Update ReactShadowNode to not add CSSNode children if parent has meas…

…ure defined

Summary: See inline comment for rationale

Reviewed By: emilsjolander

Differential Revision: D4154168

fbshipit-source-id: 6d428d4e9f4a68c88bb994ded88c817bee744563

ReactAndroid/src/main/java/com/facebook/react/uimanager/ReactShadowNode.java

@@ -142,7 +142,11 @@ public void addChildAt(ReactShadowNode child, int i) {
    mChildren.add(i, child);
    child.mParent = this;

    mCSSNode.addChildAt(child.mCSSNode, i);
    // If a CSS node has measure defined, the layout algorithm will not visit its children. Even
    // more, it asserts that you don't add children to nodes with measure functions.
    if (!mCSSNode.isMeasureDefined()) {
      mCSSNode.addChildAt(child.mCSSNode, i);
    }
    markUpdated();

    int increase = child.mIsLayoutOnly ? child.mTotalNativeChildren : 1;
@@ -159,7 +163,9 @@ public ReactShadowNode removeChildAt(int i) {
    ReactShadowNode removed = mChildren.remove(i);
    removed.mParent = null;

    mCSSNode.removeChildAt(i);
    if (!mCSSNode.isMeasureDefined()) {
      mCSSNode.removeChildAt(i);
    }
    markUpdated();

    int decrease = removed.mIsLayoutOnly ? removed.mTotalNativeChildren : 1;
@@ -191,7 +197,9 @@ public void removeAllChildren() {

    int decrease = 0;
    for (int i = getChildCount() - 1; i >= 0; i--) {
      mCSSNode.removeChildAt(i);
      if (!mCSSNode.isMeasureDefined()) {
        mCSSNode.removeChildAt(i);
      }
      ReactShadowNode toRemove = getChildAt(i);
      toRemove.mParent = null;
      decrease += toRemove.mIsLayoutOnly ? toRemove.mTotalNativeChildren : 1;
@@ -633,6 +641,12 @@ public void setShouldNotifyOnLayout(boolean shouldNotifyOnLayout) {
  }

  public void setMeasureFunction(CSSNodeAPI.MeasureFunction measureFunction) {
    if ((measureFunction == null ^ mCSSNode.isMeasureDefined()) &&
        getChildCount() != 0) {
      throw new RuntimeException(
        "Since a node with a measure function does not add any native CSSLayout children, it's " +
          "not safe to transition to/from having a measure function unless a node has no children");
    }
    mCSSNode.setMeasureFunction(measureFunction);
  }