Bug #66882 [Opn->Ana]: imagerotate by -90 degrees truncates image by 1px

Edit report at https://bugs.php.net/bug.php?id=66882&edit=1 ID: 66882 Updated by: cmb@php.net Reported by: jarrod at makin dot co Summary: imagerotate by -90 degrees truncates image by 1px -Status: Open +Status: Analyzed Type: Bug Package: GD related Operating System: RHEL6.5 PHP Version: 5.5.10 -Assigned To: +Assigned To: cmb Block user comment: N Private report: N New Comment: The issue is rather clear for square angles. As of PHP 5.5.0 the rotation is done by gdImageRotateInterpolated()[1], which has special cases for 90, 180 and 270 degrees, but not for their negative counterparts. That has already been fixed in the external libgd by adding special cases for -90, -180 and -270 degress[2]. I'm going to port these changes to PHP's bundled libgd as fix for this ticket. I'm leaving the other ticket open, because the user comments seem to refer to non-square angles (at least partially), and these issues deserve some closer investigation. [1] <https://github.com/php/php-src/blob/php-5.6.11/ext/gd/libgd/gd_interpolation.c#L2156> [2] <https://github.com/libgd/libgd/blob/gd-2.1.1/src/gd_interpolation.c#L2219-L2229> Previous Comments: ------------------------------------------------------------------------ [2015-07-13 10:39:43] jarrod at makin dot co I agree. I do appear to have reported a duplicate of #65148, the reporter observed that rotations by negative degrees truncated the picture. I will aim to build up to date php5.4, 5.5 and 5.6 this week and test. ------------------------------------------------------------------------ [2015-07-12 21:30:14] cmb@php.net Might be a duplicate of bug #65148. ------------------------------------------------------------------------ [2014-03-12 04:35:41] phpmpan at mpan dot pl A typo. I meant gdImageRotateBilinear of course, not gm.... ------------------------------------------------------------------------ [2014-03-12 04:34:16] phpmpan at mpan dot pl Confirmed for master snapshot and 5.5.10. A quick dive into the code suggests gmImageRotateBilinear contains code that handles floats inproperly by casting them to int (hence truncating) where extracting integer part was probably meant. Minimal code: $image = imagerotate(imagecreate(10, 10), -90, 0) echo imagesy($image), 'x', imagesx($image) If the source image has size of 1x1, the effects are even worse, as the functions below receive 0 as size. ------------------------------------------------------------------------ [2014-03-11 15:17:28] jarrod at makin dot co Description: ------------ Rotating an image anticlockwise by -90 degrees (clockwise 90 degrees) produces an image that is 1px narrower than you would expect and the left most vertical column of pixels are all black. However, rotating an image anticlockwise by 270 degrees (also clockwise 90 degrees) produces an image of the correct dimensions and without the line of black pixels. Test script: --------------- Source http://www.jarrodmakin.com/imagerotate.txt Usable test script http://www.jarrodmakin.com/imagerotate.php Expected result: ---------------- Paraphrasing: Dimensions are A x B Dimensions of rotation are B x A Actual result: -------------- Paraphrasing: Dimensions are A x B Dimensions of rotation are B x (A - 1) ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=66882&edit=1