PHP implements image upload and compression, _PHP tutorial

PHP implements image uploading and compression,

This article explains the implementation method of PHP image uploading and compression, and shares it with everyone for your reference. The specific content is as follows

Three files are used

• connect.php: Connect to database
• test_upload.php: Execute SQL statement
• upload_img.php: Upload images and compress them
  

The three file codes are as follows:
Connect to database: connect.php

<?php
$db_host = '';
$db_user = '';
$db_psw = '';
$db_name = '';
$db_port = '';
$sqlconn=new mysqli($db_host,$db_user,$db_psw,$db_name);
$q="set names utf8;";
$result=$sqlconn->query($q);
if (mysqli_connect_errno()) {
 printf("Connect failed: %s\n", mysqli_connect_error());
 exit();
}
?>

Execute SQL statement: test_upload.php

<?php
require ("connect.php");
require ("upload_img.php");
$real_img=$uploadfile; 
$small_img=$uploadfile_resize;
$insert_sql = "insert into img (real_img,small_img) values (?,?)";
$result = $sqlconn -> prepare($insert_sql);
$result -> bind_param("ss", $real_img,$small_img);
$result -> execute();
?>

Upload images and compress : upload_img.php

<?php 
//设置文件保存目录
$uploaddir = "upfiles/"; 
//设置允许上传文件的类型
$type=array("jpg","gif","bmp","jpeg","png"); 

//获取文件后缀名函数 
function fileext($filename) 
{ 
 return substr(strrchr($filename, '.'), 1); 
} 

//生成随机文件名函数 
function random($length) 
{ 
 $hash = 'CR-'; 
 $chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789abcdefghijklmnopqrstuvwxyz'; 
 $max = strlen($chars) - 1; 
 mt_srand((double)microtime() * 1000000); 
 for($i = 0; $i < $length; $i++) 
 { 
  $hash .= $chars[mt_rand(0, $max)]; 
 } 
 return $hash; 
} 

$a=strtolower(fileext($_FILES['filename']['name'])); 

//判断文件类型 
if(!in_array(strtolower(fileext($_FILES['filename']['name'])),$type)) 
{ 
 $text=implode(",",$type); 
 $ret_code=3;//文件类型错误
 $page_result=$text;
 $retArray = array('ret_code' => $ret_code,'page_result'=>$page_result);
 $retJson = json_encode($retArray);
 echo $retJson;
 return;
} 

//生成目标文件的文件名 
else
{ 
 $filename=explode(".",$_FILES['filename']['name']); 
 do 
 { 
  $filename[0]=random(10); //设置随机数长度 
  $name=implode(".",$filename); 
  //$name1=$name.".Mcncc"; 
  $uploadfile=$uploaddir.$name; 
 } 

 while(file_exists($uploadfile)); 

 if (move_uploaded_file($_FILES['filename']['tmp_name'],$uploadfile)) 
 { 
  if(is_uploaded_file($_FILES['filename']['tmp_name'])) 
  {
   $ret_code=1;//上传失败
  } 
 else 
 {//上传成功
  $ret_code=0;
 } 
 } 
$retArray = array('ret_code' => $ret_code);
$retJson = json_encode($retArray);
echo $retJson;
}

//压缩图片

$uploaddir_resize="upfiles_resize/";
$uploadfile_resize=$uploaddir_resize.$name;

//$pic_width_max=120;
//$pic_height_max=90;
//以上与下面段注释可以联合使用，可以使图片根据计算出来的比例压缩

$file_type=$_FILES["filename"]['type'];

function ResizeImage($uploadfile,$maxwidth,$maxheight,$name)
{
 //取得当前图片大小
 $width = imagesx($uploadfile);
 $height = imagesy($uploadfile);
 $i=0.5;
 //生成缩略图的大小
 if(($width > $maxwidth) || ($height > $maxheight))
 {
  /*
  $widthratio = $maxwidth/$width;
  $heightratio = $maxheight/$height;
  
  if($widthratio < $heightratio)
  {
   $ratio = $widthratio;
  }
  else
  {
    $ratio = $heightratio;
  }
  
  $newwidth = $width * $ratio;
  $newheight = $height * $ratio;
  */
  $newwidth = $width * $i;
  $newheight = $height * $i;
  if(function_exists("imagecopyresampled"))
  {
   $uploaddir_resize = imagecreatetruecolor($newwidth, $newheight);
   imagecopyresampled($uploaddir_resize, $uploadfile, 0, 0, 0, 0, $newwidth, $newheight, $width, $height);
  }
  else
  {
   $uploaddir_resize = imagecreate($newwidth, $newheight);
   imagecopyresized($uploaddir_resize, $uploadfile, 0, 0, 0, 0, $newwidth, $newheight, $width, $height);
  }
  
  ImageJpeg ($uploaddir_resize,$name);
  ImageDestroy ($uploaddir_resize);
 }
 else
 {
  ImageJpeg ($uploadfile,$name);
 }
}



if($_FILES["filename"]['size'])
{
 if($file_type == "image/pjpeg"||$file_type == "image/jpg"|$file_type == "image/jpeg")
 {
  //$im = imagecreatefromjpeg($_FILES[$upload_input_name]['tmp_name']);
  $im = imagecreatefromjpeg($uploadfile);
 }
 elseif($file_type == "image/x-png")
 {
  //$im = imagecreatefrompng($_FILES[$upload_input_name]['tmp_name']);
  $im = imagecreatefromjpeg($uploadfile);
 }
 elseif($file_type == "image/gif")
 {
  //$im = imagecreatefromgif($_FILES[$upload_input_name]['tmp_name']);
  $im = imagecreatefromjpeg($uploadfile);
 }
 else//默认jpg
 {
  $im = imagecreatefromjpeg($uploadfile);
 }
 if($im)
 {
  ResizeImage($im,$pic_width_max,$pic_height_max,$uploadfile_resize);
 
  ImageDestroy ($im);
 }
} 
?>

Please change the corresponding information in connect.php and test_upload.php according to the actual situation.

The above is how to upload and compress images in PHP. I hope it will be helpful to everyone in learning PHP programming

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