1. 6.x includes/image.gd.inc
  2. 7.x modules/system/image.gd.inc

GD2 toolkit for image manipulation within Drupal.

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modules/system/image.gd.inc
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<?php

/**
 * @file
 * GD2 toolkit for image manipulation within Drupal.
 */

/**
 * @addtogroup image
 * @{
 */

/**
 * Retrieve settings for the GD2 toolkit.
 */
function image_gd_settings() {
  if (image_gd_check_settings()) {
    $form['status'] = array(
      '#markup' => t('The GD toolkit is installed and working properly.'),
    );
    $form['image_jpeg_quality'] = array(
      '#type' => 'textfield',
      '#title' => t('JPEG quality'),
      '#description' => t('Define the image quality for JPEG manipulations. Ranges from 0 to 100. Higher values mean better image quality but bigger files.'),
      '#size' => 10,
      '#maxlength' => 3,
      '#default_value' => variable_get('image_jpeg_quality', 75),
      '#field_suffix' => t('%'),
    );
    $form['#element_validate'] = array(
      'image_gd_settings_validate',
    );
    return $form;
  }
  else {
    form_set_error('image_toolkit', t('The GD image toolkit requires that the GD module for PHP be installed and configured properly. For more information see <a href="@url">PHP\'s image documentation</a>.', array(
      '@url' => 'http://php.net/image',
    )));
    return FALSE;
  }
}

/**
 * Validate the submitted GD settings.
 */
function image_gd_settings_validate($form, &$form_state) {

  // Validate image quality range.
  $value = $form_state['values']['image_jpeg_quality'];
  if (!is_numeric($value) || $value < 0 || $value > 100) {
    form_set_error('image_jpeg_quality', t('JPEG quality must be a number between 0 and 100.'));
  }
}

/**
 * Verify GD2 settings (that the right version is actually installed).
 *
 * @return
 *   A boolean indicating if the GD toolkit is available on this machine.
 */
function image_gd_check_settings() {

  // GD2 support is available.
  return function_exists('imagegd2');
}

/**
 * Scale an image to the specified size using GD.
 *
 * @param $image
 *   An image object. The $image->resource, $image->info['width'], and
 *   $image->info['height'] values will be modified by this call.
 * @param $width
 *   The new width of the resized image, in pixels.
 * @param $height
 *   The new height of the resized image, in pixels.
 * @return
 *   TRUE or FALSE, based on success.
 *
 * @see image_resize()
 */
function image_gd_resize(stdClass $image, $width, $height) {
  $res = image_gd_create_tmp($image, $width, $height);
  if (!imagecopyresampled($res, $image->resource, 0, 0, 0, 0, $width, $height, $image->info['width'], $image->info['height'])) {
    return FALSE;
  }
  imagedestroy($image->resource);

  // Update image object.
  $image->resource = $res;
  $image->info['width'] = $width;
  $image->info['height'] = $height;
  return TRUE;
}

/**
 * Rotate an image the given number of degrees.
 *
 * @param $image
 *   An image object. The $image->resource, $image->info['width'], and
 *   $image->info['height'] values will be modified by this call.
 * @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 or FALSE, based on success.
 *
 * @see image_rotate()
 */
function image_gd_rotate(stdClass $image, $degrees, $background = NULL) {

  // PHP installations using non-bundled GD do not have imagerotate.
  if (!function_exists('imagerotate')) {
    watchdog('image', 'The image %file could not be rotated because the imagerotate() function is not available in this PHP installation.', array(
      '%file' => $image->source,
    ));
    return FALSE;
  }

  // PHP 5.5 GD bug: https://bugs.php.net/bug.php?id=65148: To prevent buggy
  // behavior on negative multiples of 90 degrees we convert any negative
  // angle to a positive one between 0 and 360 degrees.
  $degrees -= floor($degrees / 360) * 360;

  // Convert the hexadecimal background value to a RGBA array.
  if (isset($background)) {
    $background = array(
      'red' => $background >> 16 & 0xff,
      'green' => $background >> 8 & 0xff,
      'blue' => $background & 0xff,
      'alpha' => 0,
    );
  }
  else {

    // Background color is not specified: use transparent white as background.
    $background = array(
      'red' => 255,
      'green' => 255,
      'blue' => 255,
      'alpha' => 127,
    );
  }

  // Store the color index for the background as that is what GD uses.
  $background_idx = imagecolorallocatealpha($image->resource, $background['red'], $background['green'], $background['blue'], $background['alpha']);

  // Images are assigned a new color palette when rotating, removing any
  // transparency flags. For GIF images, keep a record of the transparent color.
  if ($image->info['extension'] == 'gif') {

    // GIF does not work with a transparency channel, but can define 1 color
    // in its palette to act as transparent.
    // Get the current transparent color, if any.
    $gif_transparent_id = imagecolortransparent($image->resource);
    if ($gif_transparent_id !== -1) {

      // The gif already has a transparent color set: remember it to set it on
      // the rotated image as well.
      $transparent_gif_color = imagecolorsforindex($image->resource, $gif_transparent_id);
      if ($background['alpha'] >= 127) {

        // We want a transparent background: use the color already set to act
        // as transparent, as background.
        $background_idx = $gif_transparent_id;
      }
    }
    else {

      // The gif does not currently have a transparent color set.
      if ($background['alpha'] >= 127) {

        // But as the background is transparent, it should get one.
        $transparent_gif_color = $background;
      }
    }
  }
  $image->resource = imagerotate($image->resource, 360 - $degrees, $background_idx);

  // GIFs need to reassign the transparent color after performing the rotate.
  if (isset($transparent_gif_color)) {
    $background = imagecolorexactalpha($image->resource, $transparent_gif_color['red'], $transparent_gif_color['green'], $transparent_gif_color['blue'], $transparent_gif_color['alpha']);
    imagecolortransparent($image->resource, $background);
  }
  $image->info['width'] = imagesx($image->resource);
  $image->info['height'] = imagesy($image->resource);
  return TRUE;
}

/**
 * Crop an image using the GD toolkit.
 *
 * @param $image
 *   An image object. The $image->resource, $image->info['width'], and
 *   $image->info['height'] values will be modified by this call.
 * @param $x
 *   The starting x offset at which to start the crop, in pixels.
 * @param $y
 *   The starting y offset at which to start the crop, in pixels.
 * @param $width
 *   The width of the cropped area, in pixels.
 * @param $height
 *   The height of the cropped area, in pixels.
 * @return
 *   TRUE or FALSE, based on success.
 *
 * @see image_crop()
 */
function image_gd_crop(stdClass $image, $x, $y, $width, $height) {
  $res = image_gd_create_tmp($image, $width, $height);
  if (!imagecopyresampled($res, $image->resource, 0, 0, $x, $y, $width, $height, $width, $height)) {
    return FALSE;
  }

  // Destroy the original image and return the modified image.
  imagedestroy($image->resource);
  $image->resource = $res;
  $image->info['width'] = $width;
  $image->info['height'] = $height;
  return TRUE;
}

/**
 * Convert an image resource to grayscale.
 *
 * Note that transparent GIFs loose transparency when desaturated.
 *
 * @param $image
 *   An image object. The $image->resource value will be modified by this call.
 * @return
 *   TRUE or FALSE, based on success.
 *
 * @see image_desaturate()
 */
function image_gd_desaturate(stdClass $image) {

  // PHP installations using non-bundled GD do not have imagefilter.
  if (!function_exists('imagefilter')) {
    watchdog('image', 'The image %file could not be desaturated because the imagefilter() function is not available in this PHP installation.', array(
      '%file' => $image->source,
    ));
    return FALSE;
  }
  return imagefilter($image->resource, IMG_FILTER_GRAYSCALE);
}

/**
 * GD helper function to create an image resource from a file.
 *
 * @param $image
 *   An image object. The $image->resource value will populated by this call.
 * @return
 *   TRUE or FALSE, based on success.
 *
 * @see image_load()
 */
function image_gd_load(stdClass $image) {
  $extension = str_replace('jpg', 'jpeg', $image->info['extension']);
  $function = 'imagecreatefrom' . $extension;
  if (function_exists($function) && ($image->resource = $function($image->source))) {
    if (imageistruecolor($image->resource)) {
      return TRUE;
    }
    else {

      // Convert indexed images to truecolor, copying the image to a new
      // truecolor resource, so that filters work correctly and don't result
      // in unnecessary dither.
      $resource = image_gd_create_tmp($image, $image->info['width'], $image->info['height']);
      if ($resource) {
        imagecopy($resource, $image->resource, 0, 0, 0, 0, imagesx($resource), imagesy($resource));
        imagedestroy($image->resource);
        $image->resource = $resource;
      }
    }
    return (bool) $image->resource;
  }
  return FALSE;
}

/**
 * GD helper to write an image resource to a destination file.
 *
 * @param $image
 *   An image object.
 * @param $destination
 *   A string file URI or path where the image should be saved.
 * @return
 *   TRUE or FALSE, based on success.
 *
 * @see image_save()
 */
function image_gd_save(stdClass $image, $destination) {
  $scheme = file_uri_scheme($destination);

  // Work around lack of stream wrapper support in imagejpeg() and imagepng().
  if ($scheme && file_stream_wrapper_valid_scheme($scheme)) {

    // If destination is not local, save image to temporary local file.
    $local_wrappers = file_get_stream_wrappers(STREAM_WRAPPERS_LOCAL);
    if (!isset($local_wrappers[$scheme])) {
      $permanent_destination = $destination;
      $destination = drupal_tempnam('temporary://', 'gd_');
    }

    // Convert stream wrapper URI to normal path.
    $destination = drupal_realpath($destination);
  }
  $extension = str_replace('jpg', 'jpeg', $image->info['extension']);
  $function = 'image' . $extension;
  if (!function_exists($function)) {
    return FALSE;
  }
  if ($extension == 'jpeg') {
    $success = $function($image->resource, $destination, variable_get('image_jpeg_quality', 75));
  }
  else {

    // Always save PNG images with full transparency.
    if ($extension == 'png') {
      imagealphablending($image->resource, FALSE);
      imagesavealpha($image->resource, TRUE);
    }
    $success = $function($image->resource, $destination);
  }

  // Move temporary local file to remote destination.
  if (isset($permanent_destination) && $success) {
    return (bool) file_unmanaged_move($destination, $permanent_destination, FILE_EXISTS_REPLACE);
  }
  return $success;
}

/**
 * Create a truecolor image preserving transparency from a provided image.
 *
 * @param $image
 *   An image object.
 * @param $width
 *   The new width of the new image, in pixels.
 * @param $height
 *   The new height of the new image, in pixels.
 * @return
 *   A GD image handle.
 */
function image_gd_create_tmp(stdClass $image, $width, $height) {
  $res = imagecreatetruecolor($width, $height);
  if ($image->info['extension'] == 'gif') {

    // Find out if a transparent color is set, will return -1 if no
    // transparent color has been defined in the image.
    $transparent = imagecolortransparent($image->resource);
    if ($transparent >= 0) {

      // Find out the number of colors in the image palette. It will be 0 for
      // truecolor images.
      $palette_size = imagecolorstotal($image->resource);
      if ($palette_size == 0 || $transparent < $palette_size) {

        // Set the transparent color in the new resource, either if it is a
        // truecolor image or if the transparent color is part of the palette.
        // Since the index of the transparency color is a property of the
        // image rather than of the palette, it is possible that an image
        // could be created with this index set outside the palette size (see
        // http://stackoverflow.com/a/3898007).
        $transparent_color = imagecolorsforindex($image->resource, $transparent);
        $transparent = imagecolorallocate($res, $transparent_color['red'], $transparent_color['green'], $transparent_color['blue']);

        // Flood with our new transparent color.
        imagefill($res, 0, 0, $transparent);
        imagecolortransparent($res, $transparent);
      }
      else {
        imagefill($res, 0, 0, imagecolorallocate($res, 255, 255, 255));
      }
    }
  }
  elseif ($image->info['extension'] == 'png') {
    imagealphablending($res, FALSE);
    $transparency = imagecolorallocatealpha($res, 0, 0, 0, 127);
    imagefill($res, 0, 0, $transparency);
    imagealphablending($res, TRUE);
    imagesavealpha($res, TRUE);
  }
  else {
    imagefill($res, 0, 0, imagecolorallocate($res, 255, 255, 255));
  }
  return $res;
}

/**
 * Get details about an image.
 *
 * @param $image
 *   An image object.
 * @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').
 *
 * @see image_get_info()
 */
function image_gd_get_info(stdClass $image) {
  $details = FALSE;
  $data = @getimagesize($image->source);
  if (isset($data) && is_array($data)) {
    $extensions = array(
      '1' => 'gif',
      '2' => 'jpg',
      '3' => 'png',
    );
    $extension = isset($extensions[$data[2]]) ? $extensions[$data[2]] : '';
    $details = array(
      'width' => $data[0],
      'height' => $data[1],
      'extension' => $extension,
      'mime_type' => $data['mime'],
    );
  }
  return $details;
}

/**
 * @} End of "addtogroup image".
 */

Functions

Namesort descending Description
image_gd_check_settings Verify GD2 settings (that the right version is actually installed).
image_gd_create_tmp Create a truecolor image preserving transparency from a provided image.
image_gd_crop Crop an image using the GD toolkit.
image_gd_desaturate Convert an image resource to grayscale.
image_gd_get_info Get details about an image.
image_gd_load GD helper function to create an image resource from a file.
image_gd_resize Scale an image to the specified size using GD.
image_gd_rotate Rotate an image the given number of degrees.
image_gd_save GD helper to write an image resource to a destination file.
image_gd_settings Retrieve settings for the GD2 toolkit.
image_gd_settings_validate Validate the submitted GD settings.

Comments

MattA’s picture

For those looking to upgrade, many of the functions in this file have been moved to the GDToolkit class. While the effect functions have been converted into their own plugins: