PDF Generation in Rails with Prawn and Prawn-to: John McCaffrey

Rails PDF Generation John McCaffrey

What we’re going to cover
Agenda
PDF Types and Libraries
Prawn
General PDF Testing
Advanced Prawn examples
Prawn-to
Q&A

Intro: after_me

John McCaffrey Presented at WindyCityRails 08
Using Prawn since 10/08
http://www.pathf.com/blogs/author/john-mccaffrey /

And you are? :include => :first_name
Col 1 Col 2 Col 3 Col 4

Why users Love PDFs
They are great for:
Reports
Static data
Forms
Invoices
Tightly controlled formatting
Print friendly
Portable
Looks the same for everyone

PDF types and libraries

PDF Library types
HTML to PDF
PDF Template binding
Dynamic

What type should I use?
What is the content? (tax form, invoice, eBook, product list)
How large will the files be?
How complex is the formatting?
Do they need to be generated ‘on demand’, or would it be a batch or background job?
Do you mind calling out to a library or command line tool?
Character encoding, utf-8, internationalization, etc
Who will be in charge of maintaining them? (developer or designer?)

Use HTML to PDF if..
You already have an html view that is structured the way you want it.
You don’t want to mess with any ‘pdf syntax’
Don’t mind requiring a native library, or command line invocation.
Don’t mind the licensing agreements or cost of commercial tools
Your team skill set is more aligned with HTML/CSS

HTML to PDF Libraries
PrinceXML
Best in class html to pdf. Passes Acid2 test
Princely ruby wrapper
Commercial: $3800 server license
HTMLDOC
Has been around for awhile
Supports a subset of html (no css, no xhtml or html 4.0)
Supports basic UTF-8/Unicode for ‘western’ languages
wkhtmltopdf
Based on WebKit rendering engine
Might be some issues in different OSes (windows)
Relatively new library

Use PDF Templates if..
The document is a form to be filled in (text fields, checkboxes, etc)
The structure is mostly static
The document is very large
The formatting is complex
You don’t mind calling out to a library

PDF Template binding
pdftk
Build document with any tool that can output as pdf
Add in the form fields with Acrobat editor
Bind fdf data against pdf template
Very powerful pdf manipulation features
iText
Java library
Very powerful
Well known with lots of examples/tutorials, and books
Can also merge/split pdf files, add watermarks, etc
Pdf Form Binding example

Use PDF Generation if..
The content/structure is dynamic
The document is not too large
The formatting is not too complex
You prefer a pure ruby library
You prefer an open source solution

PDF Generation Libraries
JasperReports
Well known java library, multiple outputs
May complicate dev/deployment dependencies
PDF::WRITER
Pure Ruby. Has been around for awhile
Many examples out there
Powerful, but ‘tedious’ syntax for positioning, styling, etc
Prawn
Lightweight, easy to learn syntax
Newer library, still in alpha, but very promising
Faster than PDF::Writer
Continues to get faster and better

I chose Prawn
Because…
Lots of clear examples
Worked well for the report style that I needed (dynamic structure, simple table-based layout)
Quick to generate pdfs on demand
Fastest pure ruby pdf tool out there
Code was well tested and easy to follow
Forum/mailing list was active and helpful

Prawn history
Gregory Brown
Mendicant project, raised $10k to work on open-source projects
Goal was to improve report and pdf generation for ruby
Ruport reporting framework (multiple report types)
Prawn
Just released Ruby Best Practices book

Prawn 101
What it can’t do
Complex formatting, nested tables
Edit existing pdfs
Encryption/security (coming soon – 9/15)
What it can do
Very easy to learn syntax
Easy Image embedding
Easy to manage table-based layouts
Simplified positioning commands

Prawn examples

Examples
Install
Gem install prawn
Or git clone git://github.com/sandal/prawn.git
Make sure the tests pass
May have to install another submodule or two

Examples
Methods
PDF
Text
Bounding_box
Font
Move_down
Mask
Page
Image
Stroke

Examples
Basic syntax examples
Text
Images
Overflow
Orientation

Text & Image Text_image_sample

Text overflow Text_overflow_sample

Page Orientation orientation sample

Examples
Intermediate
Table
Utf-8
Drawing
Bounding box
Install
Gem install prawn-layout

Tables table sample

Utf-8 UTF-8 sample

Drawing & bounding_box bounding

Prawn Performance
Numbers
Around 20 times faster than PDF::Writer
Even faster on ruby 1.9
Well designed (seems to scale linearly)
Images are only loaded once

PDF TESTING

How do I test a PDF?
Tools
Basic file and attachment testing
PDF::Reader
PDF::Inspector
Oragami library
Convert to Image and do a bit diff

How do I test a PDF?
Poor-man techniques
Nothing blew up
File is present
Mocks were invoked as expected
Generate your pdfs and look at them
PDF toolkits
Assert page size
Open PDF and read its contents
Grep for objects
Assert order of objects

Testing PDF structure

Testing PDF contents

Prawn-to

Prawn in your view
All the good stuff
script/plugin install git://github.com/thorny-sun/prawnto.git
Render pdf template with .pdf.prawn extension
DRY up common pdf configuration settings
Access to helpers (useful for currency, dates, text)

Prawn-to: controller

Prawn-to: view Prawn-to sample

Advanced Prawn with_reckless_abandon

Advanced examples
What else can we do?
Grid based layout
Labels & Calendars
Annotations & Links
Google charts

Grid Layout Grid sample

Grids & Labels Labels sample

Google Charts api Charts sample

Prawn-Format Nice and easy, just got nicer, and easier

Prawn-format
Use HTML and style syntax
Basic tags
Alter existing styles
Create new styles
Links

Prawn-format: html and style Format

Putting it all together
Mash up
Prawn, prawn-layout
Prawn-to
Prawn-format
Google charts api
Twitter- search
Heroku & git
Twitter_Timelines

More to come
Roadmap & projects
Security & encryption ( prawn-security)
Prawn-js
Clean up
Improved grid/table support
Improved docs and examples

Questions? speakerrate.com /jmccaffrey

Links
Prawn: prawn.majesticseacreature.com /
Prawn-to: cracklabs.com/prawnto
Google Charts: chart.apis.google.com /
Twitter-Search: github.com/dancroak/twitter -search
Blog: http://www.pathf.com/blogs/author/john-mccaffrey /
PDF Generation in Rails John McCaffrey

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PDF Generation in Rails with Prawn and Prawn-to: John McCaffrey

by John McCaffrey on Sep 12, 2009

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PDF Generation in Rails with Prawn and Prawn-to: John McCaffrey — Presentation Transcript