Drupal 7 Module Development

Chapter 11
This is where you can start adding new manipulations (or, in Drupal parlance,
'effects') to your image. As you can see from the drop-down menu shown, all of
the standard Drupal effects are available to be used. When you select an effect
and click on the Add button, you may get a configuration form that allows you to
specify options for that effect. Typically these configuration options will match the
arguments of the associated functions. So the Desaturate effect does not have a
configuration form, but the Scale effect does, as shown:
Once the appropriate options are entered and saved, the styles screen will be
updated with a live preview of what the new effect will look like. As you add more
and more effects, this live update will continue to reflect them. You can also adjust
the order in which the effects are applied, since this can vastly affect the resulting
image. Rotating before a crop results in an image that is different from one that is
cropped before rotating.
This may seem like a lot of configuration information for a book focused on coding,
but it provides the context for what we're about to do. As you can see, all of Drupal's
built in effects are available for use in a style, but what if you need an effect that isn't
listed? For instance, a common effect is to add a text watermark to your images. Let's
look at how we might do that.
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