Support for mapping the width and height values

[huftis]

Thank you for this extremely useful package!

I have a feature request – support for mapping the width and height values, not just setting them. This is needed when one uses geom_tile() instead of geom_rect() to draw the boxes that the geom_fit_text() text is supposed to be placed into. And geom_tile() is needed when one of the axis is discrete, i.e. a factor. Here’s a small reproducible example.

library(tidyverse)
library(ggfittext)
d = tibble(
  cat = factor(c("R1", "R2")),
  boxstart = c(3, 4),
  boxend = c(5, 10),
  boxwidth = boxend - boxstart,
  boxtext = c(strrep("R1 ", 150), strrep("R2 ", 150))
)

# Plotting boxes using geom_rect()
const_boxheight = .75
p_rect = ggplot(d, aes(
    x = (boxstart + boxend) / 2,
    y = cat,
    xmin = boxstart,
    xmax = boxend,
    ymin = as.numeric(cat) - const_boxheight / 2,
    ymax = as.numeric(cat) + const_boxheight / 2,
    label = boxtext)) +
  geom_rect() +
  geom_fit_text(reflow = TRUE, colour = "orange")
p_rect

This looks fine. But using as.numeric() on the cat factor inside aes() is an ugly hack, which causes problems later. A better solution is to use geom_tile():

# Plotting boxes using geom_tile()
d$boxheight = const_boxheight
p_tile = ggplot(d, aes(
    x = (boxstart + boxend) / 2,
    y = cat,
    width = boxwidth,
    height = boxheight,
    label = boxtext)) +
  geom_tile(height = const_boxheight) +
  geom_fit_text(reflow = TRUE, colour = "orange")
p_tile

The boxes are laid out the same, but the width and height aesthetics are not recognised by geom_fit_text(). Of course, I can set the width and height, but then it would be the same for both (all) boxes, so there would either be overflowing text or too much space inside the boxes.

Now for the reason I need to use geom_tile() instead of geom_rect(). The as.numeric() hack doesn’t work when one uses faceting with free scales and not all levels of the factor are present in all panels. Here’s a simple example:

p_rect + facet_wrap(~cat, scales = "free_y")

Note the wrong vertical placement of the box in panel R2 / the wrong y-axis labelling.

When one uses geom_tile() instead, there’s no problem, since the internals of ggplot2 handle the vertical placement and takes care of any missing levels:

# Correct placement and y axis
p_tile + facet_wrap(~cat, scales = "free_y")

But then geom_fit_text() doesn’t work properly, as it doesn’t recognise the width and height aesthestics.