rstudio knitr not running pdfcrop

Question

I'm trying to knit the mwe below to pdf using rstudio (1.2.5019)

---
title: "Test"
author: "Me"
output: 
  pdf_document: 
    fig_caption: yes
    keep_tex: yes
    fig_crop: yes
---
This should be cropped
```{r}
library(knitr)
```



```{r named-chunk}
plot(x <- 0:100, dbinom(x, size=100, prob=0.6), type='l',
     main="Not cropped", xlab="Looks good", ylab="Nok")
```

The output pdf looks fine except the plot has not been cropped with pdfcrop.

Here's the log output.

processing file: cropping.Rmd |..................
| 25% ordinary text without R code

|...................................
| 50% label: unnamed-chunk-1
|....................................................
| 75% ordinary text without R code

|......................................................................| 100% label: named-chunk

output file: cropping.knit.md

"C:/Program Files/RStudio/bin/pandoc/pandoc" +RTS -K512m -RTS cropping.utf8.md --to latex --from markdown+autolink_bare_uris+tex_math_single_backslash --output cropping.tex --self-contained --highlight-style tango --pdf-engine pdflatex --variable graphics --lua-filter "C:/Users/marti/Documents/R/win-library/3.6/rmarkdown/rmd/lua/pagebreak.lua" --lua-filter "C:/Users/marti/Documents/R/win-library/3.6/rmarkdown/rmd/lua/latex-div.lua" --variable "geometry:margin=1in"

Output created: cropping.pdf

pdfcrop works just fine from my command line but isn't called by rstudio. It is also located by rstudio.

Sys.which('pdfcrop') pdfcrop "C:\\texlive\\2019\\bin\\win32\\pdfcrop.exe"

What am I missing?

Answer 1

This actually solved it.

``` {r crop-hook,cache=FALSE}
    knit_hooks$set(crop=hook_pdfcrop)
```


```{r named-chunk, crop=TRUE}
plot(x <- 0:100, dbinom(x, size=100, prob=0.6), type='l',
     main="Not cropped", xlab="Looks good", ylab="Nok")
```

As far as I understood from the documentation this shouldn't be necessary?

Answer 2

通过livetex或miktex安装pdfcrop --- 您用来编写乳胶文档的那个。