Drupal 7 Module Development

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Working with Files and Images Drupal 7 introduced a new API for files and images, bringing the functionality of popular contributed modules like Imagecache and Imagefield into core for the first time. In this chapter, we will build two modules that take advantage of this new functionality. Some of the concepts we will cover are: • Understanding Drupal's public and private filesystems • Associating files and images with content • Implementing a stream wrapper for custom file handling • Programmatically manipulating images using image styles and effects • Understanding Drupal's new Image Styles functionality • Implementing your own image effects for use with Image Styles By the time you are done with this chapter, you should have a good understanding of how to manipulate files and images using Drupal, including some methods for retrieving remote files and images. The Twitpic and watermark modules In this chapter, we will be building the Twitpic module. This module will enable you to interact with images stored on the Twitpic website (http://twitpic. com) and integrate them with Drupal in a variety of ways. It provides a stream wrapper that allows developers to pull images from Twitpic by referring to them with a custom URI, and offers a demo of how Drupal's Image API can be used to manipulate these images.
Working with Files and Images We will also be creating a second module, which allows users to add a simple text watermark to images. Users will be able to configure the watermark so that it displays custom text in a specified color. This effect will be available for use in Image Styles, the Drupal 7 implementation of the Imagecache module. Files in Drupal When you installed Drupal for the first time, you probably got the following error and wondered why you needed to create three directories for files: Drupal defines three types of file storage, namely, public, private, and temporary. Public files are available to the world at large for viewing or downloading. This is where things such as image content, logos, and downloadable files are stored. Your public file directory must exist somewhere under Drupal's root, and it must be readable and writeable by whatever 'user' your web server is running under. Public files have no access restrictions. Anyone, at anytime, can navigate directly to a public file and view or download it. Private files are not available to the world for general download. The private files' directory should reside outside Drupal's root directory. However, it will still be writeable by the web server user. Isolating private files this way allows developers to control who can and can't access them as they wish. For instance, you could write a module that only allows users who have a specific role, to access PDFs in the private filesystem. [ 314 ]
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www.allitebooks.com
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Drupal 7 Module Development Copyrig
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Foreword Drupal has its roots in th
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About the Authors Matt Butcher is a
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Larry Garfield is a Senior Architec
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John Albin Wilkins has been a web d
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Jojodae Ganesh Sivaji has been invo
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Why Subscribe? • Fully searchable
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Table of Contents Tools for develop
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Table of Contents A shortcut for sy
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Table of Contents Using hook_node_a
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Table of Contents Creating a task 3
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Preface Chapter 5, Building an Admi
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Preface The system for handling thi
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Developing for Drupal 7 Drupal is a
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However, what we do want to start w
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The Operating System Chapter 1 Wind
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Chapter 1 Drupal core is the founda
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Chapter 1 The database We have take
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Chapter 1 The responsibility of the
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Chapter 1 While one could imagine t
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Chapter 1 We assume that you have y
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Chapter 1 The following are a few o
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Creating Your First Module We are g
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Creating Your First Module As obvio
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Creating Your First Module By Drupa
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Creating Your First Module The next
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Creating Your First Module When Dru
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Creating Your First Module Doxygen-
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Creating Your First Module The help
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Creating Your First Module Drupal s
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Creating Your First Module Finally,
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Creating Your First Module Here's o
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Creating Your First Module ); } } r
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Creating Your First Module Not in J
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Creating Your First Module There ar
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Creating Your First Module The exam
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Creating Your First Module Setting
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Creating Your First Module } ); pub
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Creating Your First Module You migh
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Creating Your First Module The repo
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Drupal’s Theme Layer This book is
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Drupal’s Theme Layer There are ac
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Drupal’s Theme Layer Theme engine
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Drupal’s Theme Layer Preprocess f
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Drupal’s Theme Layer A Drupal the
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Drupal’s Theme Layer The theme()
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Drupal’s Theme Layer Now, if you
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Drupal’s Theme Layer A similar pr
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Drupal’s Theme Layer Now, that wa
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Drupal’s Theme Layer • #suffix:
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Drupal’s Theme Layer Two powerful
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Drupal’s Theme Layer 'menu_tree__
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Drupal’s Theme Layer If a functio
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Drupal’s Theme Layer We've also s
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Drupal’s Theme Layer Summary You'
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Theming a Module After all, if you
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Theming a Module * Enables a single
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Theming a Module * First draft! * *
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Theming a Module Theming a Drupal b
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Theming a Module Converting a theme
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Theming a Module if (is_array($elem
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Theming a Module Notice that the .b
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Theming a Module } $block['content'
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Theming a Module } 'variables' => a
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Theming a Module } // Theme the use
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Theming a Module // Create links fo
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Theming a Module } // Load the acco
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Theming a Module * - $user: The use
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Theming a Module Summary In this ch
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Building an Admin Interface Startin
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Building an Admin Interface $items[
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Building an Admin Interface 'access
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Building an Admin Interface Each ar
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Building an Admin Interface Other p
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Building an Admin Interface Each el
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Building an Admin Interface Drupal
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Building an Admin Interface This is
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Building an Admin Interface Form su
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Building an Admin Interface A short
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Building an Admin Interface } retur
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Building an Admin Interface PHP mai
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Building an Admin Interface Impleme
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Building an Admin Interface Debuggi
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Building an Admin Interface This te
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Working with Content Drupal 7 intro
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Chapter 6 The Schema API allows dat
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'fields' => array( 'aid' => array(
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Chapter 6 'fieldable' => TRUE, 'ent
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Chapter 6 The return value from the
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Chapter 6 In our case, we defined t
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Chapter 6 Most entity operations in
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[ 165 ] Chapter 6 This callback sim
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Chapter 6 This page will simply gen
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Chapter 6 This hook defines a new f
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Submit callback The submit callback
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Chapter 6 // Save the initial revis
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Chapter 6 Master/slave database con
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Chapter 6 array($artwork->aid => $a
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Chapter 6 'access arguments' => arr
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Chapter 6 } foreach ($artworks as $
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Creating New Fields In the last cha
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Chapter 7 Although an advanced topi
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Chapter 7 The most important magic
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Chapter 7 } } '#type' => 'select',
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Chapter 7 Exposing fields to the Fo
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Chapter 7 $element['width'] = array
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Chapter 7 if ($widget['type'] == 'd
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Chapter 7 } return; 'field_ui_field
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Chapter 7 } function theme_dimfield
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Chapter 7 } '@height' => $item['hei
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Chapter 7 } else if ($settings['uni
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Chapter 7 We can, of course, have m
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Chapter 7 To demonstrate how entity
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[ 209 ] Chapter 7 Now look at that
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Drupal Permissions and Security Per
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Chapter 8 The preceding code checks
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Chapter 8 If we had accidentally ru
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Chapter 8 The user_access() functio
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In the first case, Are we looking a
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Chapter 8 Declaring your own access
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} Chapter 8 'page callback' => 'exa
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Chapter 8 if (!flood_is_allowed('co
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[ 227 ] Chapter 8 Enabling permissi
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Chapter 8 } $permissions = array( '
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Chapter 8 This approach is the prop
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Chapter 8 Running access checks on
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Chapter 8 Handling AJAX callbacks s
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Chapter 8 As a result, we cannot tr
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Chapter 8 This allows us to pass a
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Node Access Out-of-the-box, Drupal
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Chapter 9 The Node Access API allow
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* - "delete" * - "create" * @param
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Chapter 9 if (!user_access('access
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Chapter 9 } if (module_implements('
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Chapter 9 hook_node_access() is the
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Chapter 9 Note that the {node_acces
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Chapter 9 The basic permission 'cre
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Chapter 9 It is a good idea to writ
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Chapter 9 On node listing pages, th
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Chapter 9 Writing a complete node a
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Page 366 and 367: Installation Profiles This chapter
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Page 370 and 371: Enabling modules Just like modules
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Database Access Although Drupal 7 h
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Appendix A Result objects The retur
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Appendix A The join() methods all r
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[ 369 ] Appendix A The db_insert()
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Appendix A A Merge query says, in e
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Appendix A Slave servers Drupal als
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Security Throughout this book, we h
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Filtering The following guidelines
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First, whenever we write a query ag
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Appendix B There are both RSS feeds
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ajax_command_alert command 309 ajax
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Drupal, subsytems blocks 20 code te
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form handling 229 forms access chec
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K key() method 371 L label property
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evision handling 175 revisions hand
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U unit test 49 update queries 370 u
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Drupal 7 ISBN: 978-1-84951-286-2 Pa
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