OneFileManager : Keep the transparency on PNG - php

Question

I use for my site OneFileManager and I wish to modify a file to keep transparency on PNG files.
This modification must apparently be done on the file Console.php and would aim to keep the transparency of PNG images or possibly replace it with white (the images being posted on instagram and instagram automatically replace transparency with white)
And the portion of the code to modify appears line 644. The dev currently transforms PNG into JPG but the problem is that the background is duplicated thanks to the colors of the non-transparent part
I changed from line 644 all values ​​in PNG as below
Old code :
if ($ext == "png") {
$image = new \claviska\SimpleImage;
try {
$new_filename = uniqid(readableRandomString(8)."-") . ".jpg";
$image->fromFile($this->manager->getOption("path") . $filename)
->toFile($this->manager->getOption("path") . $new_filename, "image/jpeg");
#unlink($this->manager->getOption("path") . $filename);
$ext = "jpg";
$filename = $new_filename;
} catch (\Exception $e) {
return Common::error($e->getMessage());
}
}
With editing jpg to png
if ($ext == "png") {
$image = new \claviska\SimpleImage;
try {
$new_filename = uniqid(readableRandomString(8)."-") . ".png";
$image->fromFile($this->manager->getOption("path") . $filename)
->toFile($this->manager->getOption("path") . $new_filename, "image/png");
#unlink($this->manager->getOption("path") . $filename);
$ext = "png";
$filename = $new_filename;
} catch (\Exception $e) {
return Common::error($e->getMessage());
}
}
But this just made the transparent content no longer duplicated, but it keeps in the image the squares signifying the transparency of the image.
And i tried to use imagealphablending or imagesavealpha but no one work with OneFileManager or i dunno where to put this ^^'
If anyone can help me, thank you in advance ^^