[layoutng] Add helper functions to compute lengths

third_party/WebKit/Source/core/layout/ng/ng_length_utils.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 NGLengthUtils_h
+#define NGLengthUtils_h
+
+#include "core/CoreExport.h"
+
+namespace blink {
+class ComputedStyle;
+class LayoutUnit;
+class Length;
+class NGConstraintSpace;
+
+enum class LengthResolveType { MinSize, MaxSize, ContentSize };
+
+// Convert an inline-axis length to a layout unit using the given constraint
+// space.
+CORE_EXPORT LayoutUnit resolveInlineLength(LengthResolveType,
+                                           const Length&,
+                                           const NGConstraintSpace&);
+
+// Convert a block-axis length to a layout unit using the given constraint
+// space.
+CORE_EXPORT LayoutUnit resolveBlockLength(LengthResolveType,
+                                          const Length&,
+                                          const NGConstraintSpace&,
+                                          LayoutUnit contentContribution);
+
+// Resolves the given length to a layout unit, constraining it by the min
+// logical width and max logical width properties from the ComputedStyle
+// object.
+CORE_EXPORT LayoutUnit computeInlineSizeForFragment(const NGConstraintSpace&,
+                                                    const ComputedStyle&);
+
+// Resolves the given length to a layout unit, constraining it by the min
+// logical height and max logical height properties from the ComputedStyle
+// object.
+CORE_EXPORT LayoutUnit
+computeBlockSizeForFragment(const NGConstraintSpace&,
+                            const ComputedStyle& style,
+                            LayoutUnit contentContribution);
+
+}  // namespace blink
+
+#endif  // NGLengthUtils_h