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output: rmarkdown::github_document
---

# decapitated

Headless 'Chrome' Orchestration

## Description

The 'Chrome' browser <https://www.google.com/chrome/> has a headless mode
which can be instrumented programmatically. Tools are provided to perform headless
'Chrome' instrumentation on the command-line, including retrieving the javascript-executed web page, PDF output or screen shot of a URL.

### IMPORTANT

You'll need to set an envrionment variable `HEADLESS_CHROME` to one of these two values:

- Windows(32bit): `C:/Program Files/Google/Chrome/Application/chrome.exe`
- Windows(64bit): `C:/Program Files (x86)/Google/Chrome/Application/chrome.exe`
- macOS: `/Applications/Google\ Chrome.app/Contents/MacOS/Google\ Chrome`
- Linux: `/usr/bin/google-chrome`

A guess is made (but not verified yet) if `HEADLESS_CHROME` is non-existent.

It's best to use `~/.Renviron` to store this value for the time being.

## What's in the tin?

The following functions are implemented:

- `chrome_dump_pdf`: "Print" to PDF
- `chrome_read_html`: Read a URL via headless Chrome and return the raw or rendered '<body>' 'innerHTML' DOM elements
- `chrome_shot`: Capture a screenshot
- `chrome_version`: Get Chrome version
- `get_chrome_env`: get an envrionment variable 'HEADLESS_CHROME'
- `set_chrome_env`: set an envrionment variable 'HEADLESS_CHROME'

## Installation

```{r eval=FALSE}
devtools::install_github("hrbrmstr/decapitated")
```

```{r message=FALSE, warning=FALSE, error=FALSE, include=FALSE}
options(width=120)
```

## Usage

```{r message=FALSE, warning=FALSE, error=FALSE}
library(decapitated)

# current verison
packageVersion("decapitated")

chrome_version()

chrome_read_html("http://httpbin.org/")
```

```{r eval=FALSE, message=FALSE, warning=FALSE, error=FALSE}
chrome_dump_pdf("http://httpbin.org/")
```

```{r message=FALSE, warning=FALSE, error=FALSE, eval=FALSE}
chrome_shot("http://httpbin.org/")

## format width height colorspace filesize
## 1 PNG 1600 1200 sRGB 215680
```

![screenshot.png](screenshot.png)