intrinsicPlaceable

This node at width by height as a placeable a container reads alignment lines from while it answers an intrinsic question, or null where it has none. A Row or Column asking for its own size reads a child's baseline or alignBy line from it, so the line holds where this node moves it.

The default runs this node's measure under exactly width by height against a stand-in for the child, which measurable's own intrinsicPlaceable answers, and reads a line this node does not name by running its placement without placing anything. The real child is never measured. Override it with the four intrinsic hooks, returning measurable.intrinsicPlaceable(width, height), where this node's measure must not run for a size query; the line then stays where the child puts it.