Example of PHP method for compressing picture size and converting it to jpg format

In this paper, an example is given to describe the method of compressing picture size by PHP and converting it into jpg format. Share it for your reference, as follows:

<?php
function ImageToJPG($srcFile,$dstFile,$towidth,$toheight)
{
  $quality=80;
  $data = @GetImageSize($srcFile);
  switch ($data['2'])
  {
  case 1:
    $im = imagecreatefromgif($srcFile);
    break;
  case 2:
    $im = imagecreatefromjpeg($srcFile);
    break;
  case 3:
    $im = imagecreatefrompng($srcFile);
    break;
  case 6:
  $im = ImageCreateFromBMP( $srcFile );
  break;
  }
  // $dstX=$srcW=@ImageSX($im);
  // $dstY=$srcH=@ImageSY($im);
  $srcW=@ImageSX($im);
  $srcH=@ImageSY($im);
  //$towidth,$toheight
  if($toheight/$srcW > $towidth/$srcH){
    $b = $toheight/$srcH;
  }else{
    $b = $towidth/$srcW;
  }
  // Calculate the width and height of the scaled picture 
  // floor  Discard the decimal point and round it 
  $new_w = floor($srcW*$b);
  $new_h = floor($srcH*$b);
  $dstX=$new_w;
  $dstY=$new_h;
  $ni=@imageCreateTrueColor($dstX,$dstY);
  @ImageCopyResampled($ni,$im,0,0,0,0,$dstX,$dstY,$srcW,$srcH);
  @ImageJpeg($ni,$dstFile,$quality);
  @imagedestroy($im);
  @imagedestroy($ni);
}
//ImageToJPG(' Source file name ',' Destination file name ', Target width , High target );
ImageToJPG('test2.png','test2.jpg',80,50);

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I hope this article is helpful to everyone's PHP programming.