Implement collection of out-of-flow descendants

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

Index: third_party/WebKit/Source/core/layout/ng/ng_fragment_builder.cc
diff --git a/third_party/WebKit/Source/core/layout/ng/ng_fragment_builder.cc b/third_party/WebKit/Source/core/layout/ng/ng_fragment_builder.cc
index f886a2951c332719281328db86467a8e4486901c..0291e9377420e0a817c74a287a486ca8d87ef577 100644
--- a/third_party/WebKit/Source/core/layout/ng/ng_fragment_builder.cc
+++ b/third_party/WebKit/Source/core/layout/ng/ng_fragment_builder.cc
@@ -44,11 +44,71 @@ NGFragmentBuilder& NGFragmentBuilder::SetBlockOverflow(LayoutUnit size) {
 }
 
 NGFragmentBuilder& NGFragmentBuilder::AddChild(NGFragmentBase* child,
-                                               NGLogicalOffset offset) {
+                                               NGLogicalOffset child_offset) {
   DCHECK_EQ(type_, NGPhysicalFragmentBase::kFragmentBox)
       << "Only box fragments can have children";
   children_.append(child->PhysicalFragment());
-  offsets_.append(offset);
+  offsets_.append(child_offset);
+  // Collect child's out of flow descendants

[ikilpatrick, 2016/12/02 17:47:06]

.nit add period to end.

[atotic, 2016/12/02 19:55:15]

done

+  if (child->PhysicalFragment()->Type() ==
+      NGPhysicalFragmentBase::kFragmentBox) {

[ikilpatrick, 2016/12/02 17:47:05]

this can be fixed here or TODO+another patch, but i think we actually want
out_of_flow_descendants to live on fragment_base, i.e.

https://software.hixie.ch/utilities/js/live-dom-viewer/?%3C!DOCTYPE%20html%3E...

[atotic, 2016/12/02 19:55:15]

To rephrase:

All fragments can carry oof descendants. Therefore, oof descendants should move
from NGPhysicalFragment to NGPhysicalFragmentBase

Added TODO, this will be my next patch.

+    const NGPhysicalFragment* physical_child =
+        static_cast<const NGPhysicalFragment*>(&*child->PhysicalFragment());
+    Vector<NGCorner> block_offsets = physical_child->OutOfFlowOffsets();
+    size_t block_index = 0;
+    for (auto& block_node : physical_child->OutOfFlowDescendants()) {
+      NGCorner block_corner = block_offsets[block_index++];
+      out_of_flow_descendant_candidates_.add(block_node);

[ikilpatrick, 2016/12/02 17:47:06]

can we do:
s/block_/oof_/ here?

block is a little overloaded, oof_ prefix would be better.

(on block_offsets, block_index, block_node, block_corner).

[atotic, 2016/12/02 19:55:15]

done

+      oof_candidate_offsets_.append(
+          OutOfFlowOffset{child_offset, block_corner});
+    }
+  }
+  return *this;
+}
+
+NGFragmentBuilder& NGFragmentBuilder::AddOutOfFlowCandidateChild(
+    NGBlockNode* child,
+    NGLogicalOffset child_offset) {
+  out_of_flow_descendant_candidates_.add(child);
+  NGCorner child_corner =
+      NGCorner::Create(writing_mode_, direction_, NGPhysicalOffset());
+  oof_candidate_offsets_.append(OutOfFlowOffset{child_offset, child_corner});
+  return *this;
+}
+
+void NGFragmentBuilder::GetOutOfFlowDescendantCandidates(
+    WeakBoxList& descendants,
+    Vector<NGCorner>& descendant_corners) {

[ikilpatrick, 2016/12/02 17:47:06]

change ref to pointer as out param:
https://google.github.io/styleguide/cppguide.html#Function_Parameter_Ordering

[atotic, 2016/12/02 19:55:15]

done

+  descendants.clear();
+  descendant_corners.clear();

[ikilpatrick, 2016/12/02 17:47:06]

I would do a:
DCHECK(descendants->isEmpty());
DCHECK(descendant_corners->isEmpty());

instead.

[atotic, 2016/12/02 19:55:15]

done

+
+  DCHECK_GE(size_.inline_size, LayoutUnit(0));
+  DCHECK_GE(size_.block_size, LayoutUnit(0));

[ikilpatrick, 2016/12/02 17:47:05]

just LayoutUnit() for above lines I think.

[atotic, 2016/12/02 19:55:15]

done

+  NGPhysicalSize builder_physical_size{size_.ConvertToPhysical(writing_mode_)};
+
+  size_t offset_index = 0;
+  for (auto& block_node : out_of_flow_descendant_candidates_) {

[ikilpatrick, 2016/12/02 17:47:05]

s/block_node/oof_node/

[atotic, 2016/12/02 19:55:15]

done

+    OutOfFlowOffset oof_offset = oof_candidate_offsets_[offset_index++];
+
+    NGPhysicalOffset child_offset = oof_offset.child_offset.ConvertToPhysical(
+        writing_mode_, direction_, builder_physical_size, NGPhysicalSize());
+
+    NGCorner builder_relative_corner;
+    builder_relative_corner.type = oof_offset.descendant_corner.type;
+    builder_relative_corner.offset =
+        child_offset + oof_offset.descendant_corner.offset;

[ikilpatrick, 2016/12/02 17:47:06]

This is great, a lot simpler :)

[atotic, 2016/12/02 19:55:15]

yay

+    descendants.add(block_node);
+    descendant_corners.append(builder_relative_corner);
+  }
+  out_of_flow_descendant_candidates_.clear();
+  oof_candidate_offsets_.clear();
+}
+
+NGFragmentBuilder& NGFragmentBuilder::AddOutOfFlowDescendant(
+    NGBlockNode* descendant,
+    const NGCorner& corner) {
+  out_of_flow_descendants_.add(descendant);
+  out_of_flow_corners_.append(corner);
   return *this;
 }
 
@@ -83,11 +143,12 @@ NGPhysicalFragment* NGFragmentBuilder::ToFragment() {
   }
   return new NGPhysicalFragment(
       physical_size, overflow_.ConvertToPhysical(writing_mode_), children,
-      out_of_flow_descendants_, out_of_flow_offsets_, margin_strut_);
+      out_of_flow_descendants_, out_of_flow_corners_, margin_strut_);
 }
 
 DEFINE_TRACE(NGFragmentBuilder) {
   visitor->trace(children_);
+  visitor->trace(out_of_flow_descendant_candidates_);
   visitor->trace(out_of_flow_descendants_);
 }