<?phpfunction 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,$newheight);//PHP系統函數   imagecopyresampled($newim,$im,0,0,0,0,$newwidth,$newheight,$pic_width,$pic_height);//PHP系統函數  }  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：$im=imagecreatefromjpeg("./20140416103023202.jpg");//參數是圖片的存方路徑$maxwidth="600";//設置圖片的最大寬度$maxheight="400";//設置圖片的最大高度$name="123";//圖片的名稱，隨便取吧$filetype=".jpg";//圖片類型resizeImage($im,$maxwidth,$maxheight,$name,$filetype);//調用上面的函數