Add a display_id parameter to the desktopCapturer API.

atom/browser/api/atom_api_desktop_capturer.cc

@@ -4,32 +4,41 @@
 
 #include "atom/browser/api/atom_api_desktop_capturer.h"
 
+#include <vector>
+
 using base::PlatformThreadRef;
 
 #include "atom/common/api/atom_api_native_image.h"
 #include "atom/common/native_mate_converters/gfx_converter.h"
+#include "base/strings/string_number_conversions.h"
 #include "base/strings/utf_string_conversions.h"
 #include "chrome/browser/media/desktop_media_list.h"
 #include "content/public/browser/desktop_capture.h"
 #include "native_mate/dictionary.h"
 #include "third_party/webrtc/modules/desktop_capture/desktop_capture_options.h"
 #include "third_party/webrtc/modules/desktop_capture/desktop_capturer.h"
+#if defined(OS_WIN)
+#include "third_party/webrtc/modules/desktop_capture/win/dxgi_duplicator_controller.h"
+#include "ui/display/win/display_info.h"
+#endif  // defined(OS_WIN)
 
 #include "atom/common/node_includes.h"
 
 namespace mate {
 
-template<>
-struct Converter<DesktopMediaList::Source> {
-  static v8::Local<v8::Value> ToV8(v8::Isolate* isolate,
-                                   const DesktopMediaList::Source& source) {
+template <>
+struct Converter<atom::api::DesktopCapturer::Source> {
+  static v8::Local<v8::Value> ToV8(
+      v8::Isolate* isolate,
+      const atom::api::DesktopCapturer::Source& source) {
     mate::Dictionary dict(isolate, v8::Object::New(isolate));
-    content::DesktopMediaID id = source.id;
-    dict.Set("name", base::UTF16ToUTF8(source.name));
+    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",
-        atom::api::NativeImage::Create(isolate, gfx::Image(source.thumbnail)));
+    dict.Set("thumbnail",
+             atom::api::NativeImage::Create(
+                 isolate, gfx::Image(source.media_list_source.thumbnail)));
+    dict.Set("display_id", source.display_id);
     return ConvertToV8(isolate, dict);
   }
 };
@@ -52,6 +61,9 @@ void DesktopCapturer::StartHandling(bool capture_window,
                                     const gfx::Size& thumbnail_size) {
   webrtc::DesktopCaptureOptions options =
     content::CreateDesktopCaptureOptions();
+#if defined(OS_WIN)
+  using_directx_capturer_ = options.allow_directx_capturer();
+#endif  // defined(OS_WIN)
 
   std::unique_ptr<webrtc::DesktopCapturer> screen_capturer(
       capture_screen ? webrtc::DesktopCapturer::CreateScreenCapturer(options)
@@ -82,7 +94,53 @@ void DesktopCapturer::OnSourceThumbnailChanged(int index) {
 }
 
 bool DesktopCapturer::OnRefreshFinished() {
-  Emit("finished", media_list_->GetSources());
+  const auto media_list_sources = media_list_->GetSources();
+  std::vector<DesktopCapturer::Source> sources;
+  for (const auto& media_list_source : media_list_sources) {
+    sources.emplace_back(
+        DesktopCapturer::Source{media_list_source, std::string()});
+  }
+
+#if defined(OS_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|.
+    webrtc::DxgiDuplicatorController::Instance()->GetDeviceNames(&device_names);
+    int device_name_index = 0;
+    for (auto& source : sources) {
+      if (source.media_list_source.id.type ==
+          content::DesktopMediaID::TYPE_SCREEN) {
+        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::Int64ToString(device_id);
+      }
+    }
+  }
+#elif defined(OS_MACOSX)
+  // On Mac, the IDs across the APIs match.
+  for (auto& source : sources) {
+    if (source.media_list_source.id.type ==
+        content::DesktopMediaID::TYPE_SCREEN) {
+      source.display_id =
+          base::Int64ToString(source.media_list_source.id.id);
+    }
+  }
+#endif  // defined(OS_WIN)
+// TODO(ajmacd): Add Linux support. The IDs across APIs differ but Chrome only
+// supports capturing the entire desktop on Linux. Revisit this if individual
+// screen support is added.
+
+  Emit("finished", sources);
   return false;
 }
 

atom/browser/api/atom_api_desktop_capturer.h

@@ -5,6 +5,8 @@
 #ifndef ATOM_BROWSER_API_ATOM_API_DESKTOP_CAPTURER_H_
 #define ATOM_BROWSER_API_ATOM_API_DESKTOP_CAPTURER_H_
 
+#include <string>
+
 #include "atom/browser/api/event_emitter.h"
 #include "chrome/browser/media/desktop_media_list_observer.h"
 #include "chrome/browser/media/native_desktop_media_list.h"
@@ -17,6 +19,12 @@ namespace api {
 class DesktopCapturer: public mate::EventEmitter<DesktopCapturer>,
                        public DesktopMediaListObserver {
  public:
+  struct Source {
+    DesktopMediaList::Source media_list_source;
+    // Will be an empty string if not available.
+    std::string display_id;
+  };
+
   static mate::Handle<DesktopCapturer> Create(v8::Isolate* isolate);
 
   static void BuildPrototype(v8::Isolate* isolate,
@@ -40,6 +48,9 @@ class DesktopCapturer: public mate::EventEmitter<DesktopCapturer>,
 
  private:
   std::unique_ptr<DesktopMediaList> media_list_;
+#if defined(OS_WIN)
+  bool using_directx_capturer_;
+#endif  // defined(OS_WIN)
 
   DISALLOW_COPY_AND_ASSIGN(DesktopCapturer);
 };

docs/api/structures/desktop-capturer-source.md

@@ -12,3 +12,8 @@
   `thumbnailSize` specified in the `options` passed to
   `desktopCapturer.getSources`. The actual size depends on the scale of the
   screen or window.
+* `display_id` String - A unique identifier that will correspond to the `id` of
+  the matching [Display](display.md) returned by the [Screen API](../screen.md).
+  On some platforms, this is equivalent to the `XX` portion of the `id` field
+  above and on others it will differ. It will be an empty string if not
+  available.

lib/browser/desktop-capturer.js

@@ -43,7 +43,8 @@ desktopCapturer.emit = (event, name, sources) => {
     return {
       id: source.id,
       name: source.name,
-      thumbnail: source.thumbnail.toDataURL()
+      thumbnail: source.thumbnail.toDataURL(),
+      display_id: source.display_id
     }
   })
 

lib/renderer/api/desktop-capturer.js

@@ -35,7 +35,8 @@ exports.getSources = function (options, callback) {
         results.push({
           id: source.id,
           name: source.name,
-          thumbnail: nativeImage.createFromDataURL(source.thumbnail)
+          thumbnail: nativeImage.createFromDataURL(source.thumbnail),
+          display_id: source.display_id
         })
       })
       return results

spec/api-desktop-capturer-spec.js

@@ -1,5 +1,5 @@
 const assert = require('assert')
-const {desktopCapturer, remote} = require('electron')
+const {desktopCapturer, remote, screen} = require('electron')
 
 const isCI = remote.getGlobal('isCi')
 
@@ -40,7 +40,7 @@ describe('desktopCapturer', () => {
     desktopCapturer.getSources({types: ['window', 'screen']}, callback)
   })
 
-  it('responds to subsequest calls of different options', (done) => {
+  it('responds to subsequent calls of different options', (done) => {
     let callCount = 0
     const callback = (error, sources) => {
       callCount++
@@ -51,4 +51,33 @@ describe('desktopCapturer', () => {
     desktopCapturer.getSources({types: ['window']}, callback)
     desktopCapturer.getSources({types: ['screen']}, callback)
   })
+
+  it('returns an empty display_id for window sources on Windows and Mac', (done) => {
+    // Linux doesn't return any window sources.
+    if (process.platform !== 'win32' && process.platform !== 'darwin') {
+      return done()
+    }
+    desktopCapturer.getSources({types: ['window']}, (error, sources) => {
+      assert.equal(error, null)
+      assert.notEqual(sources.length, 0)
+      sources.forEach((source) => { assert.equal(source.display_id.length, 0) })
+      done()
+    })
+  })
+
+  it('returns display_ids matching the Screen API on Windows and Mac', (done) => {
+    if (process.platform !== 'win32' && process.platform !== 'darwin') {
+      return done()
+    }
+    const displays = screen.getAllDisplays()
+    desktopCapturer.getSources({types: ['screen']}, (error, sources) => {
+      assert.equal(error, null)
+      assert.notEqual(sources.length, 0)
+      assert.equal(sources.length, displays.length)
+      for (let i = 0; i < sources.length; i++) {
+        assert.equal(sources[i].display_id, displays[i].id)
+      }
+      done()
+    })
+  })
 })