Today, I wrote a PHP generated image. I want to view it with the browser, but every time I open it, it is a string of random code. It looks like the binary data of the image source. Then I checked that the response header is text/html. Then I clearly set image/jpeg

header("Content-type", "image/jpeg");

This shows that TP sets text/html by default. After checking the official document, it didn't say anything. Only after checking online did you know that TP has a Response class. By default, all controllers output text/html. The official document didn't say anything, so you had to turn to the Response class yourself

ThinkPHP6\vendor\topthink\framework\src\think\Response.php

The base class Response is inherited by these classes. I tried the File class, but the File is an output File and the browser downloads it directly

$file = new File('123.jpg');
$response = $file->mimeType('image/jpeg');

throw new HttpResponseException($response);

Look at the base class Response

 /**
     * Create Response object
     * @access public
     * @param  mixed  $data output data
     * @param  string $type type of output
     * @param  int    $code Status code
     * @return Response
     */
    public static function create($data = '', string $type = 'html', int $code = 200): Response
    {
        $class = false !== strpos($type, '\\') ? $type : '\\think\\response\\' . ucfirst(strtolower($type));

        return Container::getInstance()->invokeClass($class, [$data, $code]);
    }

Here is to automatically find the response class under the response directory, but I just want to set a response header to display my picture. After searching the document, I can't find a method, and then I look at the Html class under the directory. Then we can write a custom class to output the response format we want

/**
 * Html Response
 */
class Html extends Response
{
    /**
     * Output type
     * @var string
     */
    protected $contentType = 'text/html';

    public function __construct(Cookie $cookie, $data = '', int $code = 200)
    {
        $this->init($data, $code);
        $this->cookie = $cookie;
    }
}

So I wrote a Jpeg class in the response directory

/**
 * Html Response
 */
class Jpeg extends Response
{
    /**
     * Output type
     * @var string
     */
    protected $contentType = 'image/jpeg';

    public function __construct(Cookie $cookie, $data = '', int $code = 200)
    {
        $this->init($data, $code);
        $this->cookie = $cookie;
    }
}

You can output pictures

$response = Response::create('', 'Jpeg');
$image->blob('JPEG');
throw new HttpResponseException($response);

There may be a way not to be so troublesome, but the TP official document doesn't write anything, and I can't find other methods at once, which makes my header() function useless. Here is a quote from a netizen of ThinkPHP forum

The definition of framework is to develop applications more quickly and conveniently
If I use a framework, I still need to pay attention to the terms and conditions, and then define or modify many formal specifications, what else do I use the framework for
Put the cart before the horse and pick the bone in the egg