Returns the node's preferred width for use in layout calculations. If the node is resizable, its parent should treat this value as the node's ideal width within its range. If the node is not resizable, just returns its layoutBounds width, which should be treated as the rigid width of the node.

Layout code which calls this method should first check the content-bias of the node. If the node has a vertical content-bias, then callers should pass in a height value that the preferred width should be based on. If the node has either a horizontal or null content-bias, then the caller should pass in -1.

Node subclasses with a vertical content-bias should honor the height parameter whether -1 or a positive value. All other subclasses may ignore the height parameter (which will likely be -1).

Parameters:

height the height that should be used if preferred width depends on it

Returns: the preferred width that the node should be resized to during layout The result will never be NaN, nor will it ever be negative.