Make LayoutText::CollectLineBoxRects() to utilize NGInlineCursor

This patch change |LayoutText::CollectLineBoxRects()| to utilize |NGInlineCursor|
instead of |NGInlineFragmentTraversal::SelfFragmentsOf()| as preparation of
migrating to |NGFragmentItem|.


This patch also makes |NGInlineCursor::MoveTo()| to work during layout to use
previous layout result for scroll anchoring.

Bug: 982194
Change-Id: I9f046540ab797f274b88072f26bb241e101175d6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1855152
Commit-Queue: Yoshifumi Inoue <yosin@chromium.org>
Commit-Queue: Koji Ishii <kojii@chromium.org>
Reviewed-by: Koji Ishii <kojii@chromium.org>
Auto-Submit: Yoshifumi Inoue <yosin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#706323}

third_party/blink/renderer/core/layout/layout_text.cc

@@ -55,7 +55,6 @@
 #include "third_party/blink/renderer/core/layout/ng/inline/ng_abstract_inline_text_box.h"
 #include "third_party/blink/renderer/core/layout/ng/inline/ng_fragment_item.h"
 #include "third_party/blink/renderer/core/layout/ng/inline/ng_inline_cursor.h"
-#include "third_party/blink/renderer/core/layout/ng/inline/ng_inline_fragment_traversal.h"
 #include "third_party/blink/renderer/core/layout/ng/inline/ng_inline_node.h"
 #include "third_party/blink/renderer/core/layout/ng/inline/ng_offset_mapping.h"
 #include "third_party/blink/renderer/core/layout/ng/inline/ng_physical_text_fragment.h"
@@ -450,17 +449,16 @@ static IntRect EllipsisRectForBox(InlineTextBox* box,
 template <typename PhysicalRectCollector>
 void LayoutText::CollectLineBoxRects(const PhysicalRectCollector& yield,
                                      ClippingOption option) const {
-  if (const NGPhysicalBoxFragment* box_fragment =
-          ContainingBlockFlowFragment()) {
-    const auto children =
-        NGInlineFragmentTraversal::SelfFragmentsOf(*box_fragment, this);
-    for (const auto& child : children) {
+  if (IsInLayoutNGInlineFormattingContext()) {
+    NGInlineCursor cursor;
+    cursor.MoveTo(*this);
+    for (; cursor; cursor.MoveToNextForSameLayoutObject()) {
       if (UNLIKELY(option != ClippingOption::kNoClipping)) {
         DCHECK_EQ(option, ClippingOption::kClipToEllipsis);
-        if (child.fragment->IsHiddenForPaint())
+        if (cursor.IsHiddenForPaint())
           continue;
       }
-      yield(child.RectInContainerBox());
+      yield(cursor.CurrentRect());
     }
     return;
   }

third_party/blink/renderer/core/layout/ng/inline/ng_inline_cursor.cc

@@ -54,7 +54,9 @@ NGInlineCursor::NGInlineCursor(const LayoutBlockFlow& block_flow) {
     return;
   }
 
-  NOTREACHED();
+  // We reach here in case of |ScrollANchor::NotifyBeforeLayout()| via
+  // |LayoutText::PhysicalLinesBoundingBox()|
+  // See external/wpt/css/css-scroll-anchoring/wrapped-text.html
 }
 
 NGInlineCursor::NGInlineCursor(const NGFragmentItems& items)
@@ -75,6 +77,8 @@ NGInlineCursor::NGInlineCursor(const NGInlineCursor& other)
       current_paint_fragment_(other.current_paint_fragment_),
       layout_inline_(other.layout_inline_) {}
 
+NGInlineCursor::NGInlineCursor() = default;
+
 bool NGInlineCursor::operator==(const NGInlineCursor& other) const {
   if (root_paint_fragment_) {
     return root_paint_fragment_ == other.root_paint_fragment_ &&
@@ -262,6 +266,10 @@ const PhysicalOffset NGInlineCursor::CurrentOffset() const {
   return PhysicalOffset();
 }
 
+const PhysicalRect NGInlineCursor::CurrentRect() const {
+  return PhysicalRect(CurrentOffset(), CurrentSize());
+}
+
 TextDirection NGInlineCursor::CurrentResolvedDirection() const {
   if (current_paint_fragment_)
     return current_paint_fragment_->PhysicalFragment().ResolvedDirection();
@@ -317,21 +325,26 @@ void NGInlineCursor::MakeNull() {
   }
   if (fragment_items_)
     return MoveToItem(items_.end());
-  NOTREACHED();
 }
 
 void NGInlineCursor::InternalMoveTo(const LayoutObject& layout_object) {
   DCHECK(layout_object.IsInLayoutNGInlineFormattingContext());
-  if (root_paint_fragment_) {
-    const auto fragments = NGPaintFragment::InlineFragmentsFor(&layout_object);
-    if (!fragments.IsInLayoutNGInlineFormattingContext() || fragments.IsEmpty())
-      return MakeNull();
-    return MoveTo(fragments.front());
+  if (fragment_items_) {
+    item_iter_ = items_.begin();
+    while (current_item_ && CurrentLayoutObject() != &layout_object)
+      MoveToNextItem();
+    return;
   }
-  DCHECK(IsItemCursor());
-  item_iter_ = items_.begin();
-  while (current_item_ && CurrentLayoutObject() != &layout_object)
-    MoveToNextItem();
+  const auto fragments = NGPaintFragment::InlineFragmentsFor(&layout_object);
+  if (!fragments.IsInLayoutNGInlineFormattingContext() || fragments.IsEmpty())
+    return MakeNull();
+  if (!root_paint_fragment_) {
+    // We reach here in case of |ScrollANchor::NotifyBeforeLayout()| via
+    // |LayoutText::PhysicalLinesBoundingBox()|
+    // See external/wpt/css/css-scroll-anchoring/wrapped-text.html
+    root_paint_fragment_ = fragments.front().Root();
+  }
+  return MoveTo(fragments.front());
 }
 
 void NGInlineCursor::MoveTo(const LayoutObject& layout_object) {

third_party/blink/renderer/core/layout/ng/inline/ng_inline_cursor.h

@@ -21,6 +21,7 @@ class NGFragmentItems;
 class NGPaintFragment;
 class NGPhysicalBoxFragment;
 struct PhysicalOffset;
+struct PhysicalRect;
 struct PhysicalSize;
 
 // This class traverses fragments in an inline formatting context.
@@ -38,6 +39,7 @@ class CORE_EXPORT NGInlineCursor {
   explicit NGInlineCursor(const NGFragmentItems& items);
   explicit NGInlineCursor(const NGPaintFragment& root_paint_fragment);
   NGInlineCursor(const NGInlineCursor& other);
+  NGInlineCursor();
 
   bool operator==(const NGInlineCursor& other) const;
   bool operator!=(const NGInlineCursor& other) const {
@@ -110,6 +112,7 @@ class CORE_EXPORT NGInlineCursor {
 
   // The offset relative to the root of the inline formatting context.
   const PhysicalOffset CurrentOffset() const;
+  const PhysicalRect CurrentRect() const;
   const PhysicalSize CurrentSize() const;
 
   // Returns start/end of offset in text content of current text fragment.
@@ -171,11 +174,6 @@ class CORE_EXPORT NGInlineCursor {
  private:
   using ItemsSpan = base::span<const std::unique_ptr<NGFragmentItem>>;
 
-  // |NGInlineCursor| is either paint fragment cursor or fragment item cursor.
-  // TODO(yosin): When we implement default constructor of |NGInlineCursor|,
-  // we'll call it "void cursor" instead of "null cursor".
-  NGInlineCursor() = delete;
-
   // True if current position is descendant or self of |layout_object|.
   // Note: This function is used for moving cursor in culled inline boxes.
   bool IsInclusiveDescendantOf(const LayoutObject& layout_object) const;