Bug 1732737 - Add VirtualDesktop handling to window occlusion on Windows r=gfx-reviewers,bradwerth

Implementation of WindowOcclusionCalculator::Initialize() is borrowed from InitializeVirtualDesktopManagerTask::Run().
And implementation of WindowOcclusionCalculator::IsWindowOnCurrentVirtualDesktop() is borrowed from chromium's WindowOcclusionCalculator::IsWindowOnCurrentVirtualDesktop()

Differential Revision: https://phabricator.services.mozilla.com/D133327

widget/windows/WinWindowOcclusionTracker.cpp

@@ -24,6 +24,7 @@
 #include "mozilla/StaticPrefs_widget.h"
 #include "mozilla/StaticPtr.h"
 #include "nsBaseWidget.h"
+#include "nsWindow.h"
 #include "transport/runnable_utils.h"
 #include "WinUtils.h"
 
@@ -322,6 +323,12 @@ void WinWindowOcclusionTracker::Ensure() {
 
   sTracker = new WinWindowOcclusionTracker(thread);
   WindowOcclusionCalculator::CreateInstance();
+
+  RefPtr<Runnable> runnable =
+      WrapRunnable(RefPtr<WindowOcclusionCalculator>(
+                       WindowOcclusionCalculator::GetInstance()),
+                   &WindowOcclusionCalculator::Initialize);
+  sTracker->mSerializedTaskDispatcher->PostTaskToCalculator(runnable.forget());
 }
 
 /* static */
@@ -765,6 +772,27 @@ void WinWindowOcclusionTracker::WindowOcclusionCalculator::ClearInstance() {
   sCalculator = nullptr;
 }
 
+void WinWindowOcclusionTracker::WindowOcclusionCalculator::Initialize() {
+  MOZ_ASSERT(IsInWinWindowOcclusionThread());
+  MOZ_ASSERT(!mVirtualDesktopManager);
+  CALC_LOG(LogLevel::Info, "Initialize()");
+
+#ifndef __MINGW32__
+  if (!IsWin10OrLater()) {
+    return;
+  }
+
+  RefPtr<IVirtualDesktopManager> desktopManager;
+  HRESULT hr = ::CoCreateInstance(
+      CLSID_VirtualDesktopManager, NULL, CLSCTX_INPROC_SERVER,
+      __uuidof(IVirtualDesktopManager), getter_AddRefs(desktopManager));
+  if (FAILED(hr)) {
+    return;
+  }
+  mVirtualDesktopManager = desktopManager;
+#endif
+}
+
 void WinWindowOcclusionTracker::WindowOcclusionCalculator::Shutdown(
     layers::SynchronousTask* aTask) {
   MOZ_ASSERT(IsInWinWindowOcclusionThread());
@@ -777,6 +805,7 @@ void WinWindowOcclusionTracker::WindowOcclusionCalculator::Shutdown(
     mOcclusionUpdateRunnable->Cancel();
     mOcclusionUpdateRunnable = nullptr;
   }
+  mVirtualDesktopManager = nullptr;
 }
 
 void WinWindowOcclusionTracker::WindowOcclusionCalculator::
@@ -1288,9 +1317,35 @@ Maybe<bool> WinWindowOcclusionTracker::WindowOcclusionCalculator::
     return Some(true);
   }
 
-  // XXX VirtualDesktopManager is going to be handled by Bug 1732737.
+  BOOL onCurrentDesktop;
+  HRESULT hr = mVirtualDesktopManager->IsWindowOnCurrentVirtualDesktop(
+      aHwnd, &onCurrentDesktop);
+  if (FAILED(hr)) {
+    // In this case, we do not know the window is in which virtual desktop.
+    return Nothing();
+  }
 
-  return Nothing();
+  if (onCurrentDesktop) {
+    return Some(true);
+  }
+
+  GUID workspaceGuid;
+  hr = mVirtualDesktopManager->GetWindowDesktopId(aHwnd, &workspaceGuid);
+  if (FAILED(hr)) {
+    // In this case, we do not know the window is in which virtual desktop.
+    return Nothing();
+  }
+
+  // IsWindowOnCurrentVirtualDesktop() is flaky for newly opened windows,
+  // which causes test flakiness. Occasionally, it incorrectly says a window
+  // is not on the current virtual desktop when it is. In this situation,
+  // it also returns GUID_NULL for the desktop id.
+  if (workspaceGuid == GUID_NULL) {
+    // In this case, we do not know the window is in which virtual desktop.
+    return Nothing();
+  }
+
+  return Some(false);
 }
 
 #undef LOG

widget/windows/WinWindowOcclusionTracker.h

@@ -99,6 +99,7 @@ class WinWindowOcclusionTracker final : public DisplayStatusListener,
     // Returns existing WindowOcclusionCalculator instance.
     static WindowOcclusionCalculator* GetInstance() { return sCalculator; }
 
+    void Initialize();
     void Shutdown(layers::SynchronousTask* aTask);
 
     void EnableOcclusionTrackingForWindow(HWND hwnd);
@@ -236,7 +237,6 @@ class WinWindowOcclusionTracker final : public DisplayStatusListener,
     HWND mMovingWindow = 0;
 
     // Only used on Win10+.
-    // XXX VirtualDesktopManager is going to be handled by Bug 1732737.
     RefPtr<IVirtualDesktopManager> mVirtualDesktopManager;
 
     // Used to serialize tasks related to mRootWindowHwndsOcclusionState.