ccontext:SetLineJoin(line_join)
line_join
parameter can be one of the following constants:
#CAIRO_LINE_JOIN_MITER#CAIRO_LINE_JOIN_ROUND#CAIRO_LINE_JOIN_BEVELAs with the other stroke parameters, the current line join style is examined by ccontext:Stroke() and ccontext:StrokeExtents(), but does not have any effect during path construction.
The default line join style is #CAIRO_LINE_JOIN_MITER.