Remove the requirement of D3D_FEATURE_LEVEL_11_0, but export the D3D_FEATURE_LEVEL through APIs

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.
  */
 
@@ skipping 13 matching lines @@
 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;
+  // Default feature levels contain D3D 9.1 through D3D 11.0.
   _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) {

[Sergey Ulanov, 2016/11/07 19:37:16]

Do we need this check at all? Maybe just log feature_level below, when we fail
to get IDXGIDevice?

[Hzj_jie, 2016/11/08 01:25:39]

Indeed I cannot quite tell whether the following d3d_device_.As() statement or
DxgiOutputDuplicator::DuplicateOutput() will fail. Unfortunately, nothing has
been mentioned in MSDN. That's the reason I removed the "return false" here, and
export the version in API.
I can totally remove this check once the API version has been exported and
logged by client.

     LOG(LS_WARNING) << "D3D11CreateDevice returns an instance without DirectX "
-                       "11 support, level "
-                    << feature_level;
-    return false;
+                       "11 support, level " << feature_level
+                    << ". Following initialization may fail.";
+    // D3D_FEATURE_LEVEL_11_0 is not officially documented on MSDN to be a
+    // requirement of Dxgi duplicator APIs.
   }
 
   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";
+                       "11. Error "
+                    << error.ErrorMessage() << " with code " << error.Error();
     return false;
   }
 
   return true;
 }
 
 // static
 std::vector<D3dDevice> D3dDevice::EnumDevices() {
   ComPtr<IDXGIFactory1> factory;
   _com_error error = CreateDXGIFactory1(__uuidof(IDXGIFactory1),
@@ skipping 18 matching lines @@
       LOG(LS_WARNING) << "IDXGIFactory1::EnumAdapters returns an unexpected "
                          "error "
                       << error.ErrorMessage() << " with code " << error.Error();
       return std::vector<D3dDevice>();
     }
   }
   return result;
 }
 
 }  // namespace webrtc