cairoStroke. A dash pattern
is specified by dashes, a list of positive values. Each value
provides the length of alternate "on" and "off" portions of the
stroke. The offset specifies an offset into the pattern at which
the stroke begins.cairoSetDash(cr, dashes, offset)CAIRO_LINE_CAP_ROUND or CAIRO_LINE_CAP_SQUARE in order
to distributed dots or squares along a path.
Note: The length values are in user-space units as evaluated at the
time of stroking. This is not necessarily the same as the user
space at the time of cairoSetDash.
If num.dashes is 0 dashing is disabled.
If num.dashes is 1 a symmetric pattern is assumed with alternating
on and off portions of the size specified by the single value in
dashes.
If any value in dashes is negative, or if all values are 0, then
cr will be put into an error state with a status of
#CAIRO_STATUS_INVALID_DASH.