OpenHarmony集成OCR三方库实现文字提取 原创 精华

/**
 * 初始化文字识别引擎
 * @param lang 识别的语言, eg:eng、chi_sim、 eng+chi_sim,为Null或不传则为中英文（eng+chi_sim）
 * @param trainDir 训练模型目录，为Null或不传则为默认目录
 *
 * @return 初始化是否成功 0=>成功，-1=>失败
 */
export const initOCR: (lang: string, trainDir: string) => Promise<number>;

export const initOCR: (lang: string, trainDir: string, callback: AsyncCallback<number>) => void;

/**
 * 开始识别
 * @param imagePath 图片路径（当前支持的图片格式为png, jpg, tiff）
 *
 * @return 识别结果
 */
export const startOCR: (imagePath: string) => Promise<string>;
export const startOCR: (imagePath: string, callback: AsyncCallback<string>) => void;


/**
 * 销毁资源
 */
export const destroyOCR: () => void;
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EXTERN_C_START
static napi_value Init(napi_env env, napi_value exports) {
napi_property_descriptor desc[] = {
{
"initOCR", nullptr, InitOCR, nullptr, nullptr, nullptr, napi_default, nullptr
},
{
"startOCR", nullptr, StartOCR, nullptr, nullptr, nullptr, napi_default, nullptr
},
{
"destroyOCR", nullptr, DestroyOCR, nullptr, nullptr, nullptr, napi_default, nullptr
},
{
};
napi_define_properties(env, exports, sizeof(desc) / sizeof(desc[0]), desc);
return exports;
}
EXTERN_C_END

static napi_module demoModule = {
.nm_version = 1,
.nm_flags = 0,
.nm_filename = nullptr,
.nm_register_func = Init,
.nm_modname = "tesseract",
.nm_priv = ((void *)0),
.reserved = {
0
},
};

extern "C" __attribute__((constructor)) void RegisterHelloModule(void) {
napi_module_register(& demoModule);
}
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static napi_value StartOCR(napi_env env, napi_callback_info info) {
    OH_LOG_ERROR(LogType::LOG_APP, "OCR StartOCR 111");
    size_t argc = 2;
    napi_value args[2] = { nullptr };
	//1. 获取参数
    napi_get_cb_info(env, info, &argc, args, nullptr, nullptr);


    //2. 共享数据
    auto addonData = new StartOCRAddOnData{
        .asyncWork = nullptr,
    };
    //3. N-API类型转成C/C++类型
    char imagePath[1024] = { 0 };
    size_t length = 0;
    napi_get_value_string_utf8(env, args[0], imagePath, 1024, &length);

    addonData->args0 = string(imagePath);

    napi_create_reference(env, args[1], 1, &addonData->callback);

    //4. 创建async work
    napi_value resourceName = nullptr;
    napi_create_string_utf8(env, "startOCR", NAPI_AUTO_LENGTH, &resourceName);
    napi_create_async_work(env, nullptr, resourceName, executeStartOCR, completeStartOCRForCallback, (void *)addonData, &addonData->asyncWork);

    //将创建的async work加到队列中，由底层调度执行
    napi_queue_async_work(env, addonData->asyncWork);

    napi_value result = 0;
    napi_get_null(env, &result);

    return result;
}
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static void executeStartOCR(napi_env env, void* data) {
    //通过data来获取数据
    StartOCRAddOnData * addonData = (StartOCRAddOnData *)data;
    napi_value resultValue;
    try {
        if (api != nullptr) {
            //调用具体的实现，读取图片像素
            PIX * pix = pixRead((const char*)addonData->args0.c_str());
            //设置api的图片像素
            api->SetImage(pix);

            //调用文字提取接口，获取图片中的文字
            char * result = api->GetUTF8Text();
            addonData->result = result;

            //释放资源
            pixDestroy (& pix);
            delete[] result;
        }
    } catch (std::exception e) {
        std::string error = "Error: ";
        if (initResult != 0) {
            error += "please first init tesseractocr.";
        } else {
            error += e.what();
        }
        addonData->result = error;
    }
}
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static void completeStartOCRForCallback(napi_env env, napi_status status, void * data) {
    StartOCRAddOnData * addonData = (StartOCRAddOnData *)data;
    napi_value callback = nullptr;
    napi_get_reference_value(env, addonData->callback, &callback);
    napi_value undefined = nullptr;
    napi_get_undefined(env, &undefined);
    napi_value result = nullptr;
    napi_create_string_utf8(env, addonData->result.c_str(), addonData->result.length(), &result);

    //执行回调函数
    napi_value returnVal = nullptr;
    napi_call_function(env, undefined, callback, 1, &result, &returnVal);

    //删除napi_ref对象
    if (addonData->callback != nullptr) {
        napi_delete_reference(env, addonData->callback);
    }

    //删除异步工作项
    napi_delete_async_work(env, addonData->asyncWork);
    delete addonData;
}
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build() {
    Column() {
      Row() {
        Text('点击图片进行文字提取  提取结果 ： ').fontSize('30fp').fontColor(Color.Blue)
        Text(this.ocrResult).fontSize('50fp').fontColor(Color.Red)
      }.margin('10vp').height('10%').alignItems(VerticalAlign.Center)

      Grid() {
        ForEach(this.images, (item, index) => {
          GridItem() {
            AnimalItem({
              path1: item[0],
              path2: item[1]
            });
          }
        })
      }
      .padding({left: this.columnSpace, right: this.columnSpace})
      .columnsTemplate("1fr 1fr 1fr")      // Grid宽度均分成3份
      .rowsTemplate("1fr 1fr")     // Grid高度均分成2份
      .rowsGap(this.rowSpace)                  // 设置行间距
      .columnsGap(this.columnSpace)            // 设置列间距
      .width('100%')
      .height('90%')
    }
    .backgroundColor(Color.Pink)
  }
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build() {
    Row() {
      Column() {
        Image('/common/idImages/aobamao.jpg')
          .onClick(() => {
            //点击图片进行信息识别
            console.log('OCR begin dialog open 111');
            this.ocrDialog.open();
            ToolUtils.ocrResult(ToolUtils.aobamao, (result) => {
              console.log('111 OCR result = ' + result);
              this.result = result;
              this.ocrDialog.close();
            });
          })
          .margin('10vp')
          .objectFit(ImageFit.Auto)
          .height('50%')

        Image('/common/idImages/weixiaobao.jpg')
          .onClick(() => {
            //点击图片进行信息识别
            this.ocrDialog.open();
            ToolUtils.ocrResult(ToolUtils.weixiaobao, (result) => {
              console.log('111 OCR result = ' + result);
              this.result = result;
              this.ocrDialog.close();
            });
          })
          .margin('10vp')
          .objectFit(ImageFit.Auto)
          .height('50%')
      }
      .width(this.screenWidth/2)
      .padding('20vp')

      Column() {
        Text(this.title).height('10%').fontSize('30fp').fontColor(this.titleColor)

        Column() {
          Text(this.result)
            .fontColor('#0000FF')
            .fontSize('50fp')
        }.justifyContent(FlexAlign.Center).alignItems(HorizontalAlign.Center).height('90%')
      }
      .justifyContent(FlexAlign.Start)
      .width('50%')

    }
    .width('100%')
    .height('100%')
  }
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Row() {
      Column() {
        Image('/common/save2FileImages/testImage1.png')
          .onClick(() => {
            //点击图片进行信息识别
            ToolUtils.ocrResult(ToolUtils.testImage1, (result) => {
              let path = this.dir + 'ocrresult1.txt';
              try {
                let fd = fileio.openSync(path, 0o100 | 0o2, 0o666);
                fileio.writeSync(fd, result);
                fileio.closeSync(fd);
                this.displayText = '文件写入' + path;
              } catch (e) {
                console.log('OCR fileio error = ' + e);
              }
            });
          })
        Image('/common/save2FileImages/testImage2.png')
          .onClick(() => {
            //点击图片进行信息识别
            ToolUtils.ocrResult(ToolUtils.testImage2, (result) => {
              let path = this.dir + 'ocrresult2.txt';
              let fd = fileio.openSync(path, 0o100 | 0o2, 0o666);
              fileio.writeSync(fd, result);
              fileio.closeSync(fd);
              this.displayText = '文件写入' + path;
            });
          })
      }
      Column() {
        Text(this.title)
        Column() {
          Text(this.displayText)
        }
      }
    }
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