firstValidRenderObject method

RenderObject? firstValidRenderObject(RenderObject renderObject)

Returns the first render object that complies with the following:

• Its parent data is CellParentData
• Its parent is a RenderSliverLayoutGrid
• If is an renderObject with less depth that the renderObject it can only have a RenderRepaintBoundary or RenderIndexedSemantics in between or a RenderRepaintBoundary and RenderIndexedSemantics in that order. These render objects could be added by the SliverLayoutGrid for accesibility and performance Notice this methid can return if it can't finde a render object that complies with these conditions

Implementation

RenderObject? firstValidRenderObject(RenderObject renderObject) {
  RenderObject targetObject = renderObject;

  bool isValidRenderObject(RenderObject renderObject) {
    return renderObject.parent is RenderSliverLayoutGrid &&
        renderObject.parentData is CellParentData;
  }

  // First check, true if there is no `RenderRepaintBoundary` and `RenderIndexedSemantics`
  // and renderObject is valid
  if (isValidRenderObject(targetObject)) {
    return targetObject;
  } else {
    targetObject = renderObject.parent as RenderObject;
  }

  // Second check, true if there is a `RenderRepaintBoundary` and its
  // parent is valid
  if (targetObject is RenderRepaintBoundary &&
      isValidRenderObject(targetObject)) {
    return targetObject;
  } else if (targetObject is! RenderIndexedSemantics) {
    targetObject = targetObject.parent as RenderObject;
  }

  // Third check, true if there is a `RenderIndexedSemantics` and its
  // parent is valid
  // It can be nested [RenderRepaintBoundary/RenderIndexedSemantics/TargetRenderObject]
  if (targetObject is RenderIndexedSemantics &&
      isValidRenderObject(targetObject)) {
    return targetObject;
  }

  return null;
}