naratext

{naratext} renders text to nativeRaster images in memory.

This relies of glyph rendering features in the {grid} package.

What’s in the box

• nr_text() to render text to in-memory nativeRaster images

ToDo

• Reconcile the different font handling mechanisms between textshaping and grDevices::glyphFont()
• Tightly crop the returned nativeRaster
• Return baseline offset from bottom of raster so that other compositors (e.g. {nara}) now how to place text correctly
• Move to textshaping’s C interface?

Installation from GitHub

Also requires installation of:

• CRAN packages:
  • {textshaping} to calculate positions of rendered glyph
  • {ragg} as a graphics device that allows direct capture of the output to an image in memory (and supports glyph rendering)
  • ‘{bittermelon}’ for handling bitmap fonts
• GitHub packages
  • {nara} for nativeRaster utilities

install.packages('remotes')
remotes::install_github('coolbutuseless/nara')
install.packages(c('textshaping', 'ragg'))

remotes::install_github('coolbutuseless/naratext')

Example - full font rendering

library(grid)
library(nara)
library(naratext)

strings <- c('Ping', ' #RStats')
font_files <- c(
  system.file("fonts", "Montserrat", "static", "Montserrat-BoldItalic.ttf", package="grDevices"),
  system.file("fonts", "Montserrat", "static", "Montserrat-Medium.ttf"    , package="grDevices")
)
color <- c('red', 'blue')
txt <- nr_text(strings, font_files = font_files, color = color, scale = 10, background = 'lightblue')
dim(txt)

#> [1] 147 801

class(txt)

#> [1] "nativeRaster"

grid.raster(txt, interpolate = FALSE)

Example - Bitmap font rendering

library(grid)
library(nara)
library(naratext)

font_file <- system.file("fonts/spleen/spleen-8x16.hex.gz", package = "bittermelon") 
font <- bittermelon::read_hex(font_file)
txt <- nr_text_bitmap("Ping #RStats", font = font, fill = 'lightpink')
dim(txt)

#> [1] 16 96

grid::grid.newpage(); grid::grid.raster(txt, interpolate = FALSE)

font <- bittermelon::read_monobit("~/projectsdata/spleen/spleen-32x64.bdf", quietly = TRUE)
txt <- nr_text_bitmap("Ping #RStats", font = font, fill = 'lightgreen')
dim(txt)

#> [1]  64 384

grid::grid.newpage(); grid::grid.raster(txt, interpolate = FALSE)