[Chromoting] Improve DirectX capturer to support multiple outputs

webrtc/modules/desktop_capture/win/dxgi_adapter_duplicator.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/dxgi_adapter_duplicator.h"
+
+#include <comdef.h>
+#include <DXGI.h>
+
+#include "webrtc/base/logging.h"
+
+namespace webrtc {
+
+using Microsoft::WRL::ComPtr;
+
+namespace {
+
+bool IsValidRect(const RECT& rect) {
+  return rect.left >= 0 && rect.top >= 0 &&
+         rect.right > rect.left && rect.bottom > rect.top;
+}
+
+}  // namespace
+
+bool DxgiAdapterDuplicator::Initialize(const D3dDevice& device) {
+  if (DoInitialize(device)) {
+    return true;
+  }
+  duplicators_.clear();
+  return false;
+}
+
+bool DxgiAdapterDuplicator::DoInitialize(const D3dDevice& device) {
+  for (int i = 0;; i++) {
+    ComPtr<IDXGIOutput> output;
+    _com_error error = device.dxgi_adapter()->EnumOutputs(
+        i, output.GetAddressOf());
+    if (error.Error() == S_OK && output) {
+      DXGI_OUTPUT_DESC desc;
+      error = _com_error(output->GetDesc(&desc));
+      if (error.Error() == S_OK) {
+        if (desc.AttachedToDesktop && IsValidRect(desc.DesktopCoordinates)) {
+          ComPtr<IDXGIOutput1> output1;
+          error = _com_error(output.As(&output1));
+          if (error.Error() != S_OK || !output1) {
+            LOG(LS_WARNING) << "Failed to convert IDXGIOutput to IDXGIOutput1, "
+                               "this usually means the system does not support "
+                               "DirectX 11";
+            return false;
+          }
+          duplicators_.emplace_back(device, output1, desc);
+          if (!duplicators_.back().Initialize()) {
+            return false;
+          }
+          if (desktop_rect_.is_empty()) {
+            desktop_rect_ = duplicators_.back().desktop_rect();
+          } else {
+            desktop_rect_.JoinWith(duplicators_.back().desktop_rect());
+          }
+        }
+      } else {
+        LOG(LS_WARNING) << "Failed to get output description of device " << i
+                        << ", ignore.";
+      }
+    } else if (error.Error() == DXGI_ERROR_NOT_FOUND) {
+      return true;

[Sergey Ulanov, 2016/07/08 22:36:54]

break; and return true after the loop

[Hzj_jie, 2016/07/11 00:54:59]

Done.

+    } else {
+      return false;

[Sergey Ulanov, 2016/07/08 22:36:53]

handle error cases first:

if (error.Error() == DXGI_ERROR_NOT_FOUND)
  break;

if (error.Error() != S_OK || !output) {
  LOG ERROR
  return false;
}

...

[Hzj_jie, 2016/07/11 00:54:59]

Done.

+    }
+  }
+}
+
+bool DxgiAdapterDuplicator::Duplicate(
+    DesktopFrame* target, const DesktopFrame* last_frame) {

[Sergey Ulanov, 2016/07/08 22:36:53]

one argument per line, please
(clang-format should handle this properly)

[Hzj_jie, 2016/07/11 00:54:59]

Done.

+  for (size_t i = 0; i < duplicators_.size(); i++) {

[Sergey Ulanov, 2016/07/08 22:36:53]

for (auto& duplicator: duplicators_)...

[Hzj_jie, 2016/07/11 00:54:59]

Oh, I thought for each and auto& are both discouraged.

[Sergey Ulanov, 2016/07/20 19:05:17]

Nope, see https://chromium-cpp.appspot.com/
auto should be avoided in range-based for loops, but auto& is fine.

[Hzj_jie, 2016/07/22 18:43:43]

Got it, I have updated both this file and DxgiDuplicatorContainer.

+    if (!duplicators_[i].Duplicate(target, last_frame)) {
+      return false;
+    }
+  }
+  return true;
+}
+
+bool DxgiAdapterDuplicator::Duplicate(
+    int id, DesktopFrame* target, const DesktopFrame* last_frame) {

[Sergey Ulanov, 2016/07/08 22:36:53]

one argument per line, please
(clang-format should handle this properly)

[Hzj_jie, 2016/07/11 00:54:59]

Done.

+  if (id < 0 || id >= static_cast<int>(duplicators_.size())) {
+    return false;
+  }
+  return duplicators_[id].Duplicate(target, last_frame, DesktopVector());
+}
+
+DesktopRect DxgiAdapterDuplicator::ScreenRect(int id) const {
+  if (id < 0 || id >= static_cast<int>(duplicators_.size())) {
+    return DesktopRect();
+  }
+  return duplicators_[id].desktop_rect();
+}
+
+}  // namespace webrtc