php 使用GD库为页面增加水印

<?php
header ("Content-type: image/png");
$conn = mysql_connect("localhost", "root", "");		//连接数据库
$colname_rs_article = $_GET['id'];				//获取参数id

mysql_select_db("cms", $conn);					//执行SQL
$query_rs_article = sprintf("SELECT * FROM articles WHERE article_id = %s", $colname_rs_article);
$rs_article = mysql_query($query_rs_article, $conn) or die(mysql_error());
$row_rs_article = mysql_fetch_assoc($rs_article);
$totalRows_rs_article = mysql_num_rows($rs_article);

$image = ImageCreateTrueColor(700, 1000);					//创建画布
$bg = ImageColorAllocate($image, 255, 255, 255);		//设置背景为白色
ImageFill($image, 0, 0, $bg);
$text_color = ImageColorAllocate($image, 0, 0, 0);		//设置文字颜色为黑色
imagestring($image, 5, 0, 0, $row_rs_article['title'], $text_color);		//输出文章标题
imagestring($image, 3, 0, 20, $row_rs_article['author'], $text_color);	//输出文章作者
imagestring($image, 4, 0, 60, $row_rs_article['content'], $text_color);	//输出文章内容
$logo = ImageCreateFromPNG('logo.png');			//获得水印图片
$logoW = ImageSX($logo);
$logoH = ImageSY($logo);
ImageCopy($image, $logo, 0, 0, 0, 0, $logoW, $logoH);			//合并文字图片与水印图片
ImageJPEG($image); // output to browser
ImageDestroy($logo);
ImageDestroy($image);
?>