[LayoutNG] Abort a layout once the BFC offset is resolved.

third_party/WebKit/Source/core/layout/ng/ng_block_layout_algorithm.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 NGBlockLayoutAlgorithm_h
 #define NGBlockLayoutAlgorithm_h
 
 #include "core/CoreExport.h"
 #include "core/layout/ng/geometry/ng_margin_strut.h"
 #include "core/layout/ng/ng_block_break_token.h"
 #include "core/layout/ng/ng_block_node.h"
 #include "core/layout/ng/ng_box_fragment.h"
 #include "core/layout/ng/ng_constraint_space_builder.h"
 #include "core/layout/ng/ng_layout_algorithm.h"
 #include "platform/wtf/RefPtr.h"
 
 namespace blink {
 
 class NGConstraintSpace;
 class NGLayoutResult;
-struct NGInflowChildData;
-struct NGPreviousInflowPosition;
+
+// This struct is used for communicating to a child the position of the
+// previous inflow child.
+struct NGPreviousInflowPosition {
+  LayoutUnit bfc_block_offset;
+  LayoutUnit logical_block_offset;
+  NGMarginStrut margin_strut;
+};
+
+// This strut holds information for the current inflow child. The data is not
+// useful outside of handling this single inflow child.
+struct NGInflowChildData {
+  NGLogicalOffset bfc_offset_estimate;
+  NGMarginStrut margin_strut;
+  NGBoxStrut margins;
+};
 
 // Updates the fragment's BFC offset if it's not already set.
-void MaybeUpdateFragmentBfcOffset(const NGConstraintSpace&,
+bool MaybeUpdateFragmentBfcOffset(const NGConstraintSpace&,
                                   LayoutUnit bfc_block_offset,
                                   NGFragmentBuilder* builder);
 
 // Positions pending floats starting from {@origin_block_offset} and relative
 // to container's BFC offset.
-void PositionPendingFloats(LayoutUnit origin_block_offset,
-                           NGFragmentBuilder* container_builder,
-                           NGConstraintSpace* space);
+void PositionPendingFloats(
+    LayoutUnit origin_block_offset,
+    NGFragmentBuilder* container_builder,
+    Vector<RefPtr<NGUnpositionedFloat>>* unpositioned_floats,
+    NGConstraintSpace* space);
 
 // A class for general block layout (e.g. a <div> with no special style).
 // Lays out the children in sequence.
 class CORE_EXPORT NGBlockLayoutAlgorithm
     : public NGLayoutAlgorithm<NGBlockNode, NGBlockBreakToken> {
  public:
   // Default constructor.
   // @param node The input node to perform layout upon.
   // @param space The constraint space which the algorithm should generate a
   //              fragment within.
   // @param break_token The break token from which the layout should start.
   NGBlockLayoutAlgorithm(NGBlockNode node,
                          NGConstraintSpace* space,
                          NGBlockBreakToken* break_token = nullptr);
 
   Optional<MinMaxContentSize> ComputeMinMaxContentSize() const override;
   virtual RefPtr<NGLayoutResult> Layout() override;
 
  private:
   NGBoxStrut CalculateMargins(NGLayoutInputNode child);
 
   // Creates a new constraint space for the current child.
   RefPtr<NGConstraintSpace> CreateConstraintSpaceForChild(
       const NGLayoutInputNode child,
-      const NGInflowChildData& child_data);
+      const NGInflowChildData& child_data,
+      const WTF::Optional<NGLogicalOffset> floats_bfc_offset = WTF::nullopt);
 
   // @return Estimated BFC offset for the "to be layout" child.
-  NGInflowChildData PrepareChildLayout(const NGPreviousInflowPosition&,
-                                       NGLayoutInputNode);
+  WTF::Optional<NGInflowChildData> PrepareChildLayout(
+      const NGPreviousInflowPosition&,
+      NGLayoutInputNode);
 
-  NGPreviousInflowPosition FinishChildLayout(
+  WTF::Optional<NGPreviousInflowPosition> FinishChildLayout(
       const NGConstraintSpace&,
       const NGPreviousInflowPosition& prev_data,
       const NGInflowChildData& child_data,
-      const NGLayoutInputNode child,
-      NGLayoutResult*);
+      NGLayoutInputNode child,
+      NGBreakToken* child_break_token,
+      RefPtr<NGLayoutResult>);
 
   // Positions the fragment that establishes a new formatting context.
   //
   // This uses Layout Opportunity iterator to position the fragment.
   // That's because an element that establishes a new block formatting context
   // must not overlap the margin box of any floats in the same block formatting
   // context as the element itself.
   //
   // So if necessary, we clear the new BFC by placing it below any preceding
   // floats or place it adjacent to such floats if there is sufficient space.
   //
   // Example:
   // <div id="container">
   //   <div id="float"></div>
   //   <div id="new-fc" style="margin-top: 20px;"></div>
   // </div>
   // 1) If #new-fc is small enough to fit the available space right from #float
   //    then it will be placed there and we collapse its margin.
   // 2) If #new-fc is too big then we need to clear its position and place it
   //    below #float ignoring its vertical margin.
-  NGLogicalOffset PositionNewFc(const NGLayoutInputNode& child,
-                                const NGPreviousInflowPosition&,
-                                const NGBoxFragment&,
-                                const NGInflowChildData& child_data,
-                                const NGConstraintSpace& child_space);
+  bool PositionNewFc(const NGLayoutInputNode& child,
+                     const NGPreviousInflowPosition&,
+                     const NGLayoutResult&,
+                     const NGInflowChildData& child_data,
+                     const NGConstraintSpace& child_space,
+                     WTF::Optional<NGLogicalOffset>* child_bfc_offset);
 
   // Positions the fragment that knows its BFC offset.
-  NGLogicalOffset PositionWithBfcOffset(const NGLogicalOffset& bfc_offset);
+  WTF::Optional<NGLogicalOffset> PositionWithBfcOffset(
+      const NGLogicalOffset& bfc_offset);
+  bool PositionWithBfcOffset(const NGLogicalOffset& bfc_offset,
+                             WTF::Optional<NGLogicalOffset>* child_bfc_offset);
 
   // Positions using the parent BFC offset.
   // Fragment doesn't know its offset but we can still calculate its BFC
   // position because the parent fragment's BFC is known.
   // Example:
   //   BFC Offset is known here because of the padding.
   //   <div style="padding: 1px">
   //     <div id="empty-div" style="margins: 1px"></div>
   NGLogicalOffset PositionWithParentBfc(const NGConstraintSpace&,
                                         const NGInflowChildData& child_data,
@@ skipping 22 matching lines @@
   NGLogicalOffset CalculateLogicalOffset(
       const NGBoxStrut& child_margins,
       const WTF::Optional<NGLogicalOffset>& known_fragment_offset);
 
   NGLogicalSize child_available_size_;
   NGLogicalSize child_percentage_size_;
 
   NGBoxStrut border_scrollbar_padding_;
   LayoutUnit content_size_;
   LayoutUnit max_inline_size_;
+
+  bool abort_when_bfc_resolved_;
+
+  Vector<RefPtr<NGUnpositionedFloat>> unpositioned_floats_;
 };
 
 }  // namespace blink
 
 #endif  // NGBlockLayoutAlgorithm_h