From: scratch65535 at att dot net
Operating system: W2K
PHP version: 5.2.11
PHP Bug Type: GD related
Bug description: PNG alpha blending doesn't seem to work
Description:
------------
I am trying to combine PNG images by 'pasting' them onto a transparent
background such that I end up with one large image (the 'assembly') rather
than a multitude of small ones. I'm using PNG because I need more than 8
bits/pixel. I created the images in p'shop 7.
Using a GIF works fine, apart from it having too few bits per pixel.
Using a PNG with a designated xparent color ("GIF mode", as it were) also
works fine.
PNG with alpha doesn't. I don't know whether the problem is in the
documentation, in imageCreateFromPNG(), in my understanding, or somewhere
else. I've fooled around with different combinations (e.g., putting in or
taking out imageAlphaBlending() for the $dest value) but nothing seems to
help.
(Using PNGs in 'GIF mode' will be my fallback if alpha is broken, but it
would mean re-doing all my images so I'm hoping alpha is NOT broken)
Reproduce code:
---------------
$png = 1 ;
if ( $png == 1 ) // png in 'gif mode'
{
$dest = imageCreateTrueColor( 200, 200 ) ;
$xparent = imageColorAllocate( $dest, 220,2,240 ) ;
imageFilledRectangle($dest, 0,0, 200,200, $xparent) ;
imageColorTransparent($dest, $xparent);
$src = imageCreateFromPNG( 'TESTcolor.png' ) ;
$srcxparent = imageColorAllocate( $src, 0xFF,0,0xFF ) ;
imageColorTransparent($src, $srcxparent ) ;
imageCopyMerge( $dest, $src, 50, 50, 0, 0, 100, 100, 100 ) ;
header('Content-Type: image/png') ;
imagePNG( $dest ) ;
}
else // png with alpha
{
$dest = imageCreateTrueColor( 200, 200 ) ;
$xparent = imageColorAllocateAlpha( $dest, 0xFF,0x99,0xFF, 0 );
imageFilledRectangle($dest, 0,0, 200,200, $xparent) ;
imageAlphaBlending( $dest, 1 ) ;
imageSaveAlpha( $dest, 1 ) ;
$src = imageCreateFromPNG( 'TESTalpha.png' ) ;
imageAlphaBlending( $src, 1 ) ;
imageSaveAlpha( $src, 1 ) ;
imageCopyMerge( $dest, $src, 50, 50, 0, 0, 100, 100, 100 ) ;
header('Content-Type: image/png') ;
imagePNG( $dest ) ;
}
Expected result:
----------------
I expect to see a dark blue outline box on the background color of the
page itself.
Actual result:
--------------
I see a dark blue outline box on an opaque white field overlaying the
assembly field that I painted magenta. I can get rid of the magenta by
calling imageColorTransparent() on $dest, but nothing I can do gets rid of
the white background of the box.
--
Edit bug report at http://bugs.php.net/?id=50183&edit=1
--
Try a snapshot (PHP 5.2):
http://bugs.php.net/fix.php?id=50183&r=trysnapshot52
Try a snapshot (PHP 5.3):
http://bugs.php.net/fix.php?id=50183&r=trysnapshot53
Try a snapshot (PHP 6.0):
http://bugs.php.net/fix.php?id=50183&r=trysnapshot60
Fixed in SVN:
http://bugs.php.net/fix.php?id=50183&r=fixed
Fixed in SVN and need be documented:
http://bugs.php.net/fix.php?id=50183&r=needdocs
Fixed in release:
http://bugs.php.net/fix.php?id=50183&r=alreadyfixed
Need backtrace:
http://bugs.php.net/fix.php?id=50183&r=needtrace
Need Reproduce Script:
http://bugs.php.net/fix.php?id=50183&r=needscript
Try newer version:
http://bugs.php.net/fix.php?id=50183&r=oldversion
Not developer issue:
http://bugs.php.net/fix.php?id=50183&r=support
Expected behavior:
http://bugs.php.net/fix.php?id=50183&r=notwrong
Not enough info:
http://bugs.php.net/fix.php?id=50183&r=notenoughinfo
Submitted twice:
http://bugs.php.net/fix.php?id=50183&r=submittedtwice
register_globals:
http://bugs.php.net/fix.php?id=50183&r=globals
PHP 4 support discontinued: http://bugs.php.net/fix.php?id=50183&r=php4
Daylight Savings: http://bugs.php.net/fix.php?id=50183&r=dst
IIS Stability:
http://bugs.php.net/fix.php?id=50183&r=isapi
Install GNU Sed:
http://bugs.php.net/fix.php?id=50183&r=gnused
Floating point limitations:
http://bugs.php.net/fix.php?id=50183&r=float
No Zend Extensions:
http://bugs.php.net/fix.php?id=50183&r=nozend
MySQL Configuration Error:
http://bugs.php.net/fix.php?id=50183&r=mysqlcfg
