Bug 1899960 - P1: Don't cache implicit states. r=Jamie

This also removes some duplication and unifies the logic we use for
states that are calculated from other ones.

Differential Revision: https://phabricator.services.mozilla.com/D250356

accessible/base/States.h

@@ -295,9 +295,9 @@ const uint64_t LAST_ENTRY = CURRENT;
 /**
  * States that must be calculated by RemoteAccessible and are thus not cached.
  */
-const uint64_t kRemoteCalculatedStates =
-    states::FOCUSED | states::INVISIBLE | states::OFFSCREEN | states::ENABLED |
-    states::SENSITIVE | states::COLLAPSED | states::OPAQUE1;
+const uint64_t kRemoteCalculatedStates = states::FOCUSED | states::INVISIBLE |
+                                         states::OFFSCREEN | states::SENSITIVE |
+                                         states::OPAQUE1;
 
 }  // namespace a11y
 }  // namespace mozilla

accessible/basetypes/Accessible.cpp

@@ -698,6 +698,24 @@ void Accessible::ApplyImplicitState(uint64_t& aState) const {
   if (Opacity() == 1.0f && !(aState & states::INVISIBLE)) {
     aState |= states::OPAQUE1;
   }
+
+  const uint32_t kExpandCollapseStates = states::COLLAPSED | states::EXPANDED;
+  if ((aState & kExpandCollapseStates) == kExpandCollapseStates) {
+    // Cannot be both expanded and collapsed -- this happens in ARIA expanded
+    // combobox because of limitation of ARIAMap.
+    // XXX: Perhaps we will be able to make this less hacky if we support
+    // extended states in ARIAMap, e.g. derive COLLAPSED from
+    // EXPANDABLE && !EXPANDED.
+    aState &= ~states::COLLAPSED;
+  }
+
+  if (!(aState & states::UNAVAILABLE)) {
+    aState |= states::ENABLED | states::SENSITIVE;
+  }
+
+  if (aState & kExpandCollapseStates) {
+    aState |= states::EXPANDABLE;
+  }
 }
 
 bool Accessible::NameIsEmpty() const {

accessible/generic/LocalAccessible.cpp

@@ -1602,26 +1602,14 @@ void LocalAccessible::ARIAGroupPosition(int32_t* aLevel, int32_t* aSetSize,
   }
 }
 
-uint64_t LocalAccessible::State() {
+uint64_t LocalAccessible::ExplicitState() const {
   if (IsDefunct()) return states::DEFUNCT;
 
   uint64_t state = NativeState();
   // Apply ARIA states to be sure accessible states will be overridden.
   ApplyARIAState(&state);
 
-  const uint32_t kExpandCollapseStates = states::COLLAPSED | states::EXPANDED;
-  if ((state & kExpandCollapseStates) == kExpandCollapseStates) {
-    // Cannot be both expanded and collapsed -- this happens in ARIA expanded
-    // combobox because of limitation of ARIAMap.
-    // XXX: Perhaps we will be able to make this less hacky if we support
-    // extended states in ARIAMap, e.g. derive COLLAPSED from
-    // EXPANDABLE && !EXPANDED.
-    state &= ~states::COLLAPSED;
-  }
-
   if (!(state & states::UNAVAILABLE)) {
-    state |= states::ENABLED | states::SENSITIVE;
-
     // If the object is a current item of container widget then mark it as
     // ACTIVE. This allows screen reader virtual buffer modes to know which
     // descendant is the current one that would get focus if the user navigates
@@ -1630,9 +1618,11 @@ uint64_t LocalAccessible::State() {
     if (widget && widget->CurrentItem() == this) state |= states::ACTIVE;
   }
 
-  if ((state & states::COLLAPSED) || (state & states::EXPANDED)) {
-    state |= states::EXPANDABLE;
-  }
+  return state;
+}
+
+uint64_t LocalAccessible::State() {
+  uint64_t state = ExplicitState();
 
   ApplyImplicitState(state);
   return state;
@@ -3938,7 +3928,7 @@ already_AddRefed<AccAttributes> LocalAccessible::BundleFieldsForCache(
     if (IsInitialPush(CacheDomain::State)) {
       // Most states are updated using state change events, so we only send
       // these for the initial cache push.
-      uint64_t state = State();
+      uint64_t state = ExplicitState();
       // Exclude states which must be calculated by RemoteAccessible.
       state &= ~kRemoteCalculatedStates;
       fields->SetAttribute(CacheKey::State, state);

accessible/generic/LocalAccessible.h

@@ -765,6 +765,8 @@ class LocalAccessible : public nsISupports, public Accessible {
    */
   void NativeDescription(nsString& aDescription) const;
 
+  uint64_t ExplicitState() const;
+
   /**
    * Return object attributes provided by native markup. It doesn't take into
    * account ARIA.

accessible/ipc/RemoteAccessible.cpp

@@ -1580,13 +1580,6 @@ uint64_t RemoteAccessible::State() {
             mCachedFields->GetAttribute<uint64_t>(CacheKey::State)) {
       VERIFY_CACHE(CacheDomain::State);
       state = *rawState;
-      // Handle states that are derived from other states.
-      if (!(state & states::UNAVAILABLE)) {
-        state |= states::ENABLED | states::SENSITIVE;
-      }
-      if (state & states::EXPANDABLE && !(state & states::EXPANDED)) {
-        state |= states::COLLAPSED;
-      }
     }
 
     ApplyImplicitState(state);