Create ggproto object

Geom

# Construct new_Geom class inheired from Geom class
new_Geom <- ggproto("new_Geom", Geom,
                      required_aes = c("x", "y"),
                      defaut_aes = aes(fill="yello"),
                      draw_key_key = draw_key_polygon,
                      draw_group = function(data, panel_scales, coord){
                      
                      coords <- coord$transform(data, panel_scales)
                      
                      grid::polygonGrob(
                            x = coords_df$x,
                            y = coords_df$y,
                            gp = grid::gpar(col = coords_df$colour,
                                            fill = coords_df$fill,
                                            alpha = coords_df$alpha)
                                        )
                      }

ggproto demo code.txt

# create ggproto object
# 會發現語法承襲自proto的系統，不需要像是RC system的field等
new_ggproto_object <- ggproto("Class_name",
                               parent_ggproto_class,
                               x = 0
                               f1_method = function(self,n){
                                 self$x <- self$x + n
                                 self$x
                               }