How to reorient a picture with EXIF data using PHP GD

Sorry for the briefness, lack of time strikes again.
In this code snippet, $tmpFile is the path to the image file, and for simplicity’s sake here it’s always a JPG.
We define our own function “custImageFlip” to flip the picture (and I put it at the end because it’s secondary, but if you want to use the code as-is you’ll need to put it at the top), but if your target is PHP>=5.5, you can just use PHP’s native imageflip.

Code for the switch is hugely based on code by someone in the comments in PHP’s documentation.
Code for the PHP<5.5 implementation to flip the image is from another comment in PHP’s doc.

Last but not least, a great image pack that will allow you to test all those picture rotations and flips: https://github.com/recurser/exif-orientation-examples

$tmpImage = @imagecreatefromjpeg($tmpFile);
$exif = exif_read_data($tmpFile);
//die(json_encode($exif));
if($exif!==false) {
	$ort=1;
	if(isset($exif['Orientation'])) {
		// orientation is usually here
		$ort=$exif['Orientation'];
	} elseif(isset($exif['IFD0']) && isset($exif['IFD0']['Orientation'])) {
		// but apparently it can be here sometimes?
		$ort=$exif['IFD0']['Orientation'];
	}
	switch($ort) {
		case 1: // nothing
			break;
		case 2: // horizontal flip
			$tmpImage=custImageFlip($tmpImage,2);
			break;
		case 3: // 180 rotate left
			$tmpImage=imagerotate($tmpImage,180,0);
			break;
		case 4: // vertical flip
			$tmpImage=custImageFlip($tmpImage,1);
			break;
		case 5: // vertical flip + 90 rotate right
			$tmpImage=custImageFlip($tmpImage,1);
			$tmpImage=imagerotate($tmpImage,-90,0);
			break;
		case 6: // 90 rotate right
			$tmpImage=imagerotate($tmpImage,-90,0);
			break;
		case 7: // horizontal flip + 90 rotate right
			$tmpImage=custImageFlip($tmpImage,2);
			$tmpImage=imagerotate($tmpImage,-90,0);
			break;
		case 8: // 90 rotate left
			$tmpImage=imagerotate($tmpImage,90,0);
			break;
	}
}

// ImageFlip from https://php.net/manual/en/function.imagecopy.php#89658
function custImageFlip($imgsrc,$mode) {
	$width=imagesx($imgsrc);
	$height=imagesy($imgsrc);

	$src_x=0;
	$src_y=0;
	$src_width=$width;
	$src_height=$height;

	switch ($mode) {
		case '1': //vertical
			$src_y=$height-1;
			$src_height=-$height;
			break;
		case '2': //horizontal
			$src_x=$width-1;
			$src_width=-$width;
			break;
		case '3': //both
			$src_x=$width-1;
			$src_y=$height-1;
			$src_width=-$width;
			$src_height=-$height;
			break;
		default:
			return $imgsrc;
	}
	$imgdest = imagecreatetruecolor ($width,$height);
	if(imagecopyresampled($imgdest, $imgsrc, 0, 0, $src_x, $src_y , $width, $height, $src_width, $src_height)){
		return $imgdest;
	}
	return $imgsrc;
}