[LayoutNG] Misc fixes in ShapingLineBreaker

third_party/WebKit/Source/platform/fonts/shaping/ShapeResult.cpp

 /*
  * Copyright (c) 2012 Google Inc. All rights reserved.
  * Copyright (C) 2013 BlackBerry Limited. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 165 matching lines @@
 ShapeResult::~ShapeResult() {}
 
 size_t ShapeResult::ByteSize() const {
   size_t self_byte_size = sizeof(this);
   for (unsigned i = 0; i < runs_.size(); ++i) {
     self_byte_size += runs_[i]->ByteSize();
   }
   return self_byte_size;
 }
 
+unsigned ShapeResult::StartIndexForResult() const {
+  return !Rtl() ? runs_.front()->start_index_ : runs_.back()->start_index_;
+}
+
+unsigned ShapeResult::EndIndexForResult() const {
+  return StartIndexForResult() + NumCharacters();
+}
+
+// If the position is outside of the result, returns the start or the end offset
+// depends on the position.
 unsigned ShapeResult::OffsetForPosition(float target_x,
                                         bool include_partial_glyphs) const {
   unsigned characters_so_far = 0;
   float current_x = 0;
 
   if (Rtl()) {
+    if (target_x <= 0)
+      return num_characters_;
     characters_so_far = num_characters_;
     for (unsigned i = 0; i < runs_.size(); ++i) {
       if (!runs_[i])
         continue;
       characters_so_far -= runs_[i]->num_characters_;
       float next_x = current_x + runs_[i]->width_;
       float offset_for_run = target_x - current_x;
       if (offset_for_run >= 0 && offset_for_run <= runs_[i]->width_) {
         // The x value in question is within this script run.
         const unsigned index = runs_[i]->CharacterIndexForXPosition(
             offset_for_run, include_partial_glyphs);
         return characters_so_far + index;
       }
       current_x = next_x;
     }
   } else {
+    if (target_x <= 0)
+      return 0;
     for (unsigned i = 0; i < runs_.size(); ++i) {
       if (!runs_[i])
         continue;
       float next_x = current_x + runs_[i]->width_;
       float offset_for_run = target_x - current_x;
       if (offset_for_run >= 0 && offset_for_run <= runs_[i]->width_) {
         const unsigned index = runs_[i]->CharacterIndexForXPosition(
             offset_for_run, include_partial_glyphs);
         return characters_so_far + index;
       }
@@ skipping 253 matching lines @@
   result->width_ = run->width_;
   result->num_glyphs_ = count;
   DCHECK_EQ(result->num_glyphs_, count);  // no overflow
   result->has_vertical_offsets_ =
       font_data->PlatformData().IsVerticalAnyUpright();
   result->runs_.push_back(std::move(run));
   return result.Release();
 }
 
 }  // namespace blink