Implement a JavaScript API for document scanning

chrome/browser/extensions/api/document_scan/document_scan_interface_chromeos.cc

+// Copyright 2014 The Chromium 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 "chrome/browser/extensions/api/document_scan/document_scan_interface_chromeos.h"
+
+#include "base/base64.h"
+#include "base/task_runner_util.h"
+#include "base/threading/worker_pool.h"
+#include "chromeos/dbus/dbus_thread_manager.h"
+#include "chromeos/dbus/lorgnette_manager_client.h"
+#include "third_party/cros_system_api/dbus/service_constants.h"
+
+namespace {
+
+const char kImageScanFailedError[] = "Image scan failed";
+const char kScannerImageMimeTypePng[] = "image/png";
+const char kPngImageDataUrlPrefix[] = "data:image/png;base64,";
+
+}  // namespace
+
+namespace extensions {
+
+namespace api {
+
+DocumentScanInterfaceChromeos::DocumentScanInterfaceChromeos()
+    : lorgnette_manager_client_(nullptr) {}
+
+DocumentScanInterfaceChromeos::~DocumentScanInterfaceChromeos() {}
+
+void DocumentScanInterfaceChromeos::ListScanners(
+    const ListScannersResultsCallback& callback) {
+  GetLorgnetteManagerClient()->ListScanners(base::Bind(
+           &DocumentScanInterfaceChromeos::OnScannerListReceived,
+           base::Unretained(this),
+           callback));
+}
+
+void DocumentScanInterfaceChromeos::OnScannerListReceived(
+    const ListScannersResultsCallback& callback,
+    bool succeeded,
+    const chromeos::LorgnetteManagerClient::ScannerTable &scanners) {
+  std::vector<ScannerDescription> scanner_descriptions;
+  for (chromeos::LorgnetteManagerClient::ScannerTable::const_iterator iter =
+           scanners.begin();
+       iter != scanners.end();
+       ++iter) {
+    ScannerDescription description;
+    description.name = iter->first;
+    const chromeos::LorgnetteManagerClient::ScannerTableEntry &entry =
+        iter->second;
+    chromeos::LorgnetteManagerClient::ScannerTableEntry::const_iterator info_it;
+    info_it = entry.find(lorgnette::kScannerPropertyManufacturer);
+    if (info_it != entry.end()) {
+      description.manufacturer = info_it->second;
+    }
+    info_it = entry.find(lorgnette::kScannerPropertyModel);
+    if (info_it != entry.end()) {
+      description.model = info_it->second;
+    }
+    info_it = entry.find(lorgnette::kScannerPropertyType);
+    if (info_it != entry.end()) {
+      description.scanner_type = info_it->second;
+    }
+    description.image_mime_type = kScannerImageMimeTypePng;
+    scanner_descriptions.push_back(description);
+  }
+  callback.Run(scanner_descriptions, "");
+}
+
+void DocumentScanInterfaceChromeos::Scan(const std::string& scanner_name,
+                                         ScanMode mode,
+                                         int resolution_dpi,
+                                         const ScanResultsCallback& callback) {
+  VLOG(1) << "Choosing scanner " << scanner_name;
+  chromeos::LorgnetteManagerClient::ScanProperties properties;
+  switch (mode) {
+    case kScanModeColor:
+      properties.mode = lorgnette::kScanPropertyModeColor;
+      break;
+
+    case kScanModeGray:
+      properties.mode = lorgnette::kScanPropertyModeGray;
+      break;
+
+    case kScanModeLineart:
+      properties.mode = lorgnette::kScanPropertyModeLineart;
+      break;
+
+    default:
+      // Leave the mode parameter empty, thereby using the default.
+      break;
+  }
+
+  if (resolution_dpi != 0) {
+    properties.resolution_dpi = resolution_dpi;
+  }
+
+  const bool kTasksAreSlow = true;
+  scoped_refptr<base::TaskRunner> task_runner =
+      base::WorkerPool::GetTaskRunner(kTasksAreSlow);
+
+  pipe_reader_.reset(new chromeos::PipeReaderForString(
+      task_runner,
+      base::Bind(&DocumentScanInterfaceChromeos::OnScanDataCompleted,
+                 base::Unretained(this))));
+  base::File file = pipe_reader_->StartIO();
+  base::PlatformFile platform_file = file.TakePlatformFile();
+  VLOG(1) << "ScanImage platform_file is " << platform_file;
+  GetLorgnetteManagerClient()->ScanImage(
+      scanner_name, platform_file, properties,
+      base::Bind(&DocumentScanInterfaceChromeos::OnScanCompleted,
+                 base::Unretained(this),
+                 callback));
+}
+
+void DocumentScanInterfaceChromeos::OnScanCompleted(
+    const ScanResultsCallback &callback, bool succeeded) {
+  VLOG(1) << "ScanImage returns " << succeeded;
+  if (pipe_reader_.get()) {
+    pipe_reader_->OnDataReady(-1);  // terminate data stream
+  }
+
+  std::string error_string;
+  if (!succeeded) {
+    error_string = kImageScanFailedError;
+  }
+
+  callback.Run(GetImageURL(scanned_image_data_), kScannerImageMimeTypePng,
+                           error_string);
+}
+
+std::string DocumentScanInterfaceChromeos::GetImageURL(std::string image_data) {
+  std::string image_data_base64;
+  base::Base64Encode(image_data, &image_data_base64);
+  return std::string(kPngImageDataUrlPrefix) + image_data_base64;
+}
+
+void DocumentScanInterfaceChromeos::OnScanDataCompleted() {
+  pipe_reader_->GetData(&scanned_image_data_);
+  pipe_reader_.reset();
+}
+
+chromeos::LorgnetteManagerClient*
+    DocumentScanInterfaceChromeos::GetLorgnetteManagerClient() {
+  if (!lorgnette_manager_client_) {
+    lorgnette_manager_client_ =
+        chromeos::DBusThreadManager::Get()->GetLorgnetteManagerClient();
+    CHECK(lorgnette_manager_client_);
+  }
+  return lorgnette_manager_client_;
+}
+
+// static
+DocumentScanInterface *DocumentScanInterface::CreateInstance() {
+  return new DocumentScanInterfaceChromeos();
+}
+
+}  // namespace api
+
+}  // namespace extensions