OpenCV开发之——人脸识别库生成so文件

发表于 2021-08-17 分类于开发， H-音、视频开发， OpenCV 阅读时长 ≈ 3 分钟

一概述

本文介绍通过ndk-build和cmake分别编译过程
人脸识别库由face-detection下的jni生成的so文件和sdk生成的so合并后成为app的so文件

二 ndk-build和cmake编译

2.1 ndk-build编译

运行环境(ndk添加到环境变量中)

1	path=D:\SoftWare\Android\SDK\ndk\android-ndk-r15c

执行ndk-build执行，显示如下消息说明ndk配置成功

C:\Users\Admin>ndk-build
Android NDK: Could not find application project directory !
Android NDK: Please define the NDK_PROJECT_PATH variable to point to it.
D:\SoftWare\Android\SDK\ndk\android-ndk-r15c\build\\..\build\core\build-local.mk:151: *** Android NDK: Aborting    .  Stop.

ndk-build构建依赖文件

Application.mk：指定 ndk-build 的项目级设置。如ABI，Platform

APP_STL := gnustl_static
APP_CPPFLAGS := -frtti -fexceptions
APP_ABI := armeabi-v7a
APP_PLATFORM := android-8

Android.mk：文件位于项目 jni/ 目录的子目录中，用于向构建系统描述源文件和共享库

LOCAL_PATH := $(call my-dir)

include $(CLEAR_VARS)

#OPENCV_INSTALL_MODULES:=off
#OPENCV_LIB_TYPE:=SHARED
ifdef OPENCV_ANDROID_SDK
  ifneq ("","$(wildcard $(OPENCV_ANDROID_SDK)/OpenCV.mk)")
    include ${OPENCV_ANDROID_SDK}/OpenCV.mk
  else
    include ${OPENCV_ANDROID_SDK}/sdk/native/jni/OpenCV.mk
  endif
else
  include ../../sdk/native/jni/OpenCV.mk
endif

LOCAL_SRC_FILES  := DetectionBasedTracker_jni.cpp
LOCAL_C_INCLUDES += $(LOCAL_PATH)
LOCAL_LDLIBS     += -llog -ldl
LOCAL_MODULE     := detection_based_tracker
include $(BUILD_SHARED_LIBRARY)

ndk-build编译face-detection/jni文件

在项目/jni上右键—>Open In—>Terminal

在打开后的终端，执行ndk-build指令

Android NDK: android-8 is unsupported. Using minimum supported version android-14.
Android NDK: WARNING: APP_PLATFORM android-14 is higher than android:minSdkVersion 1 in D:/Code/Android/OpenCV-android-sdk-453/samples/face-detection/AndroidManifest.xml. NDK binaries will *not* be comptible with
 devices older than android-14. See https://android.googlesource.com/platform/ndk/+/master/docs/user/common_problems.md for more information.
D:/Code/Android/OpenCV-android-sdk-453/samples/face-detection/jni/Android.mk:14: ../../sdk/native/jni/OpenCV.mk: No such file or directory
make: *** No rule to make target `../../sdk/native/jni/OpenCV.mk'.  Stop.

根据提示信息做如下修改

Android.mk

1 2	include ../../sdk/native/jni/OpenCV.mk 修改为 include ../../../sdk/native/jni/OpenCV.mk #LOCAL_SRC_FILES := DetectionBasedTracker_jni.cpp(注释掉)

Application.mk

1	APP_ABI := armeabi-v7a 修改为 APP_ABI := armeabi-v7a arm64-v8a

重新执行ndk-build执行，libs和obj文件夹下生成对应的so文件

2.2 cmake编译

Cmake运行环境

官网下载地址：https://cmake.org/download/

环境变量配置

1 2	path=D:\SoftWare\cmake-3.18.2-win64-x64 path=C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.29.30133\bin\Hostx64\x64

Cmake构建文件

CMakeLists.txt：编译配置工具

终端执行camek指令

jni文件夹下新建build文件夹(用于cmake指令的生成目录)
右键build，依次选择：Open In——>Terminal，在终端中打开build
在终端中执行如下cmake指令
1
cmake .. -DOpenCV_DIR=..\..\..\sdk\native\jni\abi-arm64-v8a -DANDROID_TOOLCHAIN=clang -DANDROID_STL=c++_shared
指令说明：
- ..表示执行上一层目录下的CMakeLists.txt文件
- OpenCV_DIR，ANDROID_TOOLCHAIN，ANDROID_STL表示build.gradle中执行cmake时传递进来的参数，用等号链接
执行后的效果图