harmony 鸿蒙Using Image_NativeModule to Encode Images

2025-06-12
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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.

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

Calling the Native APIs

For details about the APIs, see Image_NativeModule.

Create a native C++ application in DevEco Studio. The project created by default contains the index.ets file, and a hello.cpp or napi_init.cpp file is generated in the entry\src\main\cpp directory. In this example, the generated file is hello.cpp. 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 encoding parameters are specified, the ImageSource or Pixelmap object is encoded 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 encoding 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.


      #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;
          }

          // Specify encoding parameters and encode the ImageSource 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;
          }

          // Specify encoding parameters and encode the PixelMap 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;
      }