Comment générer une fonction de vignette d'image en php

<?php
/*
 * Created on 2011-3-18
 *
 * To change the template for this generated file go to
 * Window - Preferences - PHPeclipse - PHP - Code Templates
*/
/*构造函数-生成缩略图+水印,参数说明:
$srcFile-图片文件名,
$dstFile-另存文件名,
$markwords-水印文字,
$markimage-水印图片,
$dstW-图片保存宽度,
$dstH-图片保存高度,
$rate-图片保存品质*/
makethumb("1.jpg", "aa/b.jpg", "50", "50");
function makethumb($srcFile, $dstFile, $dstW, $dstH, $rate = 100, $markwords = null, $markimage = null) {
  $data = GetImageSize($srcFile);
  switch ($data[2]) {
    case 1:
      $im = @ImageCreateFromGIF($srcFile);
    break;
    case 2:
      $im = @ImageCreateFromJPEG($srcFile);
    break;
    case 3:
      $im = @ImageCreateFromPNG($srcFile);
    break;
  }
  if (!$im) return False;
  $srcW = ImageSX($im);
  $srcH = ImageSY($im);
  $dstX = 0;
  $dstY = 0;
  if ($srcW * $dstH > $srcH * $dstW) {
    $fdstH = round($srcH * $dstW / $srcW);
    $dstY = floor(($dstH - $fdstH) / 2);
    $fdstW = $dstW;
  } else {
    $fdstW = round($srcW * $dstH / $srcH);
    $dstX = floor(($dstW - $fdstW) / 2);
    $fdstH = $dstH;
  }
  $ni = ImageCreateTrueColor($dstW, $dstH);
  $dstX = ($dstX < 0) ? 0 : $dstX;
  $dstY = ($dstX < 0) ? 0 : $dstY;
  $dstX = ($dstX > ($dstW / 2)) ? floor($dstW / 2) : $dstX;
  $dstY = ($dstY > ($dstH / 2)) ? floor($dstH / s) : $dstY;
  $white = ImageColorAllocate($ni, 255, 255, 255);
  $black = ImageColorAllocate($ni, 0, 0, 0);
  imagefilledrectangle($ni, 0, 0, $dstW, $dstH, $white); // 填充背景色
  ImageCopyResized($ni, $im, $dstX, $dstY, 0, 0, $fdstW, $fdstH, $srcW, $srcH);
  if ($markwords != null) {
    $markwords = iconv("gb2312", "UTF-8", $markwords);
    //转换文字编码
    ImageTTFText($ni, 20, 30, 450, 560, $black, "simhei.ttf", $markwords); //写入文字水印
    //参数依次为，文字大小|偏转度|横坐标|纵坐标|文字颜色|文字类型|文字内容
    
  } elseif ($markimage != null) {
    $wimage_data = GetImageSize($markimage);
    switch ($wimage_data[2]) {
      case 1:
        $wimage = @ImageCreateFromGIF($markimage);
      break;
      case 2:
        $wimage = @ImageCreateFromJPEG($markimage);
      break;
      case 3:
        $wimage = @ImageCreateFromPNG($markimage);
      break;
    }
    imagecopy($ni, $wimage, 500, 560, 0, 0, 88, 31); //写入图片水印,水印图片大小默认为88*31
    imagedestroy($wimage);
  }
  ImageJpeg($ni, $dstFile, $rate);
  ImageJpeg($ni, $srcFile, $rate);
  imagedestroy($im);
  imagedestroy($ni);
}
?>