Easy Random Background Images for WordPress

Here’s a fantastic little solution I found from Dan Benjamin that allows you to drop a simple php script in a folder of images to display them at random.

By Nathan Ingram   |  December 27, 2011

Here’s a fantastic little solution I found from Dan Benjamin that allows you to drop a simple php script in a folder of images to display them at random. This code is really light and works perfectly in all my tests.

I’m using it to randomize background images on the content module of an iThemes Builder site. You can also use it to display a random image from a folder in a post as well. Yes you can do this with something like NextGen Gallery, but a simple solution like this is better if you don’t need all the features of a full gallery plugin.

Here’s all you have to do…

  1. Save the code below or copy and paste it into your text editor of choice.
  2. Save it as rotate.php (or whatever you want to call it) into a folder of images on  your web site.
  3. Add the script like you would add an image.  <img src=”path-to-your-images/rotate.php”> or for a background in css, add this to the element background-image: url(path-to-your-images/rotate.php);

Here’s an Example:

The picture below is randomly generated from the images in an upload directory of this site. Hit refresh to see it randomize.

Now Here’s the Code…

Note: I’ve removed all the commenting to make the code shorter. If you want to see the comments, view Dan Benjamin’s original article here.

<?php

$folder = '.';

$extList = array();
$extList['gif'] = 'image/gif';
$extList['jpg'] = 'image/jpeg';
$extList['jpeg'] = 'image/jpeg';
$extList['png'] = 'image/png';

$img = null;

if (substr($folder,-1) != '/') {
	$folder = $folder.'/';
}

if (isset($_GET['img'])) {
	$imageInfo = pathinfo($_GET['img']);
	if (
	    isset( $extList[ strtolower( $imageInfo['extension'] ) ] ) &&
        file_exists( $folder.$imageInfo['basename'] )
    ) {
		$img = $folder.$imageInfo['basename'];
	}
} else {
	$fileList = array();
	$handle = opendir($folder);
	while ( false !== ( $file = readdir($handle) ) ) {
		$file_info = pathinfo($file);
		if (
		    isset( $extList[ strtolower( $file_info['extension'] ) ] )
		) {
			$fileList[] = $file;
		}
	}
	closedir($handle);

	if (count($fileList) > 0) {
		$imageNumber = time() % count($fileList);
		$img = $folder.$fileList[$imageNumber];
	}
}

if ($img!=null) {
	$imageInfo = pathinfo($img);
	$contentType = 'Content-type: '.$extList[ $imageInfo['extension'] ];
	header ($contentType);
	readfile($img);
} else {
	if ( function_exists('imagecreate') ) {
		header ("Content-type: image/png");
		$im = @imagecreate (100, 100)
		    or die ("Cannot initialize new GD image stream");
		$background_color = imagecolorallocate ($im, 255, 255, 255);
		$text_color = imagecolorallocate ($im, 0,0,0);
		imagestring ($im, 2, 5, 5,  "IMAGE ERROR", $text_color);
		imagepng ($im);
		imagedestroy($im);
	}
}

?>

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