php多张图片拼接成一张图片

<?php
$imgs    = array();
$imgs[0] = "imgs/1.jpg";
$imgs[1] = "imgs/2.jpg";
$imgs[2] = "imgs/3.jpg";
$imgs[3] = "imgs/4.jpg";
$target  = "emp.jpg"; //背景图片
 
$target_img = Imagecreatefromjpeg($target);
 
$source = array();
 
foreach ($imgs as $k => $v) {
    $source[$k]["source"] = Imagecreatefromjpeg($v);
     
    $source[$k]["size"] = getimagesize($v);
     
}
 
//imagecopy ($target_img,$source[0]["source"],2,2,0,0,$source[0]["size"][0],$source[0]["size"][1]);
//imagecopy ($target_img,$source[1]["source"],250,2,0,0,$source[1]["size"][0],$source[1]["size"][1]);
$num1 = 0;
$num  = 1;
$tmp  = 2;
$tmpy = 2; //图片之间的间距
for ($i = 0; $i < 4; $i++) {
    imagecopy($target_img, $source[$i]["source"], $tmp, $tmpy, 0, 0, $source[$i]["size"][0], $source[$i]["size"][1]);
     
    $tmp = $tmp + $source[$i]["size"][0];
    $tmp = $tmp + 5;
    if ($i == $num) {
        $tmpy = $tmpy + $source[$i]["size"][1];
        $tmpy = $tmpy + 5;
        $tmp  = 2;
        $num  = $num + 3;
    }
}
Imagejpeg($target_img, "pin.jpg");
 
?>
<img src="pin.jpg">