[layoutng] Bidirectional interoperability between layoutng and legacy layout

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

Index: third_party/WebKit/Source/core/layout/ng/ng_box.cc
diff --git a/third_party/WebKit/Source/core/layout/ng/ng_box.cc b/third_party/WebKit/Source/core/layout/ng/ng_box.cc
index a32d9852d34ca0e34953bb9d2bef0ebffd990c52..d5e1bafae6771664a5536c84479b44c6b06716f7 100644
--- a/third_party/WebKit/Source/core/layout/ng/ng_box.cc
+++ b/third_party/WebKit/Source/core/layout/ng/ng_box.cc
@@ -5,19 +5,40 @@
 #include "core/layout/ng/ng_box.h"
 
 #include "core/layout/LayoutObject.h"
+#include "core/layout/ng/layout_ng_block_flow.h"
 #include "core/layout/ng/ng_block_layout_algorithm.h"
 #include "core/layout/ng/ng_box_iterator.h"
 #include "core/layout/ng/ng_fragment.h"
+#include "core/layout/LayoutBlockFlow.h"
 #include "core/layout/LayoutBox.h"
 
 namespace blink {
 
 NGFragment* NGBox::layout(const NGConstraintSpace& constraintSpace) {
-  NGBlockLayoutAlgorithm algorithm(style(), childIterator());
-  m_layoutBox->clearNeedsLayout();
-  NGFragment* fragment = algorithm.layout(constraintSpace);
-  m_layoutBox->setLogicalWidth(fragment->inlineSize());
-  m_layoutBox->setLogicalHeight(fragment->blockSize());
+  // We can either use the new layout code to do the layout and then copy the
+  // resulting size to the LayoutObject, or use the old layout code and
+  // synthesize a fragment.
+  NGFragment* fragment = nullptr;
+  if (canUseNewLayout()) {
+    NGBlockLayoutAlgorithm algorithm(style(), childIterator());
+    fragment = algorithm.layout(constraintSpace);
+    m_layoutBox->setLogicalWidth(fragment->inlineSize());
+    m_layoutBox->setLogicalHeight(fragment->blockSize());
+    if (m_layoutBox->isLayoutBlock())
+      toLayoutBlock(m_layoutBox)->layoutPositionedObjects(true);
+    m_layoutBox->clearNeedsLayout();
+  } else {
+    if (m_layoutBox->isLayoutNGBlockFlow() && m_layoutBox->needsLayout()) {
+      toLayoutNGBlockFlow(m_layoutBox)->LayoutBlockFlow::layoutBlock(true);
+    } else {
+      m_layoutBox->layoutIfNeeded();
+    }
+    LayoutRect overflow = m_layoutBox->layoutOverflowRect();
+    // This does not handle writing modes correctly (for overflow & the enums)
+    fragment = new NGFragment(
+        m_layoutBox->logicalWidth(), m_layoutBox->logicalHeight(),
+        overflow.width(), overflow.height(), HorizontalTopBottom, LeftToRight);
+  }
   return fragment;
 }
 
@@ -36,4 +57,17 @@ NGBox NGBox::nextSibling() const {
 NGBox NGBox::firstChild() const {
   return m_layoutBox ? NGBox(m_layoutBox->slowFirstChild()) : NGBox();
 }
+
+void NGBox::positionUpdated(const NGFragment& fragment) {
+  m_layoutBox->setLogicalLeft(fragment.inlineOffset());
+  m_layoutBox->setLogicalTop(fragment.blockOffset());
+}
+
+bool NGBox::canUseNewLayout() {
+  if (!m_layoutBox)
+    return true;
+  if (m_layoutBox->isLayoutBlockFlow() && !m_layoutBox->childrenInline())
+    return true;
+  return false;
+}
 }  // namespace blink