function icon (params) return function (ctx, width, height, fg)
local wh = math.min (width, height) * .5
+ ctx:translate (math.floor (width * .5 - wh), math.floor (height * .5 - wh))
ctx:set_line_width (1)
ctx:rectangle (wh * .25, wh * .75, wh * 1.5 , .5 * wh)