1# 使用Image_NativeModule完成多图对象编码
2
3图像打包类，用于创建以及释放ImagePacker实例，并编码多图对象。
4
5## 开发步骤
6
7### 添加链接库
8
9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libimage_packer.so 以及日志依赖libhilog_ndk.z.so。
10
11```txt
12target_link_libraries(entry PUBLIC libhilog_ndk.z.so libimage_packer.so)
13```
14
15### Native接口调用
16
17具体接口说明请参考[API文档](../../reference/apis-image-kit/_image___native_module.md)。
18
19在hello.cpp中实现C API接口调用逻辑，示例代码如下：
20
21**编码接口使用示例**
22
23在创建ImagePacker实例，指定打包参数后将Picture多图对象打包至文件或者缓冲区。
24
25> **说明：**
26> 根据MIME标准，标准编码格式为image/jpeg。当使用image编码时，打包参数中的编码格式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。
27
28   ```c++
29
30    #include "imagepicture_native.h"
31    #include "common/log_common.h"
32    #include <bits/alltypes.h>
33    #include <unistd.h>
34    #include <sys/types.h>
35    #include <sys/stat.h>
36    #include <fcntl.h>
37    #include <sstream>
38
39    #define AUTO 0
40    #define SDR 1
41
42    class ImagePictureNative {
43    public:
44        Image_ErrorCode errorCode = IMAGE_SUCCESS;
45        OH_DecodingOptionsForPicture *options = nullptr;
46        OH_ImagePackerNative *imagePacker = nullptr;
47        OH_PackingOptions *packerOptions = nullptr;
48        OH_PictureNative *picture = nullptr;
49        OH_ImageSourceNative *source = nullptr;
50        ImagePictureNative() {}
51        ~ImagePictureNative() {}
52    };
53
54    static ImagePictureNative *thisPicture = new ImagePictureNative();
55
56    // 处理napi返回值
57    napi_value getJsResult(napi_env env, int result) {
58        napi_value resultNapi = nullptr;
59        napi_create_int32(env, result, &resultNapi);
60        return resultNapi;
61    }
62
63    // 释放ImageSource
64    Image_ErrorCode ReleaseImageSource(OH_ImageSourceNative *&source) {
65        if (source != nullptr) {
66            thisPicture->errorCode = OH_ImageSourceNative_Release(source);
67            source = nullptr;
68            return thisPicture->errorCode;
69        }
70    OH_LOG_DEBUG(LOG_APP, "ReleaseImageSource source is null !");
71        return IMAGE_SUCCESS;
72    }
73
74    // 设置编码参数
75    void SetPackOptions(OH_PackingOptions *packerOptions, Image_MimeType format, uint32_t quality, bool needsPackProperties,
76                        int32_t desiredDynamicRange) {
77        OH_PackingOptions_SetMimeType(packerOptions, &format);
78        OH_PackingOptions_SetQuality(packerOptions, quality);
79        OH_PackingOptions_SetNeedsPackProperties(packerOptions, needsPackProperties);
80        OH_PackingOptions_SetDesiredDynamicRange(packerOptions, desiredDynamicRange);
81    }
82
83    // 编码PackToData
84    static napi_value PackToDataFromPicture(napi_env env, napi_callback_info info) {
85        size_t argc = 2;
86        napi_value args[2] = {nullptr};
87        if (napi_get_cb_info(env, info, &argc, args, nullptr, nullptr) != napi_ok) {
88            OH_LOG_ERROR(LOG_APP, "napi_get_cb_info failed !");
89            return getJsResult(env, thisPicture->errorCode);
90        }
91        uint32_t fd = 0;
92        napi_get_value_uint32(env, args[0], &fd);
93        size_t outDataSize = 10000 * 10000;
94        uint8_t *outData = new uint8_t[10000 * 10000];
95
96        if (thisPicture->packerOptions == nullptr) {
97            thisPicture->errorCode = OH_PackingOptions_Create(&thisPicture->packerOptions);
98        }
99        if (thisPicture->imagePacker == nullptr) {
100            thisPicture->errorCode = OH_ImagePackerNative_Create(&thisPicture->imagePacker);
101        }
102
103        char strFormat[20];
104        size_t strFormatSize;
105        napi_get_value_string_utf8(env, args[1], strFormat, 20, &strFormatSize);
106        OH_LOG_DEBUG(LOG_APP, "PackToDataFromPicture format: %{public}s", strFormat);
107
108        Image_MimeType format;
109        format.size = strFormatSize;
110        format.data = const_cast<char *>(strFormat);
111        uint32_t quality = 98;
112        bool needsPackProperties = true;
113        int32_t desiredDynamicRange = AUTO;
114        SetPackOptions(thisPicture->packerOptions, format, quality, needsPackProperties, desiredDynamicRange);
115
116        thisPicture->errorCode = OH_ImagePackerNative_PackToDataFromPicture(
117            thisPicture->imagePacker, thisPicture->packerOptions, thisPicture->picture, outData, &outDataSize);
118        if (thisPicture->errorCode != IMAGE_SUCCESS) {
119        OH_LOG_ERROR(LOG_APP, "OH_ImagePackerNative_PackToDataFromPicture failed, errCode: %{public}d.",
120                thisPicture->errorCode);
121            delete[] outData;
122            return getJsResult(env, thisPicture->errorCode);
123        } else {
124            ReleaseImageSource(thisPicture->source);
125            OH_ImageSourceNative_CreateFromData(outData, outDataSize, &thisPicture->source);
126            OH_ImagePackerNative_PackToFileFromImageSource(thisPicture->imagePacker, thisPicture->packerOptions,
127                                                        thisPicture->source, fd);
128            ReleaseImageSource(thisPicture->source);
129        OH_LOG_DEBUG(LOG_APP, "OH_ImagePackerNative_PackToDataFromPicture success !");
130        }
131
132        return getJsResult(env, thisPicture->errorCode);
133    }
134
135    // 编码PackToFile
136    static napi_value PackToFileFromPicture(napi_env env, napi_callback_info info) {
137        size_t argc = 2;
138        napi_value args[2] = {nullptr};
139        if (napi_get_cb_info(env, info, &argc, args, nullptr, nullptr) != napi_ok) {
140        OH_LOG_ERROR(LOG_APP, "napi_get_cb_info failed !");
141            return getJsResult(env, thisPicture->errorCode);
142        }
143        uint32_t fd = 0;
144        napi_get_value_uint32(env, args[0], &fd);
145
146        if (thisPicture->packerOptions == nullptr) {
147            thisPicture->errorCode = OH_PackingOptions_Create(&thisPicture->packerOptions);
148        }
149        if (thisPicture->imagePacker == nullptr) {
150            thisPicture->errorCode = OH_ImagePackerNative_Create(&thisPicture->imagePacker);
151        }
152
153        char strFormat[20];
154        size_t strFormatSize;
155        napi_get_value_string_utf8(env, args[1], strFormat, 20, &strFormatSize);
156    OH_LOG_ERROR(LOG_APP, "PackToFileFromPicture format: %{public}s", strFormat);
157
158        Image_MimeType format;
159        format.size = strFormatSize;
160        format.data = const_cast<char *>(strFormat);
161        uint32_t quality = 98;
162        bool needsPackProperties = false;
163        int32_t desiredDynamicRange = SDR;
164        SetPackOptions(thisPicture->packerOptions, format, quality, needsPackProperties, desiredDynamicRange);
165
166        thisPicture->errorCode = OH_ImagePackerNative_PackToFileFromPicture(
167            thisPicture->imagePacker, thisPicture->packerOptions, thisPicture->picture, fd);
168
169        if (thisPicture->errorCode != IMAGE_SUCCESS) {
170        OH_LOG_ERROR(LOG_APP, "OH_ImagePackerNative_PackToFileFromPicture failed, errCode: %{public}d.",
171            thisPicture->errorCode);
172
173            return getJsResult(env, thisPicture->errorCode);
174        } else {
175        OH_LOG_DEBUG(LOG_APP, "OH_ImagePackerNative_PackToFileFromPicture success !");
176        }
177
178        return getJsResult(env, thisPicture->errorCode);
179    }
180   ```
181