How to dynamically generate random pictures of specified size in PHP_php tips

The example in this article describes the method of dynamically generating random pictures of specified sizes in PHP. Share it with everyone for your reference, the details are as follows:

<&#63;php
$image_width = 100;
$image_height = 100;
$image_str = '';
if (isset($_GET['w']))
{
  $image_width = intval($_GET['w']);
}
if (isset($_GET['h']))
{
  $image_height = intval($_GET['h']);
}
if (isset($_GET['s']))
{
  $image_str = $_GET['s'];
}
$img = imagecreate($image_width, $image_height);
$color = imagecolorallocate($img, mt_rand(157,255), mt_rand(157,255), mt_rand(157,255));
imagefilledrectangle($img, 0, $image_height, $image_width, 0, $color);
$step = mt_rand(15, 30);
$start = mt_rand(0, $step);
$color = imagecolorallocate($img, mt_rand(200,255), mt_rand(200,255), mt_rand(200,255));
imagesetthickness($img, mt_rand(3, 10));
if ($image_height > $image_width)
{
  for ($i=$start; $i<$image_height * 2; $i+=$step)
  {
    imageline($img, 0, $i, $i, 0, $color);
  }
}
else
{
  for ($i=$start; $i<$image_width * 2; $i+=$step)
  {
    imageline($img, $i, 0, 0, $i, $color);
  }
}
if ($image_str != '')
{
  $black = imagecolorallocate($img, 0, 0, 0);
  imagestring($img, 12, 5, 5, $image_str, $black);
}
header('Content-type:image/png');
imagepng($img);
imagedestroy($img);

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I hope this article will be helpful to everyone in PHP programming.