser>::const_iterator i2 = objusers.begin();
|
|
i2 != objusers.end(); ++i2)
|
|
{
|
|
ObjUser const& ou = (*i2);
|
|
std::map<int, int>::const_iterator i3 =
|
|
object_stream_data.find(og.getObj());
|
|
if (i3 == object_stream_data.end())
|
|
{
|
|
t_object_to_obj_users[og].insert(ou);
|
|
}
|
|
else
|
|
{
|
|
t_object_to_obj_users[QPDFObjGen((*i3).second, 0)].insert(ou);
|
|
}
|
|
}
|
|
}
|
|
|
|
this->m->obj_user_to_objects = t_obj_user_to_objects;
|
|
this->m->object_to_obj_users = t_object_to_obj_users;
|
|
}
|