[php-src] Issue #13163: `imagecropauto()` not working with transparent background

Issue: https://github.com/php/php-src/issues/13163 Author: ThomasLandauer ### Description The following code: ```php <?php $gdImage = imagecreatetruecolor(100,100); imagesavealpha($gdImage, true); imagefill($gdImage, 0, 0, imagecolorallocatealpha($gdImage, 0, 0, 0, 127)); // imagepng($gdImage, '/tmp/image_transparent.png'); $result = imagecropauto($gdImage, IMG_CROP_TRANSPARENT); var_dump($result); // object(GdImage)#2 (0) { } // imagepng($result, '/tmp/image_black.png'); ``` Resulted in this output: ``` object(GdImage)#2 (0) { } ``` But I expected this output instead: ``` bool(false) ``` Docs at https://www.php.net/manual/en/function.imagecropauto.php are saying: > If the complete image was cropped, imagecrop() returns false And this should be the case here IMO. When doing the same with white background, it works as expected: ```php <?php $gdImage = imagecreatetruecolor(100,100); imagesavealpha($gdImage, true); imagefill($gdImage, 0, 0, imagecolorallocate($gdImage, 255, 255, 255)); // imagepng($gdImage, '/tmp/image_white.png'); $result = imagecropauto($gdImage, IMG_CROP_WHITE); var_dump($result); // bool(false) ``` ### PHP Version PHP 8.3.1 ### Operating System Kubuntu 22.04