Evaluate DeviceScaleFactor per captured frame

This is to ensure that the device_scale_factor stored per frame is the
latest one according to the system settings and not an old value.

Bug: chromium:383946052
Change-Id: I11e6342201678451554e6883ded48999fd996743
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/377541
Reviewed-by: Ilya Nikolaevskiy <ilnik@webrtc.org>
Commit-Queue: Palak Agarwal <agpalak@google.com>
Reviewed-by: Henrik Andreassson <henrika@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#43924}

modules/desktop_capture/win/dxgi_duplicator_controller.cc

@@ -189,12 +189,12 @@ DxgiDuplicatorController::Result DxgiDuplicatorController::DoDuplicate(
     return Result::INITIALIZATION_FAILED;
   }
 
-  if (!frame->Prepare(SelectedDesktopSize(monitor_id), monitor_id,
+  if (!frame->Prepare(SelectedDesktopSize(monitor_id), monitor_id)) {
-                      GetDeviceScaleFactor(monitor_id))) {
     return Result::FRAME_PREPARE_FAILED;
   }
 
   frame->frame()->mutable_updated_region()->Clear();
+  frame->frame()->set_device_scale_factor(GetDeviceScaleFactor(monitor_id));
 
   if (DoDuplicateUnlocked(frame->context(), monitor_id, frame->frame())) {
     succeeded_duplications_++;

modules/desktop_capture/win/dxgi_frame.cc

@@ -25,9 +25,7 @@ DxgiFrame::DxgiFrame(SharedMemoryFactory* factory) : factory_(factory) {}
 
 DxgiFrame::~DxgiFrame() = default;
 
-bool DxgiFrame::Prepare(DesktopSize size,
+bool DxgiFrame::Prepare(DesktopSize size, DesktopCapturer::SourceId source_id) {
-                        DesktopCapturer::SourceId source_id,
-                        std::optional<float> device_scale_factor) {
   if (source_id != source_id_) {
     // Once the source has been changed, the entire source should be copied.
     source_id_ = source_id;
@@ -59,7 +57,6 @@ bool DxgiFrame::Prepare(DesktopSize size,
     } else {
       frame.reset(new BasicDesktopFrame(size));
     }
-    frame->set_device_scale_factor(device_scale_factor);
     frame_ = SharedDesktopFrame::Wrap(std::move(frame));
   }
 

modules/desktop_capture/win/dxgi_frame.h

@@ -45,11 +45,8 @@ class DxgiFrame final {
   // as well as Context class.
   friend class DxgiDuplicatorController;
 
-  // Prepares current instance with desktop size, source id and device scale
+  // Prepares current instance with desktop size and source id.
-  // factor.
+  bool Prepare(DesktopSize size, DesktopCapturer::SourceId source_id);
-  bool Prepare(DesktopSize size,
-               DesktopCapturer::SourceId source_id,
-               std::optional<float> device_scale_factor);
 
   // Should not be called if Prepare() is not executed or returns false.
   Context* context();

modules/desktop_capture/win/dxgi_output_duplicator.cc

@@ -68,18 +68,12 @@ DxgiOutputDuplicator::DxgiOutputDuplicator(const D3dDevice& device,
     : device_(device),
       output_(output),
       device_name_(rtc::ToUtf8(desc.DeviceName)),
-      desktop_rect_(RECTToDesktopRect(desc.DesktopCoordinates)) {
+      desktop_rect_(RECTToDesktopRect(desc.DesktopCoordinates)),
+      monitor_(desc.Monitor) {
   RTC_DCHECK(output_);
   RTC_DCHECK(!desktop_rect_.is_empty());
   RTC_DCHECK_GT(desktop_rect_.width(), 0);
   RTC_DCHECK_GT(desktop_rect_.height(), 0);
-  DEVICE_SCALE_FACTOR device_scale_factor = DEVICE_SCALE_FACTOR_INVALID;
-  HRESULT hr = GetScaleFactorForMonitor(desc.Monitor, &device_scale_factor);
-  RTC_LOG_IF(LS_ERROR, FAILED(hr))
-      << "Failed to get scale factor for monitor: " << hr;
-  if (device_scale_factor != DEVICE_SCALE_FACTOR_INVALID) {
-    device_scale_factor_ = static_cast<float>(device_scale_factor) / 100.0f;
-  }
 }
 
 DxgiOutputDuplicator::DxgiOutputDuplicator(DxgiOutputDuplicator&& other) =
@@ -425,6 +419,17 @@ int64_t DxgiOutputDuplicator::num_frames_captured() const {
   return num_frames_captured_;
 }
 
+std::optional<float> DxgiOutputDuplicator::device_scale_factor() const {
+  DEVICE_SCALE_FACTOR device_scale_factor = DEVICE_SCALE_FACTOR_INVALID;
+  HRESULT hr = GetScaleFactorForMonitor(monitor_, &device_scale_factor);
+  if (FAILED(hr)) {
+    RTC_LOG(LS_ERROR) << "Failed to get scale factor for monitor: " << hr;
+    return std::nullopt;
+  }
+  RTC_DCHECK(device_scale_factor != DEVICE_SCALE_FACTOR_INVALID);
+  return static_cast<float>(device_scale_factor) / 100.0f;
+}
+
 void DxgiOutputDuplicator::TranslateRect(const DesktopVector& position) {
   desktop_rect_.Translate(position);
   RTC_DCHECK_GE(desktop_rect_.left(), 0);

modules/desktop_capture/win/dxgi_output_duplicator.h

@@ -86,9 +86,7 @@ class DxgiOutputDuplicator {
 
   // Device scale factor of the monitor associated with this
   // DxigOutputDuplicator.
-  std::optional<float> device_scale_factor() const {
+  std::optional<float> device_scale_factor() const;
-    return device_scale_factor_;
-  }
 
   // Moves `desktop_rect_`. See DxgiDuplicatorController::TranslateRect().
   void TranslateRect(const DesktopVector& position);
@@ -134,13 +132,13 @@ class DxgiOutputDuplicator {
   const Microsoft::WRL::ComPtr<IDXGIOutput1> output_;
   const std::string device_name_;
   DesktopRect desktop_rect_;
+  const HMONITOR monitor_;
   Microsoft::WRL::ComPtr<IDXGIOutputDuplication> duplication_;
   DXGI_OUTDUPL_DESC desc_;
   std::vector<uint8_t> metadata_;
   std::unique_ptr<DxgiTexture> texture_;
   Rotation rotation_;
   DesktopSize unrotated_size_;
-  std::optional<float> device_scale_factor_;
 
   // After each AcquireNextFrame() function call, updated_region_(s) of all
   // active Context(s) need to be updated. Since they have missed the

modules/desktop_capture/win/wgc_capture_session.cc

@@ -106,21 +106,9 @@ WgcCaptureSession::WgcCaptureSession(intptr_t source_id,
                                      ABI::Windows::Graphics::SizeInt32 size)
     : d3d11_device_(std::move(d3d11_device)),
       item_(std::move(item)),
-      size_(size) {
+      size_(size),
+      source_id_(source_id) {
   RTC_CHECK(source_id);
-  HMONITOR monitor = 0;
-  if (!GetHmonitorFromDeviceIndex(source_id, &monitor)) {
-    monitor = MonitorFromWindow(reinterpret_cast<HWND>(source_id),
-                                /*dwFlags=*/MONITOR_DEFAULTTONEAREST);
-  }
-  DEVICE_SCALE_FACTOR device_scale_factor = DEVICE_SCALE_FACTOR_INVALID;
-  HRESULT hr = GetScaleFactorForMonitor(monitor, &device_scale_factor);
-  RTC_LOG_IF(LS_ERROR, FAILED(hr))
-      << "Failed to get scale factor for monitor: " << hr;
-
-  if (device_scale_factor != DEVICE_SCALE_FACTOR_INVALID) {
-    device_scale_factor_ = static_cast<float>(device_scale_factor) / 100.0f;
-  }
 }
 
 WgcCaptureSession::~WgcCaptureSession() {
@@ -473,9 +461,31 @@ HRESULT WgcCaptureSession::ProcessFrame() {
   }
 
   DesktopFrame* current_frame = queue_.current_frame();
-  current_frame->set_device_scale_factor(device_scale_factor_);
   DesktopFrame* previous_frame = queue_.previous_frame();
 
+  // If the captured window moves to another screen, the HMONITOR assosciated
+  // with the captured window will change. Therefore, we need to get the value
+  // of HMONITOR per frame.
+  HMONITOR monitor;
+  if (!GetHmonitorFromDeviceIndex(source_id_, &monitor)) {
+    monitor = MonitorFromWindow(reinterpret_cast<HWND>(source_id_),
+                                /*dwFlags=*/MONITOR_DEFAULTTONEAREST);
+  }
+
+  // Captures the device scale factor of the monitor where the frame is captured
+  // from. This value is the same as the scale from windows settings. Valid
+  // values are some distinct numbers in the range of [1,5], for example,
+  // 1, 1.5, 2.5, etc.
+  DEVICE_SCALE_FACTOR device_scale_factor = DEVICE_SCALE_FACTOR_INVALID;
+  HRESULT scale_factor_hr =
+      GetScaleFactorForMonitor(monitor, &device_scale_factor);
+  RTC_LOG_IF(LS_ERROR, FAILED(scale_factor_hr))
+      << "Failed to get scale factor for monitor: " << scale_factor_hr;
+  if (device_scale_factor != DEVICE_SCALE_FACTOR_INVALID) {
+    current_frame->set_device_scale_factor(
+        static_cast<float>(device_scale_factor) / 100.0f);
+  }
+
   // Will be set to true while copying the frame data to the `current_frame` if
   // we can already determine that the content of the new frame differs from the
   // previous. The idea is to get a low-complexity indication of if the content

modules/desktop_capture/win/wgc_capture_session.h

@@ -149,11 +149,8 @@ class WgcCaptureSession final {
   // false.
   DesktopRegion damage_region_;
 
-  // Captures the device scale factor of the monitor where the frame is captured
+  // The unique id to represent a Source of current DesktopCapturer.
-  // from. This value is the same as the scale from windows settings. Valid
+  intptr_t source_id_;
-  // values are some distinct numbers in the range of [1,5], for example,
-  // 1, 1.5, 2.5, etc.
-  std::optional<float> device_scale_factor_;
 
   SequenceChecker sequence_checker_;
 };