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1# 使用Image_NativeModule完成多图对象解码
2<!--Kit: Image Kit-->
3<!--Subsystem: Multimedia-->
4<!--Owner: @aulight02-->
5<!--Designer: @liyang_bryan-->
6<!--Tester: @xchaosioda-->
7<!--Adviser: @zengyawen-->
8
9创建ImageSource，解码得到Picture，以及释放ImageSource实例。
10
11## 开发步骤
12
13### 添加链接库
14
15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_source.so 以及日志依赖libhilog_ndk.z.so。
16
17```txt
18target_link_libraries(entry PUBLIC libhilog_ndk.z.so libimage_source.so)
19```
20
21### Native接口调用
22
23具体接口说明请参考[API文档](../../reference/apis-image-kit/capi-image-nativemodule.md)。
24
25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：
26
27**解码接口使用示例**
28
29在创建ImageSource实例后，进行指定属性值的获取和修改，通过解码参数创建PixelMap对象，获取图像帧数等操作。
30
31```c++
32#include <hilog/log.h>
33#include <multimedia/image_framework/image/image_native.h>
34#include <multimedia/image_framework/image/image_packer_native.h>
35#include <multimedia/image_framework/image/image_source_native.h>
36#include <multimedia/image_framework/image/picture_native.h>
37#include <multimedia/image_framework/image/pixelmap_native.h>
38
39#define AUTO 0
40#define SDR 1
41
42class ImagePictureNative {
43public:
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
54class ImageAuxiliaryPictureNative {
55public:
56    Image_ErrorCode errorCode = IMAGE_SUCCESS;
57    Image_AuxiliaryPictureType type = AUXILIARY_PICTURE_TYPE_GAINMAP;
58    OH_AuxiliaryPictureNative *auxiliaryPicture = nullptr;
59    size_t BUFF_SIZE = 640 * 480 * 4; 	//辅助图size 长*宽*每像素占用字节数。
60    ImageAuxiliaryPictureNative() {}
61    ~ImageAuxiliaryPictureNative() {}
62};
63
64static ImagePictureNative *thisPicture = new ImagePictureNative();
65static ImageAuxiliaryPictureNative *thisAuxiliaryPicture = new ImageAuxiliaryPictureNative();
66
67// 释放ImageSource。
68Image_ErrorCode ReleaseImageSource(OH_ImageSourceNative *&source) {
69    if (source != nullptr) {
70        thisPicture->errorCode = OH_ImageSourceNative_Release(source);
71        source = nullptr;
72        return thisPicture->errorCode;
73    }
74    OH_LOG_DEBUG(LOG_APP, "ReleaseImageSource source is null !");
75    return IMAGE_SUCCESS;
76}
77
78// 处理napi返回值。
79napi_value getJsResult(napi_env env, int result) {
80    napi_value resultNapi = nullptr;
81    napi_create_int32(env, result, &resultNapi);
82    return resultNapi;
83}
84
85// 创造解码参数。
86static napi_value CreateDecodingOptions(napi_env env, napi_callback_info info) {
87    thisPicture->errorCode = OH_DecodingOptionsForPicture_Create(&thisPicture->options);
88
89    if (thisPicture->errorCode != IMAGE_SUCCESS) {
90        OH_LOG_ERROR(LOG_APP, "OH_DecodingOptionsForPicture_Create failed, errCode: %{public}d.",
91            thisPicture->errorCode);
92        return getJsResult(env, thisPicture->errorCode);
93    } else {
94        OH_LOG_DEBUG(LOG_APP, "OH_DecodingOptionsForPicture_Create success !");
95    }
96
97    return getJsResult(env, thisPicture->errorCode);
98}
99
100// 配置解码参数 从应用层传入。
101static napi_value SetDesiredAuxiliaryPictures(napi_env env, napi_callback_info info) {
102    size_t argc = 1;
103    napi_value args[1] = {nullptr};
104    if (napi_get_cb_info(env, info, &argc, args, nullptr, nullptr) != napi_ok || argc < 1 || args[0] == nullptr) {
105        OH_LOG_ERROR(LOG_APP, "napi_get_cb_info failed !");
106        return getJsResult(env, IMAGE_BAD_PARAMETER);
107    }
108
109    uint32_t length = 0;
110    napi_get_array_length(env, args[0], &length);
111    if (length <= 0) {
112        OH_LOG_ERROR(LOG_APP, "napi_get_array_length failed !");
113        return getJsResult(env, IMAGE_UNKNOWN_ERROR);
114    }
115    Image_AuxiliaryPictureType typeList[length];
116    for (int index = 0; index < length; index++) {
117        napi_value element;
118        uint32_t ulType = 0;
119        napi_get_element(env, args[0], index, &element);
120        napi_get_value_uint32(env, element, &ulType);
121        typeList[index] = static_cast<Image_AuxiliaryPictureType>(ulType);
122        OH_LOG_DEBUG(LOG_APP, "ulType is :%{public}d", ulType);
123    }
124
125    thisPicture->errorCode =
126        OH_DecodingOptionsForPicture_SetDesiredAuxiliaryPictures(thisPicture->options, typeList, length);
127    if (thisPicture->errorCode != IMAGE_SUCCESS) {
128        OH_LOG_ERROR(LOG_APP, "OH_DecodingOptionsForPicture_SetDesiredAuxiliaryPictures failed,errCode: %{public}d.",
129            thisPicture->errorCode);
130        return getJsResult(env, thisPicture->errorCode);
131    } else {
132        OH_LOG_DEBUG(LOG_APP, "OH_DecodingOptionsForPicture_SetDesiredAuxiliaryPictures success !");
133    }
134
135    return getJsResult(env, thisPicture->errorCode);
136}
137
138
139// 解码。
140static napi_value CreatePictureByImageSource(napi_env env, napi_callback_info info) {
141    size_t argc = 1;
142    napi_value args[1] = {nullptr};
143    napi_value result = nullptr;
144
145    if (napi_get_cb_info(env, info, &argc, args, nullptr, nullptr) != napi_ok || argc < 1 || args[0] == nullptr) {
146        OH_LOG_ERROR(LOG_APP, "CreatePicture_ napi_get_cb_info failed !");
147        return getJsResult(env, IMAGE_BAD_PARAMETER);
148    }
149    char filePath[1024];
150    size_t filePathSize;
151    napi_get_value_string_utf8(env, args[0], filePath, 1024, &filePathSize);
152    ReleaseImageSource(thisPicture->source);
153
154    thisPicture->errorCode = OH_ImageSourceNative_CreateFromUri(filePath, filePathSize, &thisPicture->source);
155    if (thisPicture->errorCode != IMAGE_SUCCESS) {
156        OH_LOG_ERROR(LOG_APP, "OH_ImageSourceNative_CreateFromUri failed, errCode: %{public}d.",
157            thisPicture->errorCode);
158        return getJsResult(env, thisPicture->errorCode);
159    } else {
160        OH_LOG_DEBUG(LOG_APP, "OH_ImageSourceNative_CreateFromUri success !");
161    }
162
163    thisPicture->errorCode =
164        OH_ImageSourceNative_CreatePicture(thisPicture->source, thisPicture->options, &thisPicture->picture);
165    thisAuxiliaryPicture->errorCode = OH_PictureNative_GetAuxiliaryPicture(thisPicture->picture,
166        thisAuxiliaryPicture->type, &thisAuxiliaryPicture->auxiliaryPicture);
167    if (thisAuxiliaryPicture->errorCode == IMAGE_SUCCESS) {
168        uint8_t* buff = new uint8_t[thisAuxiliaryPicture->BUFF_SIZE];
169        OH_AuxiliaryPictureNative_ReadPixels(thisAuxiliaryPicture->auxiliaryPicture, buff,
170            &thisAuxiliaryPicture->BUFF_SIZE);
171        OH_AuxiliaryPictureNative_Release(thisAuxiliaryPicture->auxiliaryPicture);
172        delete []buff;
173    }
174    if (thisPicture->errorCode != IMAGE_SUCCESS) {
175        OH_LOG_ERROR(LOG_APP, "ImageSourceNative_CreatePicture failed, errCode: %{public}d.", thisPicture->errorCode);
176        return getJsResult(env, thisPicture->errorCode);
177    } else {
178        napi_status status =
179            napi_create_external(env, reinterpret_cast<void *>(thisPicture->picture), nullptr, nullptr, &result);
180        if (status != napi_ok) {
181            napi_throw_error(env, nullptr, "Failed to create external object");
182            return nullptr;
183        }
184        OH_LOG_DEBUG(LOG_APP, "ImageSourceNative_CreatePicture success !");
185    }
186
187    return result;
188}
189```
190