php中png透明背景水印程序代码

//原始图像
$dst = "/upload/20120914/20120914040740-0.jpg"; //注意图片路径要正确
//得到原始图片信息
$dst_info = getimagesize($dst); 
switch ($dst_info[2])
{
case 1:
$dst_im =imagecreatefromgif($dst);break;
case 2:
$dst_im =imagecreatefromjpeg($dst);break;
case 3:
$dst_im =imagecreatefrompng($dst);break;
case 6:
$dst_im =imagecreatefromwbmp($dst);break;
default:
die("不支持的文件类型1");exit;
}
//水印图像
$src = "/images/shuiyin.png"; //注意路径要写对
$src_info = getimagesize($src);
switch ($src_info[2])
{
case 1:
$src_im =imagecreatefromgif($src);break;
case 2:
$src_im =imagecreatefromjpeg($src);break;
case 3:
$src_im =imagecreatefrompng($src);break;
case 6:
$src_im =imagecreatefromwbmp($src);break;
default:
die("不支持的文件类型1");exit;
}
 
//半透明格式水印
//$alpha = 50;//水印透明度
//imagecopymerge($dst_im,$src_im,$dst_info[0]-$src_info[0]-10,$dst_info[1]-$src_info[1]-
10,0,0,$src_info[0],$src_info[1],$alpha);
 
//支持png本身透明度的方式
imagecopy($dst_im,$src_im,$dst_info[0]-$src_info[0]-10,$dst_info[1]-$src_info[1]-10,0,0,$src_info
[0],$src_info[1]);
 
//保存图片
switch ($dst_info[2]){
case 1:
imagegif($dst_im,$dst);break;
case 2:
imagejpeg($dst_im,$dst);break;
case 3:
imagepng($dst_im,$dst);break;
case 6:
imagewbmp($dst_im,$dst);break;
default:
die("不支持的文件类型2");exit;
}
imagedestroy($dst_im);
imagedestroy($src_im);

在网上找的水印代码：
/* 
* 功能：PHP图片水印 (水印支持图片或文字) 
* 参数： 
*      $product_img    背景图片，即需要加水印的图片，暂只支持GIF,JPG,PNG格式； 
*      $waterPos        水印位置，有10种状态，0为随机位置； 
*                        1为顶端居左，2为顶端居中，3为顶端居右； 
*                        4为中部居左，5为中部居中，6为中部居右； 
*                        7为底端居左，8为底端居中，9为底端居右； 
*      $waterImage        图片水印，即作为水印的图片，暂只支持GIF,JPG,PNG格式； 
*      $waterText        文字水印，即把文字作为为水印，支持ASCII码，不支持中文； 
*      $textFont        文字大小，值为1、2、3、4或5，默认为5； 
*      $textColor        文字颜色，值为十六进制颜色值，默认为#FF0000(红色)； 
* 
* 注意：Support GD 2.0，Support FreeType、GIF Read、GIF Create、JPG 、PNG 
*      $waterImage 和 $waterText 最好不要同时使用，选其中之一即可，优先使用 $waterImage。 
*      当$waterImage有效时，参数$waterString、$stringFont、$stringColor均不生效。 
*      加水印后的图片的文件名和 $product_img 一样。 
* 作者：longware @ 2004-11-3 14:15:13 
*/ 
function imageWaterMark
($product_img,$waterPos=0,$waterImage="",$waterText="",$textFont=5,$textColor="#FF0000") 
{ 
    $isWaterImage = FALSE; 
    $formatMsg = "暂不支持该文件格式，请用图片处理软件将图片转换为GIF、JPG、PNG格式。"; 
    //读取水印文件 
    if(!empty($waterImage) && file_exists($waterImage)) 
    { 
        $isWaterImage = TRUE; 
        $water_info = getimagesize($waterImage); 
        $water_w    = $water_info[0];//取得水印图片的宽 
        $water_h    = $water_info[1];//取得水印图片的高 
        switch($water_info[2])//取得水印图片的格式 
        { 
            case 1water_im = imagecreatefromgif($waterImage);break; 
            case 2water_im = imagecreatefromjpeg($waterImage);break; 
            case 3water_im = imagecreatefrompng($waterImage);break; 
            default:die($formatMsg); 
        } 
    } 
    //读取背景图片 
    if(!empty($product_img) && file_exists($product_img)) 
    { 
        $ground_info = getimagesize($product_img); 
        $ground_w    = $ground_info[0];//取得背景图片的宽 
        $ground_h    = $ground_info[1];//取得背景图片的高 
        switch($ground_info[2])//取得背景图片的格式 
        { 
            case 1:$ground_im = imagecreatefromgif($product_img);break; 
            case 2:$ground_im = imagecreatefromjpeg($product_img);break; 
            case 3:$ground_im = imagecreatefrompng($product_img);break; 
            default:die($formatMsg); 
        } 
    } 
    else 
    { 
        die("需要加水印的图片不存在！"); 
    } 
    //水印位置 
    if($isWaterImage)//图片水印 
    { 
        $w = $water_w; 
        $h = $water_h; 
        $label = "图片的"; 
    } 
    else//文字水印 
    { 
        $temp = imagettfbbox(ceil($textFont*2.5),0,"arial.ttf",$waterText);//取得使用 TrueType 字体的文
本的范围 
        $w = $temp[2] - $temp[6]; 
        $h = $temp[3] - $temp[7]; 
        unset($temp); 
        $label = "文字区域"; 
    } 
    if( ($ground_w<$w) || ($ground_h<$h) ) 
    { 
        echo "需要加水印的图片的长度或宽度比水印".$label."还小，无法生成水印！"; 
        return; 
    } 
    switch($waterPos) 
    { 
        case 0://随机 
            $posX = rand(0,($ground_w - $w)); 
            $posY = rand(0,($ground_h - $h)); 
            break; 
        case 1://1为顶端居左 
            $posX = 0; 
            $posY = 0; 
            break; 
        case 2://2为顶端居中 
            $posX = ($ground_w - $w) / 2; 
            $posY = 0; 
            break; 
        case 3://3为顶端居右 
            $posX = $ground_w - $w; 
            $posY = 0; 
            break; 
        case 4://4为中部居左 
            $posX = 0; 
            $posY = ($ground_h - $h) / 2; 
            break; 
        case 5://5为中部居中 
            $posX = ($ground_w - $w) / 2; 
            $posY = ($ground_h - $h) / 2; 
            break; 
        case 6://6为中部居右 
            $posX = $ground_w - $w; 
            $posY = ($ground_h - $h) / 2; 
            break; 
        case 7://7为底端居左 
            $posX = 0; 
            $posY = $ground_h - $h; 
            break; 
        case 8://8为底端居中 
            $posX = ($ground_w - $w) / 2; 
            $posY = $ground_h - $h; 
            break; 
        case 9://9为底端居右 
            $posX = $ground_w - $w; 
            $posY = $ground_h - $h; 
            break; 
        default://随机 
            $posX = rand(0,($ground_w - $w)); 
            $posY = rand(0,($ground_h - $h)); 
            break;     
    } 
    //设定图像的混色模式 
    imagealphablending($ground_im, true); 
    if($isWaterImage)//图片水印 
    { 
        imagecopy($ground_im, $water_im, $posX, $posY, 0, 0, $water_w,$water_h);//拷贝水印到目标文件   
     
    } 
    else//文字水印 
    { 
        if( !empty($textColor) && (strlen($textColor)==7) ) 
        { 
            $R = hexdec(substr($textColor,1,2)); 
            $G = hexdec(substr($textColor,3,2)); 
            $B = hexdec(substr($textColor,5)); 
        } 
        else 
        { 
            die("水印文字颜色格式不正确！"); 
        } 
        imagestring ( $ground_im, $textFont, $posX, $posY, $waterText, imagecolorallocate($ground_im,
$R, $G, $B));         
    } 
    //生成水印后的图片 
    @unlink($product_img); 
    switch($ground_info[2])//取得背景图片的格式 
    { 
        case 1:imagegif($ground_im,$product_img);break; 
        case 2:imagejpeg($ground_im,$product_img);break; 
        case 3:imagepng($ground_im,$product_img);break; 
        default:die($errorMsg); 
    } 
    //释放内存 
    if(isset($water_info)) unset($water_info); 
    if(isset($water_im)) imagedestroy($water_im); 
    unset($ground_info); 
    imagedestroy($ground_im); 
}
//--------------------------------------------------------------------------------------- 
if(isset($_FILES) && !empty($_FILES['userfile']) && $_FILES['userfile']['size']>0) 
{ 
    $uploadfile = "./".time()."_".$_FILES['userfile']['name']; 
    if (copy($_FILES['userfile']['tmp_name'], $uploadfile)) 
    { 
        echo "OK<br>"; 
        //文字水印 
        imageWaterMark($uploadfile,0,"",http://www.php100.com,5,"#FF0000"); 
        //图片水印 
        //$waterImage="images/bz.gif";//水印图片路径 
        //imageWaterMark($uploadfile,0,$waterImage); 
        echo "<img src="".$uploadfile."" border="0">"; 
    } 
    else 
    { 
        echo "Fail<br>"; 
    } 
}