From debfb84ee98d246bca234fcf38250104384da597 Mon Sep 17 00:00:00 2001
From: Eitan Isaacson <eitan@monotonous.org>
Date: Thu, 10 Sep 2020 21:52:35 +0000
Subject: [PATCH] Bug 1661758 - Part 4: Implement AXUIElementForTextMarker.
 r=morgan

Differential Revision: https://phabricator.services.mozilla.com/D89066
---
 .../mac/DocAccessiblePlatformExtChild.cpp     | 11 +++++++++
 accessible/mac/GeckoTextMarker.h              |  2 ++
 accessible/mac/GeckoTextMarker.mm             | 15 ++++++++++++
 accessible/mac/HyperTextAccessibleWrap.h      |  2 ++
 accessible/mac/HyperTextAccessibleWrap.mm     | 23 +++++++++++++++++++
 accessible/mac/MOXAccessibleProtocol.h        |  3 +++
 accessible/mac/MOXTextMarkerDelegate.h        |  3 +++
 accessible/mac/MOXTextMarkerDelegate.mm       |  9 ++++++++
 8 files changed, 68 insertions(+)

diff --git a/accessible/ipc/extension/mac/DocAccessiblePlatformExtChild.cpp b/accessible/ipc/extension/mac/DocAccessiblePlatformExtChild.cpp
index 7e526b5bb2c4..989f929de2e3 100644
--- a/accessible/ipc/extension/mac/DocAccessiblePlatformExtChild.cpp
+++ b/accessible/ipc/extension/mac/DocAccessiblePlatformExtChild.cpp
@@ -182,6 +182,17 @@ mozilla::ipc::IPCResult DocAccessiblePlatformExtChild::RecvRangeOfChild(
 
 mozilla::ipc::IPCResult DocAccessiblePlatformExtChild::RecvLeafAtOffset(
     const uint64_t& aID, const int32_t& aOffset, uint64_t* aLeaf) {
+  HyperTextAccessibleWrap* acc = IdToHyperTextAccessibleWrap(aID);
+  if (!acc) {
+    return IPC_OK();
+  }
+
+  Accessible* leaf = acc->LeafAtOffset(aOffset);
+
+  MOZ_ASSERT(!leaf || leaf->Document() == acc->Document());
+
+  *aLeaf = UNIQUE_ID(leaf);
+
   return IPC_OK();
 }
 
diff --git a/accessible/mac/GeckoTextMarker.h b/accessible/mac/GeckoTextMarker.h
index f760e1d51a0a..0be436e1f005 100644
--- a/accessible/mac/GeckoTextMarker.h
+++ b/accessible/mac/GeckoTextMarker.h
@@ -45,6 +45,8 @@ class GeckoTextMarker final {
   // Return a word range right of the given offset.
   GeckoTextMarkerRange RightWordRange();
 
+  AccessibleOrProxy Leaf();
+
   bool IsValid() const { return !mContainer.IsNull(); };
 
   bool operator<(const GeckoTextMarker& aPoint) const;
diff --git a/accessible/mac/GeckoTextMarker.mm b/accessible/mac/GeckoTextMarker.mm
index deb0c440cbbc..0da208adb2a2 100644
--- a/accessible/mac/GeckoTextMarker.mm
+++ b/accessible/mac/GeckoTextMarker.mm
@@ -269,6 +269,21 @@ GeckoTextMarkerRange GeckoTextMarker::RightWordRange() {
   return GeckoTextMarkerRange(GeckoTextMarker(), GeckoTextMarker());
 }
 
+AccessibleOrProxy GeckoTextMarker::Leaf() {
+  MOZ_ASSERT(!mContainer.IsNull());
+  if (mContainer.IsProxy()) {
+    uint64_t leafID = 0;
+    DocAccessibleParent* ipcDoc = mContainer.AsProxy()->Document();
+    Unused << ipcDoc->GetPlatformExtension()->SendLeafAtOffset(
+        mContainer.AsProxy()->ID(), mOffset, &leafID);
+    return ipcDoc->GetAccessible(leafID);
+  } else if (auto htWrap = ContainerAsHyperTextWrap()) {
+    return htWrap->LeafAtOffset(mOffset);
+  }
+
+  return mContainer;
+}
+
 // GeckoTextMarkerRange
 
 GeckoTextMarkerRange::GeckoTextMarkerRange(
diff --git a/accessible/mac/HyperTextAccessibleWrap.h b/accessible/mac/HyperTextAccessibleWrap.h
index 527523f9b407..4399713c3ef3 100644
--- a/accessible/mac/HyperTextAccessibleWrap.h
+++ b/accessible/mac/HyperTextAccessibleWrap.h
@@ -49,6 +49,8 @@ class HyperTextAccessibleWrap : public HyperTextAccessible {
   void RangeOfChild(Accessible* aChild, int32_t* aStartOffset,
                     int32_t* aEndOffset);
 
+  Accessible* LeafAtOffset(int32_t aOffset);
+
  protected:
   ~HyperTextAccessibleWrap() {}
 
diff --git a/accessible/mac/HyperTextAccessibleWrap.mm b/accessible/mac/HyperTextAccessibleWrap.mm
index 8dee6f1989c9..044e313382b4 100644
--- a/accessible/mac/HyperTextAccessibleWrap.mm
+++ b/accessible/mac/HyperTextAccessibleWrap.mm
@@ -365,6 +365,29 @@ void HyperTextAccessibleWrap::RangeOfChild(Accessible* aChild,
   }
 }
 
+Accessible* HyperTextAccessibleWrap::LeafAtOffset(int32_t aOffset) {
+  HyperTextAccessible* text = this;
+  Accessible* child = nullptr;
+  int32_t innerOffset = aOffset;
+  do {
+    int32_t childIdx = text->GetChildIndexAtOffset(innerOffset);
+    if (childIdx == -1) {
+      return text;
+    }
+
+    child = text->GetChildAt(childIdx);
+    if (!child || nsAccUtils::MustPrune(child)) {
+      return text;
+    }
+
+    innerOffset -= text->GetChildOffset(childIdx);
+
+    text = child->AsHyperText();
+  } while (text);
+
+  return child;
+}
+
 TextPoint HyperTextAccessibleWrap::FindTextPoint(
     int32_t aOffset, nsDirection aDirection, nsSelectionAmount aAmount,
     EWordMovementType aWordMovementType) {
diff --git a/accessible/mac/MOXAccessibleProtocol.h b/accessible/mac/MOXAccessibleProtocol.h
index 6c6e9cd9c958..b5b55de8b53d 100644
--- a/accessible/mac/MOXAccessibleProtocol.h
+++ b/accessible/mac/MOXAccessibleProtocol.h
@@ -398,6 +398,9 @@
 // AXTextMarkerForIndex
 - (id _Nullable)moxTextMarkerForIndex:(NSNumber* _Nonnull)index;
 
+// AXUIElementForTextMarker
+- (id _Nullable)moxUIElementForTextMarker:(id _Nonnull)textMarker;
+
 // AXTextMarkerRangeForUIElement
 - (id _Nullable)moxTextMarkerRangeForUIElement:(id _Nonnull)element;
 
diff --git a/accessible/mac/MOXTextMarkerDelegate.h b/accessible/mac/MOXTextMarkerDelegate.h
index fdb534c0c743..2f12391ae974 100644
--- a/accessible/mac/MOXTextMarkerDelegate.h
+++ b/accessible/mac/MOXTextMarkerDelegate.h
@@ -74,6 +74,9 @@
 // override
 - (NSValue*)moxBoundsForTextMarkerRange:(id)textMarkerRange;
 
+// override
+- (id)moxUIElementForTextMarker:(id)textMarker;
+
 // override
 - (id)moxTextMarkerRangeForUIElement:(id)element;
 
diff --git a/accessible/mac/MOXTextMarkerDelegate.mm b/accessible/mac/MOXTextMarkerDelegate.mm
index c0813be83812..7959f3ad3955 100644
--- a/accessible/mac/MOXTextMarkerDelegate.mm
+++ b/accessible/mac/MOXTextMarkerDelegate.mm
@@ -243,6 +243,15 @@ static nsDataHashtable<nsUint64HashKey, MOXTextMarkerDelegate*> sDelegates;
   return geckoTextMarker.CreateAXTextMarker();
 }
 
+- (id)moxUIElementForTextMarker:(id)textMarker {
+  GeckoTextMarker geckoTextMarker(mGeckoDocAccessible, textMarker);
+  if (!geckoTextMarker.IsValid()) {
+    return nil;
+  }
+
+  return GetNativeFromGeckoAccessible(geckoTextMarker.Leaf());
+}
+
 - (id)moxTextMarkerRangeForUIElement:(id)element {
   if (![element isKindOfClass:[mozAccessible class]]) {
     return nil;