Bug 1640553 part 1: Add the ability for AccessibleHandler to cache accessibles by id. r=eeejay

This cache is cleared when other AccessibleHandler caches are invalidated; i.e. when an event is fired.

Differential Revision: https://phabricator.services.mozilla.com/D76665

accessible/ipc/win/handler/AccessibleHandlerControl.cpp

@@ -118,6 +118,7 @@ IMPL_IUNKNOWN1(AccessibleHandlerControl, IHandlerControl)
 HRESULT
 AccessibleHandlerControl::Invalidate() {
   ++mCacheGen;
+  mAccessibleCache.clear();
   return S_OK;
 }
 
@@ -171,5 +172,23 @@ AccessibleHandlerControl::Register(NotNull<IGeckoBackChannel*> aGecko) {
   return hr;
 }
 
+void AccessibleHandlerControl::CacheAccessible(long aUniqueId,
+                                               AccessibleHandler* aAccessible) {
+  MOZ_ASSERT(aUniqueId && aAccessible);
+  mAccessibleCache[aUniqueId] = aAccessible;
+}
+
+HRESULT AccessibleHandlerControl::GetCachedAccessible(
+    long aUniqueId, AccessibleHandler** aAccessible) {
+  MOZ_ASSERT(aUniqueId && aAccessible);
+  auto it = mAccessibleCache.find(aUniqueId);
+  if (it == mAccessibleCache.end()) {
+    return E_INVALIDARG;
+  }
+  RefPtr<AccessibleHandler> ref = it->second;
+  ref.forget(aAccessible);
+  return S_OK;
+}
+
 }  // namespace a11y
 }  // namespace mozilla

accessible/ipc/win/handler/AccessibleHandlerControl.h

@@ -11,6 +11,7 @@
 #ifndef mozilla_a11y_AccessibleHandlerControl_h
 #  define mozilla_a11y_AccessibleHandlerControl_h
 
+#  include <unordered_map>
 #  include "Factory.h"
 #  include "HandlerData.h"
 #  include "IUnknownImpl.h"
@@ -48,6 +49,8 @@ class TextChange final {
 
 }  // namespace detail
 
+class AccessibleHandler;
+
 class AccessibleHandlerControl final : public IHandlerControl {
  public:
   static HRESULT Create(AccessibleHandlerControl** aOutObject);
@@ -69,6 +72,9 @@ class AccessibleHandlerControl final : public IHandlerControl {
 
   HRESULT Register(NotNull<IGeckoBackChannel*> aGecko);
 
+  void CacheAccessible(long aUniqueId, AccessibleHandler* aAccessible);
+  HRESULT GetCachedAccessible(long aUniqueId, AccessibleHandler** aAccessible);
+
  private:
   AccessibleHandlerControl();
   ~AccessibleHandlerControl() = default;
@@ -78,6 +84,8 @@ class AccessibleHandlerControl final : public IHandlerControl {
   detail::TextChange mTextChange;
   UniquePtr<mscom::RegisteredProxy> mIA2Proxy;
   UniquePtr<mscom::RegisteredProxy> mHandlerProxy;
+  // We can't use Gecko APIs in this dll, hence the use of std::unordered_map.
+  std::unordered_map<long, RefPtr<AccessibleHandler>> mAccessibleCache;
 };
 
 extern mscom::SingletonFactory<AccessibleHandlerControl> gControlFactory;