Optimal image scaling - php

Question

I would like to ask for help in optimizing the image. I made a class where I call the function, working perfectly, just when I upload my profile picture I want to cut it into a square (800x800) and make it as optimal as possible from the center of the original picture. I don't want to use extra scripts, rather upload an optimally cropped image.
Imagecopyresampled proper parameter drop is the key :), I googled and watched videos but couldn't fix it properly or it either shifted the image or it wasn't in or distorted. I probably miscalculated the coordinates of the image.
function createthumb($name, $filename, $new_w, $new_h) {
try{
$system = explode(".", $name);
$tipus = $system[count($system)-1];
$tipus = strtolower($tipus);
$vizjel_fajl = "assets/img/watermark.png";
$vizjel_kep = imagecreatefrompng($vizjel_fajl);
if (($tipus == 'jpg') || ($tipus == 'jpeg')){
$src_img = imagecreatefromjpeg($name);
}
if ($tipus == 'gif'){
$src_img = imagecreatefromgif($name);
}
if ($tipus == 'png'){
$src_img = imagecreatefrompng($name);
}
$old_x = imageSX($src_img);
$old_y = imageSY($src_img);
$vizjel_szelesseg = imagesx($vizjel_kep);
$vizjel_magassag = imagesy($vizjel_kep);
$szelesseg_szorzo = $old_x / $vizjel_szelesseg;
$magassag_szorzo = $old_y / $vizjel_magassag;
if (($szelesseg_szorzo) >= ($magassag_szorzo)){
$aktual_szorzo = $magassag_szorzo;
} else {
$aktual_szorzo = $szelesseg_szorzo;
}
$vizjel_x = intval(($old_x - ($aktual_szorzo * $vizjel_szelesseg)) / 3);
$vizjel_y = intval(($old_y - ($aktual_szorzo * $vizjel_magassag)) / 1);
$vizjel_w = intval($aktual_szorzo * $vizjel_szelesseg);
$vizjel_h = intval($aktual_szorzo * $vizjel_magassag);
if($old_x > $old_y && $this->type != 'user'){
$thumb_w = $new_w;
$thumb_h = $old_y * ($new_h / $old_x);
}
if($old_x < $old_y && $this->type != 'user') {
$thumb_w = $old_x * ($new_w / $old_y);
$thumb_h = $new_h;
}
if($old_x == $old_y){
$thumb_w = $new_w;
$thumb_h = $new_h;
}
if($this->type == 'user'){
$thumb_w = 800;
$thumb_h = 800;
}
$dst_img = ImageCreateTrueColor($thumb_w, $thumb_h);
imagealphablending($dst_img, false);
imagesavealpha($dst_img, true);
$transparent = imagecolorallocatealpha($dst_img, 0, 0, 0, 127);
imagefilledrectangle($dst_img, 0, 0, $thumb_w, $thumb_h, $transparent);
imagecopyresampled($src_img, $vizjel_kep, $vizjel_x, $vizjel_y, 0, 0, $vizjel_w, $vizjel_h, $vizjel_szelesseg, $vizjel_magassag);
imagecopyresampled( $dst_img, $src_img, 0, 0, 0, 0, $thumb_w, $thumb_h, $old_x, $old_y );
if ((preg_match( "/png/", $system[1])) || (preg_match("/gif/", $system[1]))){
imagepng($dst_img, $filename, 1);
}else{
imagejpeg($dst_img, $filename);
}
imagedestroy($dst_img);
if (!unlink($this->target_dir.$this->name)) {
throw new userException('','Hiba a törlés során ->'. $this->name,451);
}
}
catch (userException $e){
$e->handleException();
}
}

Answer 1

Welcome LGB,
your function is not clear, I see some variables that not defined, please next time attach all of the codes.
this code returns exactly the center of the original image 800x800
<?php
//image path
$im = imagecreatefromjpeg('Images/baby.jpg');
// find the size of image
$size = min(imagesx($im), imagesy($im));
//calculate X position
if(imagesx($im) < 800){$xPos = 0;}
else{$xPos = floor((imagesx($im) - 800) / 2);}
//calculate Y position
if(imagesy($im) < 800){$yPos = 0;}
else{$yPos = floor((imagesy($im) - 800) / 2);}
//set the crop image size
$im2 = imagecrop($im, ['x' => $xPos, 'y' => $yPos, 'width' => 800, 'height' => 800]);
if ($im2 !== FALSE) {
header("Content-type: image/jpg");
imagejpeg($im2);
imagedestroy($im2);
}
imagedestroy($im);
?>
I'm guessing that your point is in this part:
//calculate X position
if(imagesx($im) < 800){$xPos = 0;}
else{$xPos = floor((imagesx($im) - 800) / 2);}
//calculate Y position
if(imagesy($im) < 800){$yPos = 0;}
else{$yPos = floor((imagesy($im) - 800) / 2);}