通过IDE集成C/C++三方库并开发napi接口
简介
应用在调用系统固件集成的C/C++三方库时，可能会由于系统固件集成端与IDE的NDK中libc++版本不一致导致调用失败，而且系统固件集成的C/C++三方库对于应用的调式也很不友好，需要多方编译调试，很不方便。因此本文将通过在IDE上适配openjpeg 三方库为例介绍IDE上适配一个C/C++三方库的具体流程。
创建工程
在开发进行三方库适配以及napi接口开发前，我们需要创建一个三方库对应的工程，具体创建工程方法可以参照文档通过IDE开发一个Napi工程。
IDE上三方库的适配
本文中我们以适配 openjpeg 为例介绍整个适配流程 。
原生库准备
下载代码
通过openjpeg github网址，通过Code>>Download ZIP选项下载最新版本的源码包，并将其解压后放在IDE工程中的CPP目录下。
- 下载openjpeg 2.5.0版本的库：
- 将库放在IDE工程：
分析编译依赖
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分析CMakeLists.txt 对于库不是很复杂且目录结构简单的库可以通过分析CMakeLists.txt文件来获取库的依赖。在openjpeg库中， 通过分析最外层CMakeLists.txt文件，可以得知编译openjpeg核心代码以及需要依赖编译库自带thirdparty，如下图：
而分析thirdparty/CMakeLists.txt文件，如果BUILD_THIRDPARTY开关未打开，将会通过FindPkgConfig自动搜索系统(IDE工具的SDK编译链)中的库文件，如下图：
并由此文件可以分析出该库非强制依赖了libz, libpng, libtiff以及liblcms2，如对libpng依赖的分析中：
IDE工具的SDK编译链中只有libz库，其他三个库是没有的，所以如果需要其他三个库的功能，我们需要将BUILD_THIRDPARTY开关打开，此开关在库顶层目录的CMakeLists.txt文件中，如下图：
到此，本库的依赖就已经分析完了。 -
通过运行cmake分析 我们除了分析CMakeLists.txt文件外，也可以通过在linux中通过cmake过程来分析对应的依赖。
我们在执行cmake的时候，会有对相关的依赖库的提示：-- Large File support - found -- Looking for include file malloc.h -- Looking for include file malloc.h - found -- Looking for _aligned_malloc -- Looking for _aligned_malloc - not found -- Looking for posix_memalign -- Looking for posix_memalign - found -- Looking for memalign -- Looking for memalign - found -- Found PkgConfig: /usr/bin/pkg-config (found version "0.29.1") -- Found ZLIB: /usr/lib/x86_64-linux-gnu/libz.so (found version "1.2.11") -- Your system seems to have a Z lib available, we will use it to generate PNG lib -- Found PNG: /usr/lib/x86_64-linux-gnu/libpng.so (found version "1.6.37") -- Your system seems to have a PNG lib available, we will use it -- Found TIFF: /usr/lib/x86_64-linux-gnu/libtiff.so (found version "4.1.0") -- Your system seems to have a TIFF lib available, we will use it -- Could NOT find LCMS2 (missing: LCMS2_LIBRARY LCMS2_INCLUDE_DIR) -- Could NOT find LCMS (missing: LCMS_LIBRARY LCMS_INCLUDE_DIR) -- LCMS2 or LCMS lib not found, activate BUILD_THIRDPARTY if you want build it -- Configuring done -- Generating done由以上信息可以查看到，编译此库需要依赖libz(found version "1.2.11")，libpng(found version "1.6.37")，libtiff(found version "4.1.0")以及liblcms2(LCMS2 or LCMS lib not found, activate BUILD_THIRDPARTY if you want build it)。从提示中可以看到，如果想要使能对应的功能且系统库中未包含该依赖的话，需要打开BUILD_THIRDPARTY 开关。
除了cmake中获取的依赖，我们也可以通过分析make编译过程获取更多的信息，具体方法可以参照三方库适配依赖分析。
重构CMakeLists
对于不复杂的库且没有其他四方库依赖的三方库，我们可以使用原生库的CMakeLists.txt文件，但是对于一些复杂的，且强制依赖其他四方库的库，使用其原生CMakeLists.txt文件，无法解决四方库依赖的问题。此时，我们就需要对三方库的CMakeLists.txt文件进行重构。
重构CMakeLists文件主要需涉及以下几点：
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动态生成配置文件 查看原生CMakeLists.txt文件中是否有configure_file配置项，如果没有可直接跳过此步骤。
在openjpeg库的原生CMakeLists.txt文件中，有2个配置文件需要动态生成：# opj_config.h generation (2/2) configure_file( ${CMAKE_CURRENT_SOURCE_DIR}/src/lib/openjp2/opj_config.h.cmake.in ${CMAKE_CURRENT_BINARY_DIR}/src/lib/openjp2/opj_config.h @ONLY ) configure_file( ${CMAKE_CURRENT_SOURCE_DIR}/src/lib/openjp2/opj_config_private.h.cmake.in ${CMAKE_CURRENT_BINARY_DIR}/src/lib/openjp2/opj_config_private.h @ONLY )configure_file带了@ONLY参数，该参数限制了变量替换，让其只替换被@VAR@引用的变量。因此我们需要分析两个文件中对应的@VAR@配置规则。首先在opj_config.h.cmake.in文件定义的对应@VAR@的定义：
/* create opj_config.h for CMake */ #cmakedefine OPJ_HAVE_STDINT_H @OPJ_HAVE_STDINT_H@ /*--------------------------------------------------------------------------*/ /* OpenJPEG Versioning */ /* Version number. */ #define OPJ_VERSION_MAJOR @OPENJPEG_VERSION_MAJOR@ #define OPJ_VERSION_MINOR @OPENJPEG_VERSION_MINOR@ #define OPJ_VERSION_BUILD @OPENJPEG_VERSION_BUILD@在分析@VAR@的赋值规则，在顶层CMakeLists.txt中：
# opj_config.h generation (1/2) # Check if some include files are provided by the system include(EnsureFileInclude) # These files are mandatory ensure_file_include("string.h" HAVE_STRING_H YES) ensure_file_include("memory.h" HAVE_MEMORY_H YES) ensure_file_include("stdlib.h" HAVE_STDLIB_H YES) ensure_file_include("stdio.h" HAVE_STDIO_H YES) ensure_file_include("math.h" HAVE_MATH_H YES) ensure_file_include("float.h" HAVE_FLOAT_H YES) ensure_file_include("time.h" HAVE_TIME_H YES) ensure_file_include("stdarg.h" HAVE_STDARG_H YES) ensure_file_include("ctype.h" HAVE_CTYPE_H YES) ensure_file_include("assert.h" HAVE_ASSERT_H YES) # For the following files, we provide an alternative, they are not mandatory ensure_file_include("stdint.h" OPJ_HAVE_STDINT_H NO) ensure_file_include("inttypes.h" OPJ_HAVE_INTTYPES_H NO)从以上内容通过分析ensure_file_include可以知道，在执行cmake时从系统中查找stdint.h文件，如果查找到则将OPJ_HAVE_STDINT_H置起，否则不会改变。而IDE上是没有stdint.h文件的，因此我们需要在配置文件之前手动将OPJ_HAVE_STDINT_H置起，如下：
set(OPJ_HAVE_STDINT_H TRUE)其他变量也是通过类似的方法分析。
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相关宏定义的设置 通过add_definitions设置三方库的相关宏定义，如下所示：
add_definitions(-DOPJ_HAVE_PNG_H=0 -DOPJ_HAVE_TIFF_H=1 -DOPJ_HAVE_LCMS2_H=1) -
源码文件编译 三方库编译的源码可以通过在linux执行make的时候查看分析到：
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src/bin/jp2/CMakeFiles/opj_dump.dir/convertpng.c.o [ 88%] Linking C executable ../../../bin/opj_dump [ 88%] Built target opj_dump Scanning dependencies of target opj_compress [ 89%] Building C object src/bin/jp2/CMakeFiles/opj_compress.dir/opj_compress.c.o [ 90%] Building C object src/bin/jp2/CMakeFiles/opj_compress.dir/convert.c.o [ 90%] Building C object src/bin/jp2/CMakeFiles/opj_compress.dir/convertbmp.c.o [ 91%] Building C object src/bin/jp2/CMakeFiles/opj_compress.dir/index.c.o [ 92%] Building C object src/bin/jp2/CMakeFiles/opj_compress.dir/__/common/color.c.o [ 92%] Building C object src/bin/jp2/CMakeFiles/opj_compress.dir/__/common/opj_getopt.c.o [ 93%] Building C object src/bin/jp2/CMakeFiles/opj_compress.dir/converttif.c.o [ 93%] Building C object src/bin/jp2/CMakeFiles/opj_compress.dir/convertpng.c.o [ 94%] Linking C executable ../../../bin/opj_compress [ 94%] Built target opj_compress Scanning dependencies of target opj_decompress [ 95%] Building C object src/bin/jp2/CMakeFiles/opj_decompress.dir/opj_decompress.c.o [ 95%] Building C object src/bin/jp2/CMakeFiles/opj_decompress.dir/convert.c.o [ 96%] Building C object src/bin/jp2/CMakeFiles/opj_decompress.dir/convertbmp.c.o [ 97%] Building C object src/bin/jp2/CMakeFiles/opj_decompress.dir/index.c.o [ 97%] Building C object src/bin/jp2/CMakeFiles/opj_decompress.dir/__/common/color.c.o [ 98%] Building C object src/bin/jp2/CMakeFiles/opj_decompress.dir/__/common/opj_getopt.c.o [ 99%] Building C object src/bin/jp2/CMakeFiles/opj_decompress.dir/converttif.c.o [ 99%] Building C object src/bin/jp2/CMakeFiles/opj_decompress.dir/convertpng.c.o [100%] Linking C executable ../../../bin/opj_decompress [100%] Built target opj_decompress由上面过程可看出，每个编译目标(Built target)所依赖的文件由上一个目标(如果上一个目标由的话)生成后以及该目标生成前的文件组成，如生成libopenjp2.so（Built target openjp）的文件是Built target openjp2_static之后以及Built target openjp之前的文件：
[ 14%] Building C object src/lib/openjp2/CMakeFiles/openjp2.dir/thread.c.o [ 15%] Building C object src/lib/openjp2/CMakeFiles/openjp2.dir/bio.c.o [ 16%] Building C object src/lib/openjp2/CMakeFiles/openjp2.dir/cio.c.o [ 16%] Building C object src/lib/openjp2/CMakeFiles/openjp2.dir/dwt.c.o [ 17%] Building C object src/lib/openjp2/CMakeFiles/openjp2.dir/event.c.o [ 18%] Building C object src/lib/openjp2/CMakeFiles/openjp2.dir/ht_dec.c.o [ 18%] Building C object src/lib/openjp2/CMakeFiles/openjp2.dir/image.c.o [ 19%] Building C object src/lib/openjp2/CMakeFiles/openjp2.dir/invert.c.o [ 20%] Building C object src/lib/openjp2/CMakeFiles/openjp2.dir/j2k.c.o [ 20%] Building C object src/lib/openjp2/CMakeFiles/openjp2.dir/jp2.c.o [ 21%] Building C object src/lib/openjp2/CMakeFiles/openjp2.dir/mct.c.o [ 22%] Building C object src/lib/openjp2/CMakeFiles/openjp2.dir/mqc.c.o [ 22%] Building C object src/lib/openjp2/CMakeFiles/openjp2.dir/openjpeg.c.o [ 23%] Building C object src/lib/openjp2/CMakeFiles/openjp2.dir/opj_clock.c.o [ 23%] Building C object src/lib/openjp2/CMakeFiles/openjp2.dir/pi.c.o [ 24%] Building C object src/lib/openjp2/CMakeFiles/openjp2.dir/t1.c.o [ 25%] Building C object src/lib/openjp2/CMakeFiles/openjp2.dir/t2.c.o [ 25%] Building C object src/lib/openjp2/CMakeFiles/openjp2.dir/tcd.c.o [ 26%] Building C object src/lib/openjp2/CMakeFiles/openjp2.dir/tgt.c.o [ 27%] Building C object src/lib/openjp2/CMakeFiles/openjp2.dir/function_list.c.o [ 27%] Building C object src/lib/openjp2/CMakeFiles/openjp2.dir/opj_malloc.c.o [ 28%] Building C object src/lib/openjp2/CMakeFiles/openjp2.dir/sparse_array.c.o因此生成libopenjpeg.so的源文件我们就可以这样写：
set(SHARED_LIB_SRC "${CMAKE_CURRENT_SOURCE_DIR}/src/lib/openjp2/thread.c" "${CMAKE_CURRENT_SOURCE_DIR}/src/lib/openjp2/bio.c" "${CMAKE_CURRENT_SOURCE_DIR}/src/lib/openjp2/cio.c" "${CMAKE_CURRENT_SOURCE_DIR}/src/lib/openjp2/dwt.c" "${CMAKE_CURRENT_SOURCE_DIR}/src/lib/openjp2/event.c" "${CMAKE_CURRENT_SOURCE_DIR}/src/lib/openjp2/ht_dec.c" "${CMAKE_CURRENT_SOURCE_DIR}/src/lib/openjp2/image.c" "${CMAKE_CURRENT_SOURCE_DIR}/src/lib/openjp2/invert.c" "${CMAKE_CURRENT_SOURCE_DIR}/src/lib/openjp2/j2k.c" "${CMAKE_CURRENT_SOURCE_DIR}/src/lib/openjp2/jp2.c" "${CMAKE_CURRENT_SOURCE_DIR}/src/lib/openjp2/mct.c" "${CMAKE_CURRENT_SOURCE_DIR}/src/lib/openjp2/mqc.c" "${CMAKE_CURRENT_SOURCE_DIR}/src/lib/openjp2/openjpeg.c" "${CMAKE_CURRENT_SOURCE_DIR}/src/lib/openjp2/opj_clock.c" "${CMAKE_CURRENT_SOURCE_DIR}/src/lib/openjp2/pi.c" "${CMAKE_CURRENT_SOURCE_DIR}/src/lib/openjp2/t1.c" "${CMAKE_CURRENT_SOURCE_DIR}/src/lib/openjp2/t2.c" "${CMAKE_CURRENT_SOURCE_DIR}/src/lib/openjp2/tcd.c" "${CMAKE_CURRENT_SOURCE_DIR}/src/lib/openjp2/tgt.c" "${CMAKE_CURRENT_SOURCE_DIR}/src/lib/openjp2/function_list.c" "${CMAKE_CURRENT_SOURCE_DIR}/src/lib/openjp2/opj_malloc.c" "${CMAKE_CURRENT_SOURCE_DIR}/src/lib/openjp2/sparse_array.c")其中CMAKE_CURRENT_SOURCE_DIR是代表当前CMakeLists.txt文件所在的路径。
-
目标文件生成 这里我们调用add_library生成一个目标文件libopenjpeg_shared.so，其依赖上面分析的源码share_lib_src：
add_library(openjp2 SHARED ${SHARED_LIB_SRC}) -
添加其他四方库依赖 如果三方库有对其他四方库依赖的话，需要通过target_link_libraries()方法添加对应的依赖。如在工程CPP目录下的CMakeLists.txt文件中的:
target_link_libraries(entry PUBLIC libace_napi.z.so openjg2) # libace_napi.z.so-系统napi库, openjg2-依赖的openjpeg库 -
完整的CMakeLists.txt
# the minimum version of CMake. cmake_minimum_required(VERSION 3.4.1) set(CMAKE_CXX_STANDARD 17) project(openjpeg) set(OPJ_HAVE_STDINT_H TRUE) set(OPJ_HAVE_INTTYPES_H TRUE) set(OPENJPEG_VERSION_MAJOR 2) set(OPENJPEG_VERSION_MINOR 5) set(OPENJPEG_VERSION_BUILD 0) set(OPENJPEG_VERSION "${OPENJPEG_VERSION_MAJOR}.${OPENJPEG_VERSION_MINOR}.${OPENJPEG_VERSION_BUILD}") set(PACKAGE_VERSION "${OPENJPEG_VERSION_MAJOR}.${OPENJPEG_VERSION_MINOR}.${OPENJPEG_VERSION_BUILD}") configure_file( ${CMAKE_CURRENT_SOURCE_DIR}/src/lib/openjp2/opj_config.h.cmake.in ${CMAKE_CURRENT_SOURCE_DIR}/src/lib/openjp2/opj_config.h @ONLY ) configure_file( ${CMAKE_CURRENT_SOURCE_DIR}/src/lib/openjp2/opj_config_private.h.cmake.in ${CMAKE_CURRENT_SOURCE_DIR}/src/lib/openjp2/opj_config_private.h @ONLY ) add_definitions(-DOPJ_HAVE_PNG_H=0 -DOPJ_HAVE_TIFF_H=1 -DOPJ_HAVE_LCMS2_H=1) set(INCLUDE_DIR "${CMAKE_CURRENT_SOURCE_DIR}/src/lib/openjp2") set(SHARED_LIB_SRC "${CMAKE_CURRENT_SOURCE_DIR}/src/lib/openjp2/thread.c" "${CMAKE_CURRENT_SOURCE_DIR}/src/lib/openjp2/bio.c" "${CMAKE_CURRENT_SOURCE_DIR}/src/lib/openjp2/cio.c" "${CMAKE_CURRENT_SOURCE_DIR}/src/lib/openjp2/dwt.c" "${CMAKE_CURRENT_SOURCE_DIR}/src/lib/openjp2/event.c" "${CMAKE_CURRENT_SOURCE_DIR}/src/lib/openjp2/ht_dec.c" "${CMAKE_CURRENT_SOURCE_DIR}/src/lib/openjp2/image.c" "${CMAKE_CURRENT_SOURCE_DIR}/src/lib/openjp2/invert.c" "${CMAKE_CURRENT_SOURCE_DIR}/src/lib/openjp2/j2k.c" "${CMAKE_CURRENT_SOURCE_DIR}/src/lib/openjp2/jp2.c" "${CMAKE_CURRENT_SOURCE_DIR}/src/lib/openjp2/mct.c" "${CMAKE_CURRENT_SOURCE_DIR}/src/lib/openjp2/mqc.c" "${CMAKE_CURRENT_SOURCE_DIR}/src/lib/openjp2/openjpeg.c" "${CMAKE_CURRENT_SOURCE_DIR}/src/lib/openjp2/opj_clock.c" "${CMAKE_CURRENT_SOURCE_DIR}/src/lib/openjp2/pi.c" "${CMAKE_CURRENT_SOURCE_DIR}/src/lib/openjp2/t1.c" "${CMAKE_CURRENT_SOURCE_DIR}/src/lib/openjp2/t2.c" "${CMAKE_CURRENT_SOURCE_DIR}/src/lib/openjp2/tcd.c" "${CMAKE_CURRENT_SOURCE_DIR}/src/lib/openjp2/tgt.c" "${CMAKE_CURRENT_SOURCE_DIR}/src/lib/openjp2/function_list.c" "${CMAKE_CURRENT_SOURCE_DIR}/src/lib/openjp2/opj_malloc.c" "${CMAKE_CURRENT_SOURCE_DIR}/src/lib/openjp2/sparse_array.c") add_library(openjp2 SHARED ${SHARED_LIB_SRC}) target_include_directories(openjp2 PRIVATE ${INCLUDE_DIR})
加入编译构建
原生库源码准备完后，我们需要将库加入到工程的编译构建中。在工程目录CPP下的CMakeLists.txt文件中，通过add_subdirectory将openjpeg加入到编译中，并通过target_link_libraries添加对openjpeg的链接，如下图：
特别说明：
如果使用原生库的CMakeLists文件，编译时会提示添加目标时需要重新更改目标路径：
此时我们就需要在顶层目录的CMakeLists.txt文件中添加
set(CMAKE_BUILD_WITH_INSTALL_RPATH TRUE)
到此，我们的三方库适配已经完成并可以正常编译成功。
三方库napi接口开发
三方库napi的接口一般是由需求方提供的，对于无需求或需要自己定义接口的，我们可以根据三方库对外导出的API接口进行封装或是根据原生库的测试用例对外封装测试接口。本文中我们已封装2个openjpeg测试接口为例详细说明napi接口开发的具体流程。
定义napi接口
根据原生库的测试用例，我们封装2个测试用例接口
typedef struct {
int comps_num; // the number of components of the image.
int comps_prec; // number of bits per component per pixel
int img_width; // the image width
int img_height; // the image height
int title_width; // width of tile
int title_height; // height of title
int irreversible; // 1 : use the irreversible DWT 9-7
// 0 : use lossless compression (default)
int cblockw_init; // initial code block width, default to 64
int cblockh_init; // initial code block height, default to 64
int numresolution; // number of resolutions
int offsetx; // x component offset compared to the whole image
int offsety; // y component offset compared to the whole image
int is_rand; // Whether to generate data randomly
char file[256]; // output filename
} J2K_Info;
int OpenjpegCompress(const char *input_file, char *output_file) # 图片压缩成J2K格式
int openjpeg_create_j2k(J2K_Info *info) # 创建一张J2K格式图片
注册接口
napi_property_descriptor desc[] = {
{"openjpeg_compress", nullptr, OpenjpegCompress, nullptr, nullptr,
nullptr, napi_default, nullptr},
{"openjpeg_create_j2k", nullptr, OpenjpegCreateJ2K , nullptr, nullptr,
nullptr, napi_default, nullptr}
};
接口实现
-
openjpeg_compress接口的实现
static napi_value OpenjpegCompressMethod(napi_env env, napi_callback_info info) { napi_value result = nullptr; napi_get_undefined(env, &result); napi_value value; size_t argc = 2; napi_value args[2]; size_t size; char input_file[256] = {0}; char output_file[256] = {0}; // 获取参数 if (napi_get_cb_info(env, info, &argc, args, nullptr, nullptr) != napi_ok) { return result; } // js类型转换成C/C++类型 if (napi_get_value_string_utf8(env, args[0], input_file, sizeof(input_file), &size) != napi_ok) { return result; } // js类型转换成C/C++类型 if (napi_get_value_string_utf8(env, args[1], output_file, sizeof(output_file), &size) != napi_ok) { return result; } // 封装一个通过调用openjpeg接口实现编码的接口 // 三方库实现调用的业务逻辑接口 if (OpenjpegCompress(input_file, output_file) != 0) { return result; } // 创建返回的js类型参数 if (napi_create_int64(env, 0, &result) != napi_ok) { std::cout << "napi_create_int64" << std::endl; } // 返回最终结果。 return result; } -
openjpeg_create_j2k接口的实现
static napi_value OpenjpegCreateJ2K(napi_env env, napi_callback_info info) { napi_value result = nullptr; napi_get_undefined(env, &result); napi_value value; size_t argc = 1; J2K_Info j2kInfo; // 获取参数 if (napi_get_cb_info(env, info, &argc, &value, nullptr, nullptr) != napi_ok) { return result; } // 解析参数 if (OpenjpegGetJ2kInfo(env, value, &j2kInfo) < 0) { return result; } // 封装一个通过调用openjpeg接口实现创建J2K文件的接口 // 三方库实现调用的业务逻辑接口 if (OpenjpegCreateJ2K(&j2kInfo) < 0) { return result; } if (napi_create_int64(env, 0, &result) != napi_ok) { std::cout << "napi_create_int64" << std::endl; } return result; }解析参数接口的实现：
static int OpenjpegGetJ2kInfo(napi_env env, napi_value value, J2K_Info *info) { if (info == nullptr) { return -1; } if(GetObjectPropetry(env, value,"output_file", STRING, info->file) != napi_ok) { return -1; } if (GetObjectPropetry(env, value,"comps_prec", NUMBER, &info->comps_prec) != napi_ok) { return -1; } if (GetObjectPropetry(env, value,"img_width", NUMBER, &info->img_width) != napi_ok) { return -1; } if (GetObjectPropetry(env, value,"img_height", NUMBER, &info->img_height) != napi_ok) { return -1; } if (GetObjectPropetry(env, value,"title_width", NUMBER, &info->title_width) != napi_ok) { return -1; } if (GetObjectPropetry(env, value,"title_height", NUMBER, &info->title_height) != napi_ok) { return -1; } if (GetObjectPropetry(env, value,"irreversible", NUMBER, &info->irreversible) != napi_ok) { return -1; } GetObjectPropetry(env, value,"cblockw_init", NUMBER, &info->cblockw_init); GetObjectPropetry(env, value,"cblockh_init", NUMBER, &info->cblockh_init); GetObjectPropetry(env, value,"numresolution", NUMBER, &info->numresolution); GetObjectPropetry(env, value,"offsetx", NUMBER, &info->offsetx); GetObjectPropetry(env, value,"offsety", NUMBER, &info->offsety); GetObjectPropetry(env, value,"is_rand", BOOLEAN, &info->is_rand); return 0; }由上代码可以看出，OpenjpegGetJ2kInfo接扣调用了一个封装的接口GetObjectPropetry，该接口实现了通过调用napi的接口获取对应的数据：
static int GetObjectPropetry(napi_env env, napi_value object, std::string key, int keyType, void *retValue) { napi_value property = nullptr; napi_value result = nullptr; bool flag = false; int ret = -1; // 通过字符串获取napi_value对象 if (napi_create_string_utf8(env, key.c_str(), strlen(key.c_str()), &property) != napi_ok) { return ret; } // 判断该字符串是否对应由属性值 if (napi_has_property(env, object, property, &flag) != napi_ok && flag == true) { return ret; } // 获取字符串对应的属性值 if (napi_get_property(env, object, property, &result) != napi_ok) { return ret; } if (keyType == NUMBER) { int64_t value = 0; // JS数据类型转换成C/C++的int数据类型 if (napi_get_value_int64(env, result, &value) != napi_ok) { return ret; } *(int *)retValue = value; ret = 0; } else if (keyType == BOOLEAN) { bool value = false; // JS数据类型转换成C/C++ 的bool数据类型 if (napi_get_value_bool(env, result, &value) != napi_ok) { return ret; } *(int *)retValue = (value == true ? 1 : 0); }else if (keyType == STRING) { size_t s = 0; char buf[256] = {0}; // JS数据类型转换成C/C++的string数据类型 if (napi_get_value_string_utf8(env, result, buf, sizeof(buf), &s) != napi_ok) { return ret; } strncpy((char *)retValue, buf, strlen(buf)); ret = 0; } return 0; }
应用调用napi接口
-
应用申明接口 在确定需要封装的接口后，我们需要将这些接口定义在index.d.ts文件中(路径entry/src/main/cpp/types/libentry/index.d.ts)
export const openjpeg_compress: (srcName:string, desName:string) =>number; interface openjpegOption{ comps_num:number // the number of components of the image. comps_prec:number // number of bits per component per pixel img_width:number // the image width img_height:number // the image height title_width:number // width of tile title_height:number // height of title irreversible:number // 1 : use the irreversible DWT 9-7, // 0 : use lossless compression (default) output_file:string // output filename cblockw_init?:number // initial code block width, default to 64 cblockh_init?:number // initial code block height, default to 64 numresolution?:number // number of resolutions offsetx?:number // x component offset compared to the whole image offsety?:number // y component offset compared to the whole image is_rand?:boolean // Whether to generate data randomly } export const openjpeg_create_j2k: (option:openjpegOption) => number -
应用调用接口 在ets工程中创建2个按钮，并通过按钮调用相关的接口，具体代码如下：
Button(this.buttonTxt0) .fontSize(50) .margin({top:30}) .fontWeight(FontWeight.Normal) .onClick(() => { testNapi.openjpeg_compress(this.dir + "test_pic.bmp", this.dir + "result.j2k") }) Button(this.buttonTxt1) .fontSize(50) .margin({top:30}) .fontWeight(FontWeight.Normal) .onClick(() => { testNapi.openjpeg_create_j2k({comps_num:3,comps_prec:8, img_width:2000,img_height:2000, title_width:1000,title_height:1000, irreversible:1, output_file:this.dir + "newImage.j2k"}) })