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15 years ago
I've just checked PHP's issue tracker and a core developer says that this function was never meant to support alpha channel! and they refused to commit the provided patch! so ridicules 

Anyway i tried rodrigo's workaround and it worked quite well, thanks rodrigo for sharing it.

I came up with another idea which is much faster than his solution, (it may need a little bit more memory)



Hope it helps someone.



<?php

/**

 * PNG ALPHA CHANNEL SUPPORT for imagecopymerge();

 * by Sina Salek

 *

 * Bugfix by Ralph Voigt (bug which causes it

 * to work only for $src_x = $src_y = 0. 

 * Also, inverting opacity is not necessary.)

 * 08-JAN-2011

 *

 **/

    function imagecopymerge_alpha($dst_im, $src_im, $dst_x, $dst_y, $src_x, $src_y, $src_w, $src_h, $pct){

        // creating a cut resource

        $cut = imagecreatetruecolor($src_w, $src_h);



        // copying relevant section from background to the cut resource

        imagecopy($cut, $dst_im, 0, 0, $dst_x, $dst_y, $src_w, $src_h);

        

        // copying relevant section from watermark to the cut resource

        imagecopy($cut, $src_im, 0, 0, $src_x, $src_y, $src_w, $src_h);

        

        // insert cut resource to destination image

        imagecopymerge($dst_im, $cut, $dst_x, $dst_y, 0, 0, $src_w, $src_h, $pct);

    } 



?>
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