Android Studio 下通过 CMake 配置编译 libyuv 库

参考链接

创建 AS 工程，选择 Native C++，之后默认配置就可以了（ps: 我工程的名字也取名为 libyuv 了，你们随意）

Android Studio 下通过 CMake 配置编译 libyuv 库_第1张图片

libyuv 的源码下载下来以后，放到 src/main/cpp 目录下

Android Studio 下通过 CMake 配置编译 libyuv 库_第2张图片

修改 src/main/cpp 目录下的 CMakeList.txt

# For more information about using CMake with Android Studio, read the# documentation: https://d.android.com/studio/projects/add-native-code.html# Sets the minimum version of CMake required to build the native library.cmake_minimum_required(VERSION 3.4.1)include_directories(/home/lingyun/Projects/AndroidStudioProjects/libyuv/app/src/main/cpp/libyuv/include) # 重点，根据自己的路径进行修改add_subdirectory(/home/lingyun/Projects/AndroidStudioProjects/libyuv/app/src/main/cpp/libyuv) # 重点# Creates and names a library, sets it as either STATIC# or SHARED, and provides the relative paths to its source code.# You can define multiple libraries, and CMake builds them for you.# Gradle automatically packages shared libraries with your APK.add_library( # Sets the name of the library.        native-lib        # Sets the library as a shared library.        SHARED        # Provides a relative path to your source file(s).        native-lib.cpp)# Searches for a specified prebuilt library and stores the path as a# variable. Because CMake includes system libraries in the search path by# default, you only need to specify the name of the public NDK library# you want to add. CMake verifies that the library exists before# completing its build.find_library( # Sets the name of the path variable.        log-lib        # Specifies the name of the NDK library that        # you want CMake to locate.        log)# Specifies libraries CMake should link to your target library. You# can link multiple libraries, such as libraries you define in this# build script, prebuilt third-party libraries, or system libraries.target_link_libraries( # Specifies the target library.        native-lib        # Links the target library to the log library        # included in the NDK.        ${log-lib}        yuv) # 重点

然后再修改 libyuv 库的 CMakeList.txt (去掉一些编译生成的文件，也可以不改，按自己需要编辑)

Android Studio 下通过 CMake 配置编译 libyuv 库_第3张图片

# CMakeLists for libyuv# Originally created for "roxlu build system" to compile libyuv on windows# Run with -DTEST=ON to build unit testsPROJECT ( YUV C CXX )   # "C" is required even for C++ projectsCMAKE_MINIMUM_REQUIRED( VERSION 2.8 )OPTION( TEST "Built unit tests" OFF )SET ( ly_base_dir   ${PROJECT_SOURCE_DIR} )SET ( ly_src_dir    ${ly_base_dir}/source )SET ( ly_inc_dir    ${ly_base_dir}/include )SET ( ly_tst_dir    ${ly_base_dir}/unit_test )SET ( ly_lib_name   yuv )SET ( ly_lib_static ${ly_lib_name} )SET ( ly_lib_shared ${ly_lib_name}_shared )FILE ( GLOB_RECURSE ly_source_files ${ly_src_dir}/*.cc )LIST ( SORT         ly_source_files )FILE ( GLOB_RECURSE ly_unittest_sources ${ly_tst_dir}/*.cc )LIST ( SORT         ly_unittest_sources )INCLUDE_DIRECTORIES( BEFORE ${ly_inc_dir} )# this creates the static library (.a)ADD_LIBRARY             ( ${ly_lib_static} STATIC ${ly_source_files} )# this creates the shared library (.so)ADD_LIBRARY             ( ${ly_lib_shared} SHARED ${ly_source_files} )SET_TARGET_PROPERTIES   ( ${ly_lib_shared} PROPERTIES OUTPUT_NAME "${ly_lib_name}" )SET_TARGET_PROPERTIES   ( ${ly_lib_shared} PROPERTIES PREFIX "lib" )# this creates the conversion tool#ADD_EXECUTABLE         ( yuvconvert ${ly_base_dir}/util/yuvconvert.cc )#TARGET_LINK_LIBRARIES  ( yuvconvert ${ly_lib_static} )INCLUDE ( FindJPEG )if (JPEG_FOUND)  include_directories( ${JPEG_INCLUDE_DIR} )  target_link_libraries( yuvconvert ${JPEG_LIBRARY} )  add_definitions( -DHAVE_JPEG )endif()if(TEST)  find_library(GTEST_LIBRARY gtest)  if(GTEST_LIBRARY STREQUAL "GTEST_LIBRARY-NOTFOUND")    set(GTEST_SRC_DIR /usr/src/gtest CACHE STRING "Location of gtest sources")    if(EXISTS ${GTEST_SRC_DIR}/src/gtest-all.cc)      message(STATUS "building gtest from sources in ${GTEST_SRC_DIR}")      set(gtest_sources ${GTEST_SRC_DIR}/src/gtest-all.cc)      add_library(gtest STATIC ${gtest_sources})      include_directories(${GTEST_SRC_DIR})      include_directories(${GTEST_SRC_DIR}/include)      set(GTEST_LIBRARY gtest)    else()      message(FATAL_ERROR "TEST is set but unable to find gtest library")    endif()  endif()  add_executable(libyuv_unittest ${ly_unittest_sources})  target_link_libraries(libyuv_unittest ${ly_lib_name} ${GTEST_LIBRARY})  find_library(PTHREAD_LIBRARY pthread)  if(NOT PTHREAD_LIBRARY STREQUAL "PTHREAD_LIBRARY-NOTFOUND")    target_link_libraries(libyuv_unittest pthread)  endif()  if (JPEG_FOUND)    target_link_libraries(libyuv_unittest ${JPEG_LIBRARY})  endif()  if(NACL AND NACL_LIBC STREQUAL "newlib")    target_link_libraries(libyuv_unittest glibc-compat)  endif()  find_library(GFLAGS_LIBRARY gflags)  if(NOT GFLAGS_LIBRARY STREQUAL "GFLAGS_LIBRARY-NOTFOUND")    target_link_libraries(libyuv_unittest gflags)    add_definitions(-DLIBYUV_USE_GFLAGS)  endif()endif()# install the conversion tool, .so, .a, and all the header files#INSTALL ( PROGRAMS ${CMAKE_BINARY_DIR}/yuvconvert         DESTINATION bin )#INSTALL ( TARGETS ${ly_lib_static}                        DESTINATION lib )#INSTALL ( TARGETS ${ly_lib_shared} LIBRARY                DESTINATION lib RUNTIME DESTINATION bin )INSTALL ( DIRECTORY ${PROJECT_SOURCE_DIR}/include/     DESTINATION include )# create the .deb and .rpm packages using cpack#INCLUDE ( CM_linux_packages.cmake )

YuvUtils.java

package com.example.libyuv;public class YuvUtils {    static {        System.loadLibrary("native-lib");    }    // 创建一个YuvUtils，有三个常用的方法，第一个就是NV21转I420，然后旋转I420，最后一个是NV21转换I420并顺时针旋转90度，可以替换前两个方法    public static native void NV21ToI420(byte[] input, byte[] output, int width, int height);    public static native void RotateI420(byte[] input, byte[] output, int width, int height, int rotation);    public static native void NV21ToI420andRotate90Clockwise(byte[] input, byte[] output, int width, int height);}

native-lib.cpp

#include #include #include #include #include "libyuv/include/libyuv.h"#define LOG_TAG "libyuv"#define LOGV(...)  __android_log_print(ANDROID_LOG_VERBOSE, LOG_TAG, __VA_ARGS__)#define LOGD(...)  __android_log_print(ANDROID_LOG_DEBUG, LOG_TAG, __VA_ARGS__)#define LOGI(...)  __android_log_print(ANDROID_LOG_INFO, LOG_TAG, __VA_ARGS__)#define LOGE(...)  __android_log_print(ANDROID_LOG_ERROR, LOG_TAG, __VA_ARGS__)using namespace libyuv;extern "C" JNIEXPORT jstring JNICALLJava_com_example_libyuv_MainActivity_stringFromJNI(        JNIEnv *env,        jobject /* this */) {    std::string hello = "Hello from C++";    return env->NewStringUTF(hello.c_str());}extern "C"JNIEXPORT void JNICALLJava_com_example_libyuv_YuvUtils_NV21ToI420(JNIEnv *env, jobject instance, jbyteArray input_,                                            jbyteArray output_, jint in_width, jint in_height) {    jbyte *srcData = env->GetByteArrayElements(input_, NULL);    jbyte *dstData = env->GetByteArrayElements(output_, NULL);    NV21ToI420((const uint8_t *) srcData, in_width,               (uint8_t *) srcData + (in_width * in_height), in_width,               (uint8_t *) dstData, in_width,               (uint8_t *) dstData + (in_width * in_height), in_width / 2,               (uint8_t *) dstData + (in_width * in_height * 5 / 4), in_width / 2,               in_width, in_height);    env->ReleaseByteArrayElements(input_, srcData, 0);    env->ReleaseByteArrayElements(output_, dstData, 0);}extern "C"JNIEXPORT void JNICALLJava_com_example_libyuv_YuvUtils_RotateI420(JNIEnv *env, jobject type, jbyteArray input_,                                            jbyteArray output_, jint in_width, jint in_height,                                            jint rotation) {    jbyte *srcData = env->GetByteArrayElements(input_, NULL);    jbyte *dstData = env->GetByteArrayElements(output_, NULL);    RotationMode rotationMode = kRotate0;    switch (rotation) {        case 90:            rotationMode = kRotate90;            break;        case 180:            rotationMode = kRotate180;            break;        case 270:            rotationMode = kRotate270;            break;    }    I420Rotate((const uint8_t *) srcData, in_width,               (uint8_t *) srcData + (in_width * in_height), in_width / 2,               (uint8_t *) srcData + (in_width * in_height * 5 / 4), in_width / 2,               (uint8_t *) dstData, in_height,               (uint8_t *) dstData + (in_width * in_height), in_height / 2,               (uint8_t *) dstData + (in_width * in_height * 5 / 4), in_height / 2,               in_width, in_height,               rotationMode);    env->ReleaseByteArrayElements(input_, srcData, 0);    env->ReleaseByteArrayElements(output_, dstData, 0);}extern "C"JNIEXPORT void JNICALLJava_com_example_libyuv_YuvUtils_NV21ToI420andRotate90Clockwise(JNIEnv *env, jobject type,                                                                jbyteArray input_,                                                                jbyteArray output_,                                                                jint in_width, jint in_height) {    jbyte *srcData = env->GetByteArrayElements(input_, NULL);    jbyte *dstData = env->GetByteArrayElements(output_, NULL);    jsize size = env->GetArrayLength(input_);    NV21ToI420((const uint8_t *) srcData, in_width,               (uint8_t *) srcData + (in_width * in_height), in_width,               (uint8_t *) dstData, in_width,               (uint8_t *) dstData + (in_width * in_height), in_width / 2,               (uint8_t *) dstData + (in_width * in_height * 5 / 4), in_width / 2,               in_width, in_height);    I420Rotate((const uint8_t *) dstData, in_width,               (uint8_t *) dstData + (in_width * in_height), in_width / 2,               (uint8_t *) dstData + (in_width * in_height * 5 / 4), in_width / 2,               (uint8_t *) srcData, in_height,               (uint8_t *) srcData + (in_width * in_height), in_height / 2,               (uint8_t *) srcData + (in_width * in_height * 5 / 4), in_height / 2,               in_width, in_height,               kRotate90);    memcpy(dstData, srcData, size);//    fixme can't work//    ConvertToI420((const uint8_t *) srcData, size,//                  (uint8_t *)dstData, in_width,//                  (uint8_t *)dstData + (in_width * in_height), in_width / 2,//                  (uint8_t *)dstData + (in_width * in_height * 5 / 4), in_width / 2,//                  0, 0,//                  in_width, in_height,//                  in_width, in_height,//                  kRotate90,//                  FOURCC_NV21);////   fixme can't work//    NV12ToI420Rotate((const uint8_t *) srcData, in_width,//                     (uint8_t *) srcData + (in_width * in_height), in_width,//                     (uint8_t *)dstData, in_width,//                     (uint8_t *)dstData + (in_width * in_height * 5 / 4), in_width / 2,//                     (uint8_t *)dstData + (in_width * in_height), in_width / 2,//                     in_width, in_height,//                     kRotate90);    env->ReleaseByteArrayElements(input_, srcData, 0);    env->ReleaseByteArrayElements(output_, dstData, 0);}

build 生成的 so：

Android Studio 下通过 CMake 配置编译 libyuv 库_第4张图片

不过这个方法有个问题，就是没有把 neon 优化的代码编译进来，需要自己手动修改 CMakeList.txt，或者使用 .mk 的方式(参考0，参考1，参考2)，亦或者通过 libyuv 的官网的方法进行编译。

根据 CMakeList 的方式（启用了 neon ）编译出来的大小为 200 多 KB （只测试了 Debug）

Android Studio 下通过 CMake 配置编译 libyuv 库_第5张图片

根据 mk 的方式编译出来的 libyuv.so 的大小也为 200多 KB (只测试了 Debug)

Android Studio 下通过 CMake 配置编译 libyuv 库_第6张图片

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