[LayoutNG] Introduce NGPhysicalFragment and make NGFragment a 'view'

third_party/WebKit/Source/core/layout/ng/ng_physical_fragment_base.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 NGPhysicalFragmentBase_h
+#define NGPhysicalFragmentBase_h
+
+#include "core/CoreExport.h"
+#include "core/layout/ng/ng_constraint_space.h"
+#include "platform/LayoutUnit.h"
+#include "platform/heap/Handle.h"
+#include "wtf/Vector.h"
+
+namespace blink {
+
+// The NGPhysicalFragmentBase contains the output information from layout. The
+// fragment stores all of its information in the physical coordinate system for
+// use by paint, hit-testing etc.
+//
+// Layout code should only access output layout information through the
+// NGFragmentBase classes which transforms infromation into the logical
+// coordinate system.
+class CORE_EXPORT NGPhysicalFragmentBase
+    : public GarbageCollected<NGPhysicalFragmentBase> {
+ public:
+  enum NGFragmentType { FragmentBox = 0, FragmentText = 1 };
+
+  NGFragmentType Type() const { return static_cast<NGFragmentType>(type_); }
+
+  // The accessors in this class shouldn't be used by layout code directly,
+  // instead should be accessed by the NGFragmentBase classes. These accessors
+  // exist for paint, hit-testing, etc.
+
+  // Returns the border-box size.
+  NGPhysicalSize Size() const { return size_; }
+  LayoutUnit Width() const { return size_.width; }
+  LayoutUnit Height() const { return size_.height; }
+
+  // Returns the total size, including the contents outside of the border-box.
+  LayoutUnit WidthOverflow() const { return overflow_.width; }
+  LayoutUnit HeightOverflow() const { return overflow_.height; }
+
+  // Returns the offset relative to the parent fragement's content-box.
+  LayoutUnit LeftOffset() const {
+    DCHECK(has_been_placed_);
+    return offset_.left;
+  }
+
+  LayoutUnit TopOffset() const {
+    DCHECK(has_been_placed_);
+    return offset_.top;
+  }
+
+  // Should only be used by the parent fragement's layout.
+  void SetOffset(NGPhysicalOffset offset) {
+    DCHECK(!has_been_placed_);
+    offset_ = offset;
+    has_been_placed_ = true;
+  }
+
+  DEFINE_INLINE_TRACE_AFTER_DISPATCH() {}
+  DECLARE_TRACE();
+
+ protected:
+  NGPhysicalFragmentBase(NGPhysicalSize size,
+                         NGPhysicalSize overflow,
+                         NGFragmentType type)
+      : size_(size),
+        overflow_(overflow),
+        type_(type),
+        has_been_placed_(false) {}
+
+  NGPhysicalSize size_;
+  NGPhysicalSize overflow_;
+  NGPhysicalOffset offset_;
+
+  unsigned type_ : 1;
+  unsigned has_been_placed_ : 1;
+};
+
+}  // namespace blink
+
+#endif  // NGFragmentBase_h