123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160 |
- /*
- * Copyright (c) 2021, Matthew Olsson <mattco@serenityos.org>
- *
- * SPDX-License-Identifier: BSD-2-Clause
- */
- #include <LibPDF/Document.h>
- #include <LibPDF/Parser.h>
- namespace PDF {
- Document::Document(const ReadonlyBytes& bytes)
- : m_parser(Parser({}, bytes))
- {
- m_parser.set_document(this);
- VERIFY(m_parser.perform_validation());
- auto [xref_table, trailer] = m_parser.parse_last_xref_table_and_trailer();
- m_xref_table = xref_table;
- m_trailer = trailer;
- m_catalog = m_trailer->get_dict(this, "Root");
- build_page_tree();
- }
- Value Document::get_or_load_value(u32 index)
- {
- auto value = get_value(index);
- if (value)
- return value;
- VERIFY(m_xref_table.has_object(index));
- auto byte_offset = m_xref_table.byte_offset_for_object(index);
- auto indirect_value = m_parser.parse_indirect_value_at_offset(byte_offset);
- VERIFY(indirect_value->index() == index);
- value = indirect_value->value();
- m_values.set(index, value);
- return value;
- }
- u32 Document::get_first_page_index() const
- {
- // FIXME: A PDF can have a different default first page, which
- // should be fetched and returned here
- return 0;
- }
- u32 Document::get_page_count() const
- {
- return m_page_object_indices.size();
- }
- Page Document::get_page(u32 index)
- {
- VERIFY(index < m_page_object_indices.size());
- auto cached_page = m_pages.get(index);
- if (cached_page.has_value())
- return cached_page.value();
- auto page_object_index = m_page_object_indices[index];
- auto raw_page_object = resolve_to<DictObject>(get_or_load_value(page_object_index));
- auto resources = raw_page_object->get_dict(this, "Resources");
- auto contents = raw_page_object->get_object(this, "Contents");
- auto media_box_array = raw_page_object->get_array(this, "MediaBox");
- auto media_box = Rectangle {
- media_box_array->at(0).to_float(),
- media_box_array->at(1).to_float(),
- media_box_array->at(2).to_float(),
- media_box_array->at(3).to_float(),
- };
- auto crop_box = media_box;
- if (raw_page_object->contains("CropBox")) {
- auto crop_box_array = raw_page_object->get_array(this, "CropBox");
- crop_box = Rectangle {
- crop_box_array->at(0).to_float(),
- crop_box_array->at(1).to_float(),
- crop_box_array->at(2).to_float(),
- crop_box_array->at(3).to_float(),
- };
- }
- float user_unit = 1.0f;
- if (raw_page_object->contains("UserUnit"))
- user_unit = raw_page_object->get_value("UserUnit").to_float();
- int rotate = 0;
- if (raw_page_object->contains("Rotate")) {
- rotate = raw_page_object->get_value("Rotate").as_int();
- VERIFY(rotate % 90 == 0);
- }
- Page page { move(resources), move(contents), media_box, crop_box, user_unit, rotate };
- m_pages.set(index, page);
- return page;
- }
- Value Document::resolve(const Value& value)
- {
- if (!value.is_object())
- return value;
- auto obj = value.as_object();
- // FIXME: Surely indirect PDF objects can't contain another indirect PDF object,
- // right? Unsure from the spec, but if they can, these return values would have
- // to be wrapped with another resolve() call.
- if (obj->is_indirect_value_ref()) {
- auto object_index = static_cast<NonnullRefPtr<IndirectValueRef>>(obj)->index();
- return get_or_load_value(object_index);
- }
- if (obj->is_indirect_value())
- return static_cast<NonnullRefPtr<IndirectValue>>(obj)->value();
- return obj;
- }
- void Document::build_page_tree()
- {
- auto page_tree = m_catalog->get_dict(this, "Pages");
- add_page_tree_node_to_page_tree(page_tree);
- }
- void Document::add_page_tree_node_to_page_tree(NonnullRefPtr<DictObject> page_tree)
- {
- auto kids_array = page_tree->get_array(this, "Kids");
- auto page_count = page_tree->get("Count").value().as_int();
- if (static_cast<size_t>(page_count) != kids_array->elements().size()) {
- // This page tree contains child page trees, so we recursively add
- // these pages to the overall page tree
- for (auto& value : *kids_array) {
- auto reference = object_cast<IndirectValueRef>(value.as_object());
- auto byte_offset = m_xref_table.byte_offset_for_object(reference->index());
- auto maybe_page_tree_node = m_parser.conditionally_parse_page_tree_node_at_offset(byte_offset);
- if (maybe_page_tree_node) {
- add_page_tree_node_to_page_tree(maybe_page_tree_node.release_nonnull());
- } else {
- m_page_object_indices.append(reference->index());
- }
- }
- return;
- }
- // We know all of the kids are leaf nodes
- for (auto& value : *kids_array) {
- auto reference = object_cast<IndirectValueRef>(value.as_object());
- m_page_object_indices.append(reference->index());
- }
- }
- }
|