Bug 1730096 part 7: Support cached remote text attributes in TextLeafPoint. r=eeejay

Differential Revision: https://phabricator.services.mozilla.com/D129473

accessible/base/TextLeafRange.cpp

@@ -762,7 +762,19 @@ already_AddRefed<AccAttributes> TextLeafPoint::GetTextAttributes(
   if (mAcc->IsLocal()) {
     return GetTextAttributesLocalAcc(aIncludeDefaults);
   }
-  return nullptr;
+  RefPtr<AccAttributes> attrs = new AccAttributes();
+  if (aIncludeDefaults) {
+    Accessible* parent = mAcc->Parent();
+    if (parent && parent->IsRemote() && parent->IsHyperText()) {
+      if (auto defAttrs = parent->AsRemote()->GetCachedTextAttributes()) {
+        defAttrs->CopyTo(attrs);
+      }
+    }
+  }
+  if (auto thisAttrs = mAcc->AsRemote()->GetCachedTextAttributes()) {
+    thisAttrs->CopyTo(attrs);
+  }
+  return attrs.forget();
 }
 
 TextLeafPoint TextLeafPoint::FindTextAttrsStart(
@@ -770,10 +782,26 @@ TextLeafPoint TextLeafPoint::FindTextAttrsStart(
     const AccAttributes* aOriginAttrs, bool aIncludeDefaults) const {
   // XXX Add support for spelling errors.
   RefPtr<const AccAttributes> lastAttrs;
-  if (aOriginAttrs) {
-    lastAttrs = aOriginAttrs;
+  const bool isRemote = mAcc->IsRemote();
+  if (isRemote) {
+    // For RemoteAccessible, leaf attrs and default attrs are cached
+    // separately. To combine them, we have to copy. Since we're not walking
+    // outside the container, we don't care about defaults. Therefore, we
+    // always just fetch the leaf attrs.
+    // We ignore aOriginAttrs because it might include defaults. Fetching leaf
+    // attrs is very cheap anyway.
+    lastAttrs = mAcc->AsRemote()->GetCachedTextAttributes();
   } else {
-    lastAttrs = GetTextAttributesLocalAcc(aIncludeDefaults);
+    // For LocalAccessible, we want to avoid calculating attrs more than
+    // necessary, so we want to use aOriginAttrs if provided.
+    if (aOriginAttrs) {
+      lastAttrs = aOriginAttrs;
+      // Whether we include defaults henceforth must match aOriginAttrs, which
+      // depends on aIncludeDefaults. Defaults are always calculated even if
+      // they aren't returned, so calculation cost isn't a concern.
+    } else {
+      lastAttrs = GetTextAttributesLocalAcc(aIncludeDefaults);
+    }
   }
   if (aIncludeOrigin && aDirection == eDirNext && mOffset == 0) {
     // Even when searching forward, the only way to know whether the origin is
@@ -784,8 +812,11 @@ TextLeafPoint TextLeafPoint::FindTextAttrsStart(
     if (!point.mAcc || !point.mAcc->IsText()) {
       return *this;
     }
+    // For RemoteAccessible, we can get attributes from the cache without any
+    // calculation or copying.
     RefPtr<const AccAttributes> attrs =
-        point.GetTextAttributesLocalAcc(aIncludeDefaults);
+        isRemote ? point.mAcc->AsRemote()->GetCachedTextAttributes()
+                 : point.GetTextAttributesLocalAcc(aIncludeDefaults);
     if (!attrs->Equal(lastAttrs)) {
       return *this;
     }
@@ -799,7 +830,8 @@ TextLeafPoint TextLeafPoint::FindTextAttrsStart(
       break;
     }
     RefPtr<const AccAttributes> attrs =
-        point.GetTextAttributesLocalAcc(aIncludeDefaults);
+        isRemote ? point.mAcc->AsRemote()->GetCachedTextAttributes()
+                 : point.GetTextAttributesLocalAcc(aIncludeDefaults);
     if (!attrs->Equal(lastAttrs)) {
       // The attributes change here. If we're moving forward, we want to
       // return this point. If we're moving backward, we've now moved before

accessible/ipc/RemoteAccessibleBase.cpp

@@ -417,6 +417,19 @@ void RemoteAccessibleBase<Derived>::DOMNodeID(nsString& aID) const {
   }
 }
 
+template <class Derived>
+RefPtr<const AccAttributes>
+RemoteAccessibleBase<Derived>::GetCachedTextAttributes() {
+  MOZ_ASSERT(IsText() || IsHyperText());
+  if (mCachedFields) {
+    auto attrs =
+        mCachedFields->GetAttributeRefPtr<AccAttributes>(nsGkAtoms::style);
+    VERIFY_CACHE(CacheDomain::Text);
+    return attrs;
+  }
+  return nullptr;
+}
+
 template class RemoteAccessibleBase<RemoteAccessible>;
 
 }  // namespace a11y

accessible/ipc/RemoteAccessibleBase.h

@@ -217,6 +217,7 @@ class RemoteAccessibleBase : public Accessible, public HyperTextAccessibleBase {
 
   uint32_t GetCachedTextLength();
   Maybe<const nsTArray<int32_t>&> GetCachedTextLines();
+  RefPtr<const AccAttributes> GetCachedTextAttributes();
 
   virtual HyperTextAccessibleBase* AsHyperTextBase() override {
     return IsHyperText() ? static_cast<HyperTextAccessibleBase*>(this)