图像编码类，用于创建以及释放ImagePacker实例。
[h2]添加链接库
在进行应用开发之前，开发者需要打开native工程的src/main/cpp/CMakeLists.txt，在target_link_libraries依赖中添加libimage_packer.so 以及日志依赖libhilog_ndk.z.so。
target_link_libraries(entry PUBLIC libhilog_ndk.z.so libimage_source.so libimage_packer.so libpixelmap.so)
[h2]Native接口调用
具体接口说明请参考Image_NativeModule。
在DevEco Studio新建Native C++应用，默认生成的项目中包含index.ets文件，在entry\src\main\cpp目录下会自动生成一个cpp文件（hello.cpp或napi_init.cpp，本示例以hello.cpp文件名为例）。在hello.cpp中实现C API接口调用逻辑，示例代码如下：
编码接口使用示例
-
根据MIME标准，标准编码格式为image/jpeg。当使用image编码时，编码参数中的编码格式image_MimeType设置为image/jpeg，image编码后的文件扩展名可设为.jpg或.jpeg，可在支持image/jpeg解码的平台上使用。
-
部分接口（如：OH_ImagePackerNative_GetSupportedFormats）在API version 20以后才支持，需要开发者在进行开发时选择合适的API版本。
-
导入相关头文件。
#include <string> #include <hilog/log.h> #include <multimedia/image_framework/image/image_source_native.h> #include "napi/native_api.h" #include <multimedia/image_framework/image/image_common.h> #include <multimedia/image_framework/image/pixelmap_native.h> #include <set> #include <multimedia/image_framework/image/image_packer_native.h>
-
日志宏定义可参考下述代码按实际需求自行修改。
#undef LOG_DOMAIN #undef LOG_TAG #define LOG_DOMAIN 0x3200 #define LOG_TAG "IMAGE_SAMPLE"
-
定义ImageSourceNative类。
class ImageSourceNative { public: OH_ImageSource_Info *imageInfo; OH_ImageSourceNative *source = nullptr; OH_PixelmapNative *resPixMap = nullptr; OH_Pixelmap_ImageInfo *pixelmapImageInfo = nullptr; uint32_t frameCnt = 0; ImageSourceNative() {} ~ImageSourceNative() {} }; -
创建ImageSourceNative的一个实例。
static ImageSourceNative *g_thisImageSource = new ImageSourceNative();
-
定义一个全局变量用来记录编码所支持的格式。
static std::set<std::string> g_encodeSupportedFormats;
-
创建GetJsResult函数处理napi返回值。
// 处理napi返回值。 napi_value GetJsResult(napi_env env, int result) { napi_value resultNapi = nullptr; napi_create_int32(env, result, &resultNapi); return resultNapi; } -
创建ImagePacker实例后，指定编码参数，将ImageSource或PixelMap编码至文件或者缓冲区。
// 获取编码能力范围。 Image_ErrorCode GetEncodeSupportedFormats() { Image_MimeType* mimeType = nullptr; size_t length = 0; Image_ErrorCode errCode = OH_ImagePackerNative_GetSupportedFormats(&mimeType, &length); if (errCode != IMAGE_SUCCESS) { OH_LOG_ERROR(LOG_APP, "OH_ImagePackerNative_GetSupportedFormats failed," "errCode: %{public}d.", errCode); return errCode; } for (size_t count = 0; count < length; count++) { if (mimeType[count].data != nullptr) { g_encodeSupportedFormats.insert(std::string(mimeType[count].data)); OH_LOG_INFO(LOG_APP, "Encode supportedFormats: %{public}s", mimeType[count].data); } } return IMAGE_SUCCESS; } Image_MimeType GetMimeTypeIfEncodable(const char *format) { auto it = g_encodeSupportedFormats.find(format); if (it == g_encodeSupportedFormats.end()) { return {const_cast<char *>(""), 0}; } return {const_cast<char *>(format), strlen(format)}; } static Image_ErrorCode ReleaseImageSourcePackingResources(OH_ImagePackerNative *testPacker, OH_PackingOptions *option) { Image_ErrorCode errCode = OH_ImagePackerNative_Release(testPacker); if (errCode != IMAGE_SUCCESS) { OH_LOG_ERROR(LOG_APP, "packToFileFromImageSourceTest OH_ImagePackerNative_Release failed," "errCode: %{public}d.", errCode); OH_PackingOptions_Release(option); return errCode; } errCode = OH_PackingOptions_Release(option); if (errCode != IMAGE_SUCCESS) { OH_LOG_ERROR(LOG_APP, "packToFileFromImageSourceTest OH_PackingOptions_Release failed," "errCode: %{public}d.", errCode); } return errCode; } Image_ErrorCode packToFileFromImageSourceTest(int fd, OH_ImageSourceNative* imageSource) { // 创建ImagePacker实例。 OH_ImagePackerNative *testPacker = nullptr; Image_ErrorCode errCode = OH_ImagePackerNative_Create(&testPacker); if (errCode != IMAGE_SUCCESS) { OH_LOG_ERROR(LOG_APP, "packToFileFromImageSourceTest OH_ImagePackerNative_Create failed," "errCode: %{public}d.", errCode); return errCode; } // 获取编码能力范围。 errCode = GetEncodeSupportedFormats(); if (errCode != IMAGE_SUCCESS) { OH_ImagePackerNative_Release(testPacker); return errCode; } // 指定编码参数，将ImageSource直接编码进文件。 OH_PackingOptions *option = nullptr; errCode = OH_PackingOptions_Create(&option); if (errCode != IMAGE_SUCCESS || option == nullptr) { OH_ImagePackerNative_Release(testPacker); return errCode == IMAGE_SUCCESS ? IMAGE_BAD_PARAMETER : errCode; } Image_MimeType image_MimeType = GetMimeTypeIfEncodable(MIME_TYPE_JPEG); if (image_MimeType.data == nullptr || image_MimeType.size == 0) { OH_LOG_ERROR(LOG_APP, "packToFileFromImageSourceTest GetMimeTypeIfEncodable failed," "format can't support encode."); OH_PackingOptions_Release(option); OH_ImagePackerNative_Release(testPacker); return IMAGE_BAD_PARAMETER; } OH_PackingOptions_SetMimeType(option, &image_MimeType); // 当设备支持HDR编码，资源本身为HDR图且图片资源的格式为jpeg时，编码产物才能为HDR内容。 OH_PackingOptions_SetDesiredDynamicRange(option, IMAGE_PACKER_DYNAMIC_RANGE_AUTO); // 设置编码质量。quality默认值为0，建议不低于80；本示例统一设置为90，兼顾图片质量和文件体积。 uint32_t quality = 90; OH_PackingOptions_SetQuality(option, quality); errCode = OH_ImagePackerNative_PackToFileFromImageSource(testPacker, option, imageSource, fd); if (errCode != IMAGE_SUCCESS) { OH_LOG_ERROR(LOG_APP, "packToFileFromImageSourceTest OH_ImagePackerNative_PackToFileFromImageSource failed," "errCode: %{public}d.", errCode); OH_PackingOptions_Release(option); OH_ImagePackerNative_Release(testPacker); return errCode; } return ReleaseImageSourcePackingResources(testPacker, option); } Image_ErrorCode packToFileFromPixelmapTest(int fd, OH_PixelmapNative *pixelmap) { // 创建ImagePacker实例。 OH_ImagePackerNative *testPacker = nullptr; Image_ErrorCode errCode = OH_ImagePackerNative_Create(&testPacker); if (errCode != IMAGE_SUCCESS) { OH_LOG_ERROR(LOG_APP, "packToFileFromPixelmapTest CreatePacker OH_ImagePackerNative_Create failed," "errCode: %{public}d.", errCode); return errCode; } // 指定编码参数，将PixelMap直接编码进文件。 OH_PackingOptions *option = nullptr; errCode = OH_PackingOptions_Create(&option); if (errCode != IMAGE_SUCCESS || option == nullptr) { OH_ImagePackerNative_Release(testPacker); return errCode == IMAGE_SUCCESS ? IMAGE_BAD_PARAMETER : errCode; } char type[] = "image/jpeg"; Image_MimeType image_MimeType = {type, strlen(type)}; errCode = OH_PackingOptions_SetMimeType(option, &image_MimeType); if (errCode != IMAGE_SUCCESS) { OH_PackingOptions_Release(option); OH_ImagePackerNative_Release(testPacker); return errCode; } // 设置编码质量。quality默认值为0，建议不低于80；本示例统一设置为90，兼顾图片质量和文件体积。 uint32_t quality = 90; OH_PackingOptions_SetQuality(option, quality); errCode = OH_ImagePackerNative_PackToFileFromPixelmap(testPacker, option, pixelmap, fd); if (errCode != IMAGE_SUCCESS) { OH_LOG_ERROR(LOG_APP, "packToFileFromPixelmapTest OH_ImagePackerNative_PackToFileFromPixelmap failed," "errCode: %{public}d.", errCode); OH_PackingOptions_Release(option); OH_ImagePackerNative_Release(testPacker); return errCode; } // 释放ImagePacker实例。 errCode = OH_ImagePackerNative_Release(testPacker); testPacker = nullptr; if (errCode != IMAGE_SUCCESS) { OH_LOG_ERROR(LOG_APP, "packToFileFromPixelmapTest ReleasePacker OH_ImagePackerNative_Release failed," "errCode: %{public}d.", errCode); OH_PackingOptions_Release(option); return errCode; } // 释放PackingOptions实例。 errCode = OH_PackingOptions_Release(option); option = nullptr; if (errCode != IMAGE_SUCCESS) { OH_LOG_ERROR(LOG_APP, "packToFileFromPixelmapTest OH_PackingOptions_Release failed," "errCode: %{public}d.", errCode); return errCode; } return IMAGE_SUCCESS; } napi_value PackToFileFromImageSourceTestJs(napi_env env, napi_callback_info info) { napi_value argv[1] = {0}; size_t argc = 1; if (napi_get_cb_info(env, info, &argc, argv, nullptr, nullptr) != napi_ok) { OH_LOG_ERROR(LOG_APP, "PackToFileFromImageSourceTestJs napi_get_cb_info failed."); return nullptr; } int fd; napi_get_value_int32(env, argv[0], &fd); Image_ErrorCode errCode = packToFileFromImageSourceTest(fd, g_thisImageSource->source); if (errCode == IMAGE_SUCCESS) { OH_LOG_INFO(LOG_APP, "ImagePackerNativeCTest PackToFileFromImageSourceTestJs successfully."); } return GetJsResult(env, errCode); } napi_value PackToFileFromPixelmapTestJs(napi_env env, napi_callback_info info) { napi_value argv[1] = {0}; size_t argc = 1; if (napi_get_cb_info(env, info, &argc, argv, nullptr, nullptr) != napi_ok) { OH_LOG_ERROR(LOG_APP, "PackToFileFromPixelmapTestJs napi_get_cb_info failed."); return nullptr; } int fd; napi_get_value_int32(env, argv[0], &fd); Image_ErrorCode errCode = packToFileFromPixelmapTest(fd, g_thisImageSource->resPixMap); if (errCode != IMAGE_SUCCESS) { OH_LOG_ERROR(LOG_APP, "packToFileFromPixelmapTest failed," "errCode: %{public}d.", errCode); return GetJsResult(env, errCode); } else { OH_LOG_INFO(LOG_APP, "PackToFileFromPixelmapTestJs successfully."); } return GetJsResult(env, errCode); }