由于项目需要使用安卓平台下opencv的扩展库，对于通用的opencv库， opencv官网提供了android的SDK

但未能提供扩展库，因此需要自己进行源码编译。本文记录android平台下opencv及其扩展库的交叉编译。

前提：主机已安装android-ndk交叉编译器

安装依赖环境

sudo apt-get install build-essential libgtk2.0-dev libavcodec-dev libavformat-dev libjpeg-dev libswscale-dev libtiff5-dev
sudo apt-get install libgtk2.0-dev
sudo apt-get install pkg-config

1、源码下载

下载opencv，可手动下载源码和拓展模块源码，解压后分别命名opencv和opencv_contrib文件

Releases - OpenCV

GitHub - opencv/opencv at 4.8.0

GitHub - opencv/opencv_contrib: Repository for OpenCV's extra modules

2、源码编译

设置编译脚本build-opencv-for-android.sh

#!/bin/bash
NDK_ROOT="${1:-${ANDROID_NDK_HOME}}"
SHELL_PATH=$(pwd)echo $NDK_ROOT### ABIs setup
declare -a ANDROID_ABI_LIST=("arm64-v8a")### path setup
INSTALL_DIR="${SHELL_PATH}/android_opencv"
rm -rf "${INSTALL_DIR}/opencv"### Make each ABI target iteratly and sequentially
API_LEVEL=21
for i in "${ANDROID_ABI_LIST[@]}"
doANDROID_ABI="${i}"echo "Start building ${ANDROID_ABI} version"TEMP_BUILD_DIR="${SHELL_PATH}/build/android_${ANDROID_ABI}"# ### Remove the build folder first, and create itrm -rf "${TEMP_BUILD_DIR}"mkdir -p "${TEMP_BUILD_DIR}"cd "${TEMP_BUILD_DIR}"OPENCV_PATH="${SHELL_PATH}/opencv"OPENCV_CONTRIB_PATH="${SHELL_PATH}/opencv_contrib"INSTALL_PATH=${SHELL_PATH}/out/mkdir -p "${INSTALL_PATH}"/usr/cmake-3.23.0-rc2-linux-x86_64/bin/cmake -DCMAKE_BUILD_WITH_INSTALL_RPATH=ON \-DCMAKE_TOOLCHAIN_FILE="${NDK_ROOT}/build/cmake/android.toolchain.cmake" \-DANDROID_TOOLCHAIN=clang++ \-DANDROID_NDK="${NDK_ROOT}" \-DANDROID_NATIVE_API_LEVEL=${API_LEVEL} \-DANDROID_ABI="${ANDROID_ABI}" \-DOPENCV_EXTRA_MODULES_PATH=${OPENCV_CONTRIB_PATH}/modules \-DCMAKE_INSTALL_PREFIX=${INSTALL_PATH} \-D BUILD_ANDROID_PROJECTS=OFF\-D WITH_CUDA=OFF \-D WITH_MATLAB=OFF \-D BUILD_ANDROID_EXAMPLES=ON \-D BUILD_DOCS=OFF \-D BUILD_PERF_TESTS=OFF \-D BUILD_TESTS=OFF \${OPENCV_PATH}# # Build itmake -j4# # Install itmake install/strip# ### Remove temp build foldercd "${SHELL_PATH}"# rm -rf "${TEMP_BUILD_DIR}"echo "end building ${INSTALL_PATH} version"
done

将build-opencv-for-android.sh、opencv和opencv_contrib文件放置于同一目录下

导出NDK安装路径环境变量

export ANDROID_HOME=/usr/android-ndk-r25c/
export ANDROID_NDK_HOME=/usr/android-ndk-r25c/
./build-opencv-for-android.sh

等待编译完成，完成后，编译成功如下，库文件在 ./out/sdk/native/staticlibs/

本文在编译脚本中只设置了安卓arm64-v8a硬件平台的编译，如有需要可自行修改。

问题：编译完成后，不知道为什么，编译没有报错，但在3rdparty目录下并未编译 libtbb.a，可直接使用将官网sdk中的libtbb.a。

参考

GitHub - ShikinChen/build-opencv-for-android: 编译opencv的Android库的脚本

GitHub - tzutalin/build-opencv-for-android: An interactive script to download and build OpenCV and OpenCV contrib for Android