Fill closed arrows in element_line()

[yutannihilation]

Fixes #2922

Currently, element_grob.element_line() doesn't specify fill in gpar(). This PR specifies it to fill arrows.

library(ggplot2)

arrow = arrow(angle=10, type = "closed")
ggplot(iris, aes(x=Sepal.Length, y=Sepal.Width, color=Species)) +
  geom_point() +
  theme(axis.line = element_line(arrow=arrow)) +
  annotate("segment", x = 3, xend = min(iris$Sepal.Length), y = 4, yend = 3, arrow=arrow)

^{Created on 2018-10-02 by the reprex package (v0.2.1)}

Note that, for consistency with geom_segment() and geom_curve(), element_line() might needs arrow.fill parameter, but it seems a bit harder to introduce a new parameter to theme. So, users need to rely on this workaround if they want different colours.

[clauswilke]

Could you use tidyverse-style formatting? The same applies for the other change.

gp <- gpar(
  lwd = len0_null(size * .pt), col = colour, lty = linetype,
  lineend = lineend, fill = colour
)

[clauswilke]

And maybe reorder the parameters so col and fill go together and then lwd, lty, and lineend.

[yutannihilation]

Sure.

[clauswilke]

Thanks! This will have to wait until after the 3.1.0 release.

[yutannihilation]

Thanks for reviewing! I'll wait (and will add a NEWS bullet after the release).

[yutannihilation]

@clauswilke Could you review this again when you have time?

[yutannihilation]

Thanks!

[lock]

This old issue has been automatically locked. If you believe you have found a related problem, please file a new issue (with reprex) and link to this issue. https://reprex.tidyverse.org/