wp-includes/class-wp-image-editor-gd.php:448Flips current image.
$horzbool$vertbooltrue|WP_Error public function flip( $horz, $vert ) { $w = $this->size['width']; $h = $this->size['height']; $dst = wp_imagecreatetruecolor( $w, $h ); if ( is_gd_image( $dst ) ) { $sx = $vert ? ( $w - 1 ) : 0; $sy = $horz ? ( $h - 1 ) : 0; $sw = $vert ? -$w : $w; $sh = $horz ? -$h : $h; if ( imagecopyresampled( $dst, $this->image, 0, 0, $sx, $sy, $w, $h, $sw, $sh ) ) { if ( PHP_VERSION_ID < 80000 ) { // imagedestroy() has no effect as of PHP 8.0. imagedestroy( $this->image ); } $this->image = $dst; return true; } } return new WP_Error( 'image_flip_error', __( 'Image flip failed.' ), $this->file ); }Introduced in 3.5.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/class-wp-image-editor-gd.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.