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LibPDF: Parse nested Page Tree structures

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We now follow nested page tree nodes to find all of the actual
page dicts, whereas previously we just assumed the root level
page tree node contained all of the page children directly.
This commit is contained in:
Matthew Olsson 2021-05-02 18:53:07 -07:00 • committed by Andreas Kling
parent 8c745ad0d9
commit 3aeaceb727
4 changed files with 77 additions and 5 deletions
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48
Userland/Libraries/LibPDF/Parser.cpp
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@ -363,14 +363,14 @@ Value Parser::parse_number()
}
}
consume_whitespace();
auto string = String(m_reader.bytes().slice(start_offset, m_reader.offset() - start_offset));
float f = strtof(string.characters(), nullptr);
if (is_float)
return Value(f);
VERIFY(floorf(f) == f);
consume_whitespace();
return Value(static_cast<int>(f));
}
@ -567,6 +567,50 @@ NonnullRefPtr<DictObject> Parser::parse_dict()
return make_object<DictObject>(map);
}
RefPtr<DictObject> Parser::conditionally_parse_page_tree_node_at_offset(size_t offset)
{
m_reader.move_to(offset);
parse_number();
parse_number();
VERIFY(m_reader.matches("obj"));
m_reader.move_by(3);
consume_whitespace();
consume('<');
consume('<');
consume_whitespace();
HashMap<FlyString, Value> map;
while (true) {
if (m_reader.matches(">>"))
break;
auto name = parse_name();
auto name_string = name->name();
if (!name_string.is_one_of("Type", "Parent", "Kids", "Count")) {
// This is a page, not a page tree node
return {};
}
auto value = parse_value();
if (name_string == "Type") {
if (!value.is_object())
return {};
auto type_object = value.as_object();
if (!type_object->is_name())
return {};
auto type_name = object_cast<NameObject>(type_object);
if (type_name->name() != "Pages")
return {};
}
map.set(name->name(), value);
}
consume('>');
consume('>');
consume_whitespace();
return make_object<DictObject>(map);
}
NonnullRefPtr<StreamObject> Parser::parse_stream(NonnullRefPtr<DictObject> dict)
{
VERIFY(m_reader.matches("stream"));