# Dhalang [](https://travis-ci.com/NielsSteensma/Dhalang)
> Dhalang is a Ruby wrapper for Google's Puppeteer.
## Features
* Generate PDFs from pages
* Generate PDFs from html ( external images/stylesheets supported )
* Capture a screenshot of a webpage
## Installation
Add this line to your application's Gemfile:
gem 'Dhalang'
And then execute:
$ bundle update
Install puppeteer in your application's root directory:
$ npm install puppeteer
<sub>NodeJS v10.18.1 or greater is required</sub>
## Usage
__Get a PDF of a website url__
`Dhalang::PDF.get_from_url("https://www.google.com")`
It is important to pass the complete url, leaving out https://, http:// or www. will result in an error.
__Get a PDF of a HTML string__
`Dhalang::PDF.get_from_html("<html><head></head><body><h1>examplestring</h1></body></html>")`
__Get a PNG screenshot of a website__
`Dhalang::Screenshot.get_from_url_as_png("https://www.google.com")`
__Get a JPEG screenshot of a website__
`Dhalang::Screenshot.get_from_url_as_jpeg("https://www.google.com")`
All methods return a string containing the PDF or JPEG/PNG in binary.
## Custom PDF/screenshot options
To override the default options that are set by Dhalang you can pass as last argument a hash with the custom options you want to set.
For example to set custom margins for PDFs:
`Dhalang::PDF.get_from_url("https://www.google.com", {margin: { top: 100, right: 100, bottom: 100, left: 100}})
`
For example to only take a screenshot of the visible part of the page:
`Dhalang::Screenshot.get_from_url_as_png("https://www.google.com", {fullPage: false})
`
A list of all possible PDF options that can be set, can be found at: https://github.com/puppeteer/puppeteer/blob/main/docs/api.md#pagepdfoptions
A list of all possible screenshot options that can be set, can be found at: https://github.com/puppeteer/puppeteer/blob/main/docs/api.md#pagescreenshotoptions
## Custom user options
You may want to change the way Dhalang interacts with Puppeteer in general. User options can be set by providing them in a hash as last argument to any calls you make to the library. Are you setting both custom PDF and user options? Then they should be passed as a single hash.
For example to set a custom navigation timeout:
`Dhalang::Screenshot.get_from_url_as_jpeg("https://www.google.com", {navigationTimeout: 20000})`
Below table lists all possible configuration parameters that can be set:
| Key | Description | Default |
|--------------------|-----------------------------------------------------------------------------------------|---------------------------------|
| navigationTimeout | Amount of milliseconds until Puppeteer while timeout when navigating to the given page | 10000 |
| userAgent | User agent to send with the request | Default Puppeteer one |
| isHeadless | Indicates if Chromium should be launched headless | true |
| viewPort | Custom viewport to use for the request | Default Puppeteer one |
| httpAuthenticationCredentials | Custom HTTP authentication credentials to use for the request | None |
## Examples of using Dhalang
To return a PDF from a Rails controller you can do the following:
```
def example_controller_method
binary_pdf = Dhalang::PDF.get_from_url("https://www.google.com")
send_data(binary_pdf, filename: 'pdfofgoogle.pdf', type: 'application/pdf')
end
```
To return a PNG from a Rails controller you can do the following:
```
def example_controller_method
binary_png = Dhalang::Screenshot.get_from_url_as_png("https://www.google.com")
send_data(binary_png, filename: 'screenshotofgoogle.png', type: 'image/png')
end
```
To return a JPEG from a Rails controller you can do the following:
```
def example_controller_method
binary_jpeg = Dhalang::Screenshot.get_from_url_as_jpeg("https://www.google.com")
send_data(binary_jpeg, filename: 'screenshotofgoogle.jpeg', type: 'image/jpeg')
end
```