README.Rmd

---
output: github_document
---

<!-- README.md is generated from README.Rmd. Please edit that file -->

```{r, include = FALSE}
knitr::opts_chunk$set(
  collapse = TRUE,
  comment = "#>",
  fig.path = "man/figures/README-",
  out.width = "100%",
  dev = "ragg_png",
  dpi = 300
)
```

# marquee <img src="man/figures/logo.png" align="right" height="138" alt="" />

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<!-- badges: end -->

marquee is a markdown parser and renderer for the R graphics engine. It can be
used to render rich text formatted as markdown (CommonMark) inside R graphics
such as ggplot2 or other graphics built on grid.

## Installation

``` r
# You can install marquee from CRAN
install.packages("marquee")

# Or get the development version from Github using pak
pak::pak("r-lib/marquee")
```

## Examples

The main function of the package is `marquee_grob()` which creates a grob based
on markdown text and a style that can be rendered with grid:

```{r, fig.asp=2}
# Let's render this readme
readme <- paste(readLines("README.Rmd")[-seq_len(17)], collapse = "\n")

library(marquee)
library(grid)

fancy_style <- classic_style(
  body_font = "baskerville",
  header_font = "marker felt",
  code_font = "fira code"
) |>
  modify_style("cb", background = linearGradient(
    colours = c("lightblue", "white"),
    x1 = 0, y1 = 1, x2 = 0, y2 = 0
  ))
grob <- marquee_grob(readme, style = fancy_style)
grid.draw(grob)
```

(*The above is an image – go ahead and check*)

## Prior art

I would be remiss to not mention [gridtext](https://github.com/wilkelab/gridtext)
and [ggtext](https://github.com/wilkelab/ggtext), both by Claus Wilke. These
packages aim to solve much the same problem as marquee, but work in a different way
and don't have the same powerful textshaping backend as marquee. Most notably from
a user perspective is perhaps that gridtext understands HTML to some degree,
whereas marquee is oblivious to both HTML and CSS. Instead, it supports the [full
CommonMark spec](https://spec.commonmark.org/) with the plan to add support for
custom span elements as well.