[Chromoting] Improve DirectX capturer to support multiple outputs

webrtc/modules/desktop_capture/win/d3d_device.cc

+/*
+ *  Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "webrtc/modules/desktop_capture/win/d3d_device.h"
+
+#include <utility>
+
+#include "webrtc/system_wrappers/include/logging.h"
+
+namespace webrtc {
+
+using Microsoft::WRL::ComPtr;
+
+D3dDevice::D3dDevice() = default;

[Sergey Ulanov, 2016/08/06 01:27:56]

nit: IMO {} instead of = default; would be shorter and clearer.

[Hzj_jie, 2016/08/08 00:16:07]

http://goo.gl/4aoxDU
{} will break std::is_trivial / std::is_pod / std::is_trivially_constructible.
std containers may use (indeed some of them have already used.) these type
traits (especially std::is_trivially_contructible) to optimize allocation logic
(malloc vs. new). This may not apply to this class, as I cannot quite sure
whether there is a trivial constructor in Microsoft::WRL::ComPtr. But in
generic, it seems not a good idea to use {} instead of = default.

+D3dDevice::~D3dDevice() = default;
+
+bool D3dDevice::Initialize(const ComPtr<IDXGIAdapter>& adapter) {
+  dxgi_adapter_ = adapter;
+  if (!dxgi_adapter_) {
+    LOG(LS_WARNING) << "An empty IDXGIAdapter instance has been received.";
+    return false;
+  }
+
+  D3D_FEATURE_LEVEL feature_level;
+  _com_error error = D3D11CreateDevice(
+      adapter.Get(), D3D_DRIVER_TYPE_UNKNOWN, nullptr,
+      D3D11_CREATE_DEVICE_BGRA_SUPPORT | D3D11_CREATE_DEVICE_SINGLETHREADED,
+      nullptr, 0, D3D11_SDK_VERSION, d3d_device_.GetAddressOf(), &feature_level,
+      context_.GetAddressOf());
+  if (error.Error() != S_OK || !d3d_device_ || !context_) {
+    LOG(LS_WARNING) << "D3D11CreateDeivce returns error "
+                    << error.ErrorMessage() << " with code " << error.Error();
+    return false;
+  }
+
+  if (feature_level < D3D_FEATURE_LEVEL_11_0) {
+    LOG(LS_WARNING) << "D3D11CreateDevice returns an instance without DirectX "
+                       "11 support, level "
+                    << feature_level;
+    return false;
+  }
+
+  error = _com_error(d3d_device_.As(&dxgi_device_));
+  if (error.Error() != S_OK || !dxgi_device_) {
+    LOG(LS_WARNING) << "ID3D11Device is not an implementation of IDXGIDevice, "
+                       "this usually means the system does not support DirectX "
+                       "11";
+    return false;
+  }
+
+  return true;
+}
+
+// static
+std::vector<D3dDevice> D3dDevice::EnumDevices() {
+  ComPtr<IDXGIFactory1> factory;
+  _com_error error = _com_error(
+      CreateDXGIFactory1(__uuidof(IDXGIFactory1),
+                         reinterpret_cast<void**>(factory.GetAddressOf())));
+  if (error.Error() != S_OK || !factory) {
+    return std::vector<D3dDevice>();
+  }
+
+  std::vector<D3dDevice> result;
+  for (int i = 0;; i++) {
+    ComPtr<IDXGIAdapter> adapter;
+    error = _com_error(factory->EnumAdapters(i, adapter.GetAddressOf()));
+    if (error.Error() == S_OK) {
+      D3dDevice device;
+      if (!device.Initialize(adapter)) {
+        return std::vector<D3dDevice>();
+      }
+      result.push_back(std::move(device));
+    } else if (error.Error() == DXGI_ERROR_NOT_FOUND) {
+      break;
+    } else {
+      LOG(LS_WARNING) << "IDXGIFactory1::EnumAdapters returns an unexpected "
+                         "error "
+                      << error.ErrorMessage() << " with code " << error.Error();
+      return std::vector<D3dDevice>();
+    }
+  }
+  return result;
+}
+
+}  // namespace webrtc