Use Opportunity Iterator to position text fragments in NGLineBuilder

third_party/WebKit/Source/core/layout/ng/ng_layout_opportunity_iterator.h

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef NGLayoutOpportunityIterator_h
 #define NGLayoutOpportunityIterator_h
 
 #include "core/CoreExport.h"
 #include "core/layout/ng/ng_layout_opportunity_tree_node.h"
 #include "platform/heap/Handle.h"
 #include "wtf/Optional.h"
 #include "wtf/Vector.h"
+#include "wtf/text/StringBuilder.h"
 
 namespace blink {
 
 class NGConstraintSpace;
 typedef NGLogicalRect NGLayoutOpportunity;
 typedef Vector<NGLayoutOpportunity> NGLayoutOpportunities;
 
 class CORE_EXPORT NGLayoutOpportunityIterator final {
  public:
   // Default constructor.
   //
   // @param space Constraint space with exclusions for which this iterator needs
   //              to generate layout opportunities.
-  // @param opt_origin_point Optional origin_point parameter that is used as a
-  //                         default start point for layout opportunities.
+  // @param opt_offset Optional offset parameter that is used as a
+  //                   default start point for layout opportunities.
   // @param opt_leader_point Optional 'leader' parameter that is used to specify
   //                         the ending point of temporary excluded rectangle
   //                         which starts from 'origin'. This rectangle may
   //                         represent a text fragment for example.
   NGLayoutOpportunityIterator(
       const NGConstraintSpace* space,
-      const WTF::Optional<NGLogicalOffset>& opt_origin_point = WTF::nullopt,
+      const WTF::Optional<NGLogicalOffset>& opt_offset = WTF::nullopt,
       const WTF::Optional<NGLogicalOffset>& opt_leader_point = WTF::nullopt);
 
   // Gets the next Layout Opportunity or nullptr if the search is exhausted.
   // TODO(chrome-layout-team): Refactor with using C++ <iterator> library.
   const NGLayoutOpportunity Next();
 
+  // Offset that specifies the starting point to search layout opportunities.
+  // It's either {@code opt_offset} or space->BfcOffset().
+  NGLogicalOffset Offset() const { return offset_; }
+
 #ifndef NDEBUG
   // Prints Layout Opportunity tree for debug purposes.
   void ShowLayoutOpportunityTree() const;
 #endif
 
  private:
   // Mutable Getters.
   NGLayoutOpportunityTreeNode* MutableOpportunityTreeRoot() {
     return opportunity_tree_root_.get();
   }
 
   // Read-only Getters.
   const NGLayoutOpportunityTreeNode* OpportunityTreeRoot() const {
     return opportunity_tree_root_.get();
   }
 
   const NGConstraintSpace* constraint_space_;
 
   NGLayoutOpportunities opportunities_;
   NGLayoutOpportunities::const_iterator opportunity_iter_;
   Persistent<NGLayoutOpportunityTreeNode> opportunity_tree_root_;
+  NGLogicalOffset offset_;
 };
 
 }  // namespace blink
 
 #endif  // NGLayoutOpportunityIterator_h