<?
function ImageResize($srcFile,$toW,$toH,$toFile=""){
    if($toFile==""){ $toFile = $srcFile; }
    $info = "";
    $data = GetImageSize($srcFile,$info);
    switch ($data[2])
    {
   case 1:
    if(!function_exists("imagecreatefromgif")){
     echo "你的GD库不能使用GIF格式的图片，请使用Jpeg或PNG格式！<a href='javascript:go(-1);'>返回</a>";
     exit();
    }
    $im = ImageCreateFromGIF($srcFile);
    break;
   case 2:
    if(!function_exists("imagecreatefromjpeg")){
     echo "你的GD库不能使用jpeg格式的图片，请使用其它格式的图片！<a href='javascript:go(-1);'>返回</a>";
     exit();
    }
    $im = ImageCreateFromJpeg($srcFile);   
    break;
   case 3:
    $im = ImageCreateFromPNG($srcFile);   
    break;
   }
   $srcW=ImageSX($im);
   $srcH=ImageSY($im);
   $toWH=$toW/$toH;
   $srcWH=$srcW/$srcH;
   if($toWH<=$srcWH){
     $ftoW=$toW;
     $ftoH=$ftoW*($srcH/$srcW);
   }
   else{
    $ftoH=$toH;
    $ftoW=$ftoH*($srcW/$srcH);
   }   
   if($srcW>$toW||$srcH>$toH)
   {
   if(function_exists("imagecreatetruecolor")){
    @$ni = ImageCreateTrueColor($ftoW,$ftoH);
    if($ni) ImageCopyResampled($ni,$im,0,0,0,0,$ftoW,$ftoH,$srcW,$srcH);
    else{
    $ni=ImageCreate($ftoW,$ftoH);
     ImageCopyResized($ni,$im,0,0,0,0,$ftoW,$ftoH,$srcW,$srcH);
    }
   }else{
    $ni=ImageCreate($ftoW,$ftoH);
    ImageCopyResized($ni,$im,0,0,0,0,$ftoW,$ftoH,$srcW,$srcH);
   }
   if(function_exists('imagejpeg')) ImageJpeg($ni,$toFile);
   else ImagePNG($ni,$toFile);
   ImageDestroy($ni);
   }
   ImageDestroy($im);
}
?>