Question

I’d like to add a regex filter to the script below (just before the array_push) so that, when it encounters files that have the same prefix “_filename” and one of the matches has ‘-150×150.’ at the end of the filename, it pushes that image and skips the others with the same prefix.

However, if there are no images in that collection that have ‘-150×150.’ in the filename, it selects the image with the root prefix (_filename.ext)

For example, if the following files reside in the $dir folder:

_file.png
_file-150x150.png
_file-200x300.png
_someImage.png
_myfile.jpg
_myfile-200x200.jpg

I’d like it to push _file-150×150.png, someImage.png and myfile.jpg into the array, and skip over the others.

$dir = 'wp-content/uploads/';
if(!is_dir($dir)){return;}
$url = get_bloginfo('url').'/wp-content/uploads/';

$imgs = array();
if ($dh = opendir($dir)) 
{
    $myfilter="";
    while (($file = readdir($dh)) !== false) 
        {
        if (!is_dir($file)&& $file != "." && $file != ".." && preg_match("/^[".$myfilter."_].*\.(bmp|jpeg|gif|png|jpg)$/i", $file)) 
            {
                array_push($imgs, $file);
            }
        }
        closedir($dh);
    } else {
        die('cannot open ' . $dir);
    }
    if($imgs) 
    {
        sort($imgs); 
        echo '<div>';
        foreach ($imgs as $idx=>$img) 
        {
            $class = ($idx == count($imgs) - 1 ? ' class="last"' : '');
            echo $prelink.' src="' . $url . $img . '" alt="' .$img . '"' . $class . ' />'.$postlink;
        }
        echo '</div>';
    }

Answer 1

Assuming that the 150×150 filename will always come after the base class, here’s a regex you can use for that:

/^([^-.]+)(?:-150x150)?\.png\b(?!.*\1-150x150\.png\b)/ms

Explanation:

/
^                        #Match the start of the line
([^-.]+)                 #Match the first part of the file before the -sizeXsize
                         #And store it in the first capturing group.
(?:-150x150)?            #Match 0 or 1 of the desired size.
                         #(?:) is so that you don't store this match.
\.png\b                  #followed by .png
(?!.*\1-150x150\.png\b)  #A negative look ahead for the desired resolution.
                         #i.e. don't match the base if the desired resolution exists.
/ms                      #m is for multiline so that the ^ means start of line rather than start of string.
                         #s is for dotall so that the .* in the lookahead can match newlines.

The result will be something like this:

Array
(
    [0] => Array
        (
            [0] => _file-150x150.png
            [1] => _someImage.png
        )

    [1] => Array
        (
            [0] => _file
            [1] => _someImage
        )

)