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LibPDF: Support cascading stream filters

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You can specify multiple filters as an array, where each one is fed the
output of the one before it.
This commit is contained in:
Julian Offenhäuser 2022-10-27 20:01:56 +02:00 • committed by Andreas Kling
parent becd648a78
commit 16ed407c01
1 changed files with 13 additions and 6 deletions
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19
Userland/Libraries/LibPDF/Parser.cpp
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@ -476,13 +476,20 @@ PDFErrorOr<NonnullRefPtr<StreamObject>> Parser::parse_stream(NonnullRefPtr<DictO
m_document->security_handler()->decrypt(stream_object, m_current_reference_stack.last());
if (dict->contains(CommonNames::Filter)) {
auto filter_type = MUST(dict->get_name(m_document, CommonNames::Filter))->name();
auto maybe_bytes = Filter::decode(stream_object->bytes(), filter_type);
if (maybe_bytes.is_error()) {
warnln("Failed to decode filter: {}", maybe_bytes.error().string_literal());
return error(String::formatted("Failed to decode filter {}", maybe_bytes.error().string_literal()));
Vector<FlyString> filters;
// We may either get a single filter or an array of cascading filters
auto filter_object = TRY(dict->get_object(m_document, CommonNames::Filter));
if (filter_object->is<ArrayObject>()) {
auto filter_array = filter_object->cast<ArrayObject>();
for (size_t i = 0; i < filter_array->size(); ++i)
filters.append(TRY(filter_array->get_name_at(m_document, i))->name());
} else {
filters.append(filter_object->cast<NameObject>()->name());
}
stream_object->buffer() = maybe_bytes.release_value();
for (auto const& filter_type : filters)
stream_object->buffer() = TRY(Filter::decode(stream_object->bytes(), filter_type));
}
return stream_object;