<?php

/**

 * @file

 * API for manipulating images.

 */

/**

 * @defgroup image Image toolkits

 * @{

 * Functions for image file manipulations.

 *

 * Drupal's image toolkits provide an abstraction layer for common image file

 * manipulations like scaling, cropping, and rotating. The abstraction frees

 * module authors from the need to support multiple image libraries, and it

 * allows site administrators to choose the library that's best for them.

 *

 * PHP includes the GD library by default so a GD toolkit is installed with

 * Drupal. Other toolkits like ImageMagick are available from contrib modules.

 * GD works well for small images, but using it with larger files may cause PHP

 * to run out of memory. In contrast the ImageMagick library does not suffer

 * from this problem, but it requires the ISP to have installed additional

 * software.

 *

 * Image toolkits are discovered based on the associated module's

 * hook_image_toolkits. Additionally the image toolkit include file

 * must be identified in the files array in the module.info file. The

 * toolkit must then be enabled using the admin/config/media/image-toolkit

 * form.

 *

 * Only one toolkit may be selected at a time. If a module author wishes to call

 * a specific toolkit they can check that it is installed by calling

 * image_get_available_toolkits(), and then calling its functions directly.

 */

/**

 * Gets a list of available toolkits.

 *

 * @return

 *   An array with the toolkit names as keys and the descriptions as values.

 */

function image_get_available_toolkits() {

  // hook_image_toolkits returns an array of toolkit names.

  $toolkits = module_invoke_all('image_toolkits');

  $output = array();

  foreach ($toolkits as $name => $info) {

    // Only allow modules that aren't marked as unavailable.

    if ($info['available']) {

      $output[$name] = $info['title'];

    }

  }

  return $output;

}

/**

 * Gets the name of the currently used toolkit.

 *

 * @return

 *   String containing the name of the selected toolkit, or FALSE on error.

 */

function image_get_toolkit() {

  static $toolkit;

  if (!isset($toolkit)) {

    $toolkits = image_get_available_toolkits();

    $toolkit = variable_get('image_toolkit', 'gd');

    if (!isset($toolkits[$toolkit]) || !function_exists('image_' . $toolkit . '_load')) {

      // The selected toolkit isn't available so return the first one found. If

      // none are available this will return FALSE.

      reset($toolkits);

      $toolkit = key($toolkits);

    }

  }

  return $toolkit;

}

/**

 * Invokes the given method using the currently selected toolkit.

 *

 * @param $method

 *   A string containing the method to invoke.

 * @param $image

 *   An image object returned by image_load().

 * @param $params

 *   An optional array of parameters to pass to the toolkit method.

 *

 * @return

 *   Mixed values (typically Boolean indicating successful operation).

 */

function image_toolkit_invoke($method, stdClass $image, array $params = array()) {

  $function = 'image_' . $image->toolkit . '_' . $method;

  if (function_exists($function)) {

    array_unshift($params, $image);

    return call_user_func_array($function, $params);

  }

  watchdog('image', 'The selected image handling toolkit %toolkit can not correctly process %function.', array('%toolkit' => $image->toolkit, '%function' => $function), WATCHDOG_ERROR);

  return FALSE;

}

/**

 * Gets details about an image.

 *

 * Drupal supports GIF, JPG and PNG file formats when used with the GD

 * toolkit, and may support others, depending on which toolkits are

 * installed.

 *

 * @param $filepath

 *   String specifying the path of the image file.

 * @param $toolkit

 *   An optional image toolkit name to override the default.

 *

 * @return

 *   FALSE, if the file could not be found or is not an image. Otherwise, a

 *   keyed array containing information about the image:

 *   - "width": Width, in pixels.

 *   - "height": Height, in pixels.

 *   - "extension": Commonly used file extension for the image.

 *   - "mime_type": MIME type ('image/jpeg', 'image/gif', 'image/png').

 *   - "file_size": File size in bytes.

 */

function image_get_info($filepath, $toolkit = FALSE) {

  $details = FALSE;

  if (!is_file($filepath) && !is_uploaded_file($filepath)) {

    return $details;

  }

  if (!$toolkit) {

    $toolkit = image_get_toolkit();

  }

  if ($toolkit) {

    $image = new stdClass();

    $image->source = $filepath;

    $image->toolkit = $toolkit;

    $details = image_toolkit_invoke('get_info', $image);

    if (isset($details) && is_array($details)) {

      $details['file_size'] = filesize($filepath);

    }

  }

  return $details;

}

/**

 * Scales an image to the exact width and height given.

 *

 * This function achieves the target aspect ratio by cropping the original image

 * equally on both sides, or equally on the top and bottom. This function is

 * useful to create uniform sized avatars from larger images.

 *

 * The resulting image always has the exact target dimensions.

 *

 * @param $image

 *   An image object returned by image_load().

 * @param $width

 *   The target width, in pixels.

 * @param $height

 *   The target height, in pixels.

 *

 * @return

 *   TRUE on success, FALSE on failure.

 *

 * @see image_load()

 * @see image_resize()

 * @see image_crop()

 */

function image_scale_and_crop(stdClass $image, $width, $height) {

  $scale = max($width / $image->info['width'], $height / $image->info['height']);

  $x = ($image->info['width'] * $scale - $width) / 2;

  $y = ($image->info['height'] * $scale - $height) / 2;

  if (image_resize($image, $image->info['width'] * $scale, $image->info['height'] * $scale)) {

    return image_crop($image, $x, $y, $width, $height);

  }

  return FALSE;

}

/**

 * Scales image dimensions while maintaining aspect ratio.

 *

 * The resulting dimensions can be smaller for one or both target dimensions.

 *

 * @param $dimensions

 *   Dimensions to be modified - an array with components width and height, in

 *   pixels.

 * @param $width

 *   The target width, in pixels. If this value is NULL then the scaling will be

 *   based only on the height value.

 * @param $height

 *   The target height, in pixels. If this value is NULL then the scaling will

 *   be based only on the width value.

 * @param $upscale

 *   Boolean indicating that images smaller than the target dimensions will be

 *   scaled up. This generally results in a low quality image.

 *

 * @return

 *   TRUE if $dimensions was modified, FALSE otherwise.

 *

 * @see image_scale()

 */

function image_dimensions_scale(array &$dimensions, $width = NULL, $height = NULL, $upscale = FALSE) {

  $aspect = $dimensions['height'] / $dimensions['width'];

  // Calculate one of the dimensions from the other target dimension,

  // ensuring the same aspect ratio as the source dimensions. If one of the

  // target dimensions is missing, that is the one that is calculated. If both

  // are specified then the dimension calculated is the one that would not be

  // calculated to be bigger than its target.

  if (($width && !$height) || ($width && $height && $aspect < $height / $width)) {

    $height = (int) round($width * $aspect);

  }

  else {

    $width = (int) round($height / $aspect);

  }

  // Don't upscale if the option isn't enabled.

  if (!$upscale && ($width >= $dimensions['width'] || $height >= $dimensions['height'])) {

    return FALSE;

  }

  $dimensions['width'] = $width;

  $dimensions['height'] = $height;

  return TRUE;

}

/**

 * Scales an image while maintaining aspect ratio.

 *

 * The resulting image can be smaller for one or both target dimensions.

 *

 * @param $image

 *   An image object returned by image_load().

 * @param $width

 *   The target width, in pixels. If this value is NULL then the scaling will

 *   be based only on the height value.

 * @param $height

 *   The target height, in pixels. If this value is NULL then the scaling will

 *   be based only on the width value.

 * @param $upscale

 *   Boolean indicating that files smaller than the dimensions will be scaled

 *   up. This generally results in a low quality image.

 *

 * @return

 *   TRUE on success, FALSE on failure.

 *

 * @see image_dimensions_scale()

 * @see image_load()

 * @see image_scale_and_crop()

 */

function image_scale(stdClass $image, $width = NULL, $height = NULL, $upscale = FALSE) {

  $dimensions = $image->info;

  // Scale the dimensions - if they don't change then just return success.

  if (!image_dimensions_scale($dimensions, $width, $height, $upscale)) {

    return TRUE;

  }

  return image_resize($image, $dimensions['width'], $dimensions['height']);

}

/**

 * Resizes an image to the given dimensions (ignoring aspect ratio).

 *

 * @param $image

 *   An image object returned by image_load().

 * @param $width

 *   The target width, in pixels.

 * @param $height

 *   The target height, in pixels.

 *

 * @return

 *   TRUE on success, FALSE on failure.

 *

 * @see image_load()

 * @see image_gd_resize()

 */

function image_resize(stdClass $image, $width, $height) {

  $width = (int) round($width);

  $height = (int) round($height);

  return image_toolkit_invoke('resize', $image, array($width, $height));

}

/**

 * Rotates an image by the given number of degrees.

 *

 * @param $image

 *   An image object returned by image_load().

 * @param $degrees

 *   The number of (clockwise) degrees to rotate the image.

 * @param $background

 *   An hexadecimal integer specifying the background color to use for the

 *   uncovered area of the image after the rotation. E.g. 0x000000 for black,

 *   0xff00ff for magenta, and 0xffffff for white. For images that support

 *   transparency, this will default to transparent. Otherwise it will

 *   be white.

 *

 * @return

 *   TRUE on success, FALSE on failure.

 *

 * @see image_load()

 * @see image_gd_rotate()

 */

function image_rotate(stdClass $image, $degrees, $background = NULL) {

  return image_toolkit_invoke('rotate', $image, array($degrees, $background));

}

/**

 * Crops an image to a rectangle specified by the given dimensions.

 *

 * @param $image

 *   An image object returned by image_load().

 * @param $x

 *   The top left coordinate, in pixels, of the crop area (x axis value).

 * @param $y

 *   The top left coordinate, in pixels, of the crop area (y axis value).

 * @param $width

 *   The target width, in pixels.

 * @param $height

 *   The target height, in pixels.

 *

 * @return

 *   TRUE on success, FALSE on failure.

 *

 * @see image_load()

 * @see image_scale_and_crop()

 * @see image_gd_crop()

 */

function image_crop(stdClass $image, $x, $y, $width, $height) {

  $aspect = $image->info['height'] / $image->info['width'];

  if (empty($height)) $height = $width / $aspect;

  if (empty($width)) $width = $height * $aspect;

  $width = (int) round($width);

  $height = (int) round($height);

  return image_toolkit_invoke('crop', $image, array($x, $y, $width, $height));

}

/**

 * Converts an image to grayscale.

 *

 * @param $image

 *   An image object returned by image_load().

 *

 * @return

 *   TRUE on success, FALSE on failure.

 *

 * @see image_load()

 * @see image_gd_desaturate()

 */

function image_desaturate(stdClass $image) {

  return image_toolkit_invoke('desaturate', $image);

}

/**

 * Loads an image file and returns an image object.

 *

 * Any changes to the file are not saved until image_save() is called.

 *

 * @param $file

 *   Path to an image file.

 * @param $toolkit

 *   An optional, image toolkit name to override the default.

 *

 * @return

 *   An image object or FALSE if there was a problem loading the file. The

 *   image object has the following properties:

 *    - 'source' - The original file path.

 *    - 'info' - The array of information returned by image_get_info()

 *    - 'toolkit' - The name of the image toolkit requested when the image was

 *      loaded.

 *   Image toolkits may add additional properties. The caller is advised not to

 *   monkey about with them.

 *

 * @see image_save()

 * @see image_get_info()

 * @see image_get_available_toolkits()

 * @see image_gd_load()

 */

function image_load($file, $toolkit = FALSE) {

  if (!$toolkit) {

    $toolkit = image_get_toolkit();

  }

  if ($toolkit) {

    $image = new stdClass();

    $image->source = $file;

    $image->info = image_get_info($file, $toolkit);

    if (isset($image->info) && is_array($image->info)) {

      $image->toolkit = $toolkit;

      if (image_toolkit_invoke('load', $image)) {

        return $image;

      }

    }

  }

  return FALSE;

}

/**

 * Closes the image and saves the changes to a file.

 *

 * @param $image

 *   An image object returned by image_load(). The object's 'info' property

 *   will be updated if the file is saved successfully.

 * @param $destination

 *   Destination path where the image should be saved. If it is empty the

 *   original image file will be overwritten.

 *

 * @return

 *   TRUE on success, FALSE on failure.

 *

 * @see image_load()

 * @see image_gd_save()

 */

function image_save(stdClass $image, $destination = NULL) {

  if (empty($destination)) {

    $destination = $image->source;

  }

  if ($return = image_toolkit_invoke('save', $image, array($destination))) {

    // Clear the cached file size and refresh the image information.

    clearstatcache();

    $image->info = image_get_info($destination, $image->toolkit);

    if (drupal_chmod($destination)) {

      return $return;

    }

  }

  return FALSE;

}

/**

 * @} End of "defgroup image".

 */