[DesktopCapture] Detect screen resolution changes in DirectX capturer

webrtc/modules/desktop_capture/win/screen_capturer_win_directx.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/screen_capturer_win_directx.h"
 
+#include <string>
 #include <utility>
 
 #include "webrtc/base/checks.h"
 #include "webrtc/base/logging.h"
 #include "webrtc/base/timeutils.h"
 #include "webrtc/modules/desktop_capture/desktop_frame.h"
+#include "webrtc/modules/desktop_capture/win/screen_capture_utils.h"
 
 namespace webrtc {
 
 using Microsoft::WRL::ComPtr;
 
 // static
 bool ScreenCapturerWinDirectx::IsSupported() {
   // Forwards IsSupported() function call to DxgiDuplicatorController.
   return DxgiDuplicatorController::Instance()->IsSupported();
 }
@@ skipping 30 matching lines @@
   return DxgiDuplicatorController::Instance()
       ->ScreenRect(current_screen_id_)
       .size();
 }
 
 void ScreenCapturerWinDirectx::CaptureFrame() {
   RTC_DCHECK(callback_);
 
   int64_t capture_start_time_nanos = rtc::TimeNanos();
 
+  // The dxgi components and APIs do not update the screen resolution without
+  // a reinitialization. So we use the GetDC() function to retrieve the screen
+  // resolution to decide whether dxgi components need to be reinitialized.
+  // If the screen resolution changed, it's very likely the next Duplicate()
+  // function call will fail because of a missing monitor or the frame size is
+  // not enough to store the output. So we reinitialize dxgi components in-place
+  // to avoid a capture failure.
+  // But there is no guarantee GetDC() function returns the same resolution as
+  // dxgi APIs, we still rely on dxgi components to return the output frame
+  // size.
+  // TODO(zijiehe): Confirm whether IDXGIOutput::GetDesc() and
+  // IDXGIOutputDuplication::GetDesc() can detect the resolution change without
+  // reinitialization.
+  if (resolution_change_detector_.IsChanged(
+          GetScreenRect(kFullDesktopScreenId, std::wstring()).size())) {
+    frames_.Reset();
+    DxgiDuplicatorController::Instance()->Reset();
+    resolution_change_detector_.Reset();
+  }
+
   frames_.MoveToNextFrame();
   if (!frames_.current_frame()) {
     std::unique_ptr<DesktopFrame> new_frame;
     if (shared_memory_factory_) {
       new_frame = SharedMemoryDesktopFrame::Create(
           SelectedDesktopSize(), shared_memory_factory_.get());
     } else {
       new_frame.reset(new BasicDesktopFrame(SelectedDesktopSize()));
     }
     if (!new_frame) {
       LOG(LS_ERROR) << "Failed to allocate a new DesktopFrame.";
       // This usually means we do not have enough memory or SharedMemoryFactory
       // cannot work correctly.
       callback_->OnCaptureResult(Result::ERROR_PERMANENT, nullptr);
       return;
     }
     frames_.ReplaceCurrentFrame(SharedDesktopFrame::Wrap(std::move(new_frame)));
   }
 
   if (current_screen_id_ == kFullDesktopScreenId) {
     if (!DxgiDuplicatorController::Instance()->Duplicate(
             &context_, frames_.current_frame())) {
       // Screen size may be changed, so we need to reset the frames.
       frames_.Reset();
+      resolution_change_detector_.Reset();
       callback_->OnCaptureResult(Result::ERROR_TEMPORARY, nullptr);
       return;
     }
   } else {
     if (!DxgiDuplicatorController::Instance()->DuplicateMonitor(
             &context_, current_screen_id_, frames_.current_frame())) {
       // Screen size may be changed, so we need to reset the frames.
       frames_.Reset();
+      resolution_change_detector_.Reset();
       if (current_screen_id_ >=
           DxgiDuplicatorController::Instance()->ScreenCount()) {
         // Current monitor has been removed from the system.
         callback_->OnCaptureResult(Result::ERROR_PERMANENT, nullptr);
       } else {
         callback_->OnCaptureResult(Result::ERROR_TEMPORARY, nullptr);
       }
       return;
     }
   }
@@ skipping 15 matching lines @@
 
 bool ScreenCapturerWinDirectx::SelectSource(SourceId id) {
   if (id == current_screen_id_) {
     return true;
   }
 
   // Changing target screen may or may not impact frame size. So resetting
   // frames only when a Duplicate() function call returns false.
   if (id == kFullDesktopScreenId) {
     current_screen_id_ = id;
+    context_.Reset();
     return true;
   }
 
   int screen_count = DxgiDuplicatorController::Instance()->ScreenCount();
   if (id >= 0 && id < screen_count) {
     current_screen_id_ = id;
+    context_.Reset();
     return true;
   }
   return false;
 }
 
 }  // namespace webrtc