使用Image_NativeModule完成多图对象编码

图像编码类，用于创建以及释放ImagePacker实例，并编码多图对象。

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

loadPicture.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

定义用于图像处理的常量。

#define AUTO 0
#define SDR 1
const int MAX_SIZE = 1024;
const int MAX_FORMAT_LENGTH = 20;

loadPicture.cpp

定义ImagePictureNative类。

class ImagePictureNative {
public:
    Image_ErrorCode errorCode = IMAGE_SUCCESS;
    OH_DecodingOptionsForPicture *options = nullptr;
    OH_ImagePackerNative *imagePacker = nullptr;
    OH_PackingOptions *packerOptions = nullptr;
    OH_PictureNative *picture = nullptr;
    OH_ImageSourceNative *source = nullptr;
    ImagePictureNative() {}
    ~ImagePictureNative() {}
};

imageKits.h

创建ImagePictureNative的一个实例。

static ImagePictureNative *g_thisPicture = new ImagePictureNative();

loadPicture.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，指定编码参数后，将Picture多图对象编码至文件或缓冲区。

// 设置编码参数。
void SetPackOptions(OH_PackingOptions *packerOptions,
                    Image_MimeType format,
                    uint32_t quality,
                    bool needsPackProperties,
                    int32_t desiredDynamicRange)
{
    OH_PackingOptions_SetMimeType(packerOptions, &format);
    OH_PackingOptions_SetQuality(packerOptions, quality);
    OH_PackingOptions_SetNeedsPackProperties(packerOptions, needsPackProperties);
    OH_PackingOptions_SetDesiredDynamicRange(packerOptions, desiredDynamicRange);
}

// PackToData。
napi_value PackToDataFromPicture(napi_env env, napi_callback_info info)
{
    size_t argc = 1;
    napi_value args[1] = {nullptr};
    if (napi_get_cb_info(env, info, &argc, args, nullptr, nullptr) != napi_ok) {
        OH_LOG_ERROR(LOG_APP, "napi_get_cb_info failed!");
        return GetJsResult(env, g_thisPicture->errorCode);
    }
    
    size_t outDataSize = 10000 * 10000;
    uint8_t *outData = new uint8_t[outDataSize];

    if (g_thisPicture->packerOptions == nullptr) {
        g_thisPicture->errorCode = OH_PackingOptions_Create(&g_thisPicture->packerOptions);
    }
    if (g_thisPicture->imagePacker == nullptr) {
        g_thisPicture->errorCode = OH_ImagePackerNative_Create(&g_thisPicture->imagePacker);
    }
    
    char strFormat[MAX_FORMAT_LENGTH];
    size_t strFormatSize;
    napi_get_value_string_utf8(env, args[0], strFormat, MAX_FORMAT_LENGTH, &strFormatSize);
    OH_LOG_DEBUG(LOG_APP, "PackToDataFromPicture format: %{public}s", strFormat);

    Image_MimeType format;
    format.size = strFormatSize;
    format.data = const_cast<char *>(strFormat);
    uint32_t quality = 95;
    bool needsPackProperties = true;
    int32_t desiredDynamicRange = AUTO;
    SetPackOptions(g_thisPicture->packerOptions, format, quality, needsPackProperties, desiredDynamicRange);
    // 确保picture对象已被创建。
    g_thisPicture->errorCode = OH_ImagePackerNative_PackToDataFromPicture(
        g_thisPicture->imagePacker, g_thisPicture->packerOptions, g_thisPicture->picture, outData, &outDataSize);
    
    // 释放imagePacker和packerOptions。
    OH_PackingOptions_Release(g_thisPicture->packerOptions);
    g_thisPicture->packerOptions = nullptr;
    OH_ImagePackerNative_Release(g_thisPicture->imagePacker);
    g_thisPicture->imagePacker = nullptr;
    
    if (g_thisPicture->errorCode != IMAGE_SUCCESS) {
        OH_LOG_ERROR(LOG_APP, "OH_ImagePackerNative_PackToDataFromPicture failed, errCode: %{public}d.",
                     g_thisPicture->errorCode);
        delete[] outData;
        return GetJsResult(env, g_thisPicture->errorCode);
    } else {
        OH_LOG_DEBUG(LOG_APP, "OH_ImagePackerNative_PackToDataFromPicture success !");
    }
    delete[] outData;
    return GetJsResult(env, g_thisPicture->errorCode);
}

// PackToFile。
napi_value PackToFileFromPicture(napi_env env, napi_callback_info info)
{
    size_t argc = 2;
    napi_value args[2] = {nullptr};
    if (napi_get_cb_info(env, info, &argc, args, nullptr, nullptr) != napi_ok) {
    OH_LOG_ERROR(LOG_APP, "napi_get_cb_info failed!");
        return GetJsResult(env, g_thisPicture->errorCode);
    }
    uint32_t fd = 0;
    napi_get_value_uint32(env, args[0], &fd);

    if (g_thisPicture->packerOptions == nullptr) {
        g_thisPicture->errorCode = OH_PackingOptions_Create(&g_thisPicture->packerOptions);
    }
    if (g_thisPicture->imagePacker == nullptr) {
        g_thisPicture->errorCode = OH_ImagePackerNative_Create(&g_thisPicture->imagePacker);
    }
    
    char strFormat[MAX_FORMAT_LENGTH];
    size_t strFormatSize;
    napi_get_value_string_utf8(env, args[1], strFormat, MAX_FORMAT_LENGTH, &strFormatSize);
    OH_LOG_INFO(LOG_APP, "PackToFileFromPicture format: %{public}s", strFormat);

    Image_MimeType format;
    format.size = strFormatSize;
    format.data = const_cast<char *>(strFormat);
    uint32_t quality = 95;
    bool needsPackProperties = false;
    int32_t desiredDynamicRange = SDR;
    SetPackOptions(g_thisPicture->packerOptions, format, quality, needsPackProperties, desiredDynamicRange);
    // 确保picture对象已被创建。
    g_thisPicture->errorCode = OH_ImagePackerNative_PackToFileFromPicture(
        g_thisPicture->imagePacker, g_thisPicture->packerOptions, g_thisPicture->picture, fd);
    
    // 释放imagePacker和packerOptions。
    OH_PackingOptions_Release(g_thisPicture->packerOptions);
    g_thisPicture->packerOptions = nullptr;
    OH_ImagePackerNative_Release(g_thisPicture->imagePacker);
    g_thisPicture->imagePacker = nullptr;
    
    if (g_thisPicture->errorCode != IMAGE_SUCCESS) {
        OH_LOG_ERROR(LOG_APP, "OH_ImagePackerNative_PackToFileFromPicture failed,"
                     "errCode: %{public}d.", g_thisPicture->errorCode);
        return GetJsResult(env, g_thisPicture->errorCode);
    } else {
        OH_LOG_DEBUG(LOG_APP, "OH_ImagePackerNative_PackToFileFromPicture success !");
    }

    return GetJsResult(env, g_thisPicture->errorCode);
}

loadPicture.cpp