How to modify pictures in php

php method to modify the image size: first open the corresponding PHP file; then modify the image size through the "function resize_image($filename, $tmpname, $xmax, $ymax){...}" code .

The operating environment of this article: Windows 7 system, PHP version 5.6, DELL G3 computer.

php Modify 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; 
}
?>

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