Closed
Description
I think geom_label() could use an overhaul. It has two significant limitations:
- Labels can't be rotated (see e.g. Clarify geom_label documentation #2782 and example)
- Descent heights are ignored (see example)
library(ggplot2)
library(tibble)
data <- tibble(
text = c('abc', 'def', 'gjq'),
angle = c(0, 45, 90),
x = c(1, 2, 3)
)
ggplot(data, aes(x, label = text, angle = angle)) +
geom_label(aes(y = 1), label.padding = unit(0, "lines"), size = 10) +
geom_label(aes(y = 2), size = 10) + xlim(0.5, 3.5) + ylim(0.5, 2.5)
Created on 2018-07-28 by the reprex package (v0.2.0).
I have proof-of-concept code that addresses both issues:
library(gridtext)
library(grid)
library(tibble)
# example with rotated labels, descenders, and padding
label_data <- tibble(
label = c("Descenders: pgqjy", "This is a label\nwith two lines", "Hello!"),
x = unit(.4, "npc"),
y = unit(c(.9, .5, .3), "npc"),
box_hjust = 0,
box_vjust = 0.5,
hjust = 1,
vjust = 1,
color = "blue",
fill = "azure1",
fontsize = 10,
fontfamily = "Comic Sans MS",
angle = c(0, 45, -45),
padding = list(mar(5, 5, 3, 5)),
margin = list(mar(5, 5, 5, 5))
)
grid.newpage()
g <- labels_grob(label_data)
grid.draw(g)
# example with no padding and label frames all made the same size
label_data <- tibble(
label = c("These", "are", "multiple", "labels", "gqpj"),
x = unit(c(.1, .3, .5, .7, .9), "npc"),
y = unit(0.5, "npc"),
box_hjust = 0.5,
box_vjust = 1,
hjust = 0.5,
vjust = 1,
color = "black",
angle = 0,
fontsize = 10,
margin = list(mar(5, 5, 5, 5))
)
grid.newpage()
g <- labels_grob(label_data, align_frames = TRUE)
grid.draw(g)
Created on 2018-07-28 by the reprex package (v0.2.0).
Fundamentally, the problem is caused by very limited text handling capabilities directly in grid, so it's a fair amount of work to write code that does these things. This raises the issue of whether we should address these problems one-by-one in ggplot2 where they arise or rather write a better text-rendering library and then use that from ggplot2.