Issue with imagecopy resized PHP - php

Question

I'm trying to make a web app which has an admin site where you can upload an image. I'm already using imagecopy() to make a square photo. But when the image is too big I'm trying to resize with imagecopyresized(). I've already used this code:
$file = $_FILES['img']['tmp_name'];
$filename = $_FILES['img']['name'];
$size = 400;
$destino = imagecreatetruecolor($size, $size);
list($width, $height) = getimagesize($file);
$correction = $size / 2;
$widths = $width / 2 - $correction;
$heights = $height / 2 - $correction;
$origen = imagecreatefromjpeg($file);
$overflow = $size + 200;
if($width > $overflow){
$modified = $origen;
$ratio = $width / $height;
$growth = $width / $overflow;
$final = $overflow / $growth;
if($ratio > 1){
$newwidth = $final * $ratio;
}else{
$newwidth = $final / $ratio;
}
imagecopyresized($origen, $modified, 0, 0, 0, 0, $final, $newwidth, $width, $height);
}
imagecopy($destino, $origen, 0, 0, $widths, $heights, $size, $size);
The issue here is that there's no modification to the image that is bigger than $overflow.
$ratio is to keep the original dimensions of the photos and prevent deform.
$growth is an index that while bigger the image is, the smallest it will be copied.
$final is the final width taking the growth index as a count.

Answer 1

You've made some incorrect assumptions about how PHP handles resources and how the GD functions work.
$modified = $origen;
The above line does not give you two separate image resources; it gives you two variables pointing to the same image resource in memory. This means any operation on one will be reflected in the other.
This causes you to make two mistakes with the following line:
imagecopyresized($origen, $modified, 0, 0, 0, 0, $final, $newwidth, $width, $height);
This function doesn't resize the destination image ($origen) or the source image ($modified); it resizes the part of the image it copies from the source image (i.e., the specified part of $modified in your code).
Because $origen and $modified point to the same resource the function pastes the resized copy of the image on top of itself, like this:
Lastly you call:
imagecopy($destino, $origen, 0, 0, $widths, $heights, $size, $size);
A problem here is that $widths and $heights are calculated before the $origen resize, but in effect the problem is hidden because (as explained above) $origen isn't resized!
The result of all the above is to give you a square 'cut' from the middle of the original image, like this:
Here is how I would resize the input image to fit within 400x400px and centre it in the output:
$file = $_FILES['img']['tmp_name'];
$maxW = $maxH = 400;
list($srcW, $srcH) = getimagesize($file);
$ratio = $srcW / $srcH;
$src = imagecreatefromjpeg($file);
$dest = imagecreatetruecolor($maxW, $maxH);
if ($ratio > 1) {
// landscape.
$destH = ($maxH / $ratio);
imagecopyresized($dest, $src, 0, ($maxH / 2) - ($destH / 2), 0, 0, $maxW, $destH, $srcW, $srcH);
} else {
// portrait (or square).
$destW = ($maxW * $ratio);
imagecopyresized($dest, $src, ($maxW / 2) - ($destW / 2), 0, 0, 0, $destW, $maxH, $srcW, $srcH);
}
// now do whatever you want with $dest...
Note that this will result in black bars on the top/bottom (of a landscape image) or left/right (of a portrait image) of the output. You can just fill $dest with a colour, or transparency, before the imagecopyresized call to change this.