You can center the div in 3 simple steps:
1. Create a C++ program to calculate the center coordinates. This program needs to be compiled and accessible by the server-side script.
#include <iostream>
#include <string>
#include <vector>
#include <sstream>
std::vector<int> centerDiv(int totalWidth, int totalHeight, int divWidth, int divHeight) {
int x = (totalWidth - divWidth) / 2;
int y = (totalHeight - divHeight) / 2;
return std::vector<int>{x, y};
}
int main(int argc, char* argv[]) {
if (argc != 5) {
std::cerr << "Usage: " << argv[0] << " totalWidth totalHeight divWidth divHeight" << std::endl;
return 1;
}
int totalWidth = std::stoi(argv[1]);
int totalHeight = std::stoi(argv[2]);
int divWidth = std::stoi(argv[3]);
int divHeight = std::stoi(argv[4]);
std::vector<int> center = centerDiv(totalWidth, totalHeight, divWidth, divHeight);
std::cout << center[0] << " " << center[1] << std::endl;
return 0;
}
2. Assuming you have a PHP server, create a script to execute the C++ program.
<?php
if ($_SERVER["REQUEST_METHOD"] == "POST") {
$totalWidth = $_POST["totalWidth"];
$totalHeight = $_POST["totalHeight"];
$divWidth = $_POST["divWidth"];
$divHeight = $_POST["divHeight"];
$output = [];
$retval = NULL;
exec("path/to/your/compiled/cpp/program " . $totalWidth . " " . $totalHeight . " " . $divWidth . " " . $divHeight, $output, $retval);
if ($retval == 0) {
echo json_encode(["x" => $output[0], "y" => $output[1]]);
} else {
echo json_encode(["error" => "Error processing request"]);
}
} else {
echo "Invalid request";
}
?>
3. Use JavaScript to fetch the viewport size, the size of the <div>, and then call the PHP script.
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Center Div with C++</title>
<style>
#centeredDiv {
position: absolute;
/* Initially set to top left corner */
top: 0;
left: 0;
}
</style>
</head>
<body>
<div id="container">
<div id="centeredDiv">
<h1>Sample Content</h1>
</div>
</div>
<script>
function centerDiv() {
const div = document.getElementById('centeredDiv');
const divWidth = div.offsetWidth;
const divHeight = div.offsetHeight;
const totalWidth = window.innerWidth;
const totalHeight = window.innerHeight;
fetch('path/to/your/php/script.php', {
method: 'POST',
headers: {
'Content-Type': 'application/x-www-form-urlencoded',
},
body: `totalWidth=${totalWidth}&totalHeight=${totalHeight}&divWidth=${divWidth}&divHeight=${divHeight}`
})
.then(response => response.json())
.then(data => {
if (data.error) {
console.error(data.error);
} else {
div.style.left = `${data.x}px`;
div.style.top = `${data.y}px`;
}
})
.catch(error => console.error('Error:', error));
}
window.onload = centerDiv;
window.onresize = centerDiv;
</script>
</body>
</html>
Hope it helps.
