src/thinkextend/image/driver/Gd.php
public function water($source, $locate = THINKIMAGE_WATER_SOUTHEAST)
    {
        //资源检测
        if (empty($this->im)) {
            throw new Exception('没有可以被添加水印的图像资源');
        }

        if (!is_file($source)) {
            throw new Exception('水印图像不存在');
        }

        //获取水印图像信息
        $info = getimagesize($source);
        if (false === $info || (IMAGETYPE_GIF === $info[2] && empty($info['bits']))) {
            throw new Exception('非法水印文件');
        }

        //创建水印图像资源
        $fun   = 'imagecreatefrom' . image_type_to_extension($info[2], false);
        $water = $fun($source);

        //设定水印图像的混色模式
        imagealphablending($water, true);

        /* 设定水印位置 */
        switch ($locate) {
            /* 右下角水印 */
            case THINKIMAGE_WATER_SOUTHEAST:
                $x = $this->info['width'] - $info[0];
                $y = $this->info['height'] - $info[1];
                break;

            /* 左下角水印 */
            case THINKIMAGE_WATER_SOUTHWEST:
                $x = 0;
                $y = $this->info['height'] - $info[1];
                break;

            /* 左上角水印 */
            case THINKIMAGE_WATER_NORTHWEST:
                $x = $y = 0;
                break;

            /* 右上角水印 */
            case THINKIMAGE_WATER_NORTHEAST:
                $x = $this->info['width'] - $info[0];
                $y = 0;
                break;

            /* 居中水印 */
            case THINKIMAGE_WATER_CENTER:
                $x = ($this->info['width'] - $info[0]) / 2;
                $y = ($this->info['height'] - $info[1]) / 2;
                break;

            /* 下居中水印 */
            case THINKIMAGE_WATER_SOUTH:
                $x = ($this->info['width'] - $info[0]) / 2;
                $y = $this->info['height'] - $info[1];
                break;

            /* 右居中水印 */
            case THINKIMAGE_WATER_EAST:
                $x = $this->info['width'] - $info[0];
                $y = ($this->info['height'] - $info[1]) / 2;
                break;

            /* 上居中水印 */
            case THINKIMAGE_WATER_NORTH:
                $x = ($this->info['width'] - $info[0]) / 2;
                $y = 0;
                break;

            /* 左居中水印 */
            case THINKIMAGE_WATER_WEST:
                $x = 0;
                $y = ($this->info['height'] - $info[1]) / 2;
                break;

            default:
                /* 自定义水印坐标 */
                if (is_array($locate)) {
                    list($x, $y) = $locate;
                } else {
                    throw new Exception('不支持的水印位置类型');
                }
        }

        do {
            //添加水印
            $src = imagecreatetruecolor($info[0], $info[1]);
            // 调整默认颜色
            $color = imagecolorallocate($src, 255, 255, 255);
            imagefill($src, 0, 0, $color);

            imagecopy($src, $this->im, 0, 0, $x, $y, $info[0], $info[1]);
            imagecopy($src, $water, 0, 0, 0, 0, $info[0], $info[1]);
            imagecopymerge($this->im, $src, $x, $y, 0, 0, $info[0], $info[1], 100);

            //销毁零时图片资源
            imagedestroy($src);
        } while (!empty($this->gif) && $this->gifNext());

        //销毁水印资源
        imagedestroy($water);
        return $this;
    }
public function water($source, $locate = THINKIMAGE_WATER_SOUTHEAST)
    {
        //资源检测
        if (empty($this->im)) {
            throw new Exception('没有可以被添加水印的图像资源');
        }

        if (!is_file($source)) {
            throw new Exception('水印图像不存在');
        }

        //获取水印图像信息
        $info = getimagesize($source);
        if (false === $info || (IMAGETYPE_GIF === $info[2] && empty($info['bits']))) {
            throw new Exception('非法水印文件');
        }

        //创建水印图像资源
        $fun   = 'imagecreatefrom' . image_type_to_extension($info[2], false);
        $water = $fun($source);

        //设定水印图像的混色模式
        imagealphablending($water, true);

        /* 设定水印位置 */
        switch ($locate) {
            /* 右下角水印 */
            case THINKIMAGE_WATER_SOUTHEAST:
                $x = $this->info['width'] - $info[0];
                $y = $this->info['height'] - $info[1];
                break;

            /* 左下角水印 */
            case THINKIMAGE_WATER_SOUTHWEST:
                $x = 0;
                $y = $this->info['height'] - $info[1];
                break;

            /* 左上角水印 */
            case THINKIMAGE_WATER_NORTHWEST:
                $x = $y = 0;
                break;

            /* 右上角水印 */
            case THINKIMAGE_WATER_NORTHEAST:
                $x = $this->info['width'] - $info[0];
                $y = 0;
                break;

            /* 居中水印 */
            case THINKIMAGE_WATER_CENTER:
                $x = ($this->info['width'] - $info[0]) / 2;
                $y = ($this->info['height'] - $info[1]) / 2;
                break;

            /* 下居中水印 */
            case THINKIMAGE_WATER_SOUTH:
                $x = ($this->info['width'] - $info[0]) / 2;
                $y = $this->info['height'] - $info[1];
                break;

            /* 右居中水印 */
            case THINKIMAGE_WATER_EAST:
                $x = $this->info['width'] - $info[0];
                $y = ($this->info['height'] - $info[1]) / 2;
                break;

            /* 上居中水印 */
            case THINKIMAGE_WATER_NORTH:
                $x = ($this->info['width'] - $info[0]) / 2;
                $y = 0;
                break;

            /* 左居中水印 */
            case THINKIMAGE_WATER_WEST:
                $x = 0;
                $y = ($this->info['height'] - $info[1]) / 2;
                break;

            default:
                /* 自定义水印坐标 */
                if (is_array($locate)) {
                    list($x, $y) = $locate;
                } else {
                    throw new Exception('不支持的水印位置类型');
                }
        }

        do {
            //添加水印
            $src = imagecreatetruecolor($info[0], $info[1]);
            // 调整默认颜色
            $color = imagecolorallocate($src, 255, 255, 255);
            imagefill($src, 0, 0, $color);

            imagecopy($src, $this->im, 0, 0, $x, $y, $info[0], $info[1]);
            imagecopy($src, $water, 0, 0, 0, 0, $info[0], $info[1]);
            imagecopymerge($this->im, $src, $x, $y, 0, 0, $info[0], $info[1], 100);

            //销毁零时图片资源
            imagedestroy($src);
        } while (!empty($this->gif) && $this->gifNext());

        //销毁水印资源
        imagedestroy($water);
        return $this;
    }
添加水印

@param  string $source 水印图片路径
@param int     $locate 水印位置

@return $this
@throws Exception
@internal param int $alpha 水印透明度