Convert PNG to HTML in Rmarkdown

paint.Rmd

# PNG to HTML

Code adapted from [@gdagstn](https://gist.github.com/gdagstn/1917e0e6f7dc91a8dde7cb789326c3bb).

```{r, echo=FALSE, comment="", results="asis"}
old.hooks <- fansi::set_knit_hooks(knitr::knit_hooks)
```

```{r echo=FALSE}
library(crayon)
library(readbitmap)
options(crayon.enabled=TRUE)

# example file
# download.file('http://pixeljoint.com/files/icons/full/32x32gameboypaletteportrait16.01.06.png', destfile = "./logo.png", method = "wget", extra = "-r -p --random-wait")
file <- "~/Downloads/32x32gameboypaletteportrait16.01.06.png"

setClass("crayonmap", representation(crayons = "character", row.num = "numeric", col.num = "numeric"))


#' Create crayonmap object
#' @param file BMP, TIFF, JPG or PNG bitmap file
#' @return a "crayonmap" class object to be used by paintCrayon()

readCrayonMap <- function(file)
{
	require(crayon)
	require(readbitmap)

	pic <- read.bitmap(file)

	rgbmat <- rgb(matrix(pic[1:nrow(pic), 1:ncol(pic),], nrow = nrow(pic) * ncol(pic)))

	crayonstrings = matrix(sapply(rgbmat, function(x) crayon::make_style(x, bg = T)("  ")), nrow = nrow(pic))

	crayonstrings[,ncol(crayonstrings)] <- paste(crayonstrings[,ncol(crayonstrings)], "\n", sep = "")

	crayonstrings[,1] <- paste("   ", crayonstrings[,1], sep = "")

	crayons <- as.vector(t(crayonstrings))

	cmap <- new("crayonmap", crayons = crayons, row.num = nrow(pic), col.num = ncol(pic))

	return(cmap)
}

#' Text-based bitmap
#' @param cmap object of class "crayonmap"
#' @return a text-based bitmap directly in the terminal output. 

paintCrayon <- function(cmap)
{	
	cat("\n \n \n")

	cat(cmap@crayons, sep = "")

	cat("\n \n \n")
}
cmap <- readCrayonMap(file)
paintCrayon(cmap)
```