image.inc

<?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".
 */