/**
  * Create and load an image from a string. Format is auto-detected.
  * 
  * @param string $string Binary data, i.e. from BLOB field in the database
  * @return WideImage_Image WideImage_PaletteImage or WideImage_TrueColorImage instance
  */
 static function loadFromString($string)
 {
     if (strlen($string) < 128) {
         throw new WideImage_InvalidImageSourceException("String doesn't contain image data.");
     }
     $handle = @imagecreatefromstring($string);
     if (!self::isValidImageHandle($handle)) {
         $custom_mappers = WideImage_MapperFactory::getCustomMappers();
         foreach ($custom_mappers as $mime_type => $mapper_class) {
             $mapper = WideImage_MapperFactory::selectMapper(null, $mime_type);
             $handle = $mapper->loadFromString($string);
             if (self::isValidImageHandle($handle)) {
                 break;
             }
         }
     }
     if (!self::isValidImageHandle($handle)) {
         throw new WideImage_InvalidImageSourceException("String doesn't contain valid image data.");
     }
     return self::loadFromHandle($handle);
 }
 /**
  * Outputs the image to browser
  * 
  * Sets headers Content-length and Content-type, and echoes the image in the specified format.
  * All other headers (such as Content-disposition) must be added manually. 
  * 
  * Example:
  * <code>
  * WideImage::load('image1.png')->resize(100, 100)->output('gif');
  * </code>
  * 
  * @param string $format Image format
  */
 function output($format)
 {
     $args = func_get_args();
     $data = call_user_func_array(array($this, 'asString'), $args);
     $this->writeHeader('Content-length', strlen($data));
     $this->writeHeader('Content-type', WideImage_MapperFactory::mimeType($format));
     echo $data;
 }