ink: Make justifications relative to the ink extent of the text

In marquee: Markdown Parser and Renderer for R Graphics

Make justifications relative to the ink extent of the text

Description

Marquee measures the extent of the box around text with bearings, that is, the height of the string "mean" is the same as the height of the string "median", despite the latter having a "d" extending upwards. This makes it easier to justification text irrespective of the glyphs used to render it. However, if you want alignment to be relative to the "tight" box around the text (the bounding box of where ink has been placed), you can use the ink() function to inform marquee of your intend. In general the effect is often minuscule for horizontal justifications but can have a big effect on vertical justification depending on the presence of ascenders and descenders in the rendered glyphs.

Usage

ink(x = numeric(), use_ink = TRUE)

Arguments

x	A string giving a valid justification or a numeric between 0 and 1
use_ink	Should the values be relative to the ink extend. Will be recycled to the length of x

Value

A marquee_ink vector

Examples

# Plot to illustrate the difference in vertical alignment
library(grid)
grid.newpage()
grid.draw(
  marquee_grob(
    c("### Textbox justification (default)",
      "### Bounding box justification (using `ink()`)"),
    x = 0.5,
    y = c(0.95, 0.45),
    hjust = 0.5,
    width = NA
  )
)

# Standard justification
grid.draw(
  marquee_grob(
    "mean",
    x = 0.5,
    y = 0.75,
    hjust = "right",
    vjust = 0.5,
    width = NA
  )
)
grid.draw(
  marquee_grob(
    "median",
    x = 0.5,
    y = 0.75,
    hjust = "left",
    vjust = 0.5,
    width = NA
  )
)

# Justification using `ink()`
grid.draw(
  marquee_grob(
    "mean",
    x = 0.5,
    y = 0.25,
    hjust = "right",
    vjust = ink(0.5),
    width = NA
  )
)
grid.draw(
  marquee_grob(
    "median",
    x = 0.5,
    y = 0.25,
    hjust = "left",
    vjust = ink(0.5),
    width = NA
  )
)

marquee documentation built on April 3, 2025, 6:11 p.m.