PHP Proportional Image Scaling Detailed Explanation and Example Code

Directly upload the code, the imgzip($src,$newwid,$newhei) function takes in the original image, the required width for scaling, and the length for scaling. The code is all commented, if you don't understand, you can leave a message ha ha

<?php 
//Compress image, thumbnail
$src= "xiezheng.jpg";
$newwid=640;
$newhei= 480;
function imgzip($src,$newwid,$newhei){
 $imgInfo = getimagesize($src);
 $imgType = image_type_to_extension($imgInfo[2], false);
 $fun = "imagecreatefrom{$imgType}";
//Declare image, open image, in memory
 $image = $fun($src);
//Convenient to configure length, width, and height, set the frame as the variable wid, and the height as hei
 $wid=$imgInfo[0];
 $hei=$imgInfo[1];
//Determine the length and width to facilitate proportional scaling, specifications are according to500, 320
 if($wid>$hei){
  $wid=$newwid;
  $hei=$newwid/($wid/$hei);
 }else {
  $wid = $newhei * ($wid / $hei);
  $hei = $newhei;
 }
//Create a picture in memory
 $images2 = imagecreatetruecolor($newwid, $newhei); //Establish a500*320 image
//Copy the original image to the new image
//imagecopyresampled($dst_image, $src_image, $dst_x, $dst_y, $src_x, $src_y, $dst_w, $dst_h, $src_w, $src_h)
 imagecopyresampled($images2, $image, 0, 0, 0, 0, $wid,$hei, $imgInfo[0],$imgInfo[0]);
//Destroy the original image
 imagedestroy($image);
//Directly output the image file
 header("Content-type: ".$imgInfo[‘mime’]);
 imagejpeg($images2);
//Save the image to a new file
 imagejpeg($images2, ‘new.jpg’ 100); //10The quality of the output image code is 0-100 100 - Highest Quality
//Destroy
 imagedestroy($images2);
}
imgzip($src,$newwid,$newhei);
?>

　Effect

Before Compression

Compressed

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