[PHP知识库]图片压缩且加水印（php）

业务场景是微信小程序图片上传需要压缩原图 且保留原图（php5.6? ?thinkphp3? 无需引入其他扩展文件）按道理来说php其他版本以及框架都可用（我也没试过）

先上通用函数以及主函数（调用示例再最下面）

   
    /**
     * 图片压缩处理（主函数）
     * @param string $sFile 源图片路径
     * @param int $iWidth  自定义图片宽度
     * @param int $iHeight 自定义图片高度
     * @return string      压缩后的图片路径
     */
    protected function getThumb($sFile,$iWidth,$iHeight){
        //图片公共路径
        $public_path = '';
        //判断该图片是否存在
        if(!file_exists($public_path.$sFile)) return $sFile;
        //判断图片格式(图片文件后缀)
        $extend = explode("." , $sFile);
        $attach_fileext = strtolower($extend[count($extend) - 1]);
        if (!in_array($attach_fileext, array('jpg','png','jpeg'))){
            return false;
        }
        //压缩图片文件名称
        $sFileNameS = str_replace(".".$attach_fileext, "_".$iWidth.'_'.$iHeight.'.'.$attach_fileext, $sFile);
        //判断是否已压缩图片，若是则返回压缩图片路径
        if(file_exists($public_path.$sFileNameS)){
            return $sFileNameS;
        }
        //生成压缩图片，并存储到原图同路径下
//
        $this->resizeImage($public_path.$sFile, $public_path.$sFileNameS, $iWidth, $iHeight);
        $this->watermark($public_path.$sFileNameS,$public_path.$sFileNameS);
//       $this->resizeImage($public_path.$sFileNameS, $public_path.$sFileNameS, $iWidth, $iHeight);
        if(!file_exists($public_path.$sFileNameS)){
            return $sFile;
        }
        return $sFileNameS;
    }


    /**
     * 创建图片水印
     * @param string $dst_path 图片
     * @param string $src_path 水印图片
     */
    public function watermark($dst_path,$bc_path){
        $configs = D('Config')->where(array('name' => array('like', '_' . strtoupper('Picture') . '_' . '%')))->limit(999)->select();
        $data = array();
        foreach ($configs as $k => $v) {
            $key = str_replace('_' . strtoupper('Picture') . '_', '', strtoupper($v['name']));
            $data[$key] = $v['value'];
        }
        if($data['WATER_OPEN']!=1){
            return false;
        }
        $src_path ='http://172.0.0.83'.$data['WATER_IMAGE'];
//创建图片的实例
        $dst = imagecreatefromstring(file_get_contents($dst_path));
        $src = imagecreatefromstring(file_get_contents($src_path));
//获取水印图片的宽高
        list($src_w, $src_h) = getimagesize($src_path);
//将水印图片复制到目标图片上，最后个参数50是设置透明度，这里实现半透明效果

        $space = $this->get_water_postion($src_path,$dst_path,$data['WATER_SPACE']);
        $porintLeft = $space['porintLeft'];
        $pointTop= $space['pointTop'];
//        imagecopymerge($dst, $src, $porintLeft, $pointTop,0 , 0, $src_w, $src_h, 20);
//如果水印图片本身带透明色，则使用imagecopy方法
        imagecopy($dst, $src, $porintLeft, $pointTop, 0, 0, $src_w, $src_h);
//输出图片
        list($dst_w, $dst_h, $dst_type) = getimagesize($dst_path);
        switch ($dst_type) {
            case 1://GIF
                header('Content-Type: image/gif');
                $res = imagegif($dst,$bc_path);
                break;
            case 2://JPG
                header('Content-Type: image/jpeg');
                $res = imagejpeg($dst,$bc_path);
                break;
            case 3://PNG
                header('Content-Type: image/png');
                $res = imagepng($dst,$bc_path);
                break;
            default:
                break;
        }
        return $res;

    }
     /**
     * 生成图片
     * @param string $im 源图片路径
     * @param string $dest 目标图片路径
     * @param int $maxwidth 生成图片宽
     * @param int $maxheight 生成图片高
     */
    protected function resizeImage($im, $dest, $maxwidth, $maxheight) {
        $img = getimagesize($im);
        switch ($img[2]) {
            case 1:
                $im = @imagecreatefromgif($im);
                break;
            case 2:
                $im = @imagecreatefromjpeg($im);
                break;
            case 3:
                $im = @imagecreatefrompng($im);
                break;
        }

        $pic_width = imagesx($im);
        $pic_height = imagesy($im);
        $resizewidth_tag = false;
        $resizeheight_tag = false;
        if (($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, $newheight);
                imagecopyresampled($newim, $im, 0, 0, 0, 0, $newwidth, $newheight, $pic_width, $pic_height);
            } else {
                $newim = imagecreate($newwidth, $newheight);
                imagecopyresized($newim, $im, 0, 0, 0, 0, $newwidth, $newheight, $pic_width, $pic_height);
            }

            imagejpeg($newim, $dest);
            imagedestroy($newim);
        } else {
            imagejpeg($im, $dest);
        }
    }

    /**
     * 获取水印位置
     */
    protected function get_water_postion($src_path,$dst_path,$point){
        list($textWidth, $lineHeight) = getimagesize($src_path);
        list($imgWidth, $imgHeight) = getimagesize($dst_path);
        $textWidth = (float)$textWidth;
        $lineHeight = (float)$lineHeight;
        $imgWidth = (float)$imgWidth;
        $imgHeight = (float)$imgHeight;
        if ($point == 1) { //左上角
            $porintLeft = 0;
            $pointTop = 0;
        } elseif ($point == 2) { //上中部
            $porintLeft = floor(($imgWidth - $textWidth) / 2);
            $pointTop = 0;
        } elseif ($point == 3) { //右上部
            $porintLeft = $imgWidth - $textWidth;
            $pointTop = 0;
        } elseif ($point == 4) { //左中部
            $porintLeft = 0;
            $pointTop = floor(($imgHeight - $lineHeight) / 2);
        } elseif ($point == 5) { //正中部
            $porintLeft = floor(($imgWidth - $textWidth) / 2);
            $pointTop = floor(($imgHeight -  $lineHeight) / 2);
        } elseif ($point == 6) { //右中部
            $porintLeft = $imgWidth - $textWidth;
            $pointTop = floor(($imgHeight - $lineHeight) / 2);
        } elseif ($point == 7) { //左下部
            $porintLeft = 0;
            $pointTop = $imgHeight -$lineHeight;
        } elseif ($point == 8) { //中下部
            $porintLeft = floor(($imgWidth - $textWidth) / 2);
            $pointTop = $imgHeight -  $lineHeight ;
        } elseif ($point == 9) { //右下部
            $porintLeft = $imgWidth - $textWidth ;
            $pointTop = $imgHeight - $lineHeight ;
        }
        return array('porintLeft'=>$porintLeft,'pointTop'=>$pointTop);
    }

下面是我自己的接口示例

 public function save_weibo()
    {
        if (checkPost()) {
            //接收前端参数
            $aTitle = I('post.title', '', 'string');
            $uid = I('post.user_id', '', 'intval');
            $aContent = I('post.content', '', 'string');
            $belong = I('post.cate_id', '', 'intval');
            $category = I('post.category');
            $images = I('post.images', '', 'string');
            $address = I('post.address','','string');
            //敏感词过滤
            $re = $this->sensitive_words($aContent);
            $res = $this->sensitive_words($aTitle);
            if($re==false||$res==false){
                errorReturn('存在敏感词汇,禁止发送');
            }
            //我这里的图片是先上传原图，返回给前端id；这里拿id换图片路径；如果是路径则不需要此处
            $where['id'] = array('in', explode(',', $images)); 
            $img = M('Picture')->where($where)->getField('path', true);//获取图片路径->数据库
            //循环图片（我是多图片所以是用循环）
            foreach ($img as $k=>$v){
                $re = substr($v, strripos($v, "Uploads/"));//源文件路径->去除域名
                $this->getThumb($re,1000,1000);//压缩图片

            }
            // 执行发布，写入数据库
            $weibo_id = send_wb($uid, $aTitle, $aContent, $category, $images, $belong,$address);
            if (!$weibo_id) {
                errorReturn(L('_FAIL_PUBLISH_'));
            }
            $result['status'] = 1;
            $result['msg'] = 'success';
            $result['data'] = [L('_SUCCESS_PUBLISH_') . L('_EXCLAMATION_')];
            successReturn($result);
        }
    }

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