applyPaintTransform method Null safety

  1. @override
void applyPaintTransform(
  1. covariant RenderObject child,
  2. Matrix4 transform
)
override

Applies the transform that would be applied when painting the given child to the given matrix.

Used by coordinate conversion functions to translate coordinates local to one render object into coordinates local to another render object.

Some RenderObjects will provide a zeroed out matrix in this method, indicating that the child should not paint anything or respond to hit tests currently. A parent may supply a non-zero matrix even though it does not paint its child currently, for example if the parent is a RenderOffstage with offstage set to true. In both of these cases, the parent must return false from paintsChild.

Implementation

@override
void applyPaintTransform(RenderObject child, Matrix4 transform) {
  assert(child != null);
  assert(child == this.child);
  final SliverPhysicalParentData childParentData = child.parentData! as SliverPhysicalParentData;
  childParentData.applyPaintTransform(transform);
}