Drupal 7 Module Development

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Chapter 11 } 'type' => STREAM_WRAPPERS_READ_VISIBLE, ), ); The array is keyed on our wrapper's scheme, in this case twitpic. Each scheme must in turn define another associative array with the following keys: • name: A short descriptive name for our wrapper. • class: The name of your PHP class that implements Drupal's stream wrapper interface. • description: A sentence or two describing what this wrapper does. • type: A constant indicating what type of stream wrapper this is—readable and/or writeable, local or remote, among other things. These are defined in includes/stream_wrappers.inc and can be reviewed at: http://api. drupal.org/api/drupal/includes--stream_wrappers.inc/7 Note that in our example we have defined our wrapper as STREAM_WRAPPERS_ READ_VISIBLE. This means it is read only, but visible in Drupal's UI. An example of a wrapper that is not visible in the UI is Drupal's temp:// scheme, which is for internal use only (it is set to STREAM_WRAPPER_HIDDEN). This is all that is needed to implement your own custom stream wrapper. It may seem like a lot, but once you understand what needs to be implemented, it is really quite simple. Now that your stream wrapper is finished, you will be able access photos from Twitpic as easily as any other remote source using Drupal's File API. Now that we can do this, let's look at some of the ways in which Drupal's Image API can be used to modify and manage images. In this example we have mostly focused on the Drupal-specific part of writing stream wrappers. For more general documentation on stream wrappers see http://us2.php.net/manual/en/intro. stream.php [ 325 ]
Working with Files and Images Images in Drupal Just as the contributed Filefield module largely handled file handling in Drupal 6, two modules—Imagefield and Imagecache, largely handled image handling. Imagefield was used for attaching images to nodes, and Imagecache was used to create derivations of those images by resizing or cropping them. This was very popular for things like creating square thumbnails in a grid for image galleries. The functionality of both modules has been brought into core for Drupal 7, along with an improved API for managing this functionality from code. Image API The Drupal 7 Image API provides a variety of functions to manipulate images. By default, Drupal uses the GD image management library that is included with PHP. However Drupal also offers the ability to switch to a different library if needed. For instance, a contributed module could implement the ImageMagick library for developers who needed support for additional image types such as TIFF, which GD does not support. Working with images is similar to working with files. You get an image object by opening a local image using image_load(), and then pass this object to one of the image manipulation functions provided by Drupal. Once you've performed the desired modifications to your image, you save it using image_save(). Image API functions can only access files on your local file system. You can still use stream wrapper schemes like public:// and private:// to refer to files, but remote file systems will not function properly. The following Drupal functions are available for image manipulation: • image_crop(): Crop an image to specified dimensions. • image_desaturate(): Convert an image to grayscale. • image_resize(): Resize an image to specified dimensions. This can affect the image's aspect ratio. • image_rotate(): Rotate an image to the specified number of degrees. • image_scale(): Resize an image to specified dimensions without affecting the image's aspect ratio. • image_scale_and_crop(): Combine scale and crop in one operation. [ 326 ]
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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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• Can this user bypass node acces
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Chapter 9 For our test module, we w
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Chapter 9 When hook_node_access_rec
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Chapter 9 A few things to consider
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Chapter 9 Security considerations T
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Chapter 9 Rebuilding the {node_acce
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Page 366 and 367: Installation Profiles This chapter
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Page 386 and 387: Database Access Although Drupal 7 h
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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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