image flip bug wrong parameter

[jasonspar]

There is a bug in this routine: fix_orientation

The call to imageflip returns a boolean, not a flipped image. The fixed routine is like this:

function fix_orientation ($orientation, $fileandpath, $ext, $quality=80) {

// Gets the GD image resource for loaded image
$img_res = get_image_resource ($fileandpath, $ext);

// If it failed to load a resource, give up
if (is_null ($img_res)) {
return false;
}
// auto rotate
switch ($orientation) {

// Correct orientation, but flipped on the horizontal axis (might do it at some point in the future)
case 2:
  $ret = imageflip ($img_res, IMG_FLIP_HORIZONTAL);
break;

// Upside-Down
case 3:
  $ret = imageflip ($img_res, IMG_FLIP_VERTICAL);
break;

// Upside-Down & Flipped along horizontal axis
case 4:
  $ret = imageflip ($img_res, IMG_FLIP_BOTH);
break;

// Turned 90 deg to the left and flipped
case 5:
  $ret = imagerotate($img_res, -90, 0);
  $ret = imageflip ($img_res, IMG_FLIP_HORIZONTAL);
break;

// Turned 90 deg to the left
case 6:
  $ret = imagerotate ($img_res, -90, 0);
break;

// Turned 90 deg to the right and flipped
case 7:
  $ret = imagerotate ($img_res, 90, 0);
  $ret = imageflip ($img_res,IMG_FLIP_HORIZONTAL);
break;

// Turned 90 deg to the right
case 8:
  $ret = imagerotate ($img_res, 90, 0);
break;

}

// If theres no final image resource to output for whatever reason, give up
if (!isset ($ret)) {
return false;
}
// save image
save_image_resource ($img_res, $fileandpath, $ext, $quality);

// Free up memory
imagedestroy ($img_res);
}

[jasonspar]

You can reproduce the bug in X3.3.2 with the attached image uploaded.

[mjau-mjau]

Thanks for reporting this. Strange that imagerotate() returns the resource while imageflip() only returns a boolean. There is now only one problem in the code ... When imagerotate() is used, $img_res will refer to the original non-rotated image, so the image will not get rotated. So, for imagerotate(), we definitely need to use the return value.

I will look into it for next release. Thanks for reporting!

PS! I have a short working version of this in the files.gallery application.

function exif_orientation($orientation, &$image){
  if(empty($orientation) || !is_numeric($orientation) || $orientation < 3 || $orientation > 8) return;
  $image = imagerotate($image, array(6 => 270, 5 => 270, 3 => 180, 4 => 180, 8 => 90, 7 => 90)[$orientation], 0);
  if(in_array($orientation, array(5, 4, 7)) && function_exists('imageflip')) imageflip($image, IMG_FLIP_HORIZONTAL);
  return true;
}

[jasonspar]

I see that. How about something like this code:

function fix_orientation ($orientation, $fileandpath, $ext, $quality=80) {

// Gets the GD image resource for loaded image
$img_res = get_image_resource ($fileandpath, $ext);

// If it failed to load a resource, give up
if (is_null ($img_res)) {
return false;
}
$rotated_img = null;
$ret = false;
// auto rotate
switch($orientation) {
// need just flipping
case 2:
$ret = imageflip ($img_res, IMG_FLIP_HORIZONTAL);
break;

case 4:  // Upside-Down & Flipped along horizontal axis
   $ret = imageflip ($img_res, IMG_FLIP_VERTICAL);
   break;

// need rotation and flip
case 5:  // Turn 90 deg to the right and flip
   $rotated_img = imagerotate ($img_res, -90, 0);
   $ret = imageflip ($rotated_img, IMG_FLIP_HORIZONTAL);
   break;

case 7:  // Turned 90 deg to the left and flip
   $rotated_img = imagerotate ($img_res, 90, 0);
   $ret = imageflip ($rotated_img,IMG_FLIP_HORIZONTAL);
   break;

// rotation is enough for these
case 3: // Upside-Down
   $ret = true;
   $rotated_img = imagerotate ($img_res, 180, 0);
   break;
   
case 6:  // Turn 90 deg to the right
   $ret = true;
   $rotated_img = imagerotate ($img_res, -90, 0);
   break;

case 8:  // Turn 90 deg to the left
   $ret = true;
   $rotated_img = imagerotate ($img_res, 90, 0);
   break;

}

if (!$ret) { // If theres no final image resource to output for whatever reason, give up
return false;
}
// save image
if ($rotated_img != null) {
save_image_resource ($rotated_img, "D:/WEB/ecdrc.net/html/ces/data/hose-fixed.jpg", $ext, $quality);
imagedestroy ($rotated_img);
}
else {
save_image_resource ($img_res, "D:/WEB/ecdrc.net/html/ces/data/hose-fixed.jpg", $ext, $quality);
}
// Free up memory
imagedestroy ($img_res);
}

[jasonspar]

the last code I posted is tested against a set of images in different orientations. It passes. The code from files.gallery also has a bug with case 2 and 4. Here's a fixed version:

function exif_orientation ($orientation = -1, &$image = null) {

if (empty ($orientation) || !is_numeric ($orientation)) { // bad input
return (false);
}
if ($image == null) { // nothing to work on
return (false);
}
if ($orientation < 2 || $orientation > 8) { // do we need to mess with it
return (true);
}

// lets rotate first
$angles = array (6 => 270, 5 => 270, 3 => 180, 4 => 180, 8 => 90, 7 => 90);
$orval = $angles[$orientation];
$image = imagerotate ($image, $orval, 0);

// do we need to flip it
if (function_exists ('imageflip')) {
$horiz_flip_needed = array(2, 5, 7);
if (in_array ($orientation, $horiz_flip_needed)) {
imageflip ($image, IMG_FLIP_HORIZONTAL);
}
else if ($orientation == 4) {
imageflip ($image, IMG_FLIP_VERTICAL);
}
}
return (true);
}

[mjau-mjau]

The code from files.gallery also has a bug with case 2 and 4.

I can't see any bugs there. As you can see, the &$image is passed as a reference, and used by the caller of the function. For imagerotate() it it correctly applied to return to the reference &$image and for imageflip() it correctly applied directly on the reference resource. It's a replication of the code from the below:
https://github.com/gumlet/php-image-resize/blob/master/lib/ImageResize.php

Anyway, thanks for reporting this and making suggestions. I will definitely have it resolved for next X3 release.

[jasonspar]

Yes, that code is buggy. Here are the graphics I used to set up the cases.

I can send you the image test set as well. After you upload them, you can check which ones failed.

[jasonspar]

Here's the test set.
fliprotatetestset.zip

[mjau-mjau]

I see the images in your test set, are the same images that I have in our Files Gallery demo:
https://demo.files.gallery/?tests/exif-image-orientation

All the resized images (thumbnails) have been oriented from the code posted, and as you can see, it's definitely working as it should.