Note 8 - Stock-based Compensation - Summary of Stock Option Activity (Details) - $ / shares		12 Months Ended
		Apr. 29, 2017	Apr. 30, 2016	May 02, 2015	Apr. 29, 2017
Options outstanding, beginning of year (in shares)		418,895
Options outstanding, beginning of year (in dollars per share)	[1]	$ 12.44
Options exercisable, end of year (in dollars per share)	[1]	$ 9.64
Granted (in shares)		0	3,500	276,800
Granted (in dollars per share)	[1]
Exercised (in shares)		(27,400)
Exercised (in dollars per share)	[1]	$ 13.31
Cancelled (in shares)		(7,900)
Cancelled (in dollars per share)	[1]	$ 16.01
Options outstanding, end of year (in shares)		418,895	418,895		383,595
Options outstanding, end of year (in dollars per share)	[1]	$ 12.44	$ 12.44		$ 11.47
Options exercisable, end of year (in shares)		215,803

[1] Weighted average exercise price.