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// Copyright 2024 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "components/pdf/renderer/pdf_ocr_helper.h"
#include "base/metrics/histogram_functions.h"
#include "base/time/time.h"
#include "content/public/renderer/render_frame.h"
#include "pdf/pdf_accessibility_image_fetcher.h"
#include "pdf/pdf_features.h"
#include "third_party/blink/public/platform/browser_interface_broker_proxy.h"
namespace pdf {
namespace {
// The delay after which the idle connection to OCR service will be
// disconnected.
constexpr base::TimeDelta kIdleDisconnectDelay = base::Minutes(5);
} // namespace
//
// PdfOcrRequest
//
PdfOcrRequest::PdfOcrRequest(const ui::AXNodeID& image_node_id,
const chrome_pdf::AccessibilityImageInfo& image,
const ui::AXNodeID& root_node_id,
const ui::AXNodeID& parent_node_id,
const ui::AXNodeID& page_node_id,
uint32_t page_index)
: image_node_id(image_node_id),
image(image),
root_node_id(root_node_id),
parent_node_id(parent_node_id),
page_node_id(page_node_id),
page_index(page_index) {}
PdfOcrRequest::PdfOcrRequest(const PdfOcrRequest& other) = default;
//
// PdfOcrHelper
//
PdfOcrHelper::PdfOcrHelper(
chrome_pdf::PdfAccessibilityImageFetcher* image_fetcher,
content::RenderFrame& render_frame,
ui::AXNodeID root_node_id,
uint32_t page_count,
OnOcrDataReceivedCallback callback)
: content::RenderFrameObserver(&render_frame),
image_fetcher_(image_fetcher),
pages_per_batch_(ComputePagesPerBatch(page_count)),
remaining_page_count_(page_count),
root_node_id_(root_node_id),
on_ocr_data_received_callback_(std::move(callback)) {
// When PDF searchify is enabled, PDF OCR is not needed.
CHECK(!base::FeatureList::IsEnabled(chrome_pdf::features::kPdfSearchify));
}
PdfOcrHelper::~PdfOcrHelper() {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
}
void PdfOcrHelper::Reset(ui::AXNodeID root_node_id, uint32_t page_count) {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
CHECK_GT(page_count, 0u);
pages_per_batch_ = ComputePagesPerBatch(page_count);
remaining_page_count_ = page_count;
root_node_id_ = root_node_id;
if (!is_ocr_in_progress_) {
return;
}
batch_requests_.clear();
batch_tree_updates_.clear();
while (!all_requests_.empty()) {
all_requests_.pop();
}
is_ocr_in_progress_ = false;
}
// static
uint32_t PdfOcrHelper::ComputePagesPerBatch(uint32_t page_count) {
constexpr uint32_t kMinPagesPerBatch = 1u;
constexpr uint32_t kMaxPagesPerBatch = 20u;
return std::clamp<uint32_t>(page_count * 0.1, kMinPagesPerBatch,
kMaxPagesPerBatch);
}
void PdfOcrHelper::OcrPage(base::queue<PdfOcrRequest> page_requests) {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
CHECK(!page_requests.empty());
CHECK_GT(remaining_page_count_, 0u);
page_requests.back().is_last_on_page = true;
while (!page_requests.empty()) {
all_requests_.push(page_requests.front());
page_requests.pop();
}
if (!is_ocr_in_progress_) {
is_ocr_in_progress_ = true;
OcrNextImage();
}
}
bool PdfOcrHelper::AreAllPagesOcred() const {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
return remaining_page_count_ == 0u;
}
bool PdfOcrHelper::AreAllPagesInBatchOcred() const {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
return AreAllPagesOcred() || remaining_page_count_ % pages_per_batch_ == 0u;
}
void PdfOcrHelper::SetScreenAIAnnotatorForTesting(
mojo::PendingRemote<screen_ai::mojom::ScreenAIAnnotator>
screen_ai_annotator) {
screen_ai_annotator_.reset();
screen_ai_annotator_.Bind(std::move(screen_ai_annotator));
}
void PdfOcrHelper::ResetRemainingPageCountForTesting() {
remaining_page_count_ = 0;
}
void PdfOcrHelper::MaybeConnectToOcrService() {
if (screen_ai_annotator_.is_bound() && screen_ai_annotator_.is_connected()) {
return;
}
if (render_frame()) {
render_frame()->GetBrowserInterfaceBroker().GetInterface(
screen_ai_annotator_.BindNewPipeAndPassReceiver());
screen_ai_annotator_->SetClientType(
screen_ai::mojom::OcrClientType::kPdfViewer);
screen_ai_annotator_.reset_on_idle_timeout(kIdleDisconnectDelay);
}
}
void PdfOcrHelper::OcrNextImage() {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
if (all_requests_.empty()) {
return;
}
PdfOcrRequest request = all_requests_.front();
all_requests_.pop();
SkBitmap bitmap = image_fetcher_->GetImageForOcr(
request.page_index, request.image.page_object_index);
request.image_pixel_size = gfx::SizeF(bitmap.width(), bitmap.height());
if (bitmap.drawsNothing()) {
ReceiveOcrResultsForImage(std::move(request), ui::AXTreeUpdate());
return;
}
MaybeConnectToOcrService();
screen_ai_annotator_->PerformOcrAndReturnAXTreeUpdate(
std::move(bitmap),
base::BindOnce(&PdfOcrHelper::ReceiveOcrResultsForImage,
weak_ptr_factory_.GetWeakPtr(), std::move(request)));
base::UmaHistogramEnumeration("Accessibility.PdfOcr.PDFImages",
PdfOcrRequestStatus::kRequested);
}
void PdfOcrHelper::ReceiveOcrResultsForImage(
PdfOcrRequest request,
const ui::AXTreeUpdate& tree_update) {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
base::UmaHistogramEnumeration("Accessibility.PdfOcr.PDFImages",
PdfOcrRequestStatus::kPerformed);
// Ignore the result if the tree has changed.
if (request.root_node_id != root_node_id_) {
VLOG(1) << "Tree update for stale tree ignored.";
return;
}
const bool is_last_on_page = request.is_last_on_page;
batch_requests_.push_back(std::move(request));
batch_tree_updates_.push_back(tree_update);
if (is_last_on_page) {
CHECK_GT(remaining_page_count_, 0u);
--remaining_page_count_;
if (AreAllPagesInBatchOcred()) {
CHECK(!batch_requests_.empty());
CHECK_EQ(batch_requests_.size(), batch_tree_updates_.size());
on_ocr_data_received_callback_.Run(std::move(batch_requests_),
std::move(batch_tree_updates_));
}
}
if (all_requests_.empty()) {
is_ocr_in_progress_ = false;
} else {
OcrNextImage();
}
}
} // namespace pdf
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