wxc397update: zh-cn/application-dev/media/image/image-packer-c.md

使用Image_NativeModule完成图片编码

图像编码类，用于创建以及释放ImagePacker实例。

开发步骤

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)

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

说明：

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>

loadImageSource.cpp

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"

loadImageSource.cpp

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() {}
};

imageKits.h

创建ImageSourceNative的一个实例。

static ImageSourceNative *g_thisImageSource = new ImageSourceNative();

loadImageSource.cpp

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;
```
loadImageSource.cpp

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;
}

napi_init.cpp

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默认为0，建议quality的值不低于80
    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默认为0，建议quality的值不低于80
    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, "PackToFileFromImageSourceTestJs 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);
}

loadImageSource.cpp