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<?php

/**

 * @file

 * Hooks related to image styles and effects.

 */

/**

 * @addtogroup hooks

 * @{

 */

/**

 * Define information about image effects provided by a module.

 *

 * This hook enables modules to define image manipulation effects for use with

 * an image style.

 *

 * @return

 *   An array of image effects. This array is keyed on the machine-readable

 *   effect name. Each effect is defined as an associative array containing the

 *   following items:

 *   - "label": The human-readable name of the effect.

 *   - "effect callback": The function to call to perform this image effect.

 *   - "dimensions passthrough": (optional) Set this item if the effect doesn't

 *     change the dimensions of the image.

 *   - "dimensions callback": (optional) The function to call to transform

 *     dimensions for this effect.

 *   - "help": (optional) A brief description of the effect that will be shown

 *     when adding or configuring this image effect.

 *   - "form callback": (optional) The name of a function that will return a

 *     $form array providing a configuration form for this image effect.

 *   - "summary theme": (optional) The name of a theme function that will output

 *     a summary of this image effect's configuration.

 *

 * @see hook_image_effect_info_alter()

 */

function hook_image_effect_info() {

  $effects = array();

  $effects['mymodule_resize'] = array(

    'label' => t('Resize'),

    'help' => t('Resize an image to an exact set of dimensions, ignoring aspect ratio.'),

    'effect callback' => 'mymodule_resize_effect',

    'dimensions callback' => 'mymodule_resize_dimensions',

    'form callback' => 'mymodule_resize_form',

    'summary theme' => 'mymodule_resize_summary',

  );

  return $effects;

}

/**

 * Alter the information provided in hook_image_effect_info().

 *

 * @param $effects

 *   The array of image effects, keyed on the machine-readable effect name.

 *

 * @see hook_image_effect_info()

 */

function hook_image_effect_info_alter(&$effects) {

  // Override the Image module's crop effect with more options.

  $effects['image_crop']['effect callback'] = 'mymodule_crop_effect';

  $effects['image_crop']['dimensions callback'] = 'mymodule_crop_dimensions';

  $effects['image_crop']['form callback'] = 'mymodule_crop_form';

}

/**

 * Respond to image style updating.

 *

 * This hook enables modules to update settings that might be affected by

 * changes to an image. For example, updating a module specific variable to

 * reflect a change in the image style's name.

 *

 * @param $style

 *   The image style array that is being updated.

 */

function hook_image_style_save($style) {

  // If a module defines an image style and that style is renamed by the user

  // the module should update any references to that style.

  if (isset($style['old_name']) && $style['old_name'] == variable_get('mymodule_image_style', '')) {

    variable_set('mymodule_image_style', $style['name']);

  }

}

/**

 * Respond to image style deletion.

 *

 * This hook enables modules to update settings when a image style is being

 * deleted. If a style is deleted, a replacement name may be specified in

 * $style['name'] and the style being deleted will be specified in

 * $style['old_name'].

 *

 * @param $style

 *   The image style array that being deleted.

 */

function hook_image_style_delete($style) {

  // Administrators can choose an optional replacement style when deleting.

  // Update the modules style variable accordingly.

  if (isset($style['old_name']) && $style['old_name'] == variable_get('mymodule_image_style', '')) {

    variable_set('mymodule_image_style', $style['name']);

  }

}

/**

 * Respond to image style flushing.

 *

 * This hook enables modules to take effect when a style is being flushed (all

 * images are being deleted from the server and regenerated). Any

 * module-specific caches that contain information related to the style should

 * be cleared using this hook. This hook is called whenever a style is updated,

 * deleted, or any effect associated with the style is update or deleted.

 *

 * @param $style

 *   The image style array that is being flushed.

 */

function hook_image_style_flush($style) {

  // Empty cached data that contains information about the style.

  cache_clear_all('*', 'cache_mymodule', TRUE);

}

/**

 * Modify any image styles provided by other modules or the user.

 *

 * This hook allows modules to modify, add, or remove image styles. This may

 * be useful to modify default styles provided by other modules or enforce

 * that a specific effect is always enabled on a style. Note that modifications

 * to these styles may negatively affect the user experience, such as if an

 * effect is added to a style through this hook, the user may attempt to remove

 * the effect but it will be immediately be re-added.

 *

 * The best use of this hook is usually to modify default styles, which are not

 * editable by the user until they are overridden, so such interface

 * contradictions will not occur. This hook can target default (or user) styles

 * by checking the $style['storage'] property.

 *

 * If your module needs to provide a new style (rather than modify an existing

 * one) use hook_image_default_styles() instead.

 *

 * @see hook_image_default_styles()

 */

function hook_image_styles_alter(&$styles) {

  // Check that we only affect a default style.

  if ($styles['thumbnail']['storage'] == IMAGE_STORAGE_DEFAULT) {

    // Add an additional effect to the thumbnail style.

    $styles['thumbnail']['effects'][] = array(

      'name' => 'image_desaturate',

      'data' => array(),

      'weight' => 1,

      'effect callback' => 'image_desaturate_effect',

    );

  }

}

/**

 * Provide module-based image styles for reuse throughout Drupal.

 *

 * This hook allows your module to provide image styles. This may be useful if

 * you require images to fit within exact dimensions. Note that you should

 * attempt to re-use the default styles provided by Image module whenever

 * possible, rather than creating image styles that are specific to your module.

 * Image provides the styles "thumbnail", "medium", and "large".

 *

 * You may use this hook to more easily manage your site's changes by moving

 * existing image styles from the database to a custom module. Note however that

 * moving image styles to code instead storing them in the database has a

 * negligible effect on performance, since custom image styles are loaded

 * from the database all at once. Even if all styles are pulled from modules,

 * Image module will still perform the same queries to check the database for

 * any custom styles.

 *

 * @return

 *   An array of image styles, keyed by the style name.

 * @see image_image_default_styles()

 */

function hook_image_default_styles() {

  $styles = array();

  $styles['mymodule_preview'] = array(

    'label' => 'My module preview',

    'effects' => array(

      array(

        'name' => 'image_scale',

        'data' => array('width' => 400, 'height' => 400, 'upscale' => 1),

        'weight' => 0,

      ),

      array(

        'name' => 'image_desaturate',

        'data' => array(),

        'weight' => 1,

      ),

    ),

  );

  return $styles;

}

 /**

  * @} End of "addtogroup hooks".

  */