Implement NGBoxStrut::ConvertToPhysical with tests

Bug: 740993
Change-Id: I742b2aa94048e55204d204e0ce6fcaee7b0af6d8
Reviewed-on: https://chromium-review.googlesource.com/567776
Commit-Queue: Aleks Totic <atotic@chromium.org>
Reviewed-by: Christian Biesinger <cbiesinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#486196}

third_party/WebKit/Source/core/layout/ng/geometry/ng_box_strut.cc

@@ -18,6 +18,33 @@ bool NGBoxStrut::operator==(const NGBoxStrut& other) const {
          std::tie(inline_start, inline_end, block_start, block_end);
 }
 
+NGPhysicalBoxStrut NGBoxStrut::ConvertToPhysical(
+    NGWritingMode writing_mode,
+    TextDirection direction) const {
+  LayoutUnit direction_start = inline_start;
+  LayoutUnit direction_end = inline_end;
+  if (direction == TextDirection::kRtl)
+    std::swap(direction_start, direction_end);
+  switch (writing_mode) {
+    case kHorizontalTopBottom:
+      return NGPhysicalBoxStrut(block_start, direction_end, block_end,
+                                direction_start);
+    case kVerticalRightLeft:
+    case kSidewaysRightLeft:
+      return NGPhysicalBoxStrut(direction_start, block_start, direction_end,
+                                block_end);
+    case kVerticalLeftRight:
+      return NGPhysicalBoxStrut(direction_start, block_end, direction_end,
+                                block_start);
+    case kSidewaysLeftRight:
+      return NGPhysicalBoxStrut(direction_end, block_end, direction_start,
+                                block_start);
+    default:
+      NOTREACHED();
+      return NGPhysicalBoxStrut();
+  }
+}
+
 // Converts physical dimensions to logical ones per
 // https://drafts.csswg.org/css-writing-modes-3/#logical-to-physical
 NGBoxStrut NGPhysicalBoxStrut::ConvertToLogical(NGWritingMode writing_mode,

third_party/WebKit/Source/core/layout/ng/geometry/ng_box_strut.h

@@ -13,6 +13,8 @@
 
 namespace blink {
 
+struct NGPhysicalBoxStrut;
+
 // This struct is used for storing margins, borders or padding of a box on all
 // four edges.
 struct CORE_EXPORT NGBoxStrut {
@@ -42,6 +44,8 @@ struct CORE_EXPORT NGBoxStrut {
 
   bool IsEmpty() const;
 
+  NGPhysicalBoxStrut ConvertToPhysical(NGWritingMode, TextDirection) const;
+
   // The following two operators exist primarily to have an easy way to access
   // the sum of border and padding.
   NGBoxStrut& operator+=(const NGBoxStrut& other) {
@@ -86,6 +90,9 @@ struct CORE_EXPORT NGPhysicalBoxStrut {
   NGBoxStrut ConvertToLogical(NGWritingMode, TextDirection) const;
   NGPixelSnappedPhysicalBoxStrut SnapToDevicePixels() const;
 
+  LayoutUnit HorizontalSum() const { return left + right; }
+  LayoutUnit VerticalSum() const { return top + bottom; }
+
   LayoutUnit top;
   LayoutUnit right;
   LayoutUnit bottom;

third_party/WebKit/Source/core/layout/ng/geometry/ng_box_strut_test.cc

@@ -43,6 +43,43 @@ TEST(NGGeometryUnitsTest, ConvertPhysicalStrutToLogical) {
   EXPECT_EQ(right, logical.block_start);
 }
 
+TEST(NGGeometryUnitsTest, ConvertLogicalStrutToPhysical) {
+  LayoutUnit left{5}, right{10}, top{15}, bottom{20};
+  NGBoxStrut logical(left, right, top, bottom);
+  NGBoxStrut converted =
+      logical.ConvertToPhysical(kHorizontalTopBottom, TextDirection::kLtr)
+          .ConvertToLogical(kHorizontalTopBottom, TextDirection::kLtr);
+  EXPECT_EQ(logical, converted);
+  converted =
+      logical.ConvertToPhysical(kHorizontalTopBottom, TextDirection::kRtl)
+          .ConvertToLogical(kHorizontalTopBottom, TextDirection::kRtl);
+  EXPECT_EQ(logical, converted);
+  converted = logical.ConvertToPhysical(kVerticalLeftRight, TextDirection::kLtr)
+                  .ConvertToLogical(kVerticalLeftRight, TextDirection::kLtr);
+  EXPECT_EQ(logical, converted);
+  converted = logical.ConvertToPhysical(kVerticalLeftRight, TextDirection::kRtl)
+                  .ConvertToLogical(kVerticalLeftRight, TextDirection::kRtl);
+  EXPECT_EQ(logical, converted);
+  converted = logical.ConvertToPhysical(kVerticalRightLeft, TextDirection::kLtr)
+                  .ConvertToLogical(kVerticalRightLeft, TextDirection::kLtr);
+  EXPECT_EQ(logical, converted);
+  converted = logical.ConvertToPhysical(kVerticalRightLeft, TextDirection::kRtl)
+                  .ConvertToLogical(kVerticalRightLeft, TextDirection::kRtl);
+  EXPECT_EQ(logical, converted);
+  converted = logical.ConvertToPhysical(kSidewaysRightLeft, TextDirection::kLtr)
+                  .ConvertToLogical(kSidewaysRightLeft, TextDirection::kLtr);
+  EXPECT_EQ(logical, converted);
+  converted = logical.ConvertToPhysical(kSidewaysRightLeft, TextDirection::kRtl)
+                  .ConvertToLogical(kSidewaysRightLeft, TextDirection::kRtl);
+  EXPECT_EQ(logical, converted);
+  converted = logical.ConvertToPhysical(kSidewaysLeftRight, TextDirection::kLtr)
+                  .ConvertToLogical(kSidewaysLeftRight, TextDirection::kLtr);
+  EXPECT_EQ(logical, converted);
+  converted = logical.ConvertToPhysical(kSidewaysLeftRight, TextDirection::kRtl)
+                  .ConvertToLogical(kSidewaysLeftRight, TextDirection::kRtl);
+  EXPECT_EQ(logical, converted);
+}
+
 }  // namespace
 
 }  // namespace blink