Function painter:setdash
changes the
style of the current pen.
When this function is called without argument,
or when argument sizes
is nil
,
this function sets the current pen style
to "SolidLine"
.
Otherwise argument sizes
can be a single number or a table containing a list of numbers.
The number or the list of numbers represent the length of
successive dashes and blanks
along the drawn curve, expressed in units of the line width.
When the size of the sequence is odd, the last blank
is assumed to have the same size as the last dash.
The optional argument offset
is a length
representing the starting position of the dash sequence.