Don't assume a node with a measure function is a leaf node

Summary: Don't assume a node with a measure function is a leaf node

Reviewed By: gkassabli

Differential Revision: D4021096

fbshipit-source-id: 7e039239b1697a0ac42dce9f4b7e252a931bad7e

CSSLayout/CSSLayout.c

@@ -242,10 +242,9 @@ uint32_t CSSNodeChildCount(const CSSNodeRef node) {
 }
 
 void CSSNodeMarkDirty(const CSSNodeRef node) {
-  CSS_ASSERT(node->measure != NULL,
+  CSS_ASSERT(node->measure != NULL || CSSNodeChildCount(node) > 0,
-             "Nodes without custom measure functions "
+             "Only leaf nodes with custom measure functions"
-             "should not manually mark themselves as "
+             "should manually mark themselves as dirty");
-             "dirty");
   _CSSNodeMarkDirty(node);
 }
 
@@ -966,7 +965,7 @@ static void layoutNodeImpl(const CSSNodeRef node,
 
   // For content (text) nodes, determine the dimensions based on the text
   // contents.
-  if (node->measure) {
+  if (node->measure && CSSNodeChildCount(node) == 0) {
     const float innerWidth = availableWidth - marginAxisRow - paddingAndBorderAxisRow;
     const float innerHeight = availableHeight - marginAxisColumn - paddingAndBorderAxisColumn;
 
@@ -2100,7 +2099,7 @@ bool layoutNodeInternal(const CSSNodeRef node,
   // most
   // expensive to measure, so it's worth avoiding redundant measurements if at
   // all possible.
-  if (node->measure) {
+  if (node->measure && CSSNodeChildCount(node) == 0) {
     const float marginAxisRow = getMarginAxis(node, CSSFlexDirectionRow);
     const float marginAxisColumn = getMarginAxis(node, CSSFlexDirectionColumn);
 

tests/CSSLayoutMeasureTest.cpp

@@ -0,0 +1,44 @@
+/**
+ * Copyright (c) 2014-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+#include <CSSLayout/CSSLayout.h>
+#include <gtest/gtest.h>
+
+static CSSSize _measure(void *context,
+                        float width,
+                        CSSMeasureMode widthMode,
+                        float height,
+                        CSSMeasureMode heightMode) {
+  int *measureCount = (int *)context;
+  *measureCount = *measureCount + 1;
+  return CSSSize {
+      .width = widthMode == CSSMeasureModeUndefined ? 10 : width,
+      .height = heightMode == CSSMeasureModeUndefined ? 10 : width,
+  };
+}
+
+TEST(CSSLayoutTest, ignore_measure_on_non_leaf_node) {
+  const CSSNodeRef root = CSSNodeNew();
+  int measureCount = 0;
+  CSSNodeSetContext(root, &measureCount);
+  CSSNodeSetMeasureFunc(root, _measure);
+
+  const CSSNodeRef root_child0 = CSSNodeNew();
+  int childMeasureCount = 0;
+  CSSNodeSetContext(root_child0, &childMeasureCount);
+  CSSNodeSetMeasureFunc(root_child0, _measure);
+  CSSNodeInsertChild(root, root_child0, 0);
+
+  CSSNodeCalculateLayout(root, CSSUndefined, CSSUndefined, CSSDirectionLTR);
+
+  ASSERT_EQ(0, measureCount);
+  ASSERT_EQ(1, childMeasureCount);
+
+  CSSNodeFreeRecursive(root);
+}