maskGeometryOf function

MaskGeometry? maskGeometryOf(RenderObject? renderObject)

Same as maskGeometryFromGlobalKey for an already resolved render object.

Implementation

MaskGeometry? maskGeometryOf(RenderObject? renderObject) {
  if (renderObject == null || !renderObject.attached) {
    return null;
  }
  if (renderObject is RenderBox && !renderObject.hasSize) {
    return null;
  }

  final Rect bounds = MatrixUtils.transformRect(
    renderObject.getTransformTo(null),
    renderObject.paintBounds,
  );

  Rect clip = Rect.largest;
  RenderObject child = renderObject;
  while (true) {
    // Not typed on purpose: `parent` is AbstractNode? on older Flutter and
    // RenderObject? on newer ones.
    final parent = child.parent;
    if (parent is! RenderObject) {
      // `child` is the root render object; nothing paints outside of it.
      // RenderView.paintBounds is in physical pixels, hence `size`.
      final Rect rootBounds = child is RenderView
          ? Offset.zero & child.size
          : child.paintBounds;
      clip = clip.intersect(MatrixUtils.transformRect(
        child.getTransformTo(null),
        rootBounds,
      ));
      break;
    }

    if (parent is RenderOffstage && parent.offstage) {
      return null;
    }

    final Rect? localClip = parent.describeApproximatePaintClip(child);
    if (localClip != null) {
      clip = clip.intersect(MatrixUtils.transformRect(
        parent.getTransformTo(null),
        localClip,
      ));
    }
    child = parent;
  }

  return MaskGeometry(bounds, clip);
}