Tencent OCR API

官方文档： 文字识别 - 文档中心 - 腾讯云 (tencent.com)

编写背景（废话）：开发项目中部分依赖环境老旧，用为省事弃用 composer 引入官方SDK，故参照官方文档（链接如上），本着能跑就行的原则编写如下代码。留此文以防健忘或往后回顾。

• 仅支持图片格式
• 或可通过修改公共参数 Action、Version 调用 OCR 其他功能（通用文字识别、通用卡证识别等）。

<?php
class TxOcr
{
    # 图片识别
    // $imgFile = ""; // 选择文件(路径)
    // $fp = fopen($imgFile, "rb", 0); // 打开文件
    // $binary = fread($fp, filesize($imgFile)); // 读取文件
    // fclose($fp); // 关闭文件
    // $img_data = base64_encode($binary); // 转码成 base64
    // $resCode = $Ocr -> DutyPaidProofOCR($img_data); // 调用

    # 完税证明接口
    # $Img 为 base64 格式时， $ImgFormat 应为 "ImageBase64"
    # $Img 为 URL(如：img.xxx.com/xxx.jpg)时， $ImgFormat 应为 "ImageUrl"
    public function DutyPaidProofOCR($Img, $ImgFormat = "ImageBase64")
    {
        // 配置参数
        $SecretId = "";  // 腾讯云控制台中获取 SecretId
        $SecretKey = ""; // 腾讯云控制台中获取 SecretKey
        $api_url = "https://ocr.tencentcloudapi.com/";  // 接口请求域名
        $api_host = "ocr.tencentcloudapi.com";
        $api_service= "ocr";
        $api_action = "DutyPaidProofOCR";   // 公共参数:Action
        $api_region = "ap-guangzhou";  // 公共参数:Region
        $api_version = "2018-11-19";  // 公共参数:Version
        // 请求时间
        $request_time = time();
        $request_date = date("Y-m-d", $request_time);
        //图片参数
        $ImgFormat == "ImageBase64" ? "ImageBase64" : "ImageUrl";
        $params_data = [
            $ImgFormat => $Img,
        ];
        $params_data = json_encode($params_data);
        // 1.拼接规范请求串
        $httpRequestMethod = "POST";
        $canonicalUri = "/";
        $canonicalQueryString = "";
        $canonicalHeaders = "content-type:application/json; charset=utf-8\n"."host:".$api_host."\n";
        $signedHeaders = "content-type;host";
        // $payload = '{"Limit": 1, "Filters": [{"Values": ["\u672a\u547d\u540d"], "Name": "instance-name"}]}';
        // $hashedRequestPayload = hash("SHA256", $payload);
        $hashedRequestPayload = hash("SHA256", $params_data);
        $canonicalRequest = $httpRequestMethod."\n"
            .$canonicalUri."\n"
            .$canonicalQueryString."\n"
            .$canonicalHeaders."\n"
            .$signedHeaders."\n"
            .$hashedRequestPayload;
        // 2.拼接待签名字符串
        $algorithm = "TC3-HMAC-SHA256";
        $requestTimestamp = $request_time;
        $credentialScope = $request_date."/".$api_service."/tc3_request";
        $hashedCanonicalRequest = hash("SHA256", $canonicalRequest);
        $stringToSign = $algorithm."\n"
            .$requestTimestamp."\n"
            .$credentialScope."\n"
            .$hashedCanonicalRequest;
        // 3.计算签名
        $secretDate = hash_hmac("SHA256", $request_date, "TC3".$SecretKey, true);
        $secretService = hash_hmac("SHA256", $api_service, $secretDate, true);
        $secretSigning = hash_hmac("SHA256", "tc3_request", $secretService, true);
        $signature = hash_hmac("SHA256", $stringToSign, $secretSigning);
        // 4.拼接 Authorization
        $Authorization = $algorithm."Credential=".$SecretId."/".$credentialScope.", SignedHeaders=content-type;host, Signature=".$signature;  // HTTP 标准身份认证头部字段
        // 设置 header
        $curl_header = array(
            "Content-Type: application/json; charset=utf-8",
            "Authorization:".$Authorization,
            "Host:".$api_host,
            "X-TC-Action:".$api_action, 
            "X-TC-Region:".$api_region,
            "X-TC-Version:".$api_version,
            "X-TC-Timestamp:".$request_time,
        );
        $ocrRes = $this -> httpRequest($api_url, "POST", $params_data, $curl_header);
        if ($ocrRes) {
            $infoDetail = json_decode($ocrRes, true)['Response']['DutyPaidProofInfos'];
        }
        var_dump($infoDetail);
    }
    // http 请求
    private function httpRequest($url, $method='POST', $data='', $curl_header)
    {
        $curl = curl_init();
        curl_setopt($curl, CURLOPT_URL, $url);
        curl_setopt($curl, CURLOPT_REFERER, $_SERVER['HTTP_HOST']);
        curl_setopt($curl, CURLOPT_SSL_VERIFYPEER, 0); 
        curl_setopt($curl, CURLOPT_SSL_VERIFYHOST, 0);
        curl_setopt($curl, CURLOPT_RETURNTRANSFER, 1); 
        if ($method == 'POST') {
            curl_setopt($curl, CURLOPT_POST, 1);
            curl_setopt($curl, CURLOPT_POSTFIELDS, $data); 
            curl_setopt($curl, CURLOPT_HTTPHEADER, $curl_header);
        }
        curl_setopt($curl, CURLOPT_HEADER, 1);
        curl_setopt($curl, CURLOPT_TIMEOUT, 30);
        $result = curl_exec($curl);
        if (curl_getinfo($curl, CURLINFO_HTTP_CODE ) == "200") {
            $resHeaderSize = curl_getinfo($curl, CURLINFO_HEADER_SIZE);
            $result = substr($result, $resHeaderSize);
        }
        curl_close($curl);
        return $result;
    }
}