PHP implements equal scaling and uploads images

Sometimes when uploading pictures, the pictures are too large, which not only takes up space and consumes traffic, but also affects browsing (the sizes of pictures vary). Let’s share a method of scaling images in equal proportions without distortion. In this way, no matter how big the uploaded image is, it will be automatically compressed to the range of the size value we set. Tested and proven practical.

function resizeImage($im,$maxwidth,$maxheight,$name,$filetype)
 {
  $pic_width = imagesx($im);
  $pic_height = imagesy($im);
 
  if(($maxwidth && $pic_width > $maxwidth) || ($maxheight && $pic_height > $maxheight))
  {
   if($maxwidth && $pic_width>$maxwidth)
   {
    $widthratio = $maxwidth/$pic_width;
    $resizewidth_tag = true;
   }
 
   if($maxheight && $pic_height>$maxheight)
   {
    $heightratio = $maxheight/$pic_height;
    $resizeheight_tag = true;
   }
 
   if($resizewidth_tag && $resizeheight_tag)
   {
    if($widthratio<$heightratio)
     $ratio = $widthratio;
    else
     $ratio = $heightratio;
   }
 
   if($resizewidth_tag && !$resizeheight_tag)
    $ratio = $widthratio;
   if($resizeheight_tag && !$resizewidth_tag)
    $ratio = $heightratio;
 
   $newwidth = $pic_width * $ratio;
   $newheight = $pic_height * $ratio;
 
   if(function_exists("imagecopyresampled"))
   {
    $newim = imagecreatetruecolor($newwidth,$newheight);//PHP系统函数
      imagecopyresampled($newim,$im,0,0,0,0,$newwidth,$newheight,$pic_width,$pic_height);//PHP系统函数
   }
   else
   {
    $newim = imagecreate($newwidth,$newheight);
      imagecopyresized($newim,$im,0,0,0,0,$newwidth,$newheight,$pic_width,$pic_height);
   }
 
   $name = $name.$filetype;
   imagejpeg($newim,$name);
   imagedestroy($newim);
  }
  else
  {
   $name = $name.$filetype;
   imagejpeg($im,$name);
  }
 }
//使用方法：
$im=imagecreatefromjpeg("./20140416103023202.jpg");//参数是图片的存方路径
$maxwidth="600";//设置图片的最大宽度
$maxheight="400";//设置图片的最大高度
$name="123";//图片的名称，随便取吧
$filetype=".jpg";//图片类型
resizeImage($im,$maxwidth,$maxheight,$name,$filetype);//调用上面的函数

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