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// Copyright 2018 PDFium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "core/fpdfapi/edit/cpdf_pagecontentmanager.h"
#include <map>
#include <numeric>
#include <vector>
#include "core/fpdfapi/page/cpdf_pageobject.h"
#include "core/fpdfapi/parser/cpdf_array.h"
#include "core/fpdfapi/parser/cpdf_dictionary.h"
#include "core/fpdfapi/parser/cpdf_document.h"
#include "core/fpdfapi/parser/cpdf_reference.h"
#include "core/fpdfapi/parser/cpdf_stream.h"
CPDF_PageContentManager::CPDF_PageContentManager(
const CPDF_PageObjectHolder* obj_holder)
: obj_holder_(obj_holder), doc_(obj_holder_->GetDocument()) {
CPDF_Dictionary* page_dict = obj_holder_->GetDict();
CPDF_Object* contents_obj = page_dict->GetObjectFor("Contents");
CPDF_Array* contents_array = ToArray(contents_obj);
if (contents_array) {
contents_array_ = contents_array;
return;
}
CPDF_Reference* contents_reference = ToReference(contents_obj);
if (contents_reference) {
CPDF_Object* indirect_obj = contents_reference->GetDirect();
if (!indirect_obj)
return;
contents_array = indirect_obj->AsArray();
if (contents_array)
contents_array_ = contents_array;
else if (indirect_obj->IsStream())
contents_stream_ = indirect_obj->AsStream();
}
}
CPDF_PageContentManager::~CPDF_PageContentManager() = default;
CPDF_Stream* CPDF_PageContentManager::GetStreamByIndex(size_t stream_index) {
if (contents_stream_)
return stream_index == 0 ? contents_stream_.Get() : nullptr;
if (contents_array_) {
CPDF_Reference* stream_reference =
ToReference(contents_array_->GetObjectAt(stream_index));
if (!stream_reference)
return nullptr;
return stream_reference->GetDirect()->AsStream();
}
return nullptr;
}
size_t CPDF_PageContentManager::AddStream(std::ostringstream* buf) {
CPDF_Stream* new_stream = doc_->NewIndirect<CPDF_Stream>();
new_stream->SetData(buf);
// If there is one Content stream (not in an array), now there will be two, so
// create an array with the old and the new one. The new one's index is 1.
if (contents_stream_) {
CPDF_Array* new_contents_array = doc_->NewIndirect<CPDF_Array>();
new_contents_array->Add(contents_stream_->MakeReference(doc_.Get()));
new_contents_array->Add(new_stream->MakeReference(doc_.Get()));
CPDF_Dictionary* page_dict = obj_holder_->GetDict();
page_dict->SetFor("Contents",
new_contents_array->MakeReference(doc_.Get()));
contents_array_ = new_contents_array;
contents_stream_ = nullptr;
return 1;
}
// If there is an array, just add the new stream to it, at the last position.
if (contents_array_) {
contents_array_->Add(new_stream->MakeReference(doc_.Get()));
return contents_array_->GetCount() - 1;
}
// There were no Contents, so add the new stream as the single Content stream.
// Its index is 0.
CPDF_Dictionary* page_dict = obj_holder_->GetDict();
page_dict->SetFor("Contents", new_stream->MakeReference(doc_.Get()));
contents_stream_ = new_stream;
return 0;
}
void CPDF_PageContentManager::ScheduleRemoveStreamByIndex(size_t stream_index) {
streams_to_remove_.insert(stream_index);
}
void CPDF_PageContentManager::ExecuteScheduledRemovals() {
// This method assumes there are no dirty streams in the
// CPDF_PageObjectHolder. If there were any, their indexes would need to be
// updated.
// Since this is only called by CPDF_PageContentGenerator::GenerateContent(),
// which cleans up the dirty streams first, this should always be true.
ASSERT(obj_holder_->GetDirtyStreams().empty());
if (contents_stream_) {
// Only stream that can be removed is 0.
if (streams_to_remove_.find(0) != streams_to_remove_.end()) {
CPDF_Dictionary* page_dict = obj_holder_->GetDict();
page_dict->RemoveFor("Contents");
contents_stream_ = nullptr;
}
} else if (contents_array_) {
// Initialize a vector with the old stream indexes. This will be used to
// build a map from the old to the new indexes.
std::vector<size_t> streams_left(contents_array_->GetCount());
std::iota(streams_left.begin(), streams_left.end(), 0);
// In reverse order so as to not change the indexes in the middle of the
// loop, remove the streams.
for (auto it = streams_to_remove_.rbegin(); it != streams_to_remove_.rend();
++it) {
size_t stream_index = *it;
contents_array_->RemoveAt(stream_index);
streams_left.erase(streams_left.begin() + stream_index);
}
// Create a mapping from the old to the new stream indexes, shifted due to
// the deletion of the |streams_to_remove_|.
std::map<int32_t, size_t> stream_index_mapping;
for (size_t i = 0; i < streams_left.size(); ++i)
stream_index_mapping[streams_left[i]] = i;
// Update the page objects' content stream indexes.
for (const auto& obj : *obj_holder_->GetPageObjectList()) {
int32_t old_stream_index = obj->GetContentStream();
size_t new_stream_index = stream_index_mapping[old_stream_index];
obj->SetContentStream(new_stream_index);
}
// Even if there is a single content stream now, keep the array with a
// single element. It's valid, a second stream might be added soon, and the
// complexity of removing it is not worth it.
}
streams_to_remove_.clear();
}
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