How to change image size in php

How to change the image size in php: 1. Use the function [$xmax] to modify the maximum width of the image; 2. Use the function [$ymax] to modify the maximum height of the image; use the function [$tmpname] to upload the file to Table of contents.

php method to change the image size:

Use the following code to modify the image size or create a thumbnail.

Parameter description:

• $filename: file name.

• $tmpname: File path, such as the temporary directory during upload.

• $xmax: Maximum width after modification.

• $ymax: Maximum height after modification.

<?php
// 重置图片文件大小
function resize_image($filename, $tmpname, $xmax, $ymax)
{
    $ext = explode(".", $filename);
    $ext = $ext[count($ext)-1];
 
    if($ext == "jpg" || $ext == "jpeg")
        $im = imagecreatefromjpeg($tmpname);
    elseif($ext == "png")
        $im = imagecreatefrompng($tmpname);
    elseif($ext == "gif")
        $im = imagecreatefromgif($tmpname);
 
    $x = imagesx($im);
    $y = imagesy($im);
 
    if($x <= $xmax && $y <= $ymax)
        return $im;
 
    if($x >= $y) {
        $newx = $xmax;
        $newy = $newx * $y / $x;
    }
    else {
        $newy = $ymax;
        $newx = $x / $y * $newy;
    }
 
    $im2 = imagecreatetruecolor($newx, $newy);
    imagecopyresized($im2, $im, 0, 0, 0, 0, floor($newx), floor($newy), $x, $y);
    return $im2; 
}
?>

Related learning recommendations: php graphic tutorial

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