readPNG error in vignette

[alapo]

I have been trying to write a book which compiles to pdf, gitbook and epub. I sought a solution that would allow me to knit GIFs when I render as a gitbook while still rendering an image with pdf.

Found your function include_graphics2 which seems like it should help...but I am getting issues with your default code.

I created a blank RMarkdown file

---
title: "Untitled"
output: pdf_document
---

`{r setup, include=FALSE}
knitr::opts_chunk$set(echo = TRUE)
library(linguisticsdown)
library(knitr)
`

`{r, eval=TRUE, fig.cap = "Check your RStudio version"}
png_url <- 'https://commonmark.org/images/markdown-mark.png'
gif_url <- 'https://media.giphy.com/media/k3dcUPvxuNpK/giphy.gif'

## Not run: 
include_graphics2(gif_url, alt_path = png_url)
`

This document will result in the following error

If I change the png_url so that the extension is ".PNG instead of .png it will no longer give this error but then the image won't work (because the URL is case sensitive).

Any ideas on how to fix this?

[liao961120]

It seems to work fine on my computer (test.pdf).
(Note also your R code chunks are malformed)

Could provide your OS info?