#34336 [Csd->Bgs]: ext/gd: imagerotate destroys transparency information

ID: 34336 User updated by: techtonik@php.net Reported By: techtonik@php.net -Status: Closed +Status: Bogus Bug Type: Feature/Change Request Operating System: * -PHP Version: 5CVS, 4CVS (2005-08-31) +PHP Version: 4CVS (2005-08-31) Assigned To: pajoye New Comment: >> Why it is impossible to change the behavior to keep >> transparency by default? > BC Break, and second as you see with your picture, it is > not the best result you can have, people tend to mix > transparec and transparent color. What do you mean by "transparec and transparent color"? > There is an interpolation, which range to use to ignore > the bgd color or a transparent color? There is no easy > way without making the function way too complex. But what if bgd color is transparent color? >> Why change transparent to black while rotating in PHP4? > It's a new _feature_. We do not add new feature to PHP4 > and/or PHP5.0 I doubt that users can call changing transparent color to black while rotating. This doesn't seem like a feature to me, sorry. Previous Comments: ------------------------------------------------------------------------ [2005-09-03 12:10:10] pajoye@php.net > JFY, a new fourth parameter "ignore_transparent" was > already added to imagerotate in PHP 5.1 - see I added it in HEAD after 5.0.x was branched, but thx for the notice :) > Why it is impossible to change the behavior to keep > transparency by default? BC Break, and second as you see with your picture, it is not the best result you can have, people tend to mix transparec and transparent color. There is an interpolation, which range to use to ignore the bgd color or a transparent color? There is no easy way without making the function way too complex. > Why change transparent to black while rotating in PHP4? It's a new _feature_. We do not add new feature to PHP4 and/or PHP5.0 Status closed then --Pierre ------------------------------------------------------------------------ [2005-09-03 00:36:29] techtonik@php.net JFY, a new fourth parameter "ignore_transparent" was already added to imagerotate in PHP 5.1 - see http://php.net/imagerotate ------------------------------------------------------------------------ [2005-09-03 00:06:30] techtonik@php.net Well, it works for PHP5, but what to do with PHP4? Why it is impossible to change the behavior to keep transparency by default? Why change transparent to black while rotating in PHP4? It still seems like a bug to me. Why this doesn't work either? ... $sprTransparent = imagecolortransparent($spr); //sprite rotation $rotate = 15; $spr = imagerotate($spr, $rotate, $sprTransparent); $sprTransparent = imagecolortransparent($spr, $sprTransparent); ... ------------------------------------------------------------------------ [2005-09-02 10:10:10] pajoye@php.net Please try using this CVS snapshot: http://snaps.php.net/php5-latest.tar.gz For Windows: http://snaps.php.net/win32/php5-win32-latest.zip Try the newly added 4th argument: imagerotate($rsr, $angle, $bg_color, $keeptransparency); However, note that this is interpolated colors in the destination images (rotated), meaning that if the original image has some antialiased artifacts with the bgd color, you will notice them in the rotated image (in your case, a white border), not much can be done against that. --Pierre ------------------------------------------------------------------------ [2005-09-01 21:41:26] techtonik@php.net Description: ------------ Imagerotate doesn't preserve transparency information. Next image was used in example below: http://img24.imageshack.us/img24/228/spritepaw8alpha2os.png Reproduce code: --------------- <?php $sprName = "sprite_paw8_alpha.png"; $spr = imagecreatefrompng($sprName); //create sprite object //get sprite's transparent color $sprTransparent = imagecolortransparent($spr); //sprite rotation $rotate = 15; //rotate sprite, ?keeping transparent pixels $spr = imagerotate($spr, $rotate, $sprTransparent); header("Content-type: image/gif"); imagegif($spr); imagedestroy($spr); ?> Expected result: ---------------- Rotated image with transparent background. Actual result: -------------- Rotated image with black background. ------------------------------------------------------------------------ -- Edit this bug report at http://bugs.php.net/?id=34336&edit=1