Bad cropping images smaller that destination size.

I have found a bug with copying source image if source image sizes is smaller that destination field size.
In this case function imageapi_gd_image_crop() receive negative $x and $y values. And function imagecopyresampled() copies black color instead of transparent color to destination image.
I modify function imageapi_gd_image_crop() from original

function imageapi_gd_image_crop(&$image, $x, $y, $width, $height) {
  $res = _gd_create_tmp($image, $width, $height);

  if (!imagecopyresampled($res, $image->res, 0, 0, $x, $y, $width, $height, $width, $height)) {
    return false;
  }
  // destroy the original image and return the modified image.
  imagedestroy($image->res);
  $image->res = $res;
  $image->info['width'] = $width;
  $image->info['height'] = $height;
  return true;
}

to this:

function imageapi_gd_image_crop(&$image, $x, $y, $width, $height) {
  $res = _gd_create_tmp($image, $width, $height);
   $src_width=min($image->info['width'],$width);
   $src_height=min($image->info['height'],$height);
   $src_x=max(0,$x);
   $src_y=max(0,$y);
   $dst_x=max(0,-$x);
   $dst_y=max(0,-$y);
    if (!imagecopy($res, $image->res, $dst_x, $dst_y, $src_x, $src_y, $src_width, $src_height)) {
     return false;
   }

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

This is solve issue with background color when cropping.