choose_text_color: Get contrasting text colors for fills

In tntp/tntpr: Data Analysis Tools Customized for TNTP

Get contrasting text colors for fills

Description

Get appropriate high-contrast text colors for a vector of background colors. This function uses the W3C contrast ratio guidance (through the colorspace::contrast_ratio() function) to determine the contrast, and will raise an error if no high-enough contrast colors can be found.

Usage

choose_text_color(bg_color, text_colors = c("black", "white"), min_ratio = 4.5)

Arguments

bg_color	a vector of colors to be used as background colors
text_colors	a vector of options for text colors. Defaults to "black" and "white"
min_ratio	Minimum contrast ratio. By default this is set to 4.5, the WCAG recommendation for regular text.

Details

By default, this function uses black and white as the text color options, however custom text color options can be set with the text_colors argument.

Value

a vector of text colors the same length as bg_color.

Examples

library(ggplot2)

fills <- tntp_palette("top2_5")

diamonds |>
  dplyr::summarize(m = mean(price), .by = cut) |>
  ggplot(aes(cut, m, fill = cut)) +
  geom_col() +
  geom_text(aes(label = scales::dollar(m), color = cut), vjust = 1.5) +
  scale_fill_manual(values = fills, guide = "none") +
  scale_color_manual(values = choose_text_color(fills), guide = "none") +
  tntp_style(family = "sans")

tntp/tntpr documentation built on Dec. 1, 2024, 10:25 a.m.