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Bug #72913 imagecopy() loses single-color transparency on palette images
Submitted: 2016-08-21 15:26 UTC Modified: 2016-08-21 15:26 UTC
From: cmb@php.net Assigned: cmb
Status: Closed Package: GD related
PHP Version: 7.0.10 OS: *
Private report: No CVE-ID:
 [2016-08-21 15:26 UTC] cmb@php.net
Description:
------------
When copying a single-color transparency true-color image onto a
palette image with imagecopy(), the transparency is lost, if
compiled against the bundled libgd. With external libgd it works
fine.

That bug affects all currently supported PHP versions.

Test script:
---------------
<?php

$base64 = 'iVBORw0KGgoAAAANSUhEUgAAADIAAAAyCAIAAACRXR/mAAAABnRSTlMAAAAAAABu'
    . 'pgeRAAAAVklEQVRYw+3UQQqAMBAEwf3/p9eTBxEPiWAmWMU8oGFJqgAAuOpzWTX3'
    . 'xQUti+uRJTZ9V5aY1bOTFZLV7yZr9zt6ibv/qPXfrMpsGipbIy7oqQ8AYJED1plD'
    . 'y5PCu2sAAAAASUVORK5CYII=';
$src = imagecreatefromstring(base64_decode($base64));

$dst = imagecreate(50, 50);
$transparent = imagecolorallocatealpha($dst, 255, 255, 255, 127);
imagealphablending($dst, false);
imagesavealpha($dst, true);

imagecopy($dst, $src, 0,0, 0,0, 50,50);

imagepng($dst, __DIR__ . '/test.png');


Expected result:
----------------
An image with red circle on a _transparent_ background.

Actual result:
--------------
An image with red circle on a _black_ background.

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History

AllCommentsChangesGit/SVN commitsRelated reports
 [2016-08-21 15:26 UTC] cmb@php.net
-Assigned To: +Assigned To: cmb
 [2016-08-21 15:57 UTC] cmb@php.net
Automatic comment on behalf of cmbecker69@gmx.de
Revision: http://git.php.net/?p=php-src.git;a=commit;h=d65adac2be2c9b32d9ad9bd00399c99d492502f5
Log: Fix #72913: imagecopy() loses single-color transparency on palette images
 [2016-08-21 15:57 UTC] cmb@php.net
-Status: Assigned +Status: Closed
 [2016-10-17 10:09 UTC] bwoebi@php.net
Automatic comment on behalf of cmbecker69@gmx.de
Revision: http://git.php.net/?p=php-src.git;a=commit;h=d65adac2be2c9b32d9ad9bd00399c99d492502f5
Log: Fix #72913: imagecopy() loses single-color transparency on palette images
 
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