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Bug #40069 resizing png
Submitted: 2007-01-09 00:57 UTC Modified: 2007-01-10 12:46 UTC
From: alex at gateway-productions dot com Assigned: pajoye (profile)
Status: Not a bug Package: GD related
PHP Version: latest cvs OS: Linux
Private report: No CVE-ID: None
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 [2007-01-09 00:57 UTC] alex at gateway-productions dot com 
Description:
------------
imagecopyresampled() returns a blank resized image with alpha not the source resized with alpha


Reproduce code:
---------------
       $im = ImageCreateFromPNG($sourcefile);
       $im_dest = imagecreatetruecolor ($sourcefile_new_width, $sourcefile_new_height);
       imagealphablending($im_dest, false);
       imagecopyresampled($im_dest, $im, 0, 0, 0, 0, $sourcefile_width, $sourcefile_height, $sourcefile_new_width, $sourcefile_new_height);
       imagesavealpha($im_dest, true);
       imagepng($im_dest, $destfile);
       imagedestroy($im_dest);

Expected result:
----------------
resizing actuall source png while keeping transparency and saving file

Actual result:
--------------
returns a blank resized image with alpha not the source resized with alpha

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 [2007-01-09 00:59 UTC] iliaa@php.net 
Please try using this CVS snapshot:

  http://snaps.php.net/php5.2-latest.tar.gz
 
For Windows:
 
  http://snaps.php.net/win32/php5.2-win32-latest.zip
 [2007-01-09 01:47 UTC] pajoye@php.net 
If it does not work with the snapshots, please provide a source image (a link to).
 [2007-01-10 09:31 UTC] alex at gateway-productions dot com 
upgraded to latest cvs version, and i have the latest gd

and still does not produced desired outcome unless my code is wrong? it is still not transfering the overlayed none alpha data.

heres a link to the orginal watermark

http://gateway-productions.com/v6/media/gallery/watermark.png
 [2007-01-10 09:33 UTC] alex at gateway-productions dot com 
this is the output png code example

http://gateway-productions.com/v6/media/gallery/test.png
 [2007-01-10 09:39 UTC] alex at gateway-productions dot com 
after closer inspection of the png i noticed that it is possibly transfering correctly,. As you can see what appears to be a bit of the picture on the bottom left, but it is not resizing the png at all. 

rather overlaying without resizing the overlayed image.
 [2007-01-10 12:46 UTC] pajoye@php.net 
I suppose you are trying to resize an image (which has alpha). It works well here.

See:
http://blog.thepimp.net/misc/40069_res.png

You inverted the width/height arguments in imagecopyresampled. The correct script should be (size * 1.2 here):

$im = imagecreatefrompng($sourcefile);

$sourcefile_width = imagesx($im);
$sourcefile_height = imagesy($im);

$sourcefile_new_width = $sourcefile_width * 1.2;
$sourcefile_new_height = $sourcefile_height * 1.2;

$im_dest = imagecreatetruecolor ($sourcefile_new_width, $sourcefile_new_height);
imagealphablending($im_dest, false);
imagecopyresampled($im_dest, $im, 0, 0, 0, 0, $sourcefile_new_width, $sourcefile_new_height,
    $sourcefile_width, $sourcefile_height);

imagesavealpha($im_dest, true);
imagepng($im_dest, $destfile);
imagedestroy($im_dest);

I close the bug (no bug > bogus), feel free to reopen it if I misunderstand your problem,
 
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