# Using Image_NativeModule to Encode Images

You can use the **ImagePacker** class to create and release **ImagePacker** instances.

## How to Develop

### Adding a Link Library

Open the **src/main/cpp/CMakeLists.txt** file of the native project, add **libimage_packer.so** and **libhilog_ndk.z.so** (on which the log APIs depend) to the **target_link_libraries** dependency.

```txt
target_link_libraries(entry PUBLIC libhilog_ndk.z.so libimage_packer.so)
```

### Calling the Native APIs

For details about the APIs, see [Image_NativeModule](../../reference/apis-image-kit/_image___native_module.md).

Implement the C APIs in **hello.cpp**. Refer to the sample code below.

**Example of Using the Encoding APIs**

After an **ImagePacker** instance is created and packing parameters are specified, the ImageSource or Pixelmap image source is packed to a file or buffer.

> **NOTE**
>
> According to the MIME protocol, the standard encoding format is image/jpeg. When the APIs provided by the image module are used for encoding, **image_MimeType** of the packing parameters must be set to **image/jpeg**. The file name extension of the encoded image file can be .jpg or .jpeg, and the file can be used on platforms that support image/jpeg decoding.

   ```c++

      #include <linux/kd.h>
      #include <string>

      #include <hilog/log.h>
      #include <multimedia/image_framework/image/image_packer_native.h>
      #include <multimedia/image_framework/image/pixelmap_native.h>
      #include <multimedia/image_framework/image/image_source_native.h>

      #undef LOG_DOMAIN
      #undef LOG_TAG
      #define LOG_DOMAIN 0x3200
      #define LOG_TAG "MY_TAG"

      Image_ErrorCode packToFileFromImageSourceTest(int fd)
      {
          // Create an ImagePacker instance.
          OH_ImagePackerNative *testPacker = nullptr;
          Image_ErrorCode errCode = OH_ImagePackerNative_Create(&testPacker);
          if (errCode != IMAGE_SUCCESS) {
              OH_LOG_ERROR(LOG_APP, "ImagePackerNativeCTest CreatePacker OH_ImagePackerNative_Create failed, errCode: %{public}d.", errCode);
              return errCode;
          }

          // Create an ImageSource instance.
          OH_ImageSourceNative* imageSource = nullptr;
          errCode = OH_ImageSourceNative_CreateFromFd(fd, &imageSource);
          if (errCode != IMAGE_SUCCESS) {
              OH_LOG_ERROR(LOG_APP, "ImagePackerNativeCTest OH_ImageSourceNative_CreateFromFd  failed, errCode: %{public}d.", errCode);
              return errCode;
          }

          // Encode an ImageSource instance and pack it into a file.
          OH_PackingOptions *option = nullptr;
          OH_PackingOptions_Create(&option);
          char type[] = "image/jpeg";
          Image_MimeType image_MimeType = {type, strlen(type)};
          OH_PackingOptions_SetMimeType(option, &image_MimeType);
          // Encode the content as HDR content. (The resource must be HDR resource and the JPEG format must be supported.)
          OH_PackingOptions_SetDesiredDynamicRange(option, IMAGE_PACKER_DYNAMIC_RANGE_AUTO);
          errCode = OH_ImagePackerNative_PackToFileFromImageSource(testPacker, option, imageSource, fd);
          if (errCode != IMAGE_SUCCESS) {
              OH_LOG_ERROR(LOG_APP, "ImagePackerNativeCTest OH_ImagePackerNative_PackToFileFromImageSource failed, errCode: %{public}d.", errCode);
              return errCode;
          }

          // Release the ImagePacker instance.
          errCode = OH_ImagePackerNative_Release(testPacker);
          if (errCode != IMAGE_SUCCESS)
          {
              OH_LOG_ERROR(LOG_APP, "ImagePackerNativeCTest ReleasePacker OH_ImagePackerNative_Release failed, errCode: %{public}d.", errCode);
              return errCode;
          }
          // Release the ImageSource instance.
          errCode = OH_ImageSourceNative_Release(imageSource);
          if (errCode != IMAGE_SUCCESS)
          {
              OH_LOG_ERROR(LOG_APP, "ImagePackerNativeCTest ReleasePacker OH_ImageSourceNative_Release failed, errCode: %{public}d.", errCode);
              return errCode;
          }

          return IMAGE_SUCCESS;
      }

      Image_ErrorCode packToFileFromPixelmapTest(uint8_t *buffer, size_t buffSize, int fd)
      {
          // Create an ImagePacker instance.
          OH_ImagePackerNative *testPacker = nullptr;
          Image_ErrorCode errCode = OH_ImagePackerNative_Create(&testPacker);
          if (errCode != IMAGE_SUCCESS) {
              OH_LOG_ERROR(LOG_APP, "ImagePackerNativeCTest CreatePacker OH_ImagePackerNative_Create failed, errCode: %{public}d.", errCode);
              return errCode;
          }

          // Create a Pixelmap instance.
          OH_Pixelmap_InitializationOptions *createOpts;
          OH_PixelmapInitializationOptions_Create(&createOpts);
          OH_PixelmapInitializationOptions_SetWidth(createOpts, 6);
          OH_PixelmapInitializationOptions_SetHeight(createOpts, 4);
          OH_PixelmapInitializationOptions_SetPixelFormat(createOpts, 3);
          OH_PixelmapInitializationOptions_SetAlphaType(createOpts, 0);
          OH_PixelmapNative *pixelmap = nullptr;
          errCode = OH_PixelmapNative_CreatePixelmap(buffer, bufferSize, createOpts, &pixelmap);
          if (errCode != IMAGE_SUCCESS) {
              OH_LOG_ERROR(LOG_APP, "ImagePackerNativeCTest OH_PixelmapNative_CreatePixelmap  failed, errCode: %{public}d.", errCode);
              return errCode;
          }

          // Encode the Pixelmap instance and pack it into a file.
          OH_PackingOptions *option = nullptr;
          OH_PackingOptions_Create(&option);
          char type[] = "image/jpeg";
          Image_MimeType image_MimeType = {type, strlen(type)};
          OH_PackingOptions_SetMimeType(option, &image_MimeType);
          errCode = OH_ImagePackerNative_PackToFileFromPixelmap(testPacker, option, pixelmap, fd);
          if (errCode != IMAGE_SUCCESS) {
              OH_LOG_ERROR(LOG_APP, "ImagePackerNativeCTest OH_ImagePackerNative_PackToFileFromPixelmap  failed, errCode: %{public}d.", errCode);
              return errCode;
          }

          // Release the ImagePacker instance.
          errCode = OH_ImagePackerNative_Release(testPacker);
          if (errCode != IMAGE_SUCCESS)
          {
              OH_LOG_ERROR(LOG_APP, "ImagePackerNativeCTest ReleasePacker OH_ImagePackerNative_Release failed, errCode: %{public}d.", errCode);
              return errCode;
          }

          // Release the Pixelmap instance.
          errCode = OH_PixelmapNative_Release(pixelmap);
          if (errCode != IMAGE_SUCCESS)
          {
              OH_LOG_ERROR(LOG_APP, "ImagePackerNativeCTest ReleasePacker OH_PixelmapNative_Release failed, errCode: %{public}d.", errCode);
              return errCode;
          }

          return IMAGE_SUCCESS;
      }
   ```