Top down version of algorithm to position margins and floats in LayoutNG

third_party/WebKit/Source/core/layout/ng/ng_constraint_space_builder.cc

 // 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.
 
 #include "core/layout/ng/ng_constraint_space_builder.h"
 
 #include "core/layout/ng/ng_length_utils.h"
 
 namespace blink {
 
 NGConstraintSpaceBuilder::NGConstraintSpaceBuilder(
     const NGConstraintSpace* parent_space)
     : available_size_(parent_space->AvailableSize()),
       percentage_resolution_size_(parent_space->PercentageResolutionSize()),
       fragmentainer_space_available_(NGSizeIndefinite),
       writing_mode_(parent_space->WritingMode()),
       parent_writing_mode_(writing_mode_),
       is_fixed_size_inline_(false),
       is_fixed_size_block_(false),
       is_shrink_to_fit_(false),
       is_inline_direction_triggers_scrollbar_(false),
       is_block_direction_triggers_scrollbar_(false),
       fragmentation_type_(parent_space->BlockFragmentationType()),
       is_new_fc_(parent_space->IsNewFormattingContext()),
       text_direction_(static_cast<unsigned>(parent_space->Direction())),
+      bfc_offset_(parent_space->bfc_offset_),
       exclusions_(parent_space->Exclusions()) {}
 
 NGConstraintSpaceBuilder::NGConstraintSpaceBuilder(NGWritingMode writing_mode)
     : fragmentainer_space_available_(NGSizeIndefinite),
       writing_mode_(writing_mode),
       parent_writing_mode_(writing_mode_),
       is_fixed_size_inline_(false),
       is_fixed_size_block_(false),
       is_shrink_to_fit_(false),
       is_inline_direction_triggers_scrollbar_(false),
@@ skipping 14 matching lines @@
   percentage_resolution_size_ = percentage_resolution_size;
   return *this;
 }
 
 NGConstraintSpaceBuilder& NGConstraintSpaceBuilder::SetTextDirection(
     TextDirection text_direction) {
   text_direction_ = static_cast<unsigned>(text_direction);
   return *this;
 }
 
+NGConstraintSpaceBuilder& NGConstraintSpaceBuilder::SetMarginStrut(
+    const NGMarginStrut& margin_strut) {
+  margin_strut_ = margin_strut;
+  return *this;
+}
+
 NGConstraintSpaceBuilder& NGConstraintSpaceBuilder::SetIsFixedSizeInline(
     bool is_fixed_size_inline) {
   is_fixed_size_inline_ = is_fixed_size_inline;
   return *this;
 }
 
 NGConstraintSpaceBuilder& NGConstraintSpaceBuilder::SetIsFixedSizeBlock(
     bool is_fixed_size_block) {
   is_fixed_size_block_ = is_fixed_size_block;
   return *this;
@@ skipping 42 matching lines @@
 NGConstraintSpace* NGConstraintSpaceBuilder::ToConstraintSpace() {
   // Exclusions do not pass the formatting context boundary.
   std::shared_ptr<NGExclusions> exclusions(
       is_new_fc_ ? std::make_shared<NGExclusions>() : exclusions_);
 
   // Whether the child and the containing block are parallel to each other.
   // Example: vertical-rl and vertical-lr
   bool is_in_parallel_flow = (parent_writing_mode_ == kHorizontalTopBottom) ==
                              (writing_mode_ == kHorizontalTopBottom);
 
+  NGMarginStrut margin_strut = is_new_fc_ ? NGMarginStrut() : margin_strut_;
+  NGLogicalOffset bfc_offset = is_new_fc_ ? NGLogicalOffset() : bfc_offset_;
+
   if (is_in_parallel_flow) {
     return new NGConstraintSpace(
         static_cast<NGWritingMode>(writing_mode_),
         static_cast<TextDirection>(text_direction_),
         {available_size_.inline_size, available_size_.block_size},
         {percentage_resolution_size_.inline_size,
          percentage_resolution_size_.block_size},
         fragmentainer_space_available_, is_fixed_size_inline_,
         is_fixed_size_block_, is_shrink_to_fit_,
         is_inline_direction_triggers_scrollbar_,
         is_block_direction_triggers_scrollbar_,
         static_cast<NGFragmentationType>(fragmentation_type_), is_new_fc_,
-        exclusions);
+        margin_strut, bfc_offset, exclusions);
   }
 
   return new NGConstraintSpace(
       static_cast<NGWritingMode>(writing_mode_),
       static_cast<TextDirection>(text_direction_),
       {available_size_.block_size, available_size_.inline_size},
       {percentage_resolution_size_.block_size,
        percentage_resolution_size_.inline_size},
       fragmentainer_space_available_, is_fixed_size_block_,
       is_fixed_size_inline_, is_shrink_to_fit_,
       is_block_direction_triggers_scrollbar_,
       is_inline_direction_triggers_scrollbar_,
       static_cast<NGFragmentationType>(fragmentation_type_), is_new_fc_,
-      exclusions);
+      margin_strut, bfc_offset, exclusions);
 }
 
 }  // namespace blink