使用imagecopy功能在图像内部居中图像

Question

I have a simple script that adds an image inside an image. Here is the code:

<?php

$im = imagecreatetruecolor(650, 400);
$stamp = imagecreatefrompng('test.png');

$red = imagecolorallocate($im, 209, 231, 244);
imagefill($im, 0, 0, $red);

$marge_right = 10;
$marge_bottom = 133;
$sx = imagesx($stamp);
$sy = imagesy($stamp);

imagecopy($im, $stamp, imagesx($im) - $sx - $marge_right, imagesy($im) 
- $sy - $marge_bottom, 0, 0, imagesx($stamp), imagesy($stamp));

header('Content-type: image/png');
imagepng($im);
imagedestroy($im); 

?>

Now this will place the test image 10x from the right of the big image and 133px from bottom of image. How to place the image centered vertically depending on its height??

Thanks

Answer 1

$marge_right and $marge_bottom should correspond to the difference of horizontal and vertical sizes (respectively) between the source and destination images.

So you need to calculate the difference this way:

$marge_right = abs($dest_sx-$src_sx);
$marge_bottom = abs($dest_sy-$src_sy);

The abs is optional if you are sure the source is bigger that the source is smaller than the destination.