string2path

The string2path R package converts a text to paths of the outlines of each glyph, based on a font data. Under the hood, this package is powered by extendr framework to use these two Rust crates:

ttf-parser for parsing font data. TrueType font (.ttf) and OpenType font (.otf) are supported.
lyon for tessellation of polygons and flattening the curves.

Installation

If you are using Windows, you are lucky. Because this repository provides pre-compiled binary for you, you don’t need to install Rust toolchain.

Otherwise, you need to have Rust toolchain installed before trying to install this package. See https://www.rust-lang.org/tools/install for the installation instructions.

# install.packages("devtools")
devtools::install_github("yutannihilation/string2path")

Example

`string2path()`

library(string2path)
library(ggplot2)

# This TTF file is downloaded from https://ipafont.ipa.go.jp/.
# For installed fonts, you can use systemfonts::system_fonts()
# to lookup the path.
d <- string2path("カラテが\n高まる。", "./fonts/ipaexg.ttf")

d <- tibble::rowid_to_column(d)

ggplot(d) +
  geom_path(aes(x, y, group = path_id, colour = factor(glyph_id)), size = 1.5) +
  theme_minimal() +
  coord_equal() +
  theme(legend.position = "top") +
  scale_colour_viridis_d(option = "H")

library(gganimate)
d <- string2path("蹴", "./fonts/ipaexg.ttf")
d <- tibble::rowid_to_column(d)

ggplot(d) +
  geom_path(aes(x, y, group = path_id), size = 2, colour = "purple2", lineend = "round") +
  theme_minimal() +
  coord_equal() +
  transition_reveal(rowid)

`string2fill()`

# Sorry for my laziness, please replace the font path to the appropriate location in your system...
ttf_file <- "./fonts/iosevka-heavyitalic.ttf"

d <- string2fill("abc", ttf_file)

ggplot(d) +
  geom_polygon(aes(x, y, group = triangle_id, fill = factor(triangle_id %% 7)), colour = "grey", size = 0.1) +
  theme_minimal() +
  coord_equal() +
  theme(legend.position = "none") +
  scale_fill_viridis_d(option = "H")

`string2stroke()`

for (w in 1:9 * 0.01) {
  d <- string2stroke("abc", ttf_file, line_width = w)
  
  p <- ggplot(d) +
    geom_polygon(aes(x, y, group = triangle_id, fill = factor(triangle_id %% 2)), colour = "grey", size = 0.1) +
    theme_minimal() +
    coord_equal() +
    theme(legend.position = "none") +
    scale_fill_manual(values = c("purple", "pink"))
  plot(p)
}

`tolerance`

tolerance controls resolution of the tessellation. You can reduce tolerance to get higher resolutions.

for (tolerance in c(1e-1, 1e-2, 1e-3, 1e-4, 1e-5, 1e-6, 1e-7)) {
  d <- string2fill("abc", ttf_file, tolerance = tolerance)
  
  p <- ggplot(d) +
    geom_polygon(aes(x, y, group = triangle_id), fill = "transparent", colour = "black", size = 0.5) +
    theme_minimal() +
    coord_equal() +
    ggtitle(paste0("tolerance: ", tolerance))
  plot(p)
}

Note that tolerance parameter behaves a bit differently on string2fill() and string2stroke(). But, in either case, 1e-5 ~ 1e-6 should be enough.

for (tolerance in c(1e-1, 1e-2, 1e-3, 1e-4, 1e-5, 1e-6, 1e-7)) {
  d <- string2path("abc", ttf_file, tolerance = tolerance)
  
  p <- ggplot(d) +
    geom_path(aes(x, y, group = path_id), colour = "black", size = 0.5) +
    geom_point(aes(x, y, group = path_id), colour = "black", size = 1.5) +
    theme_minimal() +
    coord_equal() +
    ggtitle(paste0("tolerance: ", tolerance))
  plot(p)
}

chaoshengt / string2path