Creates a image form input.
echo Form::image(null, null, array('src' => 'media/img/login.png'));
string Core_Form::image( string $name , string $value [, array $attributes = null ] )
参数列表
参数 类型 描述 默认值 $namestringInput name $valuestringInput value $attributesarrayHtml attributes null 
string public static function image($name, $value, array $attributes = null)
{
    if (!empty($attributes['src']))
    {
        if (strpos($attributes['src'], '://') === false)
        {
            $attributes['src'] = Core::url($attributes['src']);
        }
    }
    $attributes['type'] = 'image';
    return Form::input($name, $value, $attributes);
}