Title: Bindings to the 'HarfBuzz' and 'Fribidi' Libraries for Text Shaping
Version: 1.0.0
Description: Provides access to the text shaping functionality in the 'HarfBuzz' library and the bidirectional algorithm in the 'Fribidi' library. 'textshaping' is a low-level utility package mainly for graphic devices that expands upon the font tool-set provided by the 'systemfonts' package.
License: MIT + file LICENSE
URL: https://github.com/r-lib/textshaping
BugReports: https://github.com/r-lib/textshaping/issues
Depends: R (≥ 3.2.0)
Imports: lifecycle, stats, stringi, systemfonts (≥ 1.1.0), utils
Suggests: covr, grDevices, grid, knitr, rmarkdown, testthat (≥ 3.0.0)
LinkingTo: cpp11 (≥ 0.2.1), systemfonts (≥ 1.0.0)
VignetteBuilder: knitr
Encoding: UTF-8
RoxygenNote: 7.3.2
SystemRequirements: freetype2, harfbuzz, fribidi
Config/build/compilation-database: true
Config/testthat/edition: 3
NeedsCompilation: yes
Packaged: 2025-01-20 08:47:24 UTC; thomas
Author: Thomas Lin Pedersen ORCID iD [cre, aut], Posit, PBC [cph, fnd]
Maintainer: Thomas Lin Pedersen <thomas.pedersen@posit.co>
Repository: CRAN
Date/Publication: 2025-01-20 11:00:01 UTC

textshaping: Bindings to the 'HarfBuzz' and 'Fribidi' Libraries for Text Shaping

Description

Provides access to the text shaping functionality in the 'HarfBuzz' library and the bidirectional algorithm in the 'Fribidi' library. 'textshaping' is a low-level utility package mainly for graphic devices that expands upon the font tool-set provided by the 'systemfonts' package.

Author(s)

Maintainer: Thomas Lin Pedersen thomas.pedersen@posit.co (ORCID)

Other contributors:

See Also

Useful links:

Get available OpenType features in a font

Description

This is a simply functions that returns the available OpenType feature tags for one or more fonts. See font_feature() for more information on how to use the different feature with a font.

Usage

get_font_features(
  family = "",
  italic = FALSE,
  bold = FALSE,
  path = NULL,
  index = 0
)

Arguments

family

The name of the font families to match

italic

logical indicating the font slant

bold

logical indicating whether the font weight

path, index

path an index of a font file to circumvent lookup based on family and style

Value

A list with an element for each of the input fonts containing the supported feature tags for that font.

Examples

# Select a random font on the system
sys_fonts <- systemfonts::system_fonts()
random_font <- sys_fonts$family[sample(nrow(sys_fonts), 1)]

# Get the features
get_font_features(random_font)

Get gibberish text in various scripts

Description

Textshaping exists partly to allow all the various scripts that exists in the world to be used in R graphics. This function returns gibberish filler text (lorem ipsum text) in various scripts for testing purpose. Some of these are transliterations of the original lorem ipsum text while others are based an a distribution model.

Usage

lorem_text(
  script = c("latin", "chinese", "arabic", "devanagari", "cyrillic", "kana", "hangul",
    "greek", "hebrew", "armenian", "georgian"),
  n = 1
)

lorem_bidi(
  ltr = c("latin", "chinese", "devanagari", "cyrillic", "kana", "hangul", "greek",
    "armenian", "georgian"),
  rtl = c("arabic", "hebrew"),
  ltr_prop = 0.9,
  n = 1
)

Arguments

script

A string giving the script to fetch gibberish for

n

The number of paragraphs to fetch. Each paragraph will be its own element in the returned character vector.

ltr, rtl

scripts to use for left-to-right and right-to-left text

ltr_prop

The approximate proportion of left-to-right text in the final string

Value

a charactor vector of length n

References

https://generator.lorem-ipsum.info

Examples

# Defaults to standard lorem ipsum
lorem_text()

# Get two paragraphs of hangul (Korean)
lorem_text("hangul", 2)

# Get gibberish bi-directional text
lorem_bidi()

Preview shaped text and the metrics for the text box

Description

This function allows you to preview the layout that shape_text() calculates. It is purely meant as a sanity check to make sure that the values calculated are sensible and shouldn't be used as a plotting function for rendering text on its own.

Usage

plot_shape(shape, id = 1)

Arguments

shape

The output of a call to shape_text()

id

The index of the text run to show in case shape contains multiples

Value

This function is called for its side effects

Examples

arab_text <- lorem_text("arabic", 2)
shape <- shape_text(
  arab_text,
  max_width = 5,
  indent = 0.2
)

try(
 plot_shape(shape)
)

Calculate glyph positions for strings

Description

Performs advanced text shaping of strings including font fallbacks, bidirectional script support, word wrapping and various character and paragraph level formatting settings.

Usage

shape_text(
  strings,
  id = NULL,
  family = "",
  italic = FALSE,
  weight = "normal",
  width = "undefined",
  features = font_feature(),
  size = 12,
  res = 72,
  lineheight = 1,
  align = "auto",
  hjust = 0,
  vjust = 0,
  max_width = NA,
  tracking = 0,
  indent = 0,
  hanging = 0,
  space_before = 0,
  space_after = 0,
  direction = "auto",
  path = NULL,
  index = 0,
  bold = deprecated()
)

Arguments

strings

A character vector of strings to shape

id

A vector grouping the strings together. If strings share an id the shaping will continue between strings

family

The name of the font families to match

italic

logical indicating the font slant

weight

The weight to query for, either in numbers (0, 100, 200, 300, 400, 500, 600, 700, 800, or 900) or strings ("undefined", "thin", "ultralight", "light", "normal", "medium", "semibold", "bold", "ultrabold", or "heavy"). NA will be interpreted as "undefined"/0

width

The width to query for either in numbers (0, 1, 2, 3, 4, 5, 6, 7, 8, or 9) or strings ("undefined", "ultracondensed", "extracondensed", "condensed", "semicondensed", "normal", "semiexpanded", "expanded", "extraexpanded", or "ultraexpanded"). NA will be interpreted as "undefined"/0

features

A systemfonts::font_feature() object or a list of them, giving the OpenType font features to set

size

The size in points to use for the font

res

The resolution to use when doing the shaping. Should optimally match the resolution used when rendering the glyphs.

lineheight

A multiplier for the lineheight

align

Within text box alignment, either 'auto', 'left', 'center', 'right', 'justified', 'justified-left', 'justified-right', 'justified-center', or 'distributed'. 'auto' and 'justified' will chose the left or right version depending on the direction of the text.

hjust, vjust

The justification of the textbox surrounding the text

max_width

The requested with of the string in inches. Setting this to something other than NA will turn on word wrapping.

tracking

Tracking of the glyphs (space adjustment) measured in 1/1000 em.

indent

The indent of the first line in a paragraph measured in inches.

hanging

The indent of the remaining lines in a paragraph measured in inches.

space_before, space_after

The spacing above and below a paragraph, measured in points

direction

The overall directional flow of the text. The default ("auto") will guess the direction based on the content of the string. Use "ltr" (left-to-right) and "rtl" (right-to-left) to turn detection of and set it manually.

path, index

path an index of a font file to circumvent lookup based on family and style

bold

logical indicating whether the font weight

Value

A list with two element: shape contains the position of each glyph, relative to the origin in the enclosing textbox. metrics contain metrics about the full strings.

shape is a data.frame with the following columns:

glyph

The placement of the the first character contributing to the glyph within the string

index

The index of the glyph in the font file

metric_id

The index of the string the glyph is part of (referencing a row in the metrics data.frame)

string_id

The index of the string the glyph came from (referencing an element in the strings input)

x_offset

The x offset in pixels from the origin of the textbox

y_offset

The y offset in pixels from the origin of the textbox

font_path

The path to the font file used during shaping of the glyph

font_index

The index of the font used to shape the glyph in the font file

font_size

The size of the font used during shaping

advance

The advancement amount to the next glyph

ascender

The ascend of the font used for the glyph. This does not measure the actual glyph

descender

The descend of the font used for the glyph. This does not measure the actual glyph

metrics is a data.frame with the following columns:

string

The text the string consist of

width

The width of the string

height

The height of the string

left_bearing

The distance from the left edge of the textbox and the leftmost glyph

right_bearing

The distance from the right edge of the textbox and the rightmost glyph

top_bearing

The distance from the top edge of the textbox and the topmost glyph

bottom_bearing

The distance from the bottom edge of the textbox and the bottommost glyph

left_border

The position of the leftmost edge of the textbox related to the origin

top_border

The position of the topmost edge of the textbox related to the origin

pen_x

The horizontal position of the next glyph after the string

pen_y

The vertical position of the next glyph after the string

ltr

The global direction of the string. If TRUE then it is left-to-right, otherwise it is right-to-left

Examples

string <- "This is a long string\nLook; It spans multiple lines\nand all"

# Shape with default settings
shape_text(string)

# Mix styles within the same string
string <- c(
  "This string will have\na ",
  "very large",
  " text style\nin the middle"
)

shape_text(string, id = c(1, 1, 1), size = c(12, 24, 12))

Calculate the width of a string, ignoring new-lines

Description

This is a very simple alternative to systemfonts::shape_string() that simply calculates the width of strings without taking any newline into account. As such it is suitable to calculate the width of words or lines that has already been splitted by ⁠\n⁠. Input is recycled to the length of strings.

Usage

text_width(
  strings,
  family = "",
  italic = FALSE,
  weight = "normal",
  width = "undefined",
  features = font_feature(),
  size = 12,
  res = 72,
  include_bearing = TRUE,
  path = NULL,
  index = 0,
  bold = deprecated()
)

Arguments

strings

A character vector of strings

family

The name of the font families to match

italic

logical indicating the font slant

weight

The weight to query for, either in numbers (0, 100, 200, 300, 400, 500, 600, 700, 800, or 900) or strings ("undefined", "thin", "ultralight", "light", "normal", "medium", "semibold", "bold", "ultrabold", or "heavy"). NA will be interpreted as "undefined"/0

width

The width to query for either in numbers (0, 1, 2, 3, 4, 5, 6, 7, 8, or 9) or strings ("undefined", "ultracondensed", "extracondensed", "condensed", "semicondensed", "normal", "semiexpanded", "expanded", "extraexpanded", or "ultraexpanded"). NA will be interpreted as "undefined"/0

features

A systemfonts::font_feature() object or a list of them, giving the OpenType font features to set

size

The size in points to use for the font

res

The resolution to use when doing the shaping. Should optimally match the resolution used when rendering the glyphs.

include_bearing

Logical, should left and right bearing be included in the string width?

path, index

path an index of a font file to circumvent lookup based on family and style

bold

logical indicating whether the font weight

Value

A numeric vector giving the width of the strings in pixels. Use the provided res value to convert it into absolute values.

Examples

strings <- c('A short string', 'A very very looong string')
text_width(strings)