Make LayoutText::GetTextBoxInfo() to use NGInlineCursor

This patch changes |LayoutText::GetTextBoxInfo()| to use |NGInlineCursor|
to reduce usage of |NGPaintFragment| for preparation of migrating
|NGFragmentItem|.

Bug: 982194
Change-Id: Ib37fae0241efaca73184710cc0af3050a041bde5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1880890
Commit-Queue: Koji Ishii <kojii@chromium.org>
Auto-Submit: Yoshifumi Inoue <yosin@chromium.org>
Reviewed-by: Koji Ishii <kojii@chromium.org>
Cr-Commit-Position: refs/heads/master@{#709410}

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

@@ -292,15 +292,14 @@ void LayoutText::InLayoutNGInlineFormattingContextWillChange(bool new_value) {
 Vector<LayoutText::TextBoxInfo> LayoutText::GetTextBoxInfo() const {
   Vector<TextBoxInfo> results;
   if (const NGOffsetMapping* mapping = GetNGOffsetMapping()) {
-    auto fragments = NGPaintFragment::InlineFragmentsFor(this);
     bool in_hidden_for_paint = false;
-    for (const NGPaintFragment* fragment : fragments) {
-      const auto& text_fragment =
-          To<NGPhysicalTextFragment>(fragment->PhysicalFragment());
+    NGInlineCursor cursor;
+    cursor.MoveTo(*this);
+    for (; cursor; cursor.MoveToNextForSameLayoutObject()) {
       // TODO(yosin): We should introduce
       // |NGPhysicalTextFragment::IsTruncated()| to skip them instead of using
       // |IsHiddenForPaint()| with ordering of fragments.
-      if (text_fragment.IsHiddenForPaint()) {
+      if (cursor.IsHiddenForPaint()) {
         in_hidden_for_paint = true;
       } else if (in_hidden_for_paint) {
         // Because of we finished original fragments (not painted), we should
@@ -309,7 +308,7 @@ Vector<LayoutText::TextBoxInfo> LayoutText::GetTextBoxInfo() const {
       }
       // We don't put generated texts, e.g. ellipsis, hyphen, etc. not in text
       // content, into results. Note: CSS "content" aren't categorized this.
-      if (text_fragment.TextType() == NGPhysicalTextFragment::kGeneratedText)
+      if (cursor.IsGeneratedTextType())
         continue;
       // When the corresponding DOM range contains collapsed whitespaces, NG
       // produces one fragment but legacy produces multiple text boxes broken at
@@ -317,22 +316,23 @@ Vector<LayoutText::TextBoxInfo> LayoutText::GetTextBoxInfo() const {
       // to match the legacy output.
       for (const NGOffsetMappingUnit& unit :
            mapping->GetMappingUnitsForTextContentOffsetRange(
-               text_fragment.StartOffset(), text_fragment.EndOffset())) {
+               cursor.CurrentTextStartOffset(),
+               cursor.CurrentTextEndOffset())) {
         DCHECK_EQ(unit.GetLayoutObject(), this);
         if (unit.GetType() == NGOffsetMappingUnitType::kCollapsed)
           continue;
         // [clamped_start, clamped_end] of |fragment| matches a legacy text box.
         const unsigned clamped_start =
-            std::max(unit.TextContentStart(), text_fragment.StartOffset());
+            std::max(unit.TextContentStart(), cursor.CurrentTextStartOffset());
         const unsigned clamped_end =
-            std::min(unit.TextContentEnd(), text_fragment.EndOffset());
+            std::min(unit.TextContentEnd(), cursor.CurrentTextEndOffset());
         DCHECK_LT(clamped_start, clamped_end);
         const unsigned box_length = clamped_end - clamped_start;
 
         // Compute rect of the legacy text box.
         LayoutRect rect =
-            text_fragment.LocalRect(clamped_start, clamped_end).ToLayoutRect();
-        rect.MoveBy(fragment->InlineOffsetToContainerBox().ToLayoutPoint());
+            cursor.CurrentLocalRect(clamped_start, clamped_end).ToLayoutRect();
+        rect.MoveBy(cursor.CurrentOffset().ToLayoutPoint());
 
         // Compute start of the legacy text box.
         if (unit.AssociatedNode()) {

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

@@ -153,6 +153,21 @@ bool NGInlineCursor::IsGeneratedText() const {
   return false;
 }
 
+bool NGInlineCursor::IsGeneratedTextType() const {
+  if (current_paint_fragment_) {
+    if (auto* text_fragment = DynamicTo<NGPhysicalTextFragment>(
+            current_paint_fragment_->PhysicalFragment())) {
+      return text_fragment->TextType() ==
+             NGPhysicalTextFragment::kGeneratedText;
+    }
+    return false;
+  }
+  if (current_item_)
+    return current_item_->Type() == NGFragmentItem::kGeneratedText;
+  NOTREACHED();
+  return false;
+}
+
 bool NGInlineCursor::IsHiddenForPaint() const {
   if (current_paint_fragment_)
     return current_paint_fragment_->PhysicalFragment().IsHiddenForPaint();
@@ -393,6 +408,22 @@ unsigned NGInlineCursor::CurrentTextEndOffset() const {
   return 0u;
 }
 
+PhysicalRect NGInlineCursor::CurrentLocalRect(unsigned start_offset,
+                                              unsigned end_offset) const {
+  DCHECK(IsText());
+  if (current_paint_fragment_) {
+    return To<NGPhysicalTextFragment>(
+               current_paint_fragment_->PhysicalFragment())
+        .LocalRect(start_offset, end_offset);
+  }
+  if (current_item_) {
+    return current_item_->LocalRect(current_item_->Text(*fragment_items_),
+                                    start_offset, end_offset);
+  }
+  NOTREACHED();
+  return PhysicalRect();
+}
+
 void NGInlineCursor::MakeNull() {
   if (root_paint_fragment_) {
     current_paint_fragment_ = nullptr;

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

@@ -98,6 +98,11 @@ class CORE_EXPORT NGInlineCursor {
   // end.
   bool IsGeneratedText() const;
 
+  // True if fragment is |NGFragmentItem::kGeneratedText| or
+  // |NGPhysicalTextFragment::kGeneratedText|.
+  // TODO(yosin): We should rename |IsGeneratedTextType()| to another name.
+  bool IsGeneratedTextType() const;
+
   // True if the current position is hidden for paint. It is error to call at
   // end.
   bool IsHiddenForPaint() const;
@@ -144,6 +149,12 @@ class CORE_EXPORT NGInlineCursor {
   unsigned CurrentTextStartOffset() const;
   unsigned CurrentTextEndOffset() const;
 
+  // The layout box of text in (start, end) range in local coordinate.
+  // Start and end offsets must be between |CurrentTextStartOffset()| and
+  // |CurrentTextEndOffset()|. It is error to call other than text.
+  PhysicalRect CurrentLocalRect(unsigned start_offset,
+                                unsigned end_offset) const;
+
   //
   // Functions to move the current position.
   //