Qt+opencv+android

下载opencv for android的包4.6.0解压

https://opencv.org/releases.html

android {
 
ANDROID_OPENCV = E:/opencv-4.6.0-android-sdk/OpenCV-android-sdk/sdk/native
 
 
INCLUDEPATH += $$ANDROID_OPENCV/jni/include/opencv2 \
               $$ANDROID_OPENCV/jni/include
 
LIBS += $$ANDROID_OPENCV/libs/armeabi-v7a/libopencv_java4.so \
			  $$ANDROID_OPENCV/staticlibs/armeabi-v7a/libopencv_calib3d.a \
        $$ANDROID_OPENCV/staticlibs/armeabi-v7a/libopencv_core.a \
        $$ANDROID_OPENCV/staticlibs/armeabi-v7a/libopencv_dnn.a \
        $$ANDROID_OPENCV/staticlibs/armeabi-v7a/libopencv_features2d.a \
        $$ANDROID_OPENCV/staticlibs/armeabi-v7a/libopencv_flann.a \
        $$ANDROID_OPENCV/staticlibs/armeabi-v7a/libopencv_highgui.a \
        $$ANDROID_OPENCV/staticlibs/armeabi-v7a/libopencv_imgcodecs.a \
        $$ANDROID_OPENCV/staticlibs/armeabi-v7a/libopencv_imgproc.a \
        $$ANDROID_OPENCV/staticlibs/armeabi-v7a/libopencv_ml.a \
        $$ANDROID_OPENCV/staticlibs/armeabi-v7a/libopencv_objdetect.a \
        $$ANDROID_OPENCV/staticlibs/armeabi-v7a/libopencv_photo.a \
        $$ANDROID_OPENCV/staticlibs/armeabi-v7a/libopencv_stitching.a \
        $$ANDROID_OPENCV/staticlibs/armeabi-v7a/libopencv_video.a \
        $$ANDROID_OPENCV/staticlibs/armeabi-v7a/libopencv_videoio.a \
        $$ANDROID_OPENCV/3rdparty/libs/armeabi-v7a/libcpufeatures.a \
        $$ANDROID_OPENCV/3rdparty/libs/armeabi-v7a/libIlmImf.a \
        $$ANDROID_OPENCV/3rdparty/libs/armeabi-v7a/liblibjasper.a \
        $$ANDROID_OPENCV/3rdparty/libs/armeabi-v7a/liblibjpeg-turbo.a \
        $$ANDROID_OPENCV/3rdparty/libs/armeabi-v7a/liblibpng.a \
        $$ANDROID_OPENCV/3rdparty/libs/armeabi-v7a/liblibprotobuf.a \
        $$ANDROID_OPENCV/3rdparty/libs/armeabi-v7a/liblibtiff.a \
        $$ANDROID_OPENCV/3rdparty/libs/armeabi-v7a/liblibwebp.a \
        $$ANDROID_OPENCV/3rdparty/libs/armeabi-v7a/libquirc.a \
        $$ANDROID_OPENCV/3rdparty/libs/armeabi-v7a/libtbb.a \
        $$ANDROID_OPENCV/3rdparty/libs/armeabi-v7a/libtegra_hal.a 
 
}

编译Android opencv
使用文件

1、QT VS2017安装选项

设置环境变量

2、安装ANT
官网下载：http://ant.apache.org/bindownload.cgi
文件解压到目标文件夹后设置环境变量
添加：ANT_HOME 到安装根路径
配置path：PATH = %ANT_HOME%/bin

在CMD下运行命令检查安装是否完成

ant -version

3、组织编译
3.1在目标文件夹内新建Android-opencv文件夹用来存放编译完成的文件

3.2点击 add entry 添加string类型数据

ANDROID_ABI           armeabi-v7a
ANDROID_PLATFORM       26

3.3点击 configure设置编译环境，点击next

3.4在toolchain file中选择ndk中的android.toolchain.cmake，点击finish

3.5 configure结束后报错问题解决

3.6去掉BUILD_ANDROID_PROJECTS BUILD_ANDROID_EXAMPLES两项重新configure
未来版本将删除与CMake < 2.8.12的兼容性CMake。更新VERSION参数值或使用…后缀告诉CMake项目不需要与旧版本兼容，修改对应cmakelists.txt内的cmake版本

安装python git

3.7修改配置选项
去掉例程

静态库生成目录

是否生成动态库

添加贡献库，具体到moudles目录

将所有的库编译到一个文件中

调用本地摄像头

添加移动端的并行架构支持

以下参数根据需求调整

BUILD_ANDROID_PROJECTS 不需要示例项目可直接取消勾选
BUILD_ANDROID_EXAMPLES = OFF
BUILD_PERF_TESTS = OFF
BUILD_TESTS = OFF
BUILD_opencv_world = OFF (生成 .so 库 libopencv_java4.so，这是一个集合，不清楚和默认编译的 libopencv_java4.so 有什么区别，默认不开启，如果开启的话不会复制 java 层函数，也就是 cmake 的 gui 界面会显示 Java wrappers: NO)
BUILD_SHARED_LIBS = OFF (如果 On 则只编译 so 库)
WITH_CUDA = OFF (CUDA 是 NVidia 推出的并行计算架构，编译非安卓 SDK 时建议添加)

WITH_OPENCL = ON (因为我们编译的是 android sdk，所以建议添加移动端的并行架构支持)

WITH_OPENCL_SVM = ON (建议开启共享虚拟内存)

调整完后再次点击Configure，完成后点击Generate。
部分选项可能需要多点几次才能出现

继续点击configure（可以多点几次，有时多点几次就可以下载成功），

安卓raw.githubusercontent.com无法访问问题
安卓程序运行时报出：

unknown host ‘raw.githubusercontent.com’. you may need to adjust the proxy settings in gradle

这种错误一般是无法访问raw.githubusercontent.com造成的
解决办法
访问网址：https://www.ipaddress.com 然后搜索raw.githubusercontent.com，得到一个新的网址，复制到hosts文件夹内

修改hosts文件权限修改访问地址

右击 hosts属性–安全 --高级

点击更改权限

添加新权限

选择主体

进入选择用户或组，点击高级

点击 立即查找 ，找到当前用户，选中 确定

hosts所有权限全部选上，确定

添加权限后一路确定
修改hosts文件保存

185.199.109.133 raw.githubusercontent.com

在目标文件中打开git 开始编译

mingw32-make
mingw32-make install