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Font Management

Source: vignettes/fonts.Rmd
fonts.Rmd

Overview

cardargus uses Jost as its default font, a modern sans-serif from Google Fonts. This article explains how to configure and manage fonts for best results.

Quick Setup 

library(cardargus)

# Automatically setup fonts (recommended)
setup_fonts()

This function:

  1. Registers Jost and Montserrat from Google Fonts
  2. Enables showtext auto mode
  3. Prepares the system for font rendering

Check Availability 

# Check if a font is available
font_available("Jost")
font_available("Arial")

# List cached fonts
list_fonts()

Register Google Fonts 

# Register a specific Google Font
register_google_font("Roboto")
register_google_font("Open Sans")
register_google_font("Lato")

Install Fonts Locally

For offline use or better performance, download fonts to your local cache:

# Download and cache fonts
install_fonts()

# Install specific fonts
install_fonts(fonts = c("Jost", "Montserrat", "Roboto"))

# Check cache location
font_cache_dir()

Using Custom Fonts 

# Use a different font in cards
card <- svg_card(
  title = "MY CARD",
  font = "Montserrat",  # Use Montserrat instead of Jost
  ...
)

CSS for SVG

cardargus embeds fonts via Google Fonts CSS in SVGs:

# Generate CSS for a font
css <- get_font_css("Jost")
cat(css)
# @import url("https://fonts.googleapis.com/css2?family=Jost:wght@400;500;600;700&display=swap");

# Multiple weights
css <- get_font_css("Montserrat", weights = c(400, 700))

Font Cache

cardargus caches downloaded fonts in a user directory:

# Get cache directory
font_cache_dir()
#> "/home/user/.cache/cardargus"

# List cached fonts
list_fonts()

Access Package Resources 

# SVGs directory (bundled logos)
svgs_dir()

# Path to a specific SVG
get_svg_path("morar_bem.svg")

# List available SVGs
list_bundled_svgs()

Troubleshooting

Font not rendering correctly

  1. Run setup_fonts() before creating cards
  2. Check if font is available: font_available("Jost")
  3. Install required packages:
install.packages(c("showtext", "sysfonts", "systemfonts"))

PNG export with rsvg

For correct font rendering in PNG exports with rsvg:

# Setup fonts first
setup_fonts()

# Download fonts for embedding
install_fonts()

# Create and export
card <- svg_card(...)
svg_to_png(card, "card.png", dpi = 300)

For perfect font rendering, use Chrome-based conversion:

# Ensure Chrome is available
ensure_chrome(download = TRUE)

# Create and export
card <- svg_card(...)
svg_to_png_chrome(card, "card.png", dpi = 300)

Chrome handles Google Fonts automatically via @import, so no local font installation is needed.

Fonts on servers

On servers without GUI:

# Option 1: Download fonts locally
install_fonts()

# Update font cache (Linux)
system("fc-cache -fv")

# Option 2: Use Chrome rendering (recommended)
ensure_chrome(download = TRUE)
svg_to_png_chrome(card, "card.png")
Font Type Description
Jost Sans-serif Default, modern
Montserrat Sans-serif Elegant alternative
Roboto Sans-serif Readable, Google Material
Open Sans Sans-serif Neutral, versatile
Lato Sans-serif Friendly, rounded

Dependencies

For full font functionality:

install.packages(c(
  "showtext",      # Font rendering
  "sysfonts",      # Font management
  "systemfonts",   # System font detection
  "gdtools"        # Text metrics
))

For Chrome-based rendering (recommended):

install.packages("chromote")