Drupal 7 Module Development

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Chapter 11 Finally we can make the modification to our image: /** * Image effect callback; add a text watermark to an image. * * @param $image * An image object returned by image_load(). * @param $data * An array of attributes to use when performing the * watermark effect. * @return * TRUE on success. FALSE on failure. */ function watermark_effect(&$image, $data) { $data['text_color'] = str_replace('#', '', $data['text_color']); $red = hexdec(substr($data['text_color'], 0, 2)); $green = hexdec(substr($data['text_color'], 2, 2)); $blue = hexdec(substr($data['text_color'], 4)); } $color = imagecolorallocate($image->resource, $red, $green, $blue); imagestring($image->resource, 5, 5, 5, $data['text'], $color); From a <strong>Drupal</strong> perspective, the important thing is that our effect callback, watermark_effect(), takes two arguments. The first is an image object just like we've encountered earlier, which contains a resource handle we can pass to GD functions for modification. The second is the data array just like the one passed to our configuration form callback, containing an associative array of user submitted configuration information. This array is keyed on the field names as specified in the form callback above. We use the information in $data to properly format our text. Beyond that this functionality is pretty straightforward. Most of the code is concerned with properly formatting the color information. In the first four lines we convert the hex color submitted by the user (found in $data['text_color']) to the RGB decimal values which we will need later. We do this by parsing each individual hex value of the string and using hexdec() to convert them to their decimal equivalent. The rest of the code relates to the image creation functionality from the GD image library. We will cover this briefly but for more details refer to the GD documentation at: http://in2.php.net/manual/en/book.image.php [ 337 ]
Working with Files and Images Once we have the color values, we use imagecolorallocate() to create a color identifier representing this color. Finally we can call imagestring(), a GD function that plots text on a string. Without going into too much detail, the following are the arguments this function takes: • A handle to the image (in this example the resource property of the image object) • A font size from 1-5 (5 being the largest) • The x and y coordinates of where the text should be plotted with (0, 0) being the top left corner of the image • The text to be plotted, in this example, the $data['text'] as submitted by the user through our configuration form • The color identifier we created with the user-submitted color choice You should now be able to install this module and have the option to watermark an image on the Image Styles admin screen, as shown in the following screenshot: You can now add this effect, alone or in combination with other effects to a new image style. This image style can then be applied to images in nodes by adjusting the display settings in the administration screens for the node's content type. The following image shows our previous example node with a user-configured watermark applied to the image: [ 338 ]
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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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Chapter 9 Using the new hook_node_a
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Chapter 9 We may alter any element
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Chapter 9 } // Check anonymous user
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Chapter 9 // Check the permission.
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Chapter 9 The key to Devel Node Acc
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Chapter 9 In the preceding case, th
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Page 366 and 367: Installation Profiles This chapter
Page 368 and 369: Chapter 12 Profile modules and them
Page 370 and 371: Enabling modules Just like modules
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Page 386 and 387: Database Access Although Drupal 7 h
Page 388 and 389: Appendix A Result objects The retur
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Page 392 and 393: [ 369 ] Appendix A The db_insert()
Page 394 and 395: Appendix A A Merge query says, in e
Page 396 and 397: Appendix A Slave servers Drupal als
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Page 400 and 401: Filtering The following guidelines
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Page 404: Appendix B There are both RSS feeds
Page 407 and 408: ajax_command_alert command 309 ajax
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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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