Drupal 7 Module Development

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
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