php图片增加水印的方法

function imageWaterMark($groundImage, $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 ($water_info[2]) {//取得水印图片的格式
            case 1:$water_im = imagecreatefromgif($waterImage);
                break;

            case 2:$water_im = imagecreatefromjpeg($waterImage);
                break;

            case 3:$water_im = imagecreatefrompng($waterImage);
                break;

            default:die($formatMsg);
        }
    }

    //读取背景图片

    if (!empty($groundImage) && file_exists($groundImage)) {

        $ground_info = getimagesize($groundImage);

        $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($groundImage);
                break;

            case 2:$ground_im = imagecreatefromjpeg($groundImage);
                break;

            case 3:$ground_im = imagecreatefrompng($groundImage);
                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 * 5), 0, "./cour.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 - 10;   // -10 是距离右侧10px 可以自己调节

            $posY = $ground_h - $h - 10;   // -10 是距离底部10px 可以自己调节

            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, $water_h); //拷贝水印到目标文件
    } else {//文字水印
        if (!emptyempty($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($groundImage);

    switch ($ground_info[2]) {//取得背景图片的格式
        case 1:imagegif($ground_im, $groundImage);
            break;

        case 2:imagejpeg($ground_im, $groundImage);
            break;

        case 3:imagepng($ground_im, $groundImage);
            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);
}

waterText('banner.jpg', 9, '','sucaihuo.com'); //背景图片,$waterPos水印位置,水印图片地址

imageWaterMark('404.jpg', 9, 'logo.gif'); //背景图片,$waterPos水印位置,水印图片地址