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项目作者： NielsSteensma

项目描述 ：
Generate PDFs and make screenshots of HTML using Puppeteer in Ruby
高级语言： Ruby
项目地址: git://github.com/NielsSteensma/Dhalang.git
创建时间： 2019-01-24T11:49:27Z
项目社区：https://github.com/NielsSteensma/Dhalang
开源协议：MIT License
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Dhalang Build Gem Version

Dhalang is a Ruby wrapper for Google’s Puppeteer.

Features

  • Generate PDFs from webpages
  • Generate PDFs from HTML ( external images/stylesheets supported )
  • Capture screenshots from webpages
  • Scrape HTML from webpages

Prerequisites

  • Node ≥ 18
  • Puppeteer ≥ 22
  • Unix shell ( Dhalang will not work on Windows shells )

Installation

Add this line to your application’s Gemfile:

  1. gem 'Dhalang'

And then execute:

  1. $ bundle update

Install puppeteer or puppeteer-core in your application’s root directory:

  1. $ npm install puppeteer 
  2. or
  3. $ npm install puppeteer-core

Usage

PDF of a website url 

  1. 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.

PDF of a HTML string 

  1. Dhalang::PDF.get_from_html("<html><head></head><body><h1>examplestring</h1></body></html>")

PNG screenshot of a website 

  1. Dhalang::Screenshot.get_from_url("https://www.google.com", :png)

JPEG screenshot of a website 

  1. Dhalang::Screenshot.get_from_url("https://www.google.com", :jpeg)

WEBP screenshot of a website 

  1. Dhalang::Screenshot.get_from_url("https://www.google.com", :webp)

HTML of a website

  1. Dhalang::Scraper.html("https://www.google.com")

Above methods either return a string containing the PDF/JPEG/PNG/WEBP in binary or the scraped HTML.

Custom 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:

  1. 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:

  1. Dhalang::Screenshot.get_from_url("https://www.google.com", :webp, {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/puppeteer.pdfoptions.md

A list of all possible screenshot options that can be set, can be found at: https://github.com/puppeteer/puppeteer/blob/main/docs/api/puppeteer.screenshotoptions.md

The default Puppeteer options contain the options headerTemplate and footerTemplate. Puppeteer expects these to be HTML strings. By default, the Dhalang
gem passes all options as arguments in a node ... shell command. In case the HTML strings are too long they might surpass the maximum
argument length of the host. For example, on Linux the MAX_ARG_LEN is 128kB. Therefore, you can also pass the headers and footers as file path using the
options headerTemplateFile and footerTemplateFile. These non-Puppeteer-options will be used to populate the Puppeteer-options headerTemplate and footerTemplate.

For example: Dhalang::PDF.get_from_url("https://www.google.com", {headerTemplateFile: '/tmp/header.html', footerTemplateFile: '/tmp/footer.html'})

Below table lists more configuration parameters that can be set:
| Key | Description | Default |
|——————————|————————————————————————————————————————————-|————————————————-|
| isHeadless | Indicates if Chromium should be launched headless (useful for debugging) | true |
| slowMo | Amount of milliseconds to slow down Puppeteer operations (useful for debugging) | 0 |
| browserWebsocketUrl | Websocket url of remote chromium browser to use | None |
| navigationTimeout | Amount of milliseconds until Puppeteer while timeout when navigating to the given page | 10000 |
| printToPDFTimeout | Amount of milliseconds until Puppeteer while timeout when calling Page.printToPDF | 0 (unlimited) |
| navigationWaitForSelector | If set, Dhalang will wait for the specified selector to appear before creating the screenshot or PDF | None |
| navigationWaitForXPath | If set, Dhalang will wait for the specified XPath to appear before creating the screenshot or PDF | None |
| userAgent | User agent to send with the request | Default Puppeteer one |
| isAutoHeight | When set to true the height of generated PDFs will be based on the scrollHeight property of the document body | false |
| viewPort | Custom viewport to use for the request | Default Puppeteer one |
| httpAuthenticationCredentials | Custom HTTP authentication credentials to use for the request | None |
| chromeOptions | A array of options that can be passed to puppeteer in addition to the mandatory ['--no-sandbox', '--disable-setuid-sandbox'] | [] |

Examples of using Dhalang

To return a PDF from a Rails controller you can do the following: 

  1. def example_controller_method
  2.   binary_pdf = Dhalang::PDF.get_from_url("https://www.google.com")  
  3.   send_data(binary_pdf, filename: 'pdfofgoogle.pdf', type: 'application/pdf')  
  4. end

To return a screenshot from a Rails controller you can do the following: 

  1. def example_controller_method
  2.   binary_png = Dhalang::Screenshot.get_from_url("https://www.google.com", :png)
  3.   send_data(binary_png, filename: 'screenshotofgoogle.png', type: 'image/png')   
  4. end