chrome/common/extensions/docs/templates/intros/mediaGalleries.html

   1 <h2 id="usage">Usage</h2>
   2
   3 <p>The mediaGalleries API lets you prompt the user for permission to access
   4 media galleries on the user's computer. The permission dialog contains common
   5 media locations for the platform and allows the user to specify additional
   6 locations. From those locations, only media files will be present in the file
   7 system objects.</p>
   8
   9 <h2 id="manifest">Manifest</h2>
  10
  11 <p>The media galleries API has two axes of permission parameters:</p>
  12
  13 <ul>
  14   <li>the locations that can be accessed</li>
  15   <li>the type of access</li>
  16 </ul>
  17
  18 <p>These two axes and the permission parameters on each axis are described
  19 in the table below:</p>
  20
  21 <table>
  22     <tr>
  23       <th>Axis</th>
  24       <th>Parameter</th>
  25       <th>Effect</th>
  26     </tr>
  27     <tr>
  28       <td rowspan="2">Locations</td>
  29       <td>none</td>
  30       <td>
  31         If you do not specify a location permission parameter, your app will
  32         not be able to access any media galleries until the user grants
  33         permission to access specific media galleries at runtime using the
  34         media gallery permission dialog.
  35       </td>
  36     </tr>
  37     <tr>
  38       <td>"allAutoDetected"</td>
  39       <td>
  40         Grants your app access to all auto-detected media galleries on the
  41         user's computer. This permission causes an install-time prompt to be
  42         displayed indicating that the app will have access to the user's media
  43         files.
  44       </td>
  45     </tr>
  46     <tr>
  47       <td rowspan="3">Access&nbsp;type</td>
  48       <td>"read"</td>
  49       <td>Grants your app the right to read files in media galleries.</td>
  50     </tr>
  51     <tr>
  52       <td>"delete"</td>
  53       <td>
  54         Grants your app the right to delete files from media galleries.
  55         "read" permission is a prerequisite for "delete". Specify both "read"
  56         and "delete" to obtain both types of permissions to media galleries.
  57       </td>
  58     </tr>
  59     <tr>
  60       <td>"copyTo"</td>
  61       <td>
  62         Grants your app the right to copy files into media galleries.
  63         Only valid media files that Chrome is capable of playing or displaying
  64         are permitted; files that Chrome is not able to validate will result
  65         in a security error. "read" and "delete" permissions are prerequisites
  66         for "copyTo". Specify "read", "delete" and "copyTo" to obtain all three
  67         types of permissions to media galleries.
  68       </td>
  69     </tr>
  70 </table>
  71
  72 <p>Notes:</p>
  73 <ul>
  74   <li>The media gallery permission dialog can be triggered programmatically.
  75   The user may have alternate media locations, so even if you specify
  76   "allAutoDetected" permsission, it is still important to provide a mechanism
  77   to open the permission dialog in your app.</li>
  78
  79   <li>There is no write access to media galleries due to the
  80   file validation requirement. However, you can write files to
  81   a different file system like the temporary file system, and then copy
  82   the files into the desired media gallery.</li>
  83
  84   <li>Access type permissions do not trigger an install-time prompt
  85   by themselves. However, the type of access will be reflected in the
  86   media gallery permission dialog, as well as the install-time prompt if
  87   "allAutoDetected" permission is requested.</li>
  88 </ul>
  89
  90 <p>Below is an example of a manifest file with mediaGalleries permissions:</p>
  91
  92 <pre data-filename="manifest.json">
  93 {
  94   "name": "My app",
  95   ...
  96   "permissions": [
  97     <b>{ "mediaGalleries": ["read", "allAutoDetected"] }</b>
  98   ],
  99   ...
 100 }
 101 </pre>
 102
 103 <p>This example manifest file will trigger an install-time permission prompt,
 104 and let the app read from all auto-detected media galleries on the
 105 user's computer. The user may add or remove galleries using the
 106 media gallery permission dialog, after which the app will be able
 107 to read all the media files from galleries that the user selected.</p>
 108
 109 <h2 id="iTunes">iTunes</h2>
 110
 111 <p>If present, the user's iTunes library can be accessed as a media gallery.
 112 In addition to the media files in the library, the "iTunes Music Library.xml"
 113 file is also presented. Regardless of where the music files are actually on the
 114 disk (and where the xml file says they are), they are mapping into an
 115 Artist/Album/Track hierarchy like iTunes does by default.  This mapping doesn't
 116 always work perfectly, so there are two things to note for Apps trying to match
 117 the xml file with files in the gallery. If the filenames for tracks within an
 118 album are not unique, they will be uniquified by adding the track id in
 119 parentheses before the extension, and if there is a colon or a slash in the
 120 artist, album, or track name, they are turned into underscore characters.</p>
 121
 122 <h2 id="Picasa">Picasa</h2>
 123
 124 <p>If present, the user's Picasa library can also be accessed as a media
 125 gallery. Directories on the filesystem scanned by Picasa are presented under
 126 folders/. Picasa Albums are presented under albums/. Albums and Folders that
 127 have duplicate names and dates will be uniquified using an incrementing
 128 integer in parenthesis before the extension. Duplicate filenames within the
 129 same Album will also be uniquified using an incrementing integer in parenthesis
 130 before the extension.</p>