Text size switch

[teunbrand]

This PR aims to fix #3799.

Briefly, it adds a size_unit parameter to geom_text/label() that allows one to use "pt" to have the size interpreted as points.

Example:

devtools::load_all("~/packages/ggplot2/")
#> ℹ Loading ggplot2

ggplot() +
  annotate("text",  x = -1, y = 0, label = "Abc", size = 10, size_unit = "mm") +
  annotate("text",  x = 1,  y = 0, label = "Def", size = 10, size_unit = "pt") +
  annotate("label", x = -1, y = 1, label = "Ghi", size = 10, size_unit = "mm") +
  annotate("label", x = 1,  y = 1, label = "Jkl", size = 10, size_unit = "pt") +
  xlim(-2, 2) + ylim(-1, 2)

^{Created on 2023-04-05 with reprex v2.0.2}

[thomasp85]

As garish as it is, arguments in ggplot2 are "." separated instead of "_" separated

[teunbrand]

Oops yes, fixed it

[thomasp85]

I'm trying to figure out if mm and pt are too limiting since grid supports a multitude of units... maybe it is not so big a deal

[teunbrand]

I can see some utility for absolute units, but I'd have no idea what to expect for 1null or 1npc text sizes.

[thomasp85]

yeah, I'm only thinking of adding the other absolute sizes, not the relative ones

[teunbrand]

I've added centimetres, inches and picas in addition to the points and millimetres. Other absolute units are 'bigpts', 'dida', 'cicero' and 'scaledpts', but I've never seen anybody use these in the wild, so I didn't add them. Let me know if you'd like to add these.

[thomasp85]

LGTM