electron_api_desktop_capturer.cc

// Copyright (c) 2015 GitHub, Inc.
// Use of this source code is governed by the MIT license that can be
// found in the LICENSE file.

#include "shell/browser/api/electron_api_desktop_capturer.h"

#include <map>
#include <memory>
#include <utility>
#include <vector>

#include "base/strings/string_number_conversions.h"
#include "base/strings/utf_string_conversions.h"
#include "base/threading/thread_restrictions.h"
#include "chrome/browser/media/webrtc/desktop_media_list.h"
#include "chrome/browser/media/webrtc/window_icon_util.h"
#include "content/public/browser/desktop_capture.h"
#include "gin/object_template_builder.h"
#include "shell/browser/javascript_environment.h"
#include "shell/common/api/electron_api_native_image.h"
#include "shell/common/gin_converters/gfx_converter.h"
#include "shell/common/gin_helper/dictionary.h"
#include "shell/common/gin_helper/event_emitter_caller.h"
#include "shell/common/node_includes.h"
#include "third_party/webrtc/modules/desktop_capture/desktop_capture_options.h"
#include "third_party/webrtc/modules/desktop_capture/desktop_capturer.h"

#if BUILDFLAG(IS_WIN)
#include "third_party/webrtc/modules/desktop_capture/win/dxgi_duplicator_controller.h"
#include "third_party/webrtc/modules/desktop_capture/win/screen_capturer_win_directx.h"
#include "ui/display/win/display_info.h"
#elif BUILDFLAG(IS_LINUX)
#include "base/logging.h"
#include "ui/base/x/x11_display_util.h"
#include "ui/base/x/x11_util.h"
#include "ui/display/util/display_util.h"
#include "ui/display/util/edid_parser.h"
#include "ui/gfx/x/randr.h"
#include "ui/gfx/x/x11_atom_cache.h"
#include "ui/gfx/x/xproto_util.h"
#endif  // BUILDFLAG(IS_WIN)

#if BUILDFLAG(IS_LINUX)
// Find the mapping between output identifier and the monitor name atom
// Note this isn't the atom string, but the numeric atom identifier,
// since this is what the WebRTC system uses as the display identifier
// Based on `GetMonitors` in ui/base/x/x11_display_util.cc
std::map<x11::RandR::Output, int32_t> GetMonitorsNameAtom(int version,
                                                          x11::RandR* randr,
                                                          x11::Window window) {
  std::map<x11::RandR::Output, int32_t> output_to_monitor;
  if (version >= 105) {
    if (auto reply = randr->GetMonitors({window}).Sync()) {
      for (size_t monitor = 0; monitor < reply->monitors.size(); monitor++) {
        for (x11::RandR::Output output : reply->monitors[monitor].outputs)
          output_to_monitor[output] =
              static_cast<int32_t>(reply->monitors[monitor].name);
      }
    }
  }
  return output_to_monitor;
}
// Get the EDID data from the |output| and stores to |edid|.
// Private function in ui/base/x/x11_display_util.cc
std::vector<uint8_t> GetEDIDProperty(x11::RandR* randr,
                                     x11::RandR::Output output) {
  constexpr const char kRandrEdidProperty[] = "EDID";
  auto future = randr->GetOutputProperty(x11::RandR::GetOutputPropertyRequest{
      .output = output,
      .property = x11::GetAtom(kRandrEdidProperty),
      .long_length = 128});
  auto response = future.Sync();
  std::vector<uint8_t> edid;
  if (response && response->format == 8 && response->type != x11::Atom::None)
    edid = std::move(response->data);
  return edid;
}

// Find the mapping from monitor name atom to the display identifier
// that the screen API uses. Based on the logic in BuildDisplaysFromXRandRInfo
// in ui/base/x/x11_display_util.cc
std::map<int32_t, uint32_t> MonitorAtomIdToDisplayId() {
  auto* connection = x11::Connection::Get();
  auto& randr = connection->randr();
  auto x_root_window = ui::GetX11RootWindow();
  int version = ui::GetXrandrVersion();

  std::map<int32_t, uint32_t> monitor_atom_to_display;

  auto resources = randr.GetScreenResourcesCurrent({x_root_window}).Sync();
  if (!resources) {
    LOG(ERROR) << "XRandR returned no displays; don't know how to map ids";
    return monitor_atom_to_display;
  }

  std::map<x11::RandR::Output, int32_t> output_to_atom =
      GetMonitorsNameAtom(version, &randr, x_root_window);

  for (size_t i = 0; i < resources->outputs.size(); i++) {
    x11::RandR::Output output_id = resources->outputs[i];
    auto output_info =
        randr.GetOutputInfo({output_id, resources->config_timestamp}).Sync();
    if (!output_info)
      continue;

    if (output_info->connection != x11::RandR::RandRConnection::Connected)
      continue;

    if (output_info->crtc == static_cast<x11::RandR::Crtc>(0))
      continue;

    auto crtc =
        randr.GetCrtcInfo({output_info->crtc, resources->config_timestamp})
            .Sync();
    if (!crtc)
      continue;
    display::EdidParser edid_parser(
        GetEDIDProperty(&randr, static_cast<x11::RandR::Output>(output_id)));
    auto output_32 = static_cast<uint32_t>(output_id);
    int64_t display_id =
        output_32 > 0xff ? 0 : edid_parser.GetIndexBasedDisplayId(output_32);
    if (!display_id)
      display_id = i;

    auto output_atom_iter = output_to_atom.find(output_id);
    if (output_atom_iter != output_to_atom.end())
      monitor_atom_to_display[output_atom_iter->second] = display_id;
  }

  return monitor_atom_to_display;
}
#endif

namespace gin {

template <>
struct Converter<electron::api::DesktopCapturer::Source> {
  static v8::Local<v8::Value> ToV8(
      v8::Isolate* isolate,
      const electron::api::DesktopCapturer::Source& source) {
    gin_helper::Dictionary dict = gin::Dictionary::CreateEmpty(isolate);
    content::DesktopMediaID id = source.media_list_source.id;
    dict.Set("name", base::UTF16ToUTF8(source.media_list_source.name));
    dict.Set("id", id.ToString());
    dict.Set("thumbnail",
             electron::api::NativeImage::Create(
                 isolate, gfx::Image(source.media_list_source.thumbnail)));
    dict.Set("display_id", source.display_id);
    if (source.fetch_icon) {
      dict.Set(
          "appIcon",
          electron::api::NativeImage::Create(
              isolate, gfx::Image(GetWindowIcon(source.media_list_source.id))));
    } else {
      dict.Set("appIcon", nullptr);
    }
    return ConvertToV8(isolate, dict);
  }
};

}  // namespace gin

namespace electron {

namespace api {

gin::WrapperInfo DesktopCapturer::kWrapperInfo = {gin::kEmbedderNativeGin};

DesktopCapturer::DesktopCapturer(v8::Isolate* isolate) {}

DesktopCapturer::~DesktopCapturer() = default;

void DesktopCapturer::StartHandling(bool capture_window,
                                    bool capture_screen,
                                    const gfx::Size& thumbnail_size,
                                    bool fetch_window_icons) {
  fetch_window_icons_ = fetch_window_icons;
#if BUILDFLAG(IS_WIN)
  if (content::desktop_capture::CreateDesktopCaptureOptions()
          .allow_directx_capturer()) {
    // DxgiDuplicatorController should be alive in this scope according to
    // screen_capturer_win.cc.
    auto duplicator = webrtc::DxgiDuplicatorController::Instance();
    using_directx_capturer_ = webrtc::ScreenCapturerWinDirectx::IsSupported();
  }
#endif  // BUILDFLAG(IS_WIN)

  // clear any existing captured sources.
  captured_sources_.clear();

  // Start listening for captured sources.
  capture_window_ = capture_window;
  capture_screen_ = capture_screen;

  {
    // Initialize the source list.
    // Apply the new thumbnail size and restart capture.
    if (capture_window) {
      window_capturer_ = std::make_unique<NativeDesktopMediaList>(
          DesktopMediaList::Type::kWindow,
          content::desktop_capture::CreateWindowCapturer());
      window_capturer_->SetThumbnailSize(thumbnail_size);
      window_capturer_->Update(
          base::BindOnce(&DesktopCapturer::UpdateSourcesList,
                         weak_ptr_factory_.GetWeakPtr(),
                         window_capturer_.get()),
          /* refresh_thumbnails = */ true);
    }

    if (capture_screen) {
      screen_capturer_ = std::make_unique<NativeDesktopMediaList>(
          DesktopMediaList::Type::kScreen,
          content::desktop_capture::CreateScreenCapturer());
      screen_capturer_->SetThumbnailSize(thumbnail_size);
      screen_capturer_->Update(
          base::BindOnce(&DesktopCapturer::UpdateSourcesList,
                         weak_ptr_factory_.GetWeakPtr(),
                         screen_capturer_.get()),
          /* refresh_thumbnails = */ true);
    }
  }
}

void DesktopCapturer::UpdateSourcesList(DesktopMediaList* list) {
  if (capture_window_ &&
      list->GetMediaListType() == DesktopMediaList::Type::kWindow) {
    capture_window_ = false;
    std::vector<DesktopCapturer::Source> window_sources;
    window_sources.reserve(list->GetSourceCount());
    for (int i = 0; i < list->GetSourceCount(); i++) {
      window_sources.emplace_back(DesktopCapturer::Source{
          list->GetSource(i), std::string(), fetch_window_icons_});
    }
    std::move(window_sources.begin(), window_sources.end(),
              std::back_inserter(captured_sources_));
  }

  if (capture_screen_ &&
      list->GetMediaListType() == DesktopMediaList::Type::kScreen) {
    capture_screen_ = false;
    std::vector<DesktopCapturer::Source> screen_sources;
    screen_sources.reserve(list->GetSourceCount());
    for (int i = 0; i < list->GetSourceCount(); i++) {
      screen_sources.emplace_back(
          DesktopCapturer::Source{list->GetSource(i), std::string()});
    }
#if BUILDFLAG(IS_WIN)
    // Gather the same unique screen IDs used by the electron.screen API in
    // order to provide an association between it and
    // desktopCapturer/getUserMedia. This is only required when using the
    // DirectX capturer, otherwise the IDs across the APIs already match.
    if (using_directx_capturer_) {
      std::vector<std::string> device_names;
      // Crucially, this list of device names will be in the same order as
      // |media_list_sources|.
      if (!webrtc::DxgiDuplicatorController::Instance()->GetDeviceNames(
              &device_names)) {
        v8::Isolate* isolate = JavascriptEnvironment::GetIsolate();
        v8::Locker locker(isolate);
        v8::HandleScope scope(isolate);
        gin_helper::CallMethod(this, "_onerror", "Failed to get sources.");

        Unpin();

        return;
      }

      int device_name_index = 0;
      for (auto& source : screen_sources) {
        const auto& device_name = device_names[device_name_index++];
        std::wstring wide_device_name;
        base::UTF8ToWide(device_name.c_str(), device_name.size(),
                         &wide_device_name);
        const int64_t device_id =
            display::win::DisplayInfo::DeviceIdFromDeviceName(
                wide_device_name.c_str());
        source.display_id = base::NumberToString(device_id);
      }
    }
#elif BUILDFLAG(IS_MAC)
    // On Mac, the IDs across the APIs match.
    for (auto& source : screen_sources) {
      source.display_id = base::NumberToString(source.media_list_source.id.id);
    }
#elif BUILDFLAG(IS_LINUX)
    // On Linux, with X11, the source id is the numeric value of the
    // display name atom and the display id is either the EDID or the
    // loop index when that display was found (see
    // BuildDisplaysFromXRandRInfo in ui/base/x/x11_display_util.cc)
    std::map<int32_t, uint32_t> monitor_atom_to_display_id =
        MonitorAtomIdToDisplayId();
    for (auto& source : screen_sources) {
      auto display_id_iter =
          monitor_atom_to_display_id.find(source.media_list_source.id.id);
      if (display_id_iter != monitor_atom_to_display_id.end())
        source.display_id = base::NumberToString(display_id_iter->second);
    }
#endif  // BUILDFLAG(IS_WIN)
    std::move(screen_sources.begin(), screen_sources.end(),
              std::back_inserter(captured_sources_));
  }

  if (!capture_window_ && !capture_screen_) {
    v8::Isolate* isolate = JavascriptEnvironment::GetIsolate();
    v8::Locker locker(isolate);
    v8::HandleScope scope(isolate);
    gin_helper::CallMethod(this, "_onfinished", captured_sources_);

    Unpin();
  }
}

// static
gin::Handle<DesktopCapturer> DesktopCapturer::Create(v8::Isolate* isolate) {
  auto handle = gin::CreateHandle(isolate, new DesktopCapturer(isolate));

  // Keep reference alive until capturing has finished.
  handle->Pin(isolate);

  return handle;
}

gin::ObjectTemplateBuilder DesktopCapturer::GetObjectTemplateBuilder(
    v8::Isolate* isolate) {
  return gin::Wrappable<DesktopCapturer>::GetObjectTemplateBuilder(isolate)
      .SetMethod("startHandling", &DesktopCapturer::StartHandling);
}

const char* DesktopCapturer::GetTypeName() {
  return "DesktopCapturer";
}

}  // namespace api

}  // namespace electron

namespace {

void Initialize(v8::Local<v8::Object> exports,
                v8::Local<v8::Value> unused,
                v8::Local<v8::Context> context,
                void* priv) {
  gin_helper::Dictionary dict(context->GetIsolate(), exports);
  dict.SetMethod("createDesktopCapturer",
                 &electron::api::DesktopCapturer::Create);
}

}  // namespace

NODE_LINKED_MODULE_CONTEXT_AWARE(electron_browser_desktop_capturer, Initialize)