Bug 1886371 part 4: Implement IRawElementProviderFragmentRoot. r=nlapre

This identifies the root of our implementation and allows for focus querying and hit testing.
We also implement IRawElementProviderSimple::get_HostRawElementProvider to connect to UIA's HWND provider.

Differential Revision: https://phabricator.services.mozilla.com/D205182

accessible/windows/msaa/MsaaRootAccessible.cpp

@@ -5,6 +5,7 @@
 
 #include "mozilla/a11y/DocAccessibleParent.h"
 #include "mozilla/dom/BrowserParent.h"
+#include "mozilla/StaticPrefs_accessibility.h"
 #include "mozilla/WindowsVersion.h"
 #include "MsaaRootAccessible.h"
 #include "Relation.h"
@@ -36,6 +37,13 @@ MsaaRootAccessible::InternalQueryInterface(REFIID aIid, void** aOutInterface) {
     return S_OK;
   }
 
+  if (StaticPrefs::accessibility_uia_enable() &&
+      aIid == IID_IRawElementProviderFragmentRoot) {
+    RefPtr<IRawElementProviderFragmentRoot> root = this;
+    root.forget(aOutInterface);
+    return S_OK;
+  }
+
   // ...Otherwise we pass through to the base COM implementation of
   // QueryInterface which is provided by MsaaDocAccessible.
   return MsaaDocAccessible::QueryInterface(aIid, aOutInterface);

accessible/windows/msaa/MsaaRootAccessible.h

@@ -8,12 +8,14 @@
 
 #include "mozilla/mscom/Aggregation.h"
 #include "MsaaDocAccessible.h"
+#include "UiaRoot.h"
 
 namespace mozilla {
 
 namespace a11y {
+class RootAccessible;
 
-class MsaaRootAccessible : public MsaaDocAccessible {
+class MsaaRootAccessible : public MsaaDocAccessible, public UiaRoot {
  public:
   explicit MsaaRootAccessible(Accessible* aAcc)
       : MsaaDocAccessible(aAcc), mOuter(&mInternalUnknown) {}

accessible/windows/uia/UiaRoot.cpp

@@ -0,0 +1,61 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "UiaRoot.h"
+
+#include "MsaaRootAccessible.h"
+#include "RootAccessible.h"
+
+using namespace mozilla;
+using namespace mozilla::a11y;
+
+// UiaRoot
+
+Accessible* UiaRoot::Acc() {
+  auto* mr = static_cast<MsaaRootAccessible*>(this);
+  return static_cast<MsaaAccessible*>(mr)->Acc();
+}
+
+// IRawElementProviderFragmentRoot
+
+STDMETHODIMP
+UiaRoot::ElementProviderFromPoint(
+    double aX, double aY,
+    __RPC__deref_out_opt IRawElementProviderFragment** aRetVal) {
+  if (!aRetVal) {
+    return E_INVALIDARG;
+  }
+  *aRetVal = nullptr;
+  Accessible* acc = Acc();
+  if (!acc) {
+    return CO_E_OBJNOTCONNECTED;
+  }
+  if (Accessible* target = acc->ChildAtPoint(
+          aX, aY, Accessible::EWhichChildAtPoint::DeepestChild)) {
+    RefPtr<IRawElementProviderFragment> fragment =
+        MsaaAccessible::GetFrom(target);
+    fragment.forget(aRetVal);
+  }
+  return S_OK;
+}
+
+STDMETHODIMP
+UiaRoot::GetFocus(__RPC__deref_out_opt IRawElementProviderFragment** aRetVal) {
+  if (!aRetVal) {
+    return E_INVALIDARG;
+  }
+  *aRetVal = nullptr;
+  Accessible* acc = Acc();
+  if (!acc) {
+    return CO_E_OBJNOTCONNECTED;
+  }
+  if (Accessible* focus = acc->FocusedChild()) {
+    RefPtr<IRawElementProviderFragment> fragment =
+        MsaaAccessible::GetFrom(focus);
+    fragment.forget(aRetVal);
+  }
+  return S_OK;
+}

accessible/windows/uia/UiaRoot.h

@@ -0,0 +1,40 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_a11y_UiaRoot_h__
+#define mozilla_a11y_UiaRoot_h__
+
+#include "objbase.h"
+#include "uiautomation.h"
+
+namespace mozilla {
+namespace a11y {
+class Accessible;
+
+/**
+ * IRawElementProviderFragmentRoot implementation.
+ */
+class UiaRoot : public IRawElementProviderFragmentRoot {
+ public:
+  // IRawElementProviderFragmentRoot
+  virtual HRESULT STDMETHODCALLTYPE ElementProviderFromPoint(
+      /* [in] */ double aX,
+      /* [in] */ double aY,
+      /* [retval][out] */
+      __RPC__deref_out_opt IRawElementProviderFragment** aRetVal);
+
+  virtual HRESULT STDMETHODCALLTYPE GetFocus(
+      /* [retval][out] */ __RPC__deref_out_opt IRawElementProviderFragment**
+          aRetVal);
+
+ private:
+  Accessible* Acc();
+};
+
+}  // namespace a11y
+}  // namespace mozilla
+
+#endif

accessible/windows/uia/moz.build

@@ -6,6 +6,7 @@
 
 SOURCES += [
     "uiaRawElmProvider.cpp",
+    "UiaRoot.cpp",
 ]
 
 LOCAL_INCLUDES += [

accessible/windows/uia/uiaRawElmProvider.cpp

@@ -12,8 +12,10 @@
 #include "LocalAccessible-inl.h"
 #include "mozilla/a11y/RemoteAccessible.h"
 #include "MsaaAccessible.h"
+#include "MsaaRootAccessible.h"
 #include "nsAccUtils.h"
 #include "nsTextEquivUtils.h"
+#include "RootAccessible.h"
 
 using namespace mozilla;
 using namespace mozilla::a11y;
@@ -250,9 +252,15 @@ STDMETHODIMP
 uiaRawElmProvider::get_HostRawElementProvider(
     __RPC__deref_out_opt IRawElementProviderSimple** aRawElmProvider) {
   if (!aRawElmProvider) return E_INVALIDARG;
-
-  // This method is not used with IAccessibleEx implementations.
   *aRawElmProvider = nullptr;
+  Accessible* acc = Acc();
+  if (!acc) {
+    return CO_E_OBJNOTCONNECTED;
+  }
+  if (acc->IsRoot()) {
+    HWND hwnd = MsaaAccessible::GetHWNDFor(acc);
+    return UiaHostProviderFromHwnd(hwnd, aRawElmProvider);
+  }
   return S_OK;
 }
 
@@ -346,7 +354,26 @@ uiaRawElmProvider::SetFocus() {
 STDMETHODIMP
 uiaRawElmProvider::get_FragmentRoot(
     __RPC__deref_out_opt IRawElementProviderFragmentRoot** aRetVal) {
-  return E_NOTIMPL;
+  if (!aRetVal) {
+    return E_INVALIDARG;
+  }
+  *aRetVal = nullptr;
+  Accessible* acc = Acc();
+  if (!acc) {
+    return CO_E_OBJNOTCONNECTED;
+  }
+  LocalAccessible* localAcc = acc->AsLocal();
+  if (!localAcc) {
+    localAcc = acc->AsRemote()->OuterDocOfRemoteBrowser();
+    if (!localAcc) {
+      return CO_E_OBJNOTCONNECTED;
+    }
+  }
+  MsaaAccessible* msaa = MsaaAccessible::GetFrom(localAcc->RootAccessible());
+  RefPtr<IRawElementProviderFragmentRoot> fragRoot =
+      static_cast<MsaaRootAccessible*>(msaa);
+  fragRoot.forget(aRetVal);
+  return S_OK;
 }
 
 // Private methods