doc/plugin.txt

   1 A FEW NOTES ON THE PLUGIN ARCHITECTURE
   2 ======================================
   3
   4 The plugin architecture of SquirrelMail is designed to make it
   5 possible to add new features without having to patch SquirrelMail
   6 itself. At the moment the plugin part of SquirrelMail should be
   7 considered "alpha" or "beta" quality code.
   8
   9 Until the functionality and code is more stable, be prepared for
  10 plugins to suddenly stop working.
  11
  12 Functionality like password changing, displaying ads and calendars
  13 should be possible to add as plugins.
  14
  15
  16 The idea
  17 --------
  18
  19 The idea is to be able to run random code at given places in the
  20 SquirrelMail code. This random code should then be able to do whatever
  21 needed to enhance the functionality of SquirrelMail. The places where
  22 code can be executed are called "hooks".
  23
  24 There are some limitations in what these hooks can do. It is difficult
  25 to use them to change the layout and to change functionality that
  26 already is in SquirrelMail.
  27
  28 Some way for the plugins to interact with the help subsystem and
  29 translations will be provided.
  30
  31
  32 The implementation
  33 ------------------
  34
  35 In the main SquirrelMail files the file functions/plugin.php. In
  36 places where hooks are made available they are executed by calling the
  37 function do_hook("hookname").
  38
  39 The do_hook traverses the array $squirrelmail_plugin_hooks["hookname"]
  40 and executes all the functions that are named in that array.
  41
  42 A plugin must reside in a subdirectory in the plugins/ directory. The
  43 name of the subdirectory is considered the name of the plugin.
  44
  45 To start using a plugin, its name must be added to the $plugins array
  46 in config.php like this:
  47
  48   $plugins[0] = "plugin_name";
  49
  50 When a plugin is registered the file plugins/plugin_name/setup.php is
  51 included and the function squirrelmail_plugin_init_plugin_name is
  52 called with no parameters.
  53
  54
  55 Writing plugins
  56 ---------------
  57
  58 A plugin must consist of at least a file called setup.php. All other
  59 files the plugin consist of should also be in the plugin directory.
  60
  61 The function squirrelmail_plugin_init_plugin_name is called to
  62 initalize a plugin. This function could look something like this:
  63
  64 function squirrelmail_plugin_init_demo () {
  65   global $squirrelmail_plugin_hooks;
  66
  67   $squirrelmail_plugin_hooks["generic_header"]["demo"] = "plugin_demo_header";
  68   $squirrelmail_plugin_hooks["menuline"]["demo"] = "plugin_demo_menuline";
  69 }
  70
  71 Note that the SquirrelMail files assume that all other SquirrelMail
  72 files are available as ../directory/file. This means that if some file
  73 in the plugin directory is requested, it must do a chdir("..") before
  74 including any of the standard SquirrelMail files.
  75
  76
  77 List of hooks
  78 -------------
  79   generic_header                  functions/page_header.php
  80   menuline                        functions/page_header.php
  81   compose_button_row              src/compose.php
  82   compose_bottom                  src/compose.php
  83   left_main_before                src/left_main.php
  84   left_main_after                 src/left_main.php
  85   * options_save                  src/options.php  (see note on options)
  86   * options_link_and_description  src/options.php  (see note on options)
  87   * options_highlight_bottom      src/options_highlight.php
  88   * options_personal_bottom       src/options_personal.php
  89   * options_personal_inside       src/options_personal.php
  90   * options_personal_save         src/options_personal.php
  91   * options_display_bottom        src/options_display.php
  92   * options_display_inside        src/options_display.php
  93   * options_display_save          src/options_display.php
  94   * options_folders_bottom        src/options_folders.php
  95   * options_folders_inside        src/options_folders.php
  96   * options_folders_save          src/options_folders.php
  97   logout                          src/signout.php
  98   login_before                    src/webmail.php
  99   login_verified                  src/webmail.php
 100   loading_prefs                   src/load_prefs.php
 101   mailbox_index_before            functions/mailbox_display.php
 102   mailbox_index_after             functions/mailbox_display.php
 103   mailbox_form_before             functions/mailbox_display.php
 104   right_main_after_header         src/right_main.php
 105   right_main_bottom               src/right_main.php
 106   login_top                       src/login.php
 107   login_bottom                    src/login.php
 108   read_body_top                   src/read_body.php
 109   read_body_bottom                src/read_body.php
 110   search_before_form              src/search.php
 111   search_after_form               src/search.php
 112   search_bottom                   src/search.php
 113   help_top                        src/help.php
 114   help_bottom                     src/help.php
 115   help_chapter                    src/help.php
 116   addrbook_html_search_below      src/addrbook_search_html.php
 117   addressbook_bottom              src/addressbook.php
 118   ^ attachment $type0/$type1      functions/mime.php
 119
 120 (*) Options
 121 -----------
 122 There are two ways to do options for your plugin.  First, you can incorporate it
 123 into an existing section of the preferences (Display, Personal, or Folders).
 124 The second way, you create your own section that they can choose from and it
 125 displays its own range of options.
 126
 127
 128 (^) Attachment Hooks
 129 --------------------
 130 When a message has attachments, this hook is called with the MIME types.  For
 131 instance, a .zip file hook is "attachment application/x-zip".  The hook should
 132 probably show a link to do a specific action, such as "Verify" or "View" for a
 133 .zip file.
 134
 135
 136 First:  Integrating into existing options
 137 -----------------------------------------
 138 There are two hooks you need to use for this one:
 139
 140 1.  options_YOUCHOOSE_inside
 141     This is the code that goes inside the table for the section you choose.  Since
 142     it is going inside an existing table, it must be in this form:
 143     ------cut here-------
 144       <tr>
 145          <td>
 146             OPTION_NAME
 147          </td>
 148          <td>
 149             OPTION_INPUT
 150          </td>
 151       </tr>
 152     ------cut here-------
 153
 154 2.  options_YOUCHOOSE_save
 155     This is the code that saves your preferences into the users' preference
 156     file.  For an example of how to do this, see src/options.php.
 157
 158
 159 Second:  Create your own section
 160 -------------------------------
 161 It is possible to create your own options sections with plugins.  There are
 162 three hooks you will need to use.
 163
 164 1.  options_link_and_description
 165     This creates the link and has a description that are shown on the options
 166     page.  This should output HTML that looks like this:
 167
 168     -----cut here-----
 169       function my_function() {
 170          global $color
 171          ?>
 172          <table width=50% cellpadding=3 cellspacing=0 border=0 align=center>
 173             <tr>
 174                <td bgcolor="<? echo $color[9] ?>">
 175                   <a href="../plugins/YOUR_PLUGIN/YOUR_OPTIONS.php">YOUR OPTIONS NAME</a>
 176                </td>
 177             </tr>
 178             <tr>
 179                <td bgcolor="<? echo $color[0] ?>">
 180                   YOUR DESCRIPTION
 181                </td>
 182             </tr>
 183          </table>
 184          <?php
 185       }
 186     -----cut here-----
 187
 188 2.  options_save
 189     Here is the code that you need to do to save your options in the
 190     preference files or manipulate whatever data you are trying to change
 191     through the options section.  You can look at options.php for details
 192     on how this is to be done.
 193
 194 3.  loading_prefs (optional)
 195     If you are wanting to save preferences to the preference files, then
 196     you need to do this step as well.  Otherwise if you are manipulating
 197     other data, ignore this step.
 198
 199     You should put the code in here that loads your preferences back
 200     into usable variables.  Examples of this can be found in the file
 201     src/load_prefs.php