Set a player's skin in PMMP

PngToPlayer.php

<?php

$path = 'your/path/to/skin.png';
$img = @imagecreatefrompng($path);
$bytes = '';
$l = (int) @getimagesize($path)[1];

for ($y = 0; $y < $l; $y++) {
    for ($x = 0; $x < 64; $x++) {
        $rgba = @imagecolorat($img, $x, $y);
        $a = ((~((int)($rgba >> 24))) << 1) & 0xff;
        $r = ($rgba >> 16) & 0xff;
        $g = ($rgba >> 8) & 0xff;
        $b = $rgba & 0xff;
        $bytes .= chr($r) . chr($g) . chr($b) . chr($a);
    }
}

@imagedestroy($img);

/** @var pocketmine\Player $player */
$player->setSkin(new pocketmine\entity\Skin("Standard_CustomSlim", $bytes)); //Standard_CustomSlim for alex
$player->sendSkin();