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）

libyuv 的源码下载下来以后，放到 src/main/cpp 目录下

 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)

      # CMakeLists for libyuv
      # Originally created for "roxlu build system" to compile libyuv on windows
      # Run with -DTEST=ON to build unit tests
      PROJECT ( YUV C CXX )   # "C" is required even for C++ projects
      CMAKE_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 <jni.h>
      #include <string>
      #include <cstring>
      #include <android/log.h>
      #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 JNICALL
      Java_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 JNICALL
      Java_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 JNICALL
      Java_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 JNICALL
      Java_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：

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）

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)

文章来源: panda1234lee.blog.csdn.net，作者：panda1234lee，版权归原作者所有，如需转载，请联系作者。

原文链接：panda1234lee.blog.csdn.net/article/details/89216200